Title of Invention

"A FUSION PROTEIN HAVING SIALIDASE ACTIVITY"

Abstract

The present invention provides new compositions and methods for preventing arid treating pathogen infection. In particular, the present invention provides compounds having an anchoring domain that anchors the compound to the surface of a target cell, and a therapeutic domain that can act extracellularly to prevent infection of a target cell by a pathogen, such as a virus. The present invention also comprises therapeutic compositions having sialidase activity, including protein-based compounds having sialidase catalytic domains. Compounds of the invention can be used for treating or preventing pathogen infection, and for treating and reducing allergic and inflammatory responses. The invention also provides compositions and methods for enhancing transduction of target cells by recombinant viruses. Such compositions and methods can be used in gene therapy.

Full Text

A NOVEL CLASS OF THERAPEUTIC PROTEIN BASED MOLECULES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of United States application 10/718,986, filed Novemver 21, 2003, entitled "Broad spectrum anti-viral therapeutics and prophylaxis", herein incorporated by reference, and claims benefit of priority to United States Provisional Application Number 60/428,535, filed November 22, 2002, entitled "Broad spectrum anti-viral therapeutics and prophylaxis", benefit of priority to United States Provisional Application Number 60/464,217, filed April 19, 2003, entitled "Class of broad spectrum anti-viral protein", benefit of priority to United States Provisional Application Number 60/561,749, filed April 13, 2004, entitled "Anti-microbial therapeutics and prophylaxis", and benefit of priority to United States Provisional Application Number 60/580,084, filed June 16, 2004, entitled "Class of broad spectrum anti-microbial agents", all of which are herein incorporated by reference. BACKGROUND OF THE INVENTION The invention relates to therapeutic compositions that can be used to prevent and treat infection of human and animal subjects by a pathogen, and specifically to proteinbased therapeutic compositions that can be used for the prevention and treatment of viral or bacterial infections. The invention also relates to therapeutic protein-based compositions that can be used to prevent or ameliorate allergic and inflammatory responses. The invention also relates to protein-based compositions for increasing transduction efficiency of a recombinant virus, such as a recombinant virus used for gene therapy. Influenza is a highly infectious acute respiratory disease that has plagued the human race since ancient times. It is characterized by recurrent annual epidemics and periodic major worldwide pandemics. Because of the high disease-related morbidity and mortality, direct and indirect social economic impacts of influenza are enormous. Yearly epidemics cause approximately 300,000 hospitalizations and 25,000 deaths in the United States alone. Four pandemics occurred in the last century; together they caused tens of millions of deaths. Mathematical models based on earlier pandemic experiences have estimated that 89,000-207,000 deaths, 18-42 million outpatient visits and 20-47 million additional illnesses will occur during the next pandemic (Meltzer, MI, Cox, NJ and Fukuda, K. (1999) Emerg Infect Dis 5:659-671). Influenza is typically caused by infection of two types of viruses, Influenza virus A and Influenza virus B (the third type Influenza virus C only causes minor common cold like symptoms). They belong to the orthomyxoviridae family of RNA viruses. Both type A and type B viruses have 8 segmented negative-strand RNA genomes enclosed in a lipid envelope derived from the host cell. The viral envelope is covered with spikes that are composed of three types of proteins: hemagglutinin (HA) which attaches virus to host cell receptors and mediates fusion of viral and cellular membranes; neuraminidase (NA) which facilitates the release of the new viruses from host cells; and a small number of M2 proteins which serve as ion channels. Infections by influenza type A and B viruses are typically initiated at the mucosal surface of the upper respiratory tract. Viral replication is primarily limited to the upper respiratory tract but can extend to the lower respiratory tract and cause bronchopneumonia that can be fatal. Influenza viral protein hemagglutinin (HA) is the major viral envelope protein. It plays an essential role in viral infection. The importance of HA is evidenced by the fact that it is the major target for protective neutralizing antibodies produced by the host immune response (Hayden, FG. (1996) In Antiviral drug resistance (ed. D. D. Richman), pp. 59-77. Chichester, UK: John Wiley & Sons Ltd.). It is now clear that HA has two different functions in viral infection. First, HA is responsible for the attachment of the virus to sialic acid cell receptors. Second, HA mediates viral entry into target cells by triggering fusion of the viral envelope with cellular membranes. HA is synthesized as a precursor protein, HAO, which is transferred through the Golgi apparatus to the cell surface as a trimeric molecular complex. HAO is further cleaved to generate the C terminus HA1 (residue 328 of HAO) and the N terminus of HA2. It is generally believed that the cleavage occurs at the cell surface or on released viruses. The cleavage of HAO into HA1/HA2 is not required for HA binding to sialic acid receptor; however, it is believed to be necessary for viral infectivity (Klenk, HD and Rott, R. (1988) Adv Vir Res. 34:247-281; Kido, H, Niwa, Y, Beppu, Y and Towatari, T. (1996) Advan Enzyme Regul 36:325-347; Skehel, JJ and Wiley, DC. (2000) Annu Rev Biochem 69:531-569; Zambon, M. (2001; Rev Med Virol 11:227-241.) Currently, influenza is controlled by vaccination and anti-viral compounds. Inactivated influenza vaccines are now in worldwide use, especially in high-risk groups. The vaccine viruses are grown in fertile hen's eggs, inactivated by chemical means and purified. The vaccines are usually trivalent, containing representative influenza A viruses (H1N1 and H3N2) and influenza B strains. The vaccine strains need to be regularly updated in order to maintain efficacy; this effort is coordinated by the World Health Organization (WHO). During inter-pandemic periods, it usually takes 8 months before the updated influenza vaccines are ready for the market (Wood, J. (2001) Phil Trans R Soc LondB 356:1953-1960). However, historically, pandemics spread to most continents within 6 months, and future pandemics are expected to spread even faster with increased international travel (Gust, ID, Hampson, AW., and Lavanchy, D. (2001) Rev Med Virol 11:59-70). Therefore it is inevitable that an effective vaccine will be unavailable or in very short supply during the first waves of future pandemics. Anti-viral compounds have become the mainstay for treating inter-pandemic diseases. Currently, they are also the only potential alternative for controlling pandemics during the initial period when vaccines are not available. Two classes of antiviral compounds are currently on the market: the M2 inhibitors, such as amantadine and rimantadine; and the NA inhibitors, which include oseltamivir (Tamiflu) and zanamivir (Relenza). Both classes of molecules have proven efficacy in prevention and treatment of influenza. However, side effects and the risk of generating drug-resistant viruses remain the top two concerns for using them widely as chemoprophylaxis (Hayden, FG. (1996) In Antiviral drug resistance (ed. D. D. Richman), pp. 59-77. Chichester, UK: John Wiley & Sons Ltd.). Most importantly, future pandemic strains, either evolved naturally or artificially created by genetic engineering in bio-warfare, may be resistant to all the available anti-viral compounds, and this will have devastating consequences globally. In summary, currently available vaccination and anti-viral compounds are limited by some fundamental shortcomings. Novel therapeutic and prophylactic modalities are needed to address future influenza pandemics. Respiratory tract infections (RTIs) are the most common, and potentially most severe, types of infectious diseases. Clinically, RTIs include sinusitis, otitis, laryngitis, bronchitis and pneumonia. Based on numerous etiology and epidemiology studies, it is clear that although many microorganisms have the potential to cause RTIs, only a handful of pathogens are responsible for vast majority of the cases. Such pathogens include S. pneumoniae, M. pneumoniae, H. influenzae, M. catarrhalis, influenza A & B, and parainfluenza virus. Besides causing CAP and AECB, several of the bacterial pathogens, such as S. pneumoniae and H. influenzae, are also the common cause of acute sinusitis, otitis media, as well as invasive infections leading to sepsis, meningitis, etc. Therefore these microorganisms are of the highest clinical importance. One common feature of all respiratory pathogenic bacteria is that they establish commensal colonization on the mucosal surface of the upper airway; such colonization precedes an infection and is prerequisite for infections. The bacterial colonization in a neonate occurs shortly after birth. During lifetime, the upper airway, specifically the nasopharynx and oropharynx, remains a dynamic ecological reservoir of microbial species with bacteria being acquired, eliminated and re-acquired continually. In most cases the bacterial flora in the pharynx is harmless. However, when the condition of the host is altered, some microorganisms may invade adjacent tissues or bloodstream to cause diseases. In addition to serving as the port of entry for mucosal and invasive infections by both bacteria and viruses, the nasopharynx is also the major source of spreading the pathogenic microorganisms between individuals, as well as the reservoir where antibiotic-resistant bacteria are selected (Garcia-Rodriguez and Martinez, J Antimicrob Chemother, (2002) 50(Suppl S2), 59-73; Soriano and Rodriguez-Cerrato, J Antimicrob Chemother, (2002) 50 Suppl S2, 51-58). It is well established clinically that individuals who are prone to RTIs tend to be persistent and recurrent carriers of the pathogenic bacteria (Garcia-Rodriguez and Martinez, J Antimicrob Chemother, (2002) 50(Suppl S2), 59-73; Mbaki et al.,Tohoku J Exp. Med., (1987) 153(2), 111-121). Helicobacter pylori is a human pathogen implicated in gastritis and peptic ulcer. The bacterium resides in the human stomach and binds to epithelial cells of the gastric antrum. It has been demonstrated that the bacterial adhesion is mediated by binding of Helicobacter pylori adhesin I and II to sialic acids on the epithelial surface. Siglecs (sialic acid binding Ig-like lectins) are members of the immunoglobulin (Ig) superfamily that bind to sialic acid and are mainly expressed by cells of the hematopoietic system. At least 11 siglecs have been discovered and they seem to exclusively recognize cell surface sialic acid as the ligand. It is believed that the binding of siglecs to sialic acid mediates cell-cell adhesion and interactions (Crocker and Varki, Trends Immunol., (2001) 22(6), 337-342; Angata and Brinkman-Van der Linden, BiOChim. Biophys. Acta, (2002) 1572(2-3), 294-316). Siglec-8 (SAF-2) is an adhesion molecule that is highly restricted to the surface of eosinophils, basophils, and mast cells, which are the central effector cells in allergic conditions including allergic rhinitis, asthma and eczema. Siglec-8 is considered to be responsible for mediating the recruitment of the three allergic cell types to the airway, the lungs and other sites of allergy. Siglec-1 (sialoadhesion) and siglec-2 (CD22) are the adhesion molecules on macrophages and B cells, both types of cells play central roles in immune reactions that lead to inflammation. Recombinant viruses, in particular adeno-associated virus (AAV), can be used to transfer the wild type cystic fibrosis transmembrane conductance regulator (CFTR) gene into the epithelial cells to correct the genetic defect that causes cystic fibrosis (Flotte and Carter, Methods Enzymol., (1998) 292, 717-732). Clinical trials with AAV vectors have shown efficient and safe delivery of the CFTR gene into epithelial cells with low levels of gene transfer (Wagner et al., Lancet, (1998) 351(9117), 1702-1703). Compared to adenoviral vectors, AAV offers more stable gene expression and diminished cellular immunity. However, the transduction efficiency of AAV in vivo is rather low in the lung (Wagner et al., Lancet, (1998) 351(9117), 1702-1703). A method that can improve transduction efficiency of AAV in vivo is needed to achieve full therapeutic potential of gene therapy for cystic fibrosis. It has been shown that negatively charged carbohydrates, such as sialic acid, inhibit the transduction efficiency of AAV vector to the well-differentiated airway epithelium, and treatment of the airway epithelium by glycosidases, including a neuraminidase, and endoglycosidase H, enhances transduction efficiency of the AAV vector (Bals et al., J Virol., (1999) 73(7), 6085-6088). BRIEF SUMMARY OF THE INVENTON The present invention recognizes that current therapeutics for preventing and treating infection by pathogens are often difficult to provide in a timely manner, can have undesirable side effects, and can lead to drug-resistant pathogen strains. The present invention also recognizes that the current approach to treat allergy and inflammation has limited efficacy and is associated with side effects. In addition, the present invention also recognizes that the current approach to administer recombinant viruses yield low transduction efficiency and unsatisfactory efficacy of the gene therapy. The present invention provides new compositions and methods for preventing and treating pathogen infection. In particular, the present invention provides compounds that can act extracellularly to prevent infection of a cell by a pathogen. Some preferred embodiments of the present invention are therapeutic compounds having an anchoring domain that anchors the compound to the surface of a target cell, and a therapeutic domain that can act extracellularly to prevent infection of the target cell by a pathogen, such as a virus or bacterium. In one aspect, the invention provides a protein-based composition for preventing or treating infection by a pathogen. The composition comprises a compound that comprises at least one therapeutic domain comprising a peptide or protein, where the therapeutic domain has at least one extracellular activity that can prevent the infection of a target cell by a pathogen, and at least one anchoring domain that can bind at or near the membrane of a target cell. In some embodiments of this aspect of the present invention, the at least one therapeutic domain comprises an inhibitory activity that prevents or impedes the infection of a target cell by a pathogen. In a preferred embodiment, the inhibitory activity inhibits the activity of a protease that can process a viral protein necessary for infection of a target cell. In a particularly preferred embodiment, the compound comprises a therapeutic domain that can inhibit the processing of the HA protein of influenza virus, and the anchoring domain can bind the compound at the surface of a respiratory epithelial cell. In some embodiments of the present invention, at least one therapeutic domain comprises a catalytic activity. In a preferred embodiment, the catalytic activity removes a moiety from the surface of a target cell that is necessary for infection of the target cell. In a particularly preferred embodiment, the therapeutic domain is a sialidase that can digest sialic acid moieties on the surface of epithelial target cells, and the anchoring domain is a GAG-binding domain of a human protein that can bind heparin or heparan sulfate moieties at the surface of an epithelial cell. In another aspect, the present invention includes pharmaceutical compositions for treating or preventing pathogen infection in a subject. Pharmaceutical compositions comprise a compound of the present invention comprising at least one therapeutic domain and at least one anchoring domain. The pharmaceutical composition can also comprise solutions, stabilizers, fillers and the like. In some preferred embodiments, the pharmaceutical composition is formulated as an inhalant. In some preferred embodiments, the pharmaceutical composition is formulated as a nasal spray. Another aspect of the present invention is a pharmaceutical composition comprising at least one sialidase. The sialidase can be isolated from any source, such as, for example, a bacterial or mammalian source, or can be a recombinant protein that is substantially homologous to a naturally occurring sialidase. A pharmaceutical composition comprising a sialidase can be formulated for nasal, tracheal, bronchial, oral, or topical administration, or can be formulated as an injectable solution or as eyedrops. A pharmaceutical composition comprising a sialidase can be used to treat or prevent pathogen infection, to treat or prevent allergy or inflammatory response, or to enhance the transduction efficiency of a recombinant virus for gene therapy. Yet another aspect of the present invention is a sialidase catalytic domain protein. In this aspect, proteins that comprise the catalytic domain of a sialidase but comprise less than the entire sialidase the catalytic domain sequence is derived from are considered sialidase catalytic domain proteins. Sialidase catalytic domain proteins can comprise other protein sequences, such as but not limited to functional domains derived from other proteins. A pharmaceutical composition comprising a sialidase can be formulated for nasal, tracheal, bronchial, oral, or topical administration, or can be formulated as an injectable solution or as eyedrops. A pharmaceutical composition comprising a sialidase can be used to treat or prevent pathogen infection, to treat or prevent allergy or inflammatory response, or to enhance the transduction efficiency of a recombinant virus for gene therapy. In yet another aspect, the present invention ir preventing infection by a pathogen. In preferred embodiments, the method comprises administering a siaidase activity, such as a sialidase 3r a sialidase catalytic domain protein, including a sialidase catalytic domain fusior treat an infection. A pathogen can be, for example, a method includes applying a pharmaceutically effective amount of a compound of the present invention to at least one target cell of a subject. Preferably, the pharmaceutical composition can applied by the use of a spray, inhalant, or topical formulation. The present invention also provides new corr positions and methods for treating allergy and inflammation. In particular, the present can act extracellularly to prevent or inhibit adhesion Some preferred embodiments of compounds for trea comprise at least one therapeutic domain that has th least one anchoring domain that anchors the compound to the surface of a target cell. In some preferred embodiments, the method comprises such as a sialidase or a sialidase catalytic domain protein, including a sialidase catalytic domain fusion protein to a subject to prevent or treat response. The allergic or inflammatory response can be asthma, allergic rhinitis, skin conditions such as eczema, or response to plant or animal toxins. The method includes applying a pharmaceutically effective amount of a c idudes a method for treating or protein, to a subject to prevent or viral or bacterial pathogen. The nvention provides compounds that and function of inflammatory cells, ing allergy or inflammation said extracellular activity and an at administering a siaidase activity, an allergic or inflammatory mpound of the present invention to at least one target cell of a subject. Preferably, the applied by the use of a spray, inhalant, or topical fornjiulation. The present invention also provides new efficiency of gene transfer by recombinant viral veci particular, the present invention provides compound reduce the physical or chemical barrier that hinders such as AAV vector. Some preferred compounds o1 efficiency of gene transfer by recombinant viral ved domain that has an extracellular activity and an at le anchors the compound to the surface of a target cell, the method comprises administering a siaidase activ catalytic domain protein, including a sialidase cataly to facilitate transduction of a target cell by a recomb includes applying an effective amount of a compoun a recombinant viral vector to at least one target cell, present invention can applied by the use of a spray, i BRIEF DESCRIPTION OF SEVERAL VIEWS OF pharmaceutical composition can Figure 1 is a schematic depiction of the primary am Figure 2 shows GAG-binding sequences of four hunjian factor 4; IL8, human interleukin 8; AT III, human an apolipoprotein E; AAMP, human angio-associated m Figure 3 is a sequence comparison between human Figure 4 is a table comparing substrate specificity of bacterial and fungal sialidases. compositions and methods for improving rs during gene therapy. In that can act extracellularly to ansduction by gene therapy vectors, ;he present invention for improving rs comprise at least one therapeutic st one anchoring domain that hi some preferred embodiments, y, such as a sialidase or a sialidase c domain fusion protein to a subject aant viral vector. The method of the present invention along with pharmaceutical composition of the ihalant, or topical formulation. THE DRAWINGS o acid structure of aprotinin. genes: PF4, human platelet thrombin III; ApoE, human gratory cell protein. alidases NEU2 and NEU4. Figure 5 depicts the nucleotide and amino acid sequences His6-AvCD. Ncol and Hindlll sites used for cloning of Construct #1 encoding into pTrc99a are shown in bold. Figure 6 depicts the nucleotide and amino acid seq AvCD. Ncol and Hindlll sites used for cloning into Figure 7 depicts the nucleotide and amino acid seq G4S-AvCD. Ncol and Hindlll sites used for cloning Figure 8 is a graph of data from an experiment sh removal of a(2,6)-linked sialic acid from MDCK ce of a(2,6)-linked sialic acid remaining on the surface various dilutions of recombinant AvCD (Construct AvCD (Construct #2) (squares). Figure 9 is a graph depicting the protection aga treating MDCK cells with recombinant AR-AvCD the isolated sialidase of A. ureafaciens. The ch (H1N1); A/PR/8 (H1N1); A/Japan/305/57 (H2> A/HongKong/8/68 (H3N2); B/Lee/40; 7. B/Marylan, Figure 10 is a graph showing the level of inhibitior the recombinant AR-AvCD sialidase and the recomb challenge viral strains are: A/PR/8 (H1N1); A/WS/3 A/HongKong/8/68 (H3N2); B/Lee/40; 7. B/Marylan ences of Construct #2 encoding ARTrc99a are shown in bold. ences of Construct #3 encoding ARnto pTrc99a are shown in bold. )wing that the AR-tag enhances the s. The Y axis shows the percentage of MDCK cells after treatment with (diamonds) or recombinant ARFigure 11 provides graphs showing that topical adm sialidase fusion protein reduces the inflammatory r influenza A (H1N1) virus. (A) The total number of samples obtained from infected animals at the indi protein concentration was determined in cell-free nal al Infected ferrets were vehicle-treated (squares) or ' AvCD sialidase fusion protein made from Construe nst influenza viruses conferred by protein made from Construct #2 or llenge viral strains are: A/WS/33 2); A/Victoria/504/2000 (H3N2); 71/59; and Turkey/Wis/66 (H9N2). of influenza virus amplification by nant AR-G4S-AvCD sialidase. The 3 (H1N1); A/Japan/305/57 (H2N2); 1/59; and Turkey/Wis/66 (H9N2). nistration of recombinant AR-AvCD sponses of ferrets infected with an nflammatory cells from nasal wash ated times after infection. (B) The wash samples of infected ferrets, ere treated with recombinant AR- #2 (triangles). Uninfected animals were also treated with recombmant AK-AvUL) Statistically significant values are labeled with * (p (si)anaase rusion protein (diamonds). .05) and ** (p Figure 12 is a table depicting inhibition of viral replication, cell protection ECSO's, and selective indexes for two sialidase catalytic dom(an fusion proteins of the present invention. All ECSO's are in mU/ml. Figure 13 is a table depicting viral replication in the respiratory tract of ferrets treated with a sialidase catalytic doman fusion proteins of the present invention and ferrets treated with a control vehicle. DETAILED DESCRIPTION OF THE INVENTION Definitions Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature usec laboratory procedures described below are well known and commonly employed in the art. Conventional methods are used for these procedures, such as those provided in the art and various general references. Where a term is provided in the singular, the inventors also contemplate the plural of that term, \\Tiere there are discrepancies in terms and definitions used in references that are incorporated by reference, the terms used in this application shall have the definitions given herein. As employed throughout the disclosure, the following terms, unless otherwise ind the following meanings: herein and the manufacture or cated, shall be understood to have A "pathogen" can be any virus or microorganism an organism. A pathogen can be a virus, bacterium, or that can infect a cell, a tissue or protozoan. . gene target mast A "target cell" is any cell that can be i interact with inflammatory cells, or a host cell that is exogenous gene transferred by a recombinant virus. A "recombinant virus" or a "recombinant vir vector" or a "gene therapy vector" is defined as a comprises one or more exogenous genes. When a recombinant virus, the exogenous gene(s) is transferred transferred to a target cell can be expressed in the cei effects. Currently, most commonly used gene therap; types of viruses: retrovirus (including lentivirus), adejno (AAV) and herpes simplex virus type 1. "Inflammatory cells" are the cells that canresponses of the immune system. Inflammatory ce lymphocytes, macrophages, basophils, eosinophils, An "extracellular activity that can prevent the pathogen" is any activity that can block or impede in by acting at or near the exterior surface of a target ce prevent the infection of a target cell by a pathogen, limited to, a catalytic activity or an inhibitory activit) can be an enzymatic activity that degrades one or mo ligands, receptors, or enzymes) on a pathogen, on a target cell, in which the one or more entities contribujte catalytic activity can also modify one or more entitle in the vicinity of a target cell, such that the infectionreduced. An inhibitory activity can be an activity thai ligand and prevents the receptor or ligand from bindi necessary for or promotes the infection process. An i inhibitor of an enzyme or receptor that prevents the a function that is necessary for or promotes the infeci cell includes the target cell membrane itself, as well i surrounding the target cell, including extracellular m infected by a pathogen or any cell that can the intended destination for an 1 vector", a "gene therapy viral tically engineered virus that cell is transduced by a to the target cell. Genes to provide the intended therapeutic viral vectors are based on four i-virus, adeno-associated virus out or participate in inflammatory s include include B lymphocytes, T cells, NK cells and monocytes. infection of a target cell by a ection of a target cell by a pathogen 1. An extracellular activity that can be an activity such as, but not . For example, a catalytic activity e entities (such as but not limited to cell, or in the vicinity of a to the infection process. A on a pathogen, on a target cell, or romoting property of the entity is for example, binds to a receptor or ig a moiety, where the binding is ihibitory activity can also be an ejnzyme or receptor from performing on process. The exterior of a target s the extracellular milieu trix, intracellular spaces, and tiirget i luminal spaces. For epithelial cells, the exterior of a luminal surface of the cell membrane that form lumi milieu near the luminal surface. An "extracellular ac of a target cell by a pathogen" can be any type of ch polypeptide, peptide, nucleic acid, peptide nucleic ai nucleotide, nucleotide analogue, small organic mole acid, carbohydrate, and the like, including combinat: however, the activity comprises a peptide or protein An "extracellular activity that can improve transfer efficiency, by a recombinant virus" is any ac physical or chemical barriers that impedes host cell acting at or near the exterior surface of a target cell, improve transduction efficiency, or gene transfer eff be an activity such as, but not limited to, a catalytic example, a catalytic activity can be an enzymatic act entities (such as but not limited to ligands, receptors target cell, or in the vicinity of a target cell, in which to the infection process. A catalytic activity can also pathogen, on a target cell, or in the vicinity of a targi promoting property of the entity is reduced. An inhib for example, binds to a receptor or ligand and preven binding a moiety, where the binding is necessary for An inhibitory activity can also be an inhibitor of an enzyme or receptor from performing a function that infection process. The exterior of a target cell includ well as the extracellular milieu surrounding the targe intracellular spaces, and luminal spaces. For epithel also includes the apical or luminal surface of the cell linings, and the extracellular milieu near the luminal that can prevent the infection of a target cell by a pat entity, including a protein, polypeptide, peptide, nu& arget cell also includes the apical or al linings, and the extracellular vity that can prevent the infection nical entity, including a protein, d, nucleic acid analogue, ale, polymer, lipids, steroid, fatty ns of any of these. Preferably, r coupled to a peptide or protein. transduction efficiency, or gene ivity that reduces or eliminates ntry by a recombinant virus by extracellular activity that can ;iency, by a recombinant virus can ctivity or an inhibitory activity. For vity that degrades one or more or enzymes) on a pathogen, on a the one or more entities contribute modify one or more entities on a cell, such that the infectiontory activity can be an activity that, s the receptor or ligand from >r promotes the infection process. ejnzyme or receptor that prevents the necessary for or promotes the s the target cell membrane itself, as cell, including extracellular matrix, 1 cells, the exterior of a target cell membrane that form luminal urface. An "extracellular activity ogen" can be any type of chemical ic acid, peptide nucleic acid, 13 nucleic acid analogue, nucleotide, nucleotide analog lipids, steroid, fatty acid, carbohydrate, and the like, these. Preferably, however, the activity comprises a peptide or protein. An "extracellular activity that can inhibit adh cells" is any activity that can prevent inflammatory ye, small organic molecule, polymer, ncluding combinations of any of eptide or protein or coupled to a ision or function of inflammatory :lls from contacting the target cell and affecting the normal physiological status of the target cell. A "domain that can anchor said at least one t of a target cell", also called an "extracellular anchon domain" refers to a chemical entity can that can stab exterior of a cell surface or is in close proximity to i anchoring domain can be reversibly or irreversibly li as, preferably, one or more therapeutic domains, and attached therapeutic moieties to be retained at or in c of a eukaryotic cell. Preferably, an extracellular anch molecule on the surface of a target cell or at least on with the surface of a target cell. For example, an extracellular anchoring domain can bind a molecule covalently or noncovalently associated w cell, or can bind a molecule present in the extracellu An extracellular anchoring domain preferably is a pe can also comprise any additional type of chemical en additional proteins, polypeptides, or peptides, a nucl acid analogue, nucleotide, nucleotide analogue, smal steroid, fatty acid, carbohydrate, or a combination of As used herein, a protein or peptide sequence reference sequence when it is either identical to a ref or more amino acid deletions, one or more additional conservative amino acid substitutions, and retains th activity as the reference sequence. Conservative subs exchanges within one of the following five groups: erapeutic domain to the membrane ig domain" or simply, "anchoring y bind a moiety that is at or on the surface of a cell. An extracellular iked to one or more moieties, such thereby cause the one or more ose proximity to the exterior surface •ring domain binds at least one molecule found in close association th the cell membrane of a target ir matrix surrounding a target cell, tide, polypeptide, or protein, and ity, including one or more c acid, peptide nucleic acid, nucleic organic molecule, polymer, lipids, any of these. is "substantially homologous" to a rence sequence, or comprises one amino acids, or more one or more same or essentially the same itutions may be defined as I. Small, aliphatic, nonpolar or slightly ] Gly II. Polar, negatively charged residues ani III. Polar, positively charged residues: H IV. Large, aliphatic nonpolar residues: M V. Large aromatic residues: Phe, Try, TIJ Within the foregoing groups, the following substituti conservative": Asp/Glu, His/Arg/Lys, Phe/Tyr/Trp, i conservative substitutions are defined to be exchangi above which are limited to supergroup (A), comprisi supergroup (B), comprising (IV) and (V) above. In a acids are specified in the application, they refer to th Leu, He, Val, Cys, Phe, and Trp, whereas hydrophili Asn, Glu, Gin, His, Arg, Lys, and Tyr. A "sialidase" is an enzyme that can remove a molecule. The sialidases (N-acylneuraminosylglycoh of enzymes that hydrolytically remove sialic acid res Sialic acids are alpha-keto acids with 9-carbon backbones outermost positions of the oligosaccharide chains tha glycolipids. One of the major types of sialic acids is which is the biosynthetic precursor for most of the ot can be, as nonlimiting examples, an oligosaccharide, ganglioside, or a synthetic molecule. For example, a alpha(2,3)-Gal, alpha(2,6)-Gal, or alpha(2,8)-Gal linl and the remainder of a substrate molecule. A sialidas linkages between the sialic acid residue and the remainder major linkages between Neu5 Ac and the penultimate side chains are found in nature, NeuSAc alpha (2,3)- Both NeuSAc alpha (2,3)-Gal and NeuSAc alpha (2,( by influenza viruses as the receptor, although human alpha (2,6)-Gal, avian and equine viruses predominai their amides: Asp, Asn, Glu, Gin 5, Arg, Lys t, Leu, He, Val, Cys >n are considered to be "highly id Met/Leu/Ile/Val. Semibetween two of groups (I)-(IV) g (I), (II), and (III) above, or to dition, where hydrophobic amino amino acids Ala, Gly, Pro, Met, amino acids refer to Ser, Thr, Asp, olar residues: Ala, Ser, Thr, Pro, sialic acid residue from a substrate 'drolases, EC 3.2.1.18) are a group dues from sialo-glycoconjugates. that are usually found at the are attached to glycoproteins and N-acetylneuraminic acid (NeuSAc), ler types. The substrate molecule a polysaccharide, a glycoprotein, a ialidase can cleave bonds having ages between a sialic acid residue can also cleave any or all of the of the substrate molecule. Two galactose residues of carbohydrate al and NeuSAc alpha (2,6)-Gal. i-Gal molecules can be recognized /iruses seem to prefer NeuSAc tly recognize NeuSAc alpha (2,3)- Gal. A sialidase can be a naturally-occurring sialidas but not limited to a sialidase whose amino acid sequ naturally-occurring sialidase, including a sequence sequence of a naturally-occurring sialidase). As usec the active portion of a naturally-occurring sialidase, sequences based on the active portion of a naturally- A "fusion protein" is a protein comprising am different sources. A fusion protein can comprise ami a naturally occurring protein or is substantially homo naturally occurring protein, and in addition can of amino acids that are derived from or substantially different naturally occurring protein. In the alternativ amino acid sequence that is derived from a naturally homologous to all or a portion of a naturally occurrin comprise from one to a very large number of amino , an engineered sialidase (such as, ice is based on the sequence of a that is substantially homologous to the tierein, "sialidase" can also mean r a peptide or protein that comprises ccurring sialidase. no acid sequences from at least two o acid sequence that is derived from ogous to all or a portion of a from one to a very large number .omologous to all or a portion of a e, a fusion protein can comprise ccurring protein or is substantially ; protein, and in addition can cids that are synthetic sequences. comprise A "sialidase catalytic domain protein" is a pr domain of a sialidase, or an amino acid sequence tha catalytic domain of a sialidase, but does not compris' the sialidase the catalytic domain is derived from, wl protein retains substantially the same activity as the i is derived from. A sialidase catalytic domain protein that are not derived from a sialidase, but this is not n protein can comprise amino acid sequences that are ( homologous to amino acid sequences of one or more comprise one or more amino acids that are not derivt to amino acid sequences of other known proteins. :ein that comprises the catalytic is substantially homologous to the s the entire amino acid sequence of erein the sialidase catalytic domain tact sialidase the catalytic domain an comprise amino acid sequences uired. A sialidase catalytic domain rived from or substantially ither known proteins, or can from or substantially homologous I. Composition for preventing or treating infect jn by a pathogen The present invention includes peptide or pro at least one domain that can anchor at least one thera eukaryotic cell and at least one therapeutic domain h can prevent the infection of a cell by a pathogen. By compounds, it is meant that the two major domains o framework, in which the amino acids are joined by p based compound can also have other chemical comp amino acid framework or backbone, including moiet activity of the anchoring domain, or moieties that co activity or the therapeutic domain. For example, the present invention can comprise compounds and moL carbohydrates, fatty acids, lipids, steroids, nucleotidi molecules, nucleic acid analogues, peptide nucleic a molecules, or even polymers. The protein-based ther also comprise modified or non-naturally occurring ar of the compounds can serve any purpose, including purification of the compound, improving the solubili (such as in a therapeutic formulation), linking domai chemical moieties to the compound, contributing to dimensional structure of the compound, increasing th increasing the stability of the compound, and contrib therapeutic activity of the compound. The peptide or protein-based compounds of tl protein or peptide sequences in addition to those that therapeutic domains. The additional protein sequenc but not limited to any of the purposes outlined above compound, improving the solubility or distribution o the compound or linking chemical moieties to the dimensional or three-dimensional structure of the co ein-based compounds that comprise eutic domain to the membrane of a ving an extracellular activity that 'peptide or protein-based" the compound have an amino acid ptide bonds. A peptide or proteinunds or groups attached to the is that contribute to the anchoring tribute to the infection-preventing rotein-based therapeutics of the cules such as but not limited to: s, nucleotide analogues, nucleic acid d molecules, small organic peutics of the present invention can lino acids. Non-amino acid portions b|ut not limited to: facilitating the y or distribution or the compound s of the compound or linking the two-dimensional or threeoverall size of the compound, ting to the anchoring activity or e present invention can also include comprise anchoring domains or s can serve any purpose, including facilitating the purification of the the compound, linking domains of compound, contributing to the twompound, increasing the overall size comp jund) of the compound, increasing the stability of me comfl anchoring activity or therapeutic activity of the protein or amino acid sequences are part of a single includes the anchoring domain or domains and thera feasible arrangement of protein sequences is within t The anchoring domain and therapeutic doma way that allows the compound to bind at or near a tar therapeutic domain can exhibit an extracellular activ of the target cell by a pathogen. The compound will or peptide-based anchoring domain and at least one domain. In this case, the domains can be arranged lin any order. The anchoring domain can be N-terminal C-terminal to the therapeutic domain. It is also possi domains flanked by at least one anchoring domain on more anchoring domains can be flanked by at least o Chemical, or preferably, peptide, linkers can optiona domains of a compound. It is also possible to have the domains in a no example, the therapeutic domain can be attached to a acid that is part of a polypeptide chain that also inclu domain. A compound of the present invention can hav In cases in which a compound has more than one domains can be the same or different. A compound o more than one therapeutic domain. In cases in which therapeutic domain, the therapeutic domains can be t compound comprises multiple anchoring domains, th arranged in tandem (with or without linkers) or on al as therapeutic domains. Where a compound compris( therapeutic domains can be arranged in tandem (with sides of other domains, such as, but not limited to, ar ound, or contributing to the . Preferably any additional polypeptide or protein chain that eutic domain or domains, but any le scope of the present invention, i can be arranged in any appropriate ;et cell membrane such that the :y that prevents or impedes infection referably have at least one protein peptide or protein-based therapeutic arly along the peptide backbone in o the therapeutic domain, or can be le to have one or more therapeutic each end. Alternatively, one or e therapeutic domain on each end. y be used to join some or all of the linear, branched arrangement. For derivatized side chain of an amino .es, or is linked to, the anchoring more than one anchoring domain, anchoring domain, the anchoring the present invention can have a compound has more than one e same or different. Where a 5 anchoring domains can be ernate sides of other domains, such multiple therapeutic domains, the or without linkers) or on alternate horing domains. A peptide or protein-based compound of the any appropriate way, including purifying naturally o proteolytically cleaving the proteins to obtain the de conjugating the functional domains to other function chemically synthesized, and optionally chemically c chemical moieties. Preferably, however, a peptide o: present invention is made by engineering a nucleic £ anchoring domain and at least one therapeutic doma acid linkers) in a continuous polypeptide. The nucle appropriate expression sequences, can be transfectec and the therapeutic protein-based compound can be Any desired chemical moieties can optionally be con based compound after purification. In some cases, ce the protein-based therapeutic for their ability to perfi modifications (such as, but not limited to glycosylat A great variety of constructs can be designed desirable activities (such as, for example, binding ac binding, catalytic, or inhibitory activity of a therapeu nucleic acid constructs can also be tested for their ef] infection of a target cell by a pathogen. In vitro and pathogens are known in the art, such as those describ infectivity of influenza virus. Anchoring Domain As used herein, an "extracellular anchoring d any moiety that can stably bind an entity that is at or cell or is in close proximity to the exterior surface serves to retain a compound of the present invention target cell. An extracellular anchoring domain preferably the surface of a target cell, or a moiety, domain, or e resent invention can be made by curring proteins, optionally red functional domains, and 1 domains. Peptides can also be njugated to other peptides or protein-based compound of the id construct to encode at least one i together (with or without nucleic acid constructs, preferably having nto prokaryotic or eukaryotic cells, ^pressed by the cells and purified, ugated to the peptide or protein- 1 lines can be chosen for expressing rm desirable post-translational n). and their protein products tested for vity of an anchoring domain, or a ic domain). The protein products of cacy in preventing or impeding vivo tests for the infectivity of d in the Examples for the main" or "anchoring domain" is n the exterior surface of a target i target cell. An anchoring domain t or near the external surface of a binds 1) a molecule expressed on tope of a molecule expressed on the surface of a target cell, 2) a chemical entity attac surface of a target cell, or 3) a molecule of the extrac cell. An anchoring domain is preferably a peptide modified or derivatized peptide or protein domain), peptide or protein. A moiety coupled to a peptide or that can contribute to the binding of the anchoring target cell surface, and is preferably an organic mole acid, peptide nucleic acid, nucleic acid analogue, nuc organic molecule, polymer, lipids, steroid, fatty acid of any of these. A molecule, complex, domain, or epitope tha may or may not be specific for the target cell. For ex bind an epitope present on molecules on or in close p occur at sites other than the vicinity of the target cell localized delivery of a therapeutic compound of the p occurrence primarily to the surface of target cells. In moiety, domain, or epitope bound by an anchoring d tissue or target cell type. Target tissue or target cell type includes the s where a pathogen invades or amplifies. For example cell that can be infected by a pathogen. A compositio comprise an anchoring domain that can bind a cell su specific for the endothelial cell type. In another cell and a composition of the present invention can b surface of many epithelial cell types, or present in tb types of epithelial cells. In this case localized deliver localization to the site of the epithelial cells that are A compound for preventing or treating infect anchoring domain that can bind at or near the surface heparan sulfate, closely related to heparin, is a type o 3d to a molecule expressed on the llular matrix surrounding a target r protein domain (including a • comprises a moiety coupled to a rotein can be any type of molecule doinain to an entity at or near the ule, such as, for example, nucleic eotide, nucleotide analogue, small carbohydrate, or any combination is bound by an anchoring domain mple, an anchoring domain may oximity to the target cell and that as well. In many cases, however, resent invention will restrict its ther cases, a molecule, complex, main may be specific to a target example, es in an animal or human body a target cell can be an endothelial of the present invention can face epitope, for example, that is , a target cell can be an epithelial nd an epitope present on the cell extracellular matrix of different of the composition can restrict its targets of the pathogen, in by a pathogen can comprise an of epithelial cells. For example, glycosaminoglycan (GAG) that is •ran recei ubiquitously present on cell membranes, including th Many proteins specifically bind to heparin/heparan s sequences in these proteins have been identified (Me (1975) Biochimica et Biophysica Acta 392: 223-232; Chemistry, Metabolism and Function. Springer-Verl binding sequences of human platelet factor 4 (PF4) ( (IL8) (SEQ ID NO:3), human antithrombin III (AT apoprotein E (ApoE) (SEQ ID NO:5), human angio (AAMP) (SEQ ID NO:6), or human amphiregulin (! shown to have very high affinity (in the nanomolar Lander, AD. (1991) Pro Natl Acad Sci USA 88:2768 Mosl, R, Pye, D. Gallagher, J and Kungl, AJ. (2002) and Lander AD (1994) Curr Bio 4:394-400; Weisgra Milne, RW and Marcel, Y. (1986) J Bio Chem 261: sequences of these proteins are distinct from their will not induce the biological activities associated wi receptor-binding domains. These sequences, or other or are identified in the future as heparin/heparan sulf substantially homologous to identified heparin/hepariui have heparin/heparan sulfate binding activity, can be domains in compounds of the present invention that example, respiratory epithelium-infecting viruses sue virus. An anchoring domain can bind a moiety that particular species or can bind a moiety that is found i one species. In cases where the anchoring domain ca the surface of target cells of more than one species, a more than one species, a therapeutic compound can (providing that the therapeutic domain is also effectr example, in the case of therapeutic compounds that cjan therapeutic compound of the present invention that h : surface of respiratory epithelium, [fate, and the GAG-binding er, FA, King, M and Gelman, RA. chauer, S. ed., pp233. Sialic Acids (1982). For example, the GAGEQ ID NO:2), human interleukin 8 I) (SEQ ID NO:4), human issociated migratory cell protein EQ ID NO:7) (Figure 2) have been ge) towards heparin (Lee, MK and 2772; Goger, B, Halden, Y, Rek, A, Biochem. 41:1640-1646; Witt, DP er, KH, Rail, SC, Mahley, RW, 68-2076). The GAG-binding eptor-binding sequences, so they the full-length proteins or the sequences that have been identified te binding sequences, or sequences sulfate binding sequences that used as epithelium-anchoringan be used to prevent or treat, for i as, but not limited to, influenza specific to the target cell type of a the target cell type of more than bind moieties that are present at d a virus or pathogen can infect .ve utility for more than one species 5 across the relevant species.) For be used against influenza virus, a s an anchoring domain that binds heparin/heparan sulfate, the compound can be used i well as avians. Therapeutic Domain A compound of the present invention include has an extracellular activity that can prevent or impe pathogen, can modulate the immune response of a efficiency of a recombinant virus. The therapeutic ac examples, a binding activity, a catalytic activity, or a embodiments of the present invention, the therapeuti function of the pathogen that contributes to infectivi other embodiments, a therapeutic domain can modif) cell or target organism. For example, the therapeutic domain can bin necessary for binding of the pathogen to a target cell can block binding of the pathogen to a target cell and a therapeutic domain can bind a molecule or epitope interaction of the molecule or epitope with a target c therapeutic domain can also have a catalytic activity epitope of the pathogen or host that allows for or host. In yet other embodiments, a therapeutic domai that is necessary for target cell infection by a pathog( activity of the host organism or of the pathogen. The therapeutic domain preferably acts extra preventing, inflammatory response-modulating, or tr place at the target cell surface or in the immediate ar including sites within the extracellular matrix, intraci tissues. A therapeutic domain is preferably a peptide modified or derivatized peptide or protein domain), peptide or protein. A moiety coupled to a peptide or mammals (including humans) as at least one therapeutic domain that e the infection of a cell by a subject, or can improve transduction ivity can be, as nonlimiting inhibitory activity. In some activity acts to modify or inhibit a f of the cell by the pathogen. In or inhibit a function of the target a receptor on a target cell that is In this way the therapeutic moiety prevent infection. In an alternative, >n a pathogen to prevent an 1 that is necessary for infection. A that can degrade a molecule or pro notes infection of a target cell by a can be an inhibitor of an activity n. The inhibited activity can be an llularly, meaning that its infectionmsduction- enhancing activity takes a surrounding the target cell, lular spaces, or luminal spaces of r protein domain (including a comprises a moiety coupled to a rotein can be any type of molecule that can prevent or impede the infection of a target c an organic molecule, such as, for example, nucleic a 11 by a pathogen, and is preferably id, peptide nucleic acid, nucleic acid analogue, nucleotide, nucleotide analogue, small orgzinic molecule, polymer, lipids, steroid, fatty acid, carbohydrate, or any combination A therapeutic domain can be a synthetic pept synthetic molecule that can be conjugated to a peptide or polypeptide, can be a naturallyoccurring peptide or protein, or a domain of naturall domain can also be a peptide or protein that is subsfc -occurring protein. A therapeutic itially homologous to a naturallyoccurring peptide or protein. A therapeutic domain can have utility in a particular species, or can prevent or impede pathogen infection in more than one species, that inhibit pathogen functions can in general be use infected by the host, while therapeutic domains that by interfering with a property of the host may or ma) cases, anchoring domains and therapeutic domains c species, so that compounds of the present invention animal health, while reducing propagation and sprea For example, when the therapeutic domain is a sialidase, a sialidase that can cleave more than one type of linkage between a sialic acid residu molecule, in particular, a sialidase that can cleave bo Gal linkages, can protect humans from infections by af any of these. de or polypeptide, or can comprise a For example, therapeutic domains in a range of species that can be nterrupt host-pathogen interactions not be species-specific. In many an be used to advance human and of the virus through animal hosts. and the remainder of a substrate h alpha(2, 6)-Gal and alpha (2, 3)- a broad-spectrum of influenza viruses, including viruses that are naturally hosted it or horses. different species such as birds, pigs Linkers A compound of the present invention can optionally include one or more linkers that can join domains of the compound. Linkers can be used to provide optimal spacing or folding of the domains of a compound. The domains of a compound joined by linkers can be therapeutic domains, anchoring domains, or any other domains or moieties of the compound that provide additional functions such as enhancing compound stability, facilitating purification, etc. A linker used to join domains of compounds of the present invention can be a chemical linker or an amino acid comprises more than one linker, the linkers can be tl compound comprises more than one linker, the linke lengths. Many chemical linkers of various compositions, flexibility, and cleavability are known in the art of o the present invention include amino acid or peptide '. known in the art. Preferably linkers are between one length, and more preferably between one and thirty; length is not a limitation in the linkers of the compo Preferably linkers comprise amino acid sequences th conformation and activity of peptides or proteins enc invention. Some preferred linkers of the present inv amino acid glycine. For example, linkers having the (GGGGS (SEQ ID NO:10))n, where n is a whole preferably between 1 and 12, can be used to link the present invention. The present invention also comprises nucleic based compounds of the present invention that comp and at least one anchoring domain. The nucleic acid optimized for expression in particular cell types, sue cells. The nucleic acid molecules or the present inver compounds of the present invention that comprise at least one anchoring domain can also comprise other not limited to sequences that enhance gene expressio in vectors, such as but not limited to expression vect r peptide linker. Where a compound : same or different. Where a s can be of the same or different Composition comprising at least one anchoring dom , polarity, reactivity, length, anic chemistry. Preferred linkers of nkers. Peptide linkers are well and one hundred amino acids in nino acids in length, although nds of the present invention, t do not interfere with the )ded by monomers of the present ntion are those that include the iequence: between 1 and 20, or more of therapeutic compounds of number dorrains acid molecules that encode proteinse at least one therapeutic domain nolecules can have codons as, for example E. coli or human ion that encode protein-based east one therapeutic domain and at ucleic acid sequences, including but The nucleic acid molecules can be n and at least one protease inhibitor In some aspects of the present invention, a th extracellular activity that can prevent the infection o rapeutic domain that has an a cell by a pathogen is a protease 24 inhibitor. The protease inhibitor can be any type a carbohydrate or polymer, but is preferably a protei of an enzyme. Preferably, the protease inhibitor inh least partially processes at least one pathogen or hos the pathogen or host cell protein is necessary for pat can process a viral protein necessary for pathogen in or an enzyme that originates from the host organism acts at or near the target cell surface, so that a comp anchored at or near the surface of a target cell can enzyme. Compounds of the present invention that can be used to inhibit infection by any pathogen that in which the protease is active at or near the surface compositions can have, for example, one of the folio of chemical entity, such as, for example, . or peptide that inhibits the activity its the activity of an enzyme that at cell protein, where the processing of ogen infectivity. The enzyme that ectivity can be a pathogen enzyme, Preferably, the processing enzyme und of the present invention that is ef ectively inhibit the activity of the comprise protease inhibitory domains requires a protease in its life cycle, >f the host cell. These protein-based structures: (Anchoring Domain)n-linker-(Protease Inhibi or: (Protease Inhibitor)n-linker-(Anchoring Dom)ain)n (n=l,2,3 or more) The protease inhibitor can be a monomeric can be multiple copies of the same polypeptide that E spacing sequence in between. Alternatively, differen inhibitors can be linked with each other, such as, for soybean protease inhibitor as protease inhibiting fun peptides can be linked directly or via a spacer compc anchoring domain can be any peptide or polypeptide of target cells. The protease inhibitor can be a naturally portion thereof) or can be an engineered protease inh used in a compound of the present invention can hav homologous to a naturally occurring protease inhibit tor)n (n= 1,2, 3 or more) form of a peptide or polypeptide or re either linked directly or with polypeptide-based protease example, aprotinin linked with tional domains. The polypeptides or sed of peptide linker sequence. The that can bind at or near the surface occurring protease inhibitor (or an active bitor. A peptide protease inhibitor a sequence substantially r, having one or more deletions, Editions, or substitutions while retaining the activit activity, of the naturally occurring protease inhibitor In one preferred embodiment of the present i the present invention is for the prevention and therapeutic domain is a protein or peptide protease i protease that can cleave the influenza virus hemaggl HA1 and HA2. A number of serine protease inhibitors have and influenza virus activation in cultured cells, in ch infected mice. They include many of the commonly aprotinin (Zhimov OP, Ikizler MR and Wright PF. ( leupeptin (Zhirnov OP, Ikizler MR and Wright PF. M, Klenk HD and Rott R.(1987) J Gen Virol 68:203 (Barbey-Morel CL, Oeltmann TN, Edwards KM and 155:667-672), e-aminocaproic acid (Zhirnov OP, Ov 1982. Arch Virol 73:263-272) and n-p-tosyl-L-lysin (Barbey-Morel CL, Oeltmann TN, Edwards KM and 155:667-672). Among these, aerosol inhalation of ^ therapeutic effects against influenza and parainfl (Zhirnov OP, Ovcharenko AV and Bukrinskaya AG Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. Zhirnov OP. (1987) JMed Virol 21:161-167; Ovchai Antiviral Res 23:107-118) as well as in human (Zhi 12 (in Russian)). Aprotinin (SEQ ID NO: 1; Figure 1) is a 58 (also called Trasylol or bovine pancreatic trypsin inh present invention can have one or more aprotinin composition of the present invention can have from i more preferably from one to three aprotinin polypep invention can also have a therapeutic domain compri substantial homology to the amino acid sequence of , or substantially retaining the same .vention, a therapeutic compound of treatment of influenza in humans, and the hibitor that can inhibit a serine itinin precursor protein HAO into een shown to reduce HA cleavage cken embryos and in lungs of used trypsin inhibitors, such as: 002) J Virol 76:8682-8689), 2002) J Virol 76:8682-8689; Tashiro J-2043), soybean protease inhibitor Wright PF. (1987) J Infect Dis chartenko AV and Bukrinskaya AG. chloromethylketone (TLCK) Wright PF. (1987) J Infect Dis protinin has shown definitive bronchopneumonia in mice (1984) JGen Virol 65:191-196; 1985) J Gen Virol 66:1633-1638; enko AV and Zhimov OP. (1994) iritiov OP. (1983) Problems Virol. 4:9- amino acid polypeptide inhibitor bitor (BPTI)). A compound of the dojnains; for example, a therapeutic ne to six aprotinin polypeptides, des. A compound of the present ing a polypeptide or peptide having protinin. uen;:a Ill) (SEQ A compound for preventing or treating influi inhibitor preferably comprises an anchoring domain epithelial cells. In some preferred embodiments, the GAG-binding sequence from a human protein, such sequence of human platelet factor 4 (PF4) (SEQ ID (SEQ ID NO:3), human antithrombin III (AT (ApoE) (SEQ ID NO:5), human angio-associated m ID NO:6), or human amphiregulin (SEQ ID NO:7) present invention can also have an anchoring domair having substantial homology to the amino acid sequ listed in SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:6, and SEQ ID NO:7. Clinically, a drug comprising aprotinin and administered by aerosol inhalation to cover the entir bronchopneumonia caused by influenza viruses, or virus, that requires serine proteases in its life cycle, anchoring domain fusion protein can be administerec uncomplicated early stage influenza cases or other in addition, an aprotinin/epithtelial anchoring domain fi prophylaxis for influenza or other viral infections be Composition comprising at least one anchoring dom .etiza that comprises a protease hat can bind at or near the surface of spithelium anchoring domain is a is, for example, the GAG-binding S[O:2), human interleukin 8 (IL8) ID NO:4), human apoprotein E gratory cell protein (AAMP) (SEQ Figure 2). A compound of the comprising a polypeptide or peptide nces of the GAG-binding domains MO:4, SEQIDNO:5, SEQ ID epithelial anchoring domain can be respiratory tract to prevent and treat ahy other virus, such as parainfluenza Alternatively, an aprotinin/epithtelial as nasal spray to treat Actions by respiratory viruses. In sion protein can be used as a ore an infection occurs. in and at least one catalytic activity In some aspects of the present invention, a th extracellular activity that can prevent the infection o activity. The enzymatic activity can be a catalytic ac modifies a host molecule or complex or a pathogen to the infectivity of the pathogen. Preferably the host molecule or complex that is removed, degraded, or n a compound of the present invention is on, at, or nea compound of the present invention that is anchored t effectively inhibit the host or pathogen molecule or rapeutic domain that has an a cell by a pathogen is a catalytic vity that removes, degrades or ijiolecule or complex that contributes molecule or complex or pathogen njiodified by the enzymatic activity of the surface of a target cell, so that a the surface of a target cell can (fomplex. the For example, a therapeutic domain can have molecule or epitope of the pathogen or target cell the binding, and subsequent entry of the pathogen into cells that allow for the entry of viruses into cells can activity of a compound of the present invention. Compounds of the present invention that coir to inhibit infection by any pathogen that uses a n long as removal of the receptor does not impair the compositions can have, for example, one of the following i catalytic activity that can digest a t is required for host-pathogen target cell. Receptors on target be the target of an enzymatic recepto: prise catalytic domains can be used r to gain entry to a target cell, as ojrganism. These protein-based structures: (Anchoring Domain)n-[linker]-(Enzymatic Ajctivity)n (n=l,2, 3 or more) or : (Enzymatic Activity)n (n=l,2, 3 or more)-[lii)iker]-(Anchoring Domain)n, where the linkers are optional. oftarget pressnt The enzymatic activity can be a monomeric can be multiple copies of the same polypeptide that i spacing sequence in between. The polypeptides or pi spacer composed of peptide linker sequence. The an polypeptide that can bind to or near the surface In one preferred embodiment of the comprises a sialidase that can eliminate or greatly surface of epithelial cells. Sialic acid is a receptor surface of respiratory epithelial cells with a sialida: interrupt early infections. The therapeutic domair protein, or an active portion thereof. . Sialic acid is least one of the receptors for parainfluenza Streptococcus pneumoniae, Mycoplasma pneumoniae catarrhalis, Pseudomonas aeruginosa, and Helicobc of respiratory epithelial cells with a sialidase vims form of a peptide or polypeptide or either linked directly or with ptides can be linked directly or via a horing domain can be any peptide or cells. invention, a therapeutic domain educe the level of sialic acid on the influenza viruses. Thus, treating the e can prevent influenza infections or can comprise a complete sialidase receptor for influenza viruses, and at , some coronavirus and rotavirus, , Haemophilus influenzae, Moraxella ter pylori. Thus, treating the surface prevent influenza or other viral for can infections or interrupt early infections, as well bacteria such as Streptococcus pneumoniae, My influenzae, Moraxella catarrhalis, and Pseudo gastrointestinal epithelial cells with a sialidase can prevent or reduce colonization of Helicobacter pylori in the stomach. Sialic acid also mediates cell adhesion and in and target cells. Therefore, treating the surface sialidase can prevent the recruitment of inflamma therefore can treat allergic reactions including asthma and allergic rhinitis. Since sialic acid serves as a barrier that hindsr cell entry by a gene therapy vector, treating the target cells with a sialidase can increase improve efficacy of the gene therapy. Preferred sialidases are the large bacterial si; sialic acids NeuSAc alpha(2,6)-Gal and NeuSAc alp bacterial sialidase enzymes from Clostridium perfrin X87369), kctinomyces viscosus (Genbank Accessio ureafaciens, or Micromonospora viridifaciens (Genbank Accession Number DO 1045) can be used. Therapeutic domains of compounds of the p a portion of the amino acid sequence of a large bact acid sequences that are substantially homologous to sequence of a large bacterial sialidase. In one preferred embodiment, a therapeutic domain comprises a sialidase encoded by Actinomyi NO: 12, or such as sialidase sequence substantially h another preferred embodiment, a therapeutic domain the Actinomyces viscosus sialidase extending from i NO: 12, or a substantially homologous sequence. Other preferred sialidases are the human sialidases such as those encoded by the genes NEU2 (SEQ ID NO:8; Genbank Accession Number Y16535; Monti, E, Preti, s prevent or reduce colonization of oplasma pneumoniae, Haemophilus nonas aeruginosa. Treating the teractions between inflammatory cells respiratory epithelial cells with a ory cells to the airway surface, and transduction efficiency, and therefore idases that can degrade the receptor ia(2,3)-Gal. For example, the gens (Genbank Accession Number Number X62276), Arthrobacter resent invention can comprise all or rial sialidase or can comprise amino all or a portion of the amino acid 3s viscosus, such as that of SEQ ID mologous to SEQ ID NO: 12. In yet comprises the catalytic domain of mino acids 274-666 of SEQ ID Rossi, E., Ballahio, A and Borsani G. (1999) Genom NO:9; Genbank Accession Number NM080741; Me Borsani, G. (2002) Neurochem Res 27:646-663) (Figure 3). Therapeutic domains of cs 57:137-143) and NEU4 (SEQ ID nti, E, Preti, A, Venerando, B and compounds of the present invention can comprise a sequences of a human sialidase or can comprise am substantially homologous to all or a portion of the sialidase. Preferably, where a therapeutic domain a sequences of a naturally occurring sialidase, or sequ portion of the amino acid sequences of a naturally o comprises essentially the same activity as the humar A compound for preventing or treating influ domain preferably comprises an anchoring domain epithelial cells. In some preferred embodiments, the GAG-binding sequence from a human protein, such amino acid sequences of human platelet factor 4 (P or a portion of the amino acid no acid sequences that are nino acid sequences of a human mprises a portion of the amino acid nces substantially homologous to a curring sialidase, the portion sialidase. nza that comprises an enzymatic hat can bind at or near the surface of epithelium-anchoring domain is a as, for example, the GAG-binding 4) (SEQ ID NO:2), human interleukin 8 (IL8) (SEQ ID NO:3), human antithrombin III (AT III) (SEQ ID NO:4), human apoprotein E (ApoE) (SEQ ID NO:5), hum protein (AAMP) (SEQ ID NO:6), and human amph An epithelial anchoring domain can also be substan occurring GAG-binding sequence, such as those lis It is also within the scope of the present invention to use compounds comprising a human sialidase, or comprising a sialidase with sub absence of an anchoring domain, in the treatment or prevention of pathogen infections, such as but not limited to influenza, paramyxovirus Pseudomonas aeruginosa infections or bacterial infi prevention of allergic and inflammatory responses, efficiency of a recombinant virus. The present invention recognizes that such i by the use of sialidases, such as, but not limited to, 1 sialidases such as NEU2 and NEU4. The sialidases or chemical engineering, or by pharmaceutical form retention at the respiratory epithelium. n angio-associated migratory cell regulin (SEQ ID NO:7) (Figure 2). ally homologous to a naturally d in Figure 2. antial homology to a sialidase, in the coronavirus, rotavirus, and ctions; in the treatment or nd to improve the transduction 'ections may be prevented or abated e A. viscosus sialidase or human an optionally be adapted, by genetic lation, to improve their half life or Because influenza viruses primarily infect the the receptor sialic acid locally in the nasal cavity an infections or interrupt early infections. The sialidasi respiratory tract as a nasal spray, and it can be used early stage of influenza (or other infection) or in pr occurs. Alternatively, it can be delivered to the treat influenza and to prevent influenza complications upper respiratory tract, removing nasopharynx area can prevent can be delivered to the upper either in therapeutic mode during phylactic mode before the infection ;r respiratory tract as an inhalant to , such as bronchopneumonia. II. Therapeutic Composition Comprising at lea The present invention includes a therapeutic one sialidase activity. The sialidase activity can be such as, for example, a bacterial or mammalian sour that is substantially homologous to at least a portion Preferred sialidases are the large bacterial sialidases acids NeuSAc alpha(2,6)-Gal and NeuSAc alpha(2,; sialidase enzymes from Clostridium perfringens (G Actinomyces viscosus (Genbank Accession Number or Micromonospora viridifaciens (Genbank Accessi homologous proteins can be used. For example, therapeutic compounds of the large bacterial sialidase or can comprise a protein w bacterial sialidase or can comprise amino acid homologous to the amino acid sequence of a large pharmaceutical composition of the present inventior (SEQ ID NO: 12), or comprises a protein sialidase. Other preferred sialidases are the human sial genes NEU2 (SEQ ID NO:8; Genbank Accession Rossi, E., Ballabio, A and Borsani G. (1999) Genon NO:9; Genbank Accession Number NM080741; M t one Sialidase Activity composition that comprises at least sialidase isolated from any source, e, or can be a recombinant protein of a naturally occurring sialidase. that can degrade the receptor sialic )-Gal. For example, the bacterial nbank Accession Number X87369), L06898), Arthrobacter ureafaciens, on Number DO 1045) or substantially resent invention can comprise a th the amino acid sequence of a large sequences that are substantially bacterial sialidase. A preferred comprises the A. viscosus sialidase substantia ly homologous to the A. viscosus dases such as those encoded by the Iumber Yl 6535; Monti, E, Preti, ics 57:137-143) and NEU4 (SEQ ID nti, E, Preti, A, Venerando, B and Borsani, G. (2002) Neurochem Res 27:646-663) (Fij compounds of the present invention can comprise a substantially homologous to the amino acid sequenc comprise amino acid sequences that are substantiall) luman sialidase protein that is js of a human sialidase or can homologous to all or a portion of the amino acid sequences of a human sialidase. Preferably, where a therapeutic domain comprises a portion of the amino acid sequences of a naturally occurring sialidase, or sequences substantially homologous to a portion of he amino acid sequences of a naturally occurring sialidase, the portion comprises essentially the same activity as the human sialidase. A pharmaceutical composition comprising a compounds, including but not limited to other proteins, that can also have therapeutic activity. A pharmaceutical composition comprising i compounds that can enhance the stability, solubility, taste, or fragrance of the composition. A pharmaceutical composition comprising a tracheal, bronchial, oral, or topical administration, o: solution or as eyedrops. A pharmaceutical composition comprising a sialidase can be used to treat or prevent pathogen infection, to treat or prevent allergy or inflammatory response, or to enhance the transduction efficiency of a recombinant virus for gene therapy. ;ure 3). Therapeutic domains of sialidase can include other sialidase can include other packaging, delivery, consistency, sialidase can be formulated for nasal, can be formulated as an injectable III. Sialidase Catalytic Domain Proteins The present invention also includes sialidase herein a "sialidase catalytic domain protein" compri: but does not comprise the entire amino acid sequenc catalytic domain proteins. As used ses a catalytic domain of a sialidase of the sialidase from which the catalytic domain is derived. A sialidase catalytic dor lain protein has sialidase activity. Preferably, a sialidase catalytic domain protein comprises at least 10%, at least 20%, at least 50%, at least 70% of the activity of the sialidase from which the catalytic domain sequence is derived. More preferably, a sialidase catalytic domain protein comprises at sequences :orm sididase least 90% of the activity of the sialidase from which derived. A sialidase catalytic domain protein can include as but not limited to additional sialidase sequences, proteins, or sequences that are not derived from proteins. Additional amino acid sequences can perfi including contributing other activities to the catalyti expression, processing, folding, or stability of the si even providing a desirable size or spacing of the pro A preferred sialidase catalytic domain protei catalytic domain of the A. viscosus sialidase. Preferasly, domain protein comprises amino acids 270-666 of the A (SEQ ID NO: 12). Preferably, an A viscosus sialidai an amino acid sequence that begins at any of the am amino acid 290 of the A. viscosus sialidase sequence the amino acids from amino acid 665 to amino acid sequence (SEQ ID NO: 12), and lacks any ,4. viscoses extending from amino acid 1 to amino acid 269. (As sialidase protein sequence extending from amino any stretch of four or more consecutive amino acids protein or amino acid sequence.) In some preferred embodiments, an A. viscoses comprises amino acids 274-681 of the A. viscosus si and lacks other A. viscosus sialidase sequence. In viscosus sialidase catalytic domain protein comprise viscosus sialidase sequence (SEQ ID NO: 12) and la sequence. In some preferred embodiments, an A. vis* protein comprises amino acids 290-666 of the A. vise NO:12) and lacks any other A. viscosus sialidase embodiments, an A. viscosus sialidase catalytic dom acid some the catalytic domain sequence is other amino acid sequences, such equences derived from other of naturally-occurring any of a number of functions, domain protein, enhancing the catalytic domain protein, or em. is a protein that comprises the ,anA. viscosus sialidase catalytic . viscosus sialidase sequence e catalytic domain protein comprises no acids from amino acid 270 to (SEQ ID NO: 12) and ends at any of •01 of said A. viscosus sialidase sialidase protein sequence used herein "lacks any A. viscosus 1 to amino acid 269" means lacks as they appear in the designated sialidase catalytic domain protein sialidase sequence (SEQ ID NO: 12) preferred embodiments, an A. amino acids 274-666 of the A. ks any other A. viscosus sialidase osus sialidase catalytic domain osus sialidase sequence (SEQ ID . In yet other preferred in orotein commises amino acids sequence. 290-681 of the A. viscosus sialidase sequence (SEQ viscosus sialidase sequence. The present invention also comprises nuclei based compounds of the present invention that com The nucleic acid molecules can have codons optimi types, such as, for example E. coli or human cells, present invention that encode protein-based compoujnds comprise at least one catalytic domain of a sialidase sequences, including but not limited to sequences nucleic acid molecules can be in vectors, such as bu The thit Fusion Proteins Sialidase catalytic domain proteins can be fusion proteins, in which the fusion protein comprises at least one sialidase catalytic domain and at least one other protein domain, including but not limited to: a purification stabiliy domain, a solubility domain, a protein size-i domain, a protein localization domain, an anchoring termini domain, a catalytic activity domain, a binding domain, or a catalytic activityenhancing domain. Preferably, the at least one other another source, such as, but not limited to, sequence one other protein domain need not be based on any l:nown protein sequence, but can be engineered and empirically tested to perform any fu) iction in the fusion protein. Purification domains can include, as nonlimi tag, a calmodulin binding domain, a maltose bindin domain, a streptavidin binding domain, an intein domain, or a chitin binding domain. Protein tags can comprise sequences that can be used for antibody detection of proteins, such as, for example, the myc tag, the hemaglutinin domains that enhance protein expression, modification, folding, stability, size, or localization can be based on sequences of know pro domains can have binding or catalytic activity or en] sialidase catalytic domain. ID NO: 12) and lacks any other A. acid molecules that encode proteinrise a catalytic domain of a sialidase. ed for expression in particular cell nucleic acid molecules or the of the present invention that can also comprise other nucleic acid enhance gene expression. The not limited to expression vectors. omain, a protein tag, a protein ncreasing domain, a protein folding domain, an N-terminal domain, a Cprotein domain is derived from 3 from another protein. The at least ing examples, one or more of a his protein domain, a streptaidin tag, or the FLAG tag. Protein eins or engineered. Other protein lance the catalytic activity of the Preferred fusion proteins of the present invention comprise at least one sialidase catalytic domain and at least one anchoring domain. Preferred anchoring domains include GAG-binding domains, such as the GAG-binding domain or human amphiregulin (SEQ ID NO:7). Sialidase catalytic domains and other domains of a fusion protein of the present invention can optionally be joined by linkers, such as but not limited to peptide linkers. A variety of peptide linkers are known in the art. A preferred linker is a peptide linker comprising glycine, such as G-G-G-G-S (SEQ ID NO: 10). The present invention also comprises nucleic acid molecules that fusion proteins of the present invention that comprise a catalytic domain of a sialidase. The nucleic acid molecules can have codons optimized for expression in particular cell types, such as, for example E. coli or human cells. The nucleic acid molecules or the present invention that encode fusion proteins of the present invention can also comprise other nucleic acid sequences, including but not limited to sequences that enhance gene expression. The nucleic acid molecules can be in vectors, such as but not limited to expression vectors. IV Pharmaceutical Compositions The present invention includes compounds of the present invention formulated as pharmaceutical compositions. The pharmaceutical compositions comprise a pharmaceutically acceptable carrier prepared for storage and preferably subsequent administration, which have a pharmaceutically effective amount of the compound in a pharmaceutically acceptable carrier or diluent. Acceptable carriers or diluents for therapeutic use are well known in the pharmaceutical art, and are described, for example, in Remington's Pharmaceutical Sciences, 18th Ed., Mack Publishing Co., Easton, PA (1990)). Preservatives, stabilizers, dyes and even flavoring agents can be provided in the pharmaceutical composition. For example, sodium benzoate, sorbic acid and esters of p-hydroxybenzoic acid can be added as preservatives. In addition, antioxidants and suspending agents can be used. Depending on the target cell, the compounds of the present invention can be formulated and used as tablets, capsules or elixirs for oral administration; salves or ointments for topical application; suppositories for rectal administration; sterile solutions, suspensions, and the like for use as inhalants or nasal sprays. Injectables can also be prepared in conventional forms either as liquid solutions or suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions. Suitable excipients are, for example, water, saline, dextrose, mannitol, lactose, lecithin, albumin, sodium glutamate, cysteine hydrochloride and the like. In addition, if desired, the injectable pharmaceutical compositions can contain minor amounts of nontoxic auxiliary substances, such as wetting agents, pH buffering agents and the like. The pharmaceutically effective amount of a test compound required as a dose will depend on the route of administration, the type of animal or patient being treated, and the physical characteristics of the specific animal under consideration. The dose can be tailored to achieve a desired effect, but will depend on such factors as weight, diet, concurrent medication and other factors which those skilled in the medical arts will recognize. In practicing the methods of the present invention, the pharmaceutical compositions can be used alone or in combination with one another, or in combination with other therapeutic or diagnostic agents. These products can be utilized in vivo, preferably in a mammalian patient, preferably in a human, or in vitro. In employing them in vivo, the pharmaceutical compositions can be administered to the patient in a variety of ways, including topically, parenterally, intravenously, subcutaneously, intramuscularly, colonically, rectally, nasally or intraperiotoneally, employing a variety of dosage forms. Such methods can also be used in testing the activity of test compounds in vivo. In preferred embodiments, these pharmaceutical compositions may be in the form of orally-administrable suspensions, solutions, tablets or lozenges; nasal sprays; inhalants; injectables, topical sprays, ointments, powders, or gels. When administered orally as a suspension, compositions of the present invention are prepared according to techniques well-known in the art of 36 pharmaceutical formulation and may contain microcrystalline cellulose for imparting bulk, alginic acid or sodium alginate as a suspending agent, methylcellulose as a viscosity enhancer, and sweeteners/flavoring agents known in the art. As immediate release tablets, these compositions may contain microcrystalline cellulose, dicalcium phosphate, starch, magnesium stearate and lactose and/or other excipients, binders, extenders, disintegrants, diluents and lubricants known in the art. Components in the formulation of a mouthwash or rinse include antimicrobials, surfactants, cosurfactants, oils, water and other additives such as sweeteners/flavoring agents known in the art. When administered by a drinking solution, the composition comprises one or more of the compounds of the present invention, dissolved in water, with appropriate pH adjustment, and with carrier. The compound may be dissolved in distilled water, tap water, spring water, and the like. The pH can preferably be adjusted to between about 3.5 and about 8.5. Sweeteners may be added, e.g., 1% (w/v) sucrose. Lozenges can be prepared according to U.S. Patent No. 3,439,089, herein incorporated by reference for these purposes. When administered by nasal aerosol or inhalation, the pharmaceutical compositions are prepared according to techniques well-known in the art of pharmaceutical formulation and may be prepared as solutions in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art. See, for example, Ansel, H. C. et al., Pharmaceutical Dosage Forms and Drug Delivery Systems, Sixth Ed. (1995). Preferably these compositions and formulations are prepared with suitable nontoxic pharmaceutically acceptable ingredients. These ingredients are known to those skilled in the preparation of nasal dosage forms and some of these can be found in Remington's Pharmaceutical Sciences, 18th Ed., Mack Publishing Co., Easton, PA (1990, a standard reference in the field. The choice of suitable carriers is highly dependent upon the exact nature of the nasal dosage form desired, e.g., solutions, suspensions, ointments, or gels. Nasal dosage forms generally contain large amounts of water in addition to the active ingredient. Minor amounts of other ingredients such as pH adjusters, emulsifiers or dispersing agents, preservatives, surfactants, jelling agents, or buffering and other stabilizing and solubilizing agents may also be present. Preferably, the nasal dosage form should be isotonic with nasal secretions. Nasal formulations can be administers as drops, sprays, aerosols or by any other intranasal dosage form. Optionally, the delivery system can be a unit dose delivery system. The volume of solution or suspension delivered per dose can preferably be anywhere from about 5 to about 2000 microliters, more preferably from about 10 to about 1000 microliters, and yet more preferably from about 50 to about 500 microliters. Delivery systems for these various dosage forms can be dropper bottles, plastic squeeze units, atomizers, nebulizers or pharmaceutical aerosols in either unit dose or multiple dose packages. The formulations of this invention may be varied to include; (1) other acids and bases to adjust the pH; (2) other tonicity imparting agents such as sorbitol, glycerin and dextrose; (3) other antimicrobial preservatives such as other parahydroxy benzoic acid esters, sorbate, benzoate, propionate, chlorbutanol, phenylethyl alcohol, benzalkonium chloride, and mercurials; (4) other viscosity imparting agents such as sodium carboxymethylcellulose, microcrystalline cellulose, polyvinylpyrrolidone, polyvinyl alcohol and other gums; (5) suitable absorption enhancers; (6) stabilizing agents such as antioxidants, like bisulfite and ascorbate, metal chelating agents such as sodium edetate and drug solubility enhancers such as polyethylene glycols. V. Method of preventing or treating infection by a pathogen The present invention also includes methods of preventing or treating infection by a pathogen. In one aspect, the method includes: treating a subject that is infected with a pathogen or at risk of being infected with a pathogen with a pharmaceutical composition of the present invention that comprises a compound that comprises at least one anchoring domain that can anchor the compound at or near the surface of a target cell and at least one therapeutic domain comprising a peptide or protein that has at least one extracellular activity that can prevent the infection of a target cell by a pathogen. In some preferred embodiments, the method includes applying a therapeutically effective amount of a pharmaceutical composition of the present invention to epithelial cells of a subject. The subject to be treated can be an animal or human subject. In another aspect, the method includes: treating a subject that is infected with a pathogen or at risk of being infected with a pathogen with a pharmaceutical composition of the present invention that comprises a protein-based compound that comprises a sialidase activity. In some preferred embodiments, the method includes applying a therapeutically effective amount of a pharmaceutical composition of the present invention to epithelial cells of a subject. The sialidase activity can be an isolated naturally occurring sialidase protein, or a recombinant protein substantially homologous to at least a portion of a naturally occurring sialidase. A preferred pharmaceutical composition comprises a sialidase with substantial homology to the A. viscosus sialidase (SEQ ID NO:12). The subject to be treated can be an animal or human subject. In yet another aspect, the method includes: treating a subject that is infected with a pathogen or at risk of being infected with a pathogen with a pharmaceutical composition of the present invention that comprises a protein-based compound that comprises a sialidase catalytic domain. In some preferred embodiments, the method includes applying a therapeutically effective amount of a pharmaceutical composition of the present invention to epithelial cells of a subject. The sialidase catalytic domain is preferably can substantially homologous to the catalytic domain of a naturally occurring sialidase. A preferred pharmaceutical composition comprises a sialidase catalytic domain with substantial homology to amino acids 274-666 the A. viscosus sialidase (SEQ ID NO:12). The subject to be treated can be an animal or human subject. A pathogen can be a viral, bacterial, or protozoan pathogen. In some embodiments, the pathogen is one of the following: influenza viruses, parainfluenza virus, respiratory syncytial virus (RSV), coronavirus, rotavirus, Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Helicobacter pylori. In one preferred embodiment, the pathogen is influenza virus. Compounds of the present invention can be designed for human use or animal use. In some aspects of the present invention, a compound of the present invention can be used to prevent pathogen infection in a class of animals, such as mammals. In some aspects of the present invention, a composition can be used for human and animal use (although the formulation may differ). In these aspects, the active domains of a compound can be effective against more than one pathogen species, type, subtype, or strain and can be active in more than one host species. For example, some preferred compounds of the present invention that comprise, for example, active domains such as protease inhibitors that prevent processing of the HA protein of influenza virus, or sialidases that remove sialic acid receptors from target cells, or anchoring domains such as domains that bind heparin or heparan sulfate, can be used in birds, mammals, or humans. Such compounds that can be effective against a range of pathogens with the capacity to infect different host species can also be used in humans to combat infection by pathogens that are naturally hosted in other species. In some preferred embodiments of the present invention, the pharmaceutical composition prevents infection by influenza, and a therapeutically effective amount of the pharmaceutical composition is applied to the respiratory epithelial cells of a subject. This can be done by the use of an inhaler, or by the use of a nasal spray. Preferably, the inhaler or nasal spray is used from one to four times a day. Because influenza viruses primarily infect the upper respiratory tract, removing the receptor sialic acid locally in the nasal cavity, pharynx, trachea and bronchi can prevent infections or interrupt early infections. The sialidase can be delivered to the upper respiratory tract as a nasal spray or as an inhalant, and it can be used either in therapeutic mode during early stage of influenza (or other infection) or in prophylactic mode before the infection occurs. Alternatively, it can be delivered to the lower respiratory tract as an inhalant to treat influenza and to prevent influenza complications, such as bronchopneumonia. Similarly, the sialidase can be delivered as nasal spray or inhalant to prevent or reduce infection by parainfluenza virus and coronavirus. It can also be delivered as an inhalant or nasal spray to prevent or reduce airway colonization by pathogenic bacteria, including Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Pseudomonas aeruginosa. The therapeutic compounds can optionally be adapted, by genetic or chemical engineering, or by pharmaceutical formulation, to improve their half-life or retention at the respiratory epithelium. Additionally, it can be delivered topically to the eyes or to surgical wounds in the form of drops, sprays or ointments to prevent and treat bacterial infection including infection by Pseudomonas aeruginosa. It can also be administered orally to treat infection by Helicobacter pylori. Dosage As will be readily apparent to one skilled in the art, the useful in vivo dosage to be administered and the particular mode of administration will vary depending upon the age, weight and type of patient being treated, the particular pharmaceutical composition employed, and the specific use for which the pharmaceutical composition is employed. The determination of effective dosage levels, that is the dose levels necessary to achieve the desired result, can be accomplished by one skilled in the art using routine methods as discussed above. In non-human animal studies, applications of the pharmaceutical compositions are commenced at higher dose levels, with the dosage being decreased until the desired effect is no longer achieved or adverse side effects are reduced or disappear. The dosage for a compound of the present invention can range broadly depending upon the desired affects, the therapeutic indication, route of administration and purity and activity of the compound. Typically, human clinical applications of products are commenced at lower dosage levels, with dosage level being increased until the desired effect is achieved. Alternatively, acceptable in vitro studies can be used to establish useful doses and routes of administration of the test compound. Typically, dosages can be between about 1 ng/kg and about 10 mg/kg, preferably between about 10 ng/kg and about 1 mg/kg, and more preferably between about 100 ng/kg and about 100 micrograms/kg. The exact formulation, route of administration and dosage can be chosen by the individual physician in view of the patient's condition (see, Fingle et al., in The Pharmacological Basis of Therapeutics (1975)). It should be noted that the attending physician would know how to and when to terminate, interrupt or adjust administration due to toxicity, organ dysfunction or other adverse effects. Conversely, the attending physician would also know to adjust treatment to higher levels if the clinical response were not adequate. The magnitude of an administrated does in the management of the disorder of interest will vary with the severity of the condition to be treated and to the route of administration. The severity of the condition may, for example, be evaluated, in part, by standard prognostic evaluation methods. Further, the dose and perhaps dose frequency, will also vary according to the age, body weight and response of the individual patient, including those for veterinary applications. Thus, in accordance with the present invention, there is further provided a method of treating and a pharmaceutical composition for treating influenza virus infection and prevention of influenza virus infection. The treatment involves administering to a patient in need of such treatment a pharmaceutical carrier and a therapeutically effective amount of any composition of the present invention, or a pharmaceutically acceptable salt thereof. In one preferred regimen, appropriate dosages are administered to each patient by either inhaler, nasal spray, or by oral lozenge. It will be understood, however, that the specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific salt or other form employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the host undergoing therapy. VI. Method of reducing, preventing, or treating allergic and inflammatory responses The present invention also includes methods of reducing, preventing, or treating an allergic or inflammatory response of a subject. In one aspect, the method includes: preventing or treating an allergic or inflammatory response of a subject with a pharmaceutical composition of the present invention that comprises a protein-based compound that comprises a sialidase activity. In some preferred embodiments, the method includes applying a therapeutically effective amount of a pharmaceutical composition of the present invention to epithelial cells of a subject. The sialidase activity can be an isolated naturally occurring sialidase protein, or a recombinant protein substantially homologous to at least a portion of a naturally occurring sialidase. A preferred pharmaceutical composition comprises a sialidase with substantial homology to the ,4. viscosus sialidase (SEQ ID NO:12). The subject to be treated can be an animal or human subject. In yet another aspect, the method includes: preventing or treating an allergic or inflammatory response of a subject with a pharmaceutical composition of the present invention that comprises a protein-based compound that comprises a sialidase catalytic domain. In some preferred embodiments, the method includes applying a therapeutically effective amount of a pharmaceutical composition of the present invention to epithelial cells of a subject. The sialidase catalytic domain is preferably can substantially homologous to the catalytic domain of a naturally occurring sialidase. A preferred pharmaceutical composition comprises a sialidase catalytic domain with substantial homology to amino acids 274-666 the A. viscosus sialidase (SEQ ID NO:12). The subject to be treated can be an animal or human subject. The allergic or inflammatory response can be and acute or chronic condition, and can include, as nonlimiting examples, asthma, other allergic responses causing respiratory distress, allergic rhinitis, eczema, psoriasis, reactions to plant or animal toxins, or autoimmune conditions. In some preferred embodiments, compounds of the present invention can be delivered as an inhalant or nasal spray to prevent or treat inflammation in the airway including, but not limited to, asthma and allergic rhinitis. Compounds of the present invention comprising sialidase activity (including sialidase catalytic domain proteins and sialidase fusion proteins) can also be administered as eye drops, ear drops, or sprays, ointments, lotions, or gels to be applied to the skin. In another aspect, the method includes treating a patient who has inflammatory diseases with the present invention that comprises a sialidase activity that is administered intravenously or as a local injection. Dosage As will be readily apparent to one skilled in the art, the useful in vivo dosage to be administered and the particular mode of administration will vary depending upon the age, weight and type of patient being treated, the particular pharmaceutical composition employed, and the specific use for which the pharmaceutical composition is employed. The determination of effective dosage levels, that is the dose levels necessary to achieve the desired result, can be accomplished by one skilled in the art using routine methods as discussed above. In non-human animal studies, applications of the pharmaceutical compositions are commenced at higher dose levels, with the dosage being decreased until the desired effect is no longer achieved or adverse side effects are reduced or disappear. The dosage for a compound of the present invention can range broadly depending upon the desired affects, the therapeutic indication, route of administration and purity and activity of the compound. Typically, human clinical applications of products are commenced at lower dosage levels, with dosage level being increased until the desired effect is achieved. Alternatively, acceptable in vitro studies can be used to establish useful doses and routes of administration of the test compound. Typically, dosages can be between about 1 ng/kg and about 10 mg/kg, preferably between about 10 ng/kg and about 1 mg/kg, and more preferably between about 100 ng/kg and about 100 micrograms/kg. The exact formulation, route of administration and dosage can be chosen by the individual physician in view of the patient's condition (see, Fingle et al., in The Pharmacological Basis of Therapeutics (1975)). It should be noted that the attending physician would know how to and when to terminate, interrupt or adjust administration due to toxicity, organ dysfunction or other adverse effects. Conversely, the attending physician would also know to adjust treatment to higher levels if the clinical response were not adequate. The magnitude of an administrated does in the management of the disorder of interest will vary with the severity of the condition to be treated and to the route of administration. The severity of the condition may, for example, be evaluated, in part, by standard prognostic evaluation methods. Further, the dose and perhaps dose frequency, will also vary according to the age, body weight and response of the individual patient, including those for veterinary applications. In some preferred regimens, appropriate dosages are administered to each patient by either inhaler, nasal spray, or by topical application. It will be understood, however, that the specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific salt or other form employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the host undergoing therapy. VI. Method of enhancing gene delivery by a recombinant viral vector The present invention also includes methods of gene delivery by a recombinant viral vector. In one aspect, the method includes: administering an effective amount of a compound of the present invention that comprises a protein having sialidase activity to at least one cell prior to or concomitant with the administration of at least one recombinant viral vector. A composition of the present invention can be provided in the same formulation as at least one recombinant viral vector, or in a separate formulation. In some preferred embodiments, the method includes applying a therapeutically effective amount of a composition of the present invention and a recombinant viral vector to cells of a subject. The subject to be treated can be an animal or human subject. In a particularly preferred embodiment, a recombinant viral vector is used to transduce epithelial target cells of a subject for gene therapy. For example, a recombinant viral vector can be used to transduce airway epithelial cells of a subject with cystic fibrosis. hi this case, a compound of the present invention can be administered by use of an inhaler. A recombinant virus comprising a therapeutic gene can be administered concurrently or separately. In other embodiments, cells can be treated with a compound of the present invention and a recombinant viral vector in vitro or "ex vivo" (that is, cells removed from a subject to be transplanted into a subject after transduction). The sialidase activity can be an isolated naturally occurring sialidase protein, or a recombinant protein substantially homologous to at least a portion of a naturally occurring sialidase, including a sialidase catalytic domain. A preferred pharmaceutical composition comprises a sialidase with substantial homology to the A. viscosus sialidase (SEQIDNO:12). A compound of the present invention can be administered to target cells from one day before to two hours subsequent to the administration of the recombinant virus. Preferably a compound of the present invention is administered to target cells from four hours to ten minutes before administration of the recombinant virus. Administration can be A recombinant virus is preferably a recombinant virus that can be used to transfer genes to mammalian cells, such as, preferably human cells. For example, a recombinant virus can be a retrovirus (including lentivirus), adeno-virus, adeno-associated virus (AAV) or herpes simplex virus type 1. The recombinant virus comprises at least one exogenous gene that is to be transferred to a target cell. The gene is preferably a therapeutic gene, but this need not be the case. For example, the gene can be a gene used to mark cells or confer drug resistance. In a preferred embodiment, the present invention includes methods of improving efficacy of a gene therapy vector. The method includes treating a patient with a compound of the present invention that comprises a sialidase activity and, in the same or a separate formation, with a recombinant virus. The compound of the present invention having sialidase activity can be administered to the patient prior to, concomitant to, or even subsequent to the administration of a recombinant virus. In one embodiment, the sialidase is substantially homologous to the Actinomyces viscosus sialidase (SEQ ID NO: 12) or a portion thereof. In one preferred embodiment, the sialidase comprises the catalytic domain of the Actinomyces viscosus sialidase. In another embodiment, the recombinant virus is AAV. In yet another embodiment, the disease is cystic fibrosis. In yet another embodiment, the recombinant virus comprises the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Dosage As will be readily apparent to one skilled in the art, the useful in vivo dosage to be administered and the particular mode of administration will vary depending upon the age, weight and type of patient being treated, the particular pharmaceutical composition employed, and the specific use for which the pharmaceutical composition is employed. The determination of effective dosage levels, that is the dose levels necessary to achieve the desired result, can be accomplished by one skilled in the art using routine methods as discussed above. In non-human animal studies, applications of the pharmaceutical compositions are commenced at higher dose levels, with the dosage being decreased until the desired effect is no longer achieved or adverse side effects are reduced or disappear. The dosage for a compound of the present invention can range broadly depending upon the desired affects, the therapeutic indication, route of administration and purity and activity of the compound. Typically, human clinical applications of products are commenced at lower dosage levels, with dosage level being increased until the desired effect is achieved. Alternatively, acceptable in vitro studies can be used to establish useful doses and routes of administration of the test compound. Typically, dosages can be between about 1 ng/kg and about 10 mg/kg, preferably between about 10 ng/kg and about 1 mg/kg, and more preferably between about 100 ng/kg and about 100 micrograms/kg. The exact formulation, route of administration and dosage can be chosen by the individual physician in view of the patient's condition (see, Fingle et al., in The Pharmacological Basis of Therapeutics (1975)). It should be noted that the attending physician would know how to and when to terminate, interrupt or adjust administration due to toxicity, organ dysfunction or other adverse effects. Conversely, the attending physician would also know to adjust treatment to higher levels if the clinical response were not adequate. The magnitude of an administrated does in the management of the disorder of interest will vary with the severity of the condition to be treated and to the route of administration. The severity of the condition may, for example, be evaluated, in part, by standard prognostic evaluation methods. Further, the dose and perhaps dose frequency, will also vary according to the age, body weight and response of the individual patient, including those for veterinary applications. In some preferred regimens, appropriate dosages are administered to each patient by either inhaler, nasal spray, or by topical application. It will be understood, however, that the specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific salt or other form employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the host undergoing therapy. Examples Example 1: Synthesizing aprotinin genes, purifying and testing aprotinin fusion proteins. Introduction Influenza viral protein hemagglutinin (HA) is the major influenza envelope protein. It plays an essential role in viral infection. The importance of HA is evidenced by the fact that it is the major target for protective neutralizing antibodies produced by the host immune response (Hayden, FG. (1996) In Antiviral drug resistance (ed. D. D. Richman), pp. 59-77. Chichester, UK: John Wiley & Sons Ltd.). It is now clear that HA has two different functions in viral infection. First, HA is responsible for the attachment of the virus to sialic acid cell receptors. Second, HA mediates viral entry into target cells by triggering fusion of the viral envelope with cellular membranes. HA is synthesized as a precursor protein, HAO, which is transferred through the Golgi apparatus to the cell surface as a trimeric molecular complex. HAO is further cleaved to generate the C terminus HA1 (residue 328 of HAO) and the N terminus of HA2. It is generally believed that the cleavage occurs at the cell surface or on released viruses. The cleavage of HAO into HA1/HA2 is not required for HA binding to a sialic acid receptor; however, it is essential for viral infectivity (Klenk, HD and Rott, R. (1988) 48 Adv VirRes. 34:247-281; Kido, H, Niwa, Y, Beppu, Y and Towatari, T. (1996) Advan Enzyme Regul 36:325-347; Skehel, JJ and Wiley, DC. (2000) Annu Rev Biochem 69:531- 569). Sensitivity of HAO to host proteases is determined by the proteolytic site in the external loop of HAO molecule. The proteolytic site may contain either a single Arg or Lys residue (monobasic cleavage site) or several Lys and/or Arg residues in R-X-K/R-R motif (multibasic cleavage site). Only the influenza A virus subtypes H5 and H7 have HA proteins carrying the multibasic cleavage site. All other influenza A, B and C viruses contain HA proteins having the monobasic cleavage site. Influenza A viruses having multibasic cleavage sites are more virulent and induce systemic infection in hosts whereas viruses with a monobasic HA site initiate infection only in the respiratory tract in mammals or in the respiratory and enteric tracts in avian species (Klenk, HD and Garten W. 1994. Trend Micro 2:39-43 for review). Fortunately, human infection by the highly virulent avian influenza A H5 and H7 subtypes, which carry the multibasic cleavage site, has so far only occurred in a handful of cases discovered mostly in Hong Kong. The vast majority of influenza infections are caused by viruses with HA proteins are cleaved at the monobasic cleavage site. Influenza virus HA subtypes 5 and 7 that contain multibasic cleavage sites are activated by furin, a member of the subtilisin-like endoproteases, or the pre-protein convertase family. Furin cleaves the virus intracellularly and is ubiquitously present in many cell types, allowing the virulent, systemic infection seen with such viruses (Klenk, HD and Garten W. 1994. Trend Micro 2:39-43; Nakayama, K. 1997. Biochem 327:625- 635). All other influenza viruses, which have HAs with monobasic cleavage sites, are activated by secreted, trypsin-like serine proteases. Enzymes that have been implicated in influenza virus activation include: plasmin (Lazarowitz SG, Goldberg AR and Choppin PW. 1973. Virology 56:172-180), mini-plasmin (Murakami M, Towatari T, Ohuchi M, Shiota M, Akao M, Okumura Y, Parry MA and Kido H. (2001) Eur JBiochem 268: 2847-2855), tryptase Clara (Kido H, Chen Y and Murakami M. (1999) In B.Dunn (ed.), Proteases of infectious agents, p.205-217, Academic Press, New York, N.Y), kallikrein, urokinase, thrombin (Scheiblauer H, Reinacher M, Tashiro M and Rott R. (1992) JInfec Dis 166:783-791), blood clotting factor Xa (Gotoh B, Ogasawara T, Toyoda T, Inocencio N, Hamaguchi M and Nagai Y. (1990) EMBOJ 9:4189-4195), acrosin (Garten W, Bosch FX, Linder D, Rott R and Klenk HD. (1981) Virology 115:361-374.), proteases from human respiratory lavage (Barbey-Morel CL, Oeltmann TN, Edwards KM and Wright PF. (1987) JInfect Dis 155:667-672) and bacterial proteases from Staphylococcus aureus (Tashiro M, Ciborowski P, Reinacher M, Pulverer G, Klenk HD and Rott R. (1987) Virology 157:421-430) and Pseudomonas aeruginosa (Callan RJ, Hartmann FA, West SE and Hinshaw VS. (1997) J Virol 71:7579-7585). Activation of influenza viruses by host serine proteases is generally considered to occur extracellularly either at the plasma membrane or after virus release from the cell. Aprotinin, also called Trasylol, or bovine pancreatic trypsin inhibitor (BPTI) is a polypeptide having 58 amino acids. It belongs to the family of Kunitz-type inhibitors and competitively inhibits a wide spectrum of serine proteases, including trypsin, chymotrypsin, plasmin and plasma kallikrein. Aprotinin has long been used as a human therapeutics, such as treatment of pancreatitis, various states of shock syndrome, hyperfibrinolytic haemorrhage and myocardial infarction. It is also used in open-heart surgery, including cardiopulmonary bypass operations, to reduce blood loss (Fritz H and Wunderer G. (1983; Arzneim-Forsch 33:479-494). The safety of aprotinin in human has been well documented through years of clinical applications. In addition, aprotinin is apparently a very weak immunogen as aprotinin-specific antibodies have not been observed in human sera so far (Fritz H and Wunderer G. (1983) Arzneim-Forsch 33:479-494). Another desired feature of aprotinin as a drug candidate is its superb stability. It can be kept at room temperature for at least 18 months without any loss of activity (Fritz H and Wunderer G. (1983,) Arzneim-Forsch 33:479-494). To achieve significant viral inhibition in animal studies that have been performed, aprotinin was administered at high doses. For example, 280 micrograms to 840 micrograms per day of aprotinin was injected intraperitoneally into each mouse for 6 days (Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. (1984) J Gen Virol 65:191- 196); a lower dosage was required for aerosol inhalation, still, each mouse was given 63 - 126 micrograms per day for 6 days (Ovcharenko AV and Zhirnov OP. (1994) Antiviral Res 23:107-118). A very high dose of aprotinin would be required in human based on extrapolation from the mouse data. Therefore to achieve better efficacy in human, the potency of aprotinin molecule needs to be significantly improved. Aprotinin functions by competitively inhibiting serine proteases that are mostly on the surface of host respiratory epithelial cells. Local concentration of aprotinin in the vicinity of host proteases is therefore the key factor determining competitive advantage of aprotinin. We use two approaches that work synergistically to boost competitive advantage of aprotinin on the surface of respiratory epithelium. First, the avidity (functional affinity) of aprotinin is increased by making multivalent aprotinin fusion proteins consisting of two, three, or more aprotinin proteins connected via linkers. Such a molecule is able to bind to membrane proteases in a multivalent fashion, which has significant kinetic advantage over the aprotinin monomer. Monomeric aprotinin binds to bovine trypsin very tightly with dissociation constant (Ki) being 6.0 x 10~14 mol/1. However, its affinity compared to other proteases, such as chymotrypsin, plasmin and Kallikrein, which have been implicated in activation of influenza viruses, is much lower with Ki being at the level of 10~8 to 10~9 mol/1 (Fritz H and Wunderer G. (1983) Arzneim-Forsch 33:479-494). Multimerization can increase aprotinin's affinity to these proteases exponentially. Second, we fuse aprotinin with a respiratory epithelium-anchoring domain. The anchoring domain localizes aprotinin to the proximity of host membrane-associated proteases and maintains a high local concentration of aprotinin on epithelial surface. The anchoring domain also increases retention time of the drug on the respiratory epithelium. Cloning Aprotinin is a single chain polypeptide having 58 amino acid residues and 3 intrachain disulfide bonds (SEQ ID NO:1). The amino acid sequence of aprotinin is shown in Figure 1. Genes encoding aprotinin and aprotinin fusion proteins are synthesized by PCR using overlapping oligonucleotides with codons optimized for E. Coli expression as templates. The PCR products are cloned into pCR2.1-TOPO vector (Invitrogen). After sequencing, the genes are subcloned into an expression vector pQE (Qiagen). The vector carries a purification tag, Hisx6, to allow easy purification of the recombinant proteins. The constructs are used to transform E. Coli. The transformed cells grown in LB- ampicillin medium to mid-log phase are induced by IPTG according to standard protocols. Cells are pelleted and lysed in phosphate-buffered-saline (PBS) by sonication. The enzymes, which have Hise purification tag, are purified using a nickel column (Qiagen). The following aprotinin fusion proteins are made: 1. Dimeric and trimeric aprotinin. Two or three aprotinin genes are linked via a flexible linker as the following constructs: Aprotinin—(GGGGS (SEQ ID NO:10))n (n=3, 4 or 5)—Aprotinin; and Aprotinin—(GGGGS(SEQ ID NO:10))n (n=3, 4 or 5)—Aprotinin— (GGGGS(SEQ ID NO:10))n (n=3, 4 or 5)—Aprotinin The length of the linker sequence may determine three-dimensional flexibility of the multimeric aprotinin and thereby influence functional affinity of the molecule. Therefore constructs having linkers with various lengths are made. Fully functional recombinant monomeric aprotinin has been produced in E. Coli (Auerswald EA, Horlein D, Reinhardt G, Schroder W and Schnabel E. (19SS).Biol Chem Hoppe-Seyler Vol 369, Suppl., pp27-35). We therefore expect proper folding of multivalent aprotinin proteins in E. coli cells. Besides expressing protein in various common E, Coli cell strains, such as BL21, JM83, etc, the multivalent aprotinin proteins are also expressed in Origami™ cells (Novagen, Bad Soden, Germany). The Origami™ cell strain does not have thioredoxin and glutathione reductase and thus has an oxidizing cytoplasm. This cell strain has been used to successfully express a number of proteins that contain disulflde bonds (Bessette PH, Aslund F, Beckwith J and Georgiou G. (1999) Pro NatlAcad Sci USA 96:13703-13708; Venturi M, Seifert C and Hunte C. (2001) J Mol 5/0/315:1-8.). 2. The epithelium cell-anchoring aprotinin. An epithelium cell-anchoring sequence is fused with aprotinin. The epithelium-anchoring sequence can be any peptide or polypeptide sequence that has affinity towards the surface of epithelial cells. We have selected three human GAG-binding sequences: PF4 (aa 47-70; SEQ ID NO: 2), IL-8 (aa 46-72; SEQ ID NO: 3), and AT III (aa 118-151; SEQ ID NO: 4) (Figure 2). These sequences bind to heparin/heparan sulfate with nanomolar-level affinities (Table 1). Heparin/Heparan Sulfate are ubiquitously present on the respiratory epithelium. In separate constructs, the GAG-binding sequences are fused with the aprotinin gene on the N terminus and on the C terminus via a generic linker sequence GGGGS as the following constructs: (GAG domain—GGGGS(SEQ ID NO: 10)—Aprotinin); and (Aprotinin—GGGGS(SEQ ID NO:10>—GAG domain) (Table Removed) Photometric trypsin inhibition assay The trypsin inhibition activity of aprotinin and aprotinin fusion proteins is measured by a photometric assay described previously in detail (Fritz H and Wunderer G. (1983) Arzneim-Forsch 33:479-494). Briefly, in this assay aprotinin inhibits the trypsincatalyzed hydrolysis of Na-benzoyl-L-arginine-p-nitroanilide (BzArgpNA or L-BAPA) (Sigma), which is followed photometrically at 405 run. One trypsin unit (UBAPA) corresponds to the hydrolysis of 1 micromole substrate per min. One inhibitor unit (!UBAPA) decreases the activity of two trypsin units by 50%, which corresponds arithmetically to the inhibition of 1 UBAPA of trypsin. The specific activity of aprotinin is given in IUBAPA/mg polypeptide. Surface plasmon resonance assay The affinities of dimeric and trimeric aprotinin with various linkers are compared against the monomeric aprotinin using surface plasmon resonance assay, or BIAcore analysis (BIAcore, Piscataway, NJ) with human plasmin as the target. Similarly, BIAcore assay with heparin as the target is used to analyze affinity between GAG binding aprotinin fusion proteins and heparin. When plasmin is used as the target, purified human plasmin (Sigma) is immobilized on the CMS chip according manufacturer's instructions (BIAcore, Piscataway, NJ). When heparin is the target, biotinylated albumin and albumin-heparin (Sigma) are captured on a streptavidin-coated BIAcore SA chip as described previously (Xiang Y and Moss B. (2003) J Virol 77:2623-2630). Example 2: Establishing improved tissue culture models for studies on influenza virus infection. Stocks of Influenza Viruses Influenza viral strains are obtained from ATCC and the repository at St. Jude Children's Research Hospital. All experiments involving influenza viruses are conducted at Bio-safety level II. Viruses are propagated by injection into the allantoic cavity of nine-day-old chicken embryos as described (Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. (1985) J Gen Virol 66:1633-1638). Alternatively, viral stocks are grown on Madin- Darby canine kidney (MDCK) cells in minimal essential medium (MEM) supplemented with 0.3% bovine serum albumin and 0.5 micrograms of trypsin per ml. After 54 incubating for 48 to 72 hours, the culture medium is clarified by low speed centrifugation. Viral particles are pelleted by ultracentrifugation through a 25% sucrose cushion. Purified viruses are suspended in 50% glycerol-O.lM Tris buffer (pH 7.3) and stored at -20°C. Plaque Assays Infectivity and titer of the viral stocks are determined by two kinds of plaque assays, a conventional one and a modified one (Tobita, K, Sugiura, A, Enomoto, C and Furuyama, M. (1975) Med Microbiol Immnuol 162:9-14; Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. (1982) Arch Virol 71:177-183). The conventional plaque assay is routinely used as a virus titration method. It requires exogenous trypsin in agar overlay added immediately after virus infection to MDCK monolayers (Tobita, K, Sugiura, A, Enomoto, C and Furuyama, M. (1975) Med Microbiol Immnuol 162:9-14). This method artificially increases infectivity of the viral stocks being tested by activating all the viral particles that have uncleaved HA. Zhirnov et. al. designed a modified plaque assay consisting of a double agar overlay, with trypsin being included in the second layer which is added 24 hours after infection (Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. (1982) Arch Virol 71:177- 183). Three days after infection, cells are fixed with a 10% formaldehyde solution, agarose layers are removed, fixed cells are stained with hematoxylin-eosin solution and plaques are counted. The modified plaque assay allows accurate determination of the real infectivity of viral stocks that contain both cleaved and uncleaved HA. Combining results from both conventional and modified plaque assays, one can distinguish viruses containing cleaved or uncleaved HA and correlate infectivity of viral stocks with the status of HA cleavage. Human Cell Culture Models 1. Short-term culture of primary human epithelial cells. Conventional in vitro influenza virus infection is mostly carried out in MDCK cells with exogenous trypsin added to the culture medium. This is far from being physiological and is inappropriate for the work proposed here because trypsin is not the protease that activate influenza viruses in vivo. Very limited numbers of in vitro tissue culture models that are able to support the growth of influenza virus without an exogenous protease have been reported so far, those being primary cultures with primate cells of renal origin, cells lining the allantoic and aminiotic cavities of embryonated eggs, fetal tracheal ring organ cultures and primary human adenoid epithelial cells (Endo Y, Carroll KN, Ikizler MR and Wright PF. (1996) J Virol 70:2055-2058). Among these, the latest work with primary human adenoid epithelial cells is the closest mimic of human conditions. In this case, Endo et. al. (Endo Y, Carroll KN, Ikizler MR and Wright PF. (1996) J Virol 70:2055-2058) isolated epithelial cells from surgical samples of human adenoids, and cultured the epithelial cells on a collagen matrix (Vitrogen 100, Celtrix Laboratories, Palo Alto, California) in Transwell inserts (Costar, Cambridge, Mass). Cells were maintained in 50% Ham's F12 and 50% Eagles minimal essential media with supplements of growth factors and trace elements. The cells reached confiuency in 10 to 14 days, remaining largely as a monolayer but with discrete patches of ciliated cells, which maintained regular ciliary activity for 1 to 3 weeks after reaching confluency. In this system, influenza A virus grew to a titer of 106 PFU/ml with a multiplicity of infection of 0.001 (Endo Y, Carroll KN, Ikizler MR and Wright PF. (1996) J Virol 70:2055-2058). Progressive cytopathogenic effects were also present during infection. The biggest drawback of this system is that it requires fresh human adenoid tissue. To solve this problem, primary human adenoid epithelial cells are replaced with primary human airway epithelial cells that are commercially available (Cambrex), and the cells are grown under the same conditions. Such short-term culture of primary human airway epithelial cells is relatively quick to establish and is useful as the first-line experimental model for most of the in vitro infection and antiviral experiments. 2. Well-differentiated human airway epithelium (WD-HAE). In order to best mimic the in vivo condition of human airway, the model of well-differentiated human airway epithelium (WD-HAE) is used. WD-HAE is stratified epithelium that has all the differentiated cells of the normal human airway epithelium, including functional ciliated cells and mucus secreting cells. Therefore, in this model system influenza viruses are most likely to be activated by host proteases that are physiologically relevant. Although WD-HAE has been widely used to study respiratory viral infections, such as respiratory syncytial virus (RSV) Zhang L, Peeples ME, Boucher RC, Collins PL and Pickles RJ. (2002) J Virol 76:5654-5666) measles virus (Sinn PL, Williams G, Vongpunsawad S, Cattaneo R and McCray PB. (2002) J Virol 76:2403-2409, or human rhinovirus, it has not previously been used to study influenza viruses. A detailed protocol of WD-HAE has been described previously (Krunkosky TM, Fischer BM, Martin LD, Jones N, Akley NJ and Adler KB. (2000) Am JRespir Cell Mol Biol 22:685-692). Briefly, commercial primary human bronchial epithelial cells (Cambrex) are cultured on Transwell-clear culture inserts (Costar) that are thin-coated with rat-tail collagen I. Cells are cultured submerged for the first 5 to 7 days in medium containing a 1:1 mixture of bronchial epithelial cell growth medium (BEGM) (Cambrex) and DMEM with high glucose with supplement of growth factors (Krunkosky TM, Fischer BM, Martin LD, Jones N, Akley NJ and Adler KB. (2000) Am JRespir Cell Mol Biol 22:685-692). When cultures are 70% confluent (days 5 to 7), the air-liquid interface is created by removing the apical medium and exposing cells only to medium on their basal surface. Cells are cultured for additional 14 days in air-liquid interphase, for a total of 21 days in culture, and are then ready for experiments. The differentiated epithelium can be maintained in vitro for weeks. Epithelial morphology and degree of differentiation is documented by routine histology (Endo Y, Carroll KN, Ikizler MR and Wright PF. (1996) J Virol 70:2055- 2058). Briefly, following fixation with 10% buffered formalin, the epithelial cells are embedded in paraffin, sectioned and stained with hematoxylin and eosin, and with periodic acid-Schiff stain for mucus secreting cells. Influenza infection is carried out in the above two model systems by adding 0.001 to 1 MOI of viruses to the differentiated cells. The titer and infectivity of viruses in the supernatant are followed over a period of 3 to 7 days. The level of influenza viral amplification and the infectivity of influenza viruses are evaluated using conventional and modified plaque assays. Example 3: Comparing functions of the aprotinin fusion proteins in vitro Anti-Viral Effects of Aprotinin Fusion Proteins 1. Pre-infection treatment. Aprotinin fusion proteins are added to primary human cell cultures at various concentrations and allowed to incubate with the cells for 1 hour. The cells are washed with fresh medium and immediately inoculated with influenza viruses at MOI 0.01 to 1. Cells are washed again after 1 hour and cultured for 3 to 5 days. Titer and infectivity of viruses in the supernatant are measured at various time points by two plaque assays. The cytopathic effect caused by viral infection is evaluated by staining viable cells with crystal violet and quantifying by measuring absorption at 570 run at the end of the experiment. The percentage of cell protection by aprotinin fusion proteins is calculated by 100x{(aprotinin treated sample-untreated infected sample)/(uninfected control-untreated infected sample)}. The drug efficacy for cell protection is described by its Effective Concentration that achieves 50% of the cell protection (ECso). Since HA activation only occurs to newly released viral particles, the first round of viral infection occurs normally and viral titer rises in the first 24 hours after infection. However, starting from the second round, infectivity of viruses drops and viral titer gradually decreases as result of aprotinin treatment. Results from this experiment differentiate various types of different aprotinin fusion proteins by their efficacies in a single prophylactic treatment. Alternatively, timing of initial viral inoculation is altered from immediately after aprotinin treatment to 2-24 hours post treatment. Viral titer, infectivity and cytopathic effect are measured for 3 to 5 day after infection as described above. Results from these experiments distinguish various aprotinin fusion proteins by the lengths of the effective window after a single prophylactic treatment. 2. Post-infection Treatment. For multi-dose treatment, cells are first infected by viral inoculations at 0.001 to 0.1 MOI for 1 hour. Various concentrations of aprotinin fusion proteins are added immediately afterwards, additional treatments are applied at 8-hour intervals during the first 48 hours post infection. Cells are cultured until day 7 post infection. Viral titer and infectivity in the media are followed during the whole process. Cytopathic effect is evaluated at the end of the experiment. For single dose treatment, cells are first infected by viral inoculations at 0.001 to 0.1 MOI for 1 hour. Treatments of aprotinin fusion proteins at various concentrations are applied at different time points during the first 48 hours after infection, but each cell sample only receives one treatment during the whole experiment. Cells are cultured until day 7 post infection. Viral titer and infectivity in the media are followed during the whole process. Cytopathic effect is evaluated at the end of the experiment. Results from these experiments distinguish different types of aprotinin fusion proteins for their therapeutic potency. Inhibition of HA Cleavage by Aprotinin Fusion Proteins To demonstrate that aprotinin fusion proteins inhibit influenza viral infection by inhibiting cleavage of influenza HA protein, a human primary epithelial cell culture is infected with influenza virus at MOI of 1. Aprotinin fusion proteins are added to the culture either right before viral inoculation or immediately after the viral infection. At 6.5 hour post infection, the culture is incubated for 1 hour in MEM lacking cold methionine and containing 35S-labeled methionine (Amersham) at a concentration of 100 microCi/ml (pulse). Thereafter, the cells are washed twice with MEM containing a 10- fold concentration of cold methionine and incubated in MEM for additional 3 hours (chase). After labeling, cells are dissolved in radioimmunoprecipitation assay (RIPA) buffer, HA is precipitated by anti-serum against the particular strain of virus used for infection (anti-influenza sera can be obtained from ATCC and Center of Disease Control and Prevention), and immunocomplex is then purified by protein G-Sepharose (Amersham). Samples are fractionated by SDS-PAGE followed by autoradiography. In samples untreated by aprotinin fusion proteins, HA1 and HA2 are expected to be the predominant HA species; while in aprotinin treated samples, HAO is expected to be the major type of HA present. Example 4: Synthesizing genes of five sialidases, expressing and purifying the sialidase proteins. Introduction Influenza viruses belong to the orthomyxoviridae family of RNA viruses. Both type A and type B viruses have 8 segmented negative-strand RNA genomes enclosed in a lipid envelope derived from the host cell. The viral envelope is covered with spikes that are composed of three proteins: hemagglutinin (HA), that attaches virus to host cell receptors and mediates fusion of viral and cellular membranes; neuraminidase (NA), which facilitates the release of the new viruses from the host cell; and a small number of M2 proteins that serve as ion channels. For Influenza A virus, HA and NA both undergo antigenic drift and antigenic shift, the viral subtypes are distinguished by serologic differences between their HA and NA proteins. There are total 15 types of HA (HI-HI 5) and 9 types of NA (N1-N9), but only three HA (H1-H3) and two NA (Nl and N2) have been found in human Influenza A virus so far (Granoff, A. & Webster, R. G., ed. Encyclopedia of Virology, 2nd Edition, Vol 2). In contrast to Influenza A virus, no distinct antigenic subtypes are recognized for Influenza virus B. While Influenza B virus circulates only in humans, Influenza A virus can be isolated from a whole host of animals, such as pigs, horses, chickens, ducks and other kinds of birds, which accounts for genetic reassortment of Influenza A virus that results in antigenic shift. Wild aquatic birds are considered to be the primordial reservoir of all influenza viruses for avian and mammalian species. There is extensive evidence for transmission of the virus between aquatic birds and other species including pigs and horses and indirect transmission to humans through pigs. Direct transmission from pigs or chickens to humans has also been documented (Ito, T. (2000) Microbiol Immunol 44(6):423-430). The host cell receptor for influenza viruses is the cell surface sialic acid. Sialic acids are a-keto acids with 9-carbon backbones that are usually found at the outermost positions of the oligosaccharide chains that are attached to glycoproteins and glycolipids. One of the major types of sialic acids is N-acetylneuraminic acid (NeuSAc), which is the biosynthetic precursor for most of the other types. Two major linkages between NeuSAc and the penultimate galactose residues of carbohydrate side chains are found in nature, NeuSAc a(2,3)-Gal and NeuSAc a(2,6)-Gal. Both NeuSAc a(2,3)-Gal and NeuSAc a(2,6)-Gal molecules can be recognized by Influenza A virus as the receptor (Schauer, R. (1982) Adv. Carbohydrate Chem & Biochem 40:131-235), while human viruses seem to prefer NeuSAc a(2,6)-Gal, avian and equine viruses predominantly recognize NeuSAc a(2,3)-Gal (Ito, T. (2000) Microbiol Immunol 44(6):423-430). Infections by influenza type A and B viruses are typically initiated at the mucosal surface of the upper respiratory tract. Viral replication is primarily limited to the upper respiratory tract but can extend to the lower respiratory tract and causes bronchopneumonia that can be fatal. The risk of death is one per 10,000 infections, but is significantly greater for high-risk groups with pre-existing cardiopulmonary conditions and for immunologically nai've individuals during a pandemic. A therapeutic compound comprising a sialidase that can effectively degrade both receptor sialic acids, NeuSAc a(2,6)-Gal and NeuSAc a(2,3)-Gal, can confer protection against the broadest range of influenza viruses, including animal viruses. It can also remain effective as the viral strains change yearly. Because sialidase targets the host cell rather than virus and acts at the "choking point" in a viral life cycle, generation of resistant virus is improbable. Protein-bound sialic acid rums over homogeneously on cell surface with half-life of 33 hours (Kreisel, W, Volk, BA, Buchsel, R. and Reutter, W. (1980) Proc Natl Acad Sci USA 77:1828-1831). Therefore we estimate that once-a-day or twice-a-day administration of a sialidase would confer sufficient protection against influenza. Sialidases are found in higher eukaryotes, as well as in some mostly pathogenic microbes, including viruses, bacteria and protozoans. Viral and bacterial sialidases have been well characterized, and the three-dimensional structures of some of them have been determined (Crennell, SJ, Garman, E, Laver, G, Vimr, E and Taylor, G. (1994) Structure 2:535-544; Janakiraman, MN, White, CL, Laver, WG, Air, GM and Luo, M. (1994) Biochemistry 33:8172-8179; Pshezhetsky, A, Richard, C, Michaud, L, Igdoura, S, Wang, S, Elsliger, M, Qu, J, Leclerc, D, Gravel, R, Dallaire, L and Potier, M. (1997) Nature Genet 15: 316-320). Several human sialidases have also been cloned in the recent years (Milner, CM, Smith, SV, Carrillo MB, Taylor, GL, Hollinshead, M and Campbell, RD. (1997) JBio Chem 272:4549-4558; Monti, E, Preti, A, Nesti, C, Ballabio, A and Borsani G. 1999. Glycobiol 9:1313-1321; Wada, T, Yoshikawa, Y, Tokuyama, S, Kuwabara, M, Akita, H and Miyagi, T. (1999) Biochem Biophy Res Communi 261:21-27; Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. (2000) Bichem J 349:343-351). All the sialidases characterized share a four amino acid motif in the amino terminal portion followed by the Asp box motif which is repeated three to five times depending on the protein. (Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. (2000) Bichem 7349:343-351; Copley, RR, Russell, RB and Ponting, CP. (2001) Protein Sci 10:285-292). While the overall amino acid identity of the sialidase superfamily is relatively low at about 20-30%, the overall fold of the molecules, especially the catalytic amino acids, are remarkably similar (Wada, T, Yoshikawa, Y, Tokuyama, S, Kuwabara, M, Akita, H and Miyagi, T. (1999) Biochem Biophy Res Communi 261:21-27; Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. (2000) Bichem J 349:343-351; Copley, RR, Russell, RB and Ponting, CP. (2001) Protein Sci 10:285-292). The sialidases are generally divided into two families: "small" sialidases have molecular weight of about 42 kDa and do not require divalent metal ion for maximal activity; "large" sialidases have molecular weight above 65 kDa and may require divalent metal ion for activity (Wada, T, Yoshikawa, Y, Tokuyama, S, Kuwabara, M, Akita, H and Miyagi, T. (1999) Biochem Biophy Res Communi 261:21-27; Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. (2000) Bichem J349:343-351; Copley, RR, Russell, RB and Ponting, CP. (2001) Protein Sci 10:285-292). Over fifteen sialidase proteins have been purified and they vary greatly from one another in substrate specificities and enzymatic kinetics. To confer a broad-spectrum protection against influenza viruses, a sialidase needs to effectively degrade sialic acid in both a(2,6)-Gal and a(2,3)-Gal linkages and in the context of glycoproteins and some glycolipids. Viral sialidases, such as those from influenza A virus, fowl plague virus and Newcastle disease virus, are generally specific for NeuSAc a(2,3)-Gal and only degrade NeuSAc a(2,6)-Gal very inefficiently. Small bacterial sialidases generally react poorly to sialic acid in the context of glycoproteins and glycolipids. By contrast, large bacterial sialidases can effectively cleave sialic acid in both (a,2-6) linkage and (a,2-3) linkage in the context of most natural substrates (Figure 4; Vimr, DR. (1994) Trends Microbiol 2: 271-277; Drzeniek, R. (1973) HistochemJ5:271-290; Roggentin, P, Kleineidam, RG and Schauer, R. (1995) Biol Chem Hoppe-Seyler 376:569-575; Roggentin, P, Schauer, R, Hoyer, LL and Vimr, ER. (1993) Mol Microb 9:915-921). Because of their broad substrate specificities, large bacterial sialidases are better candidates. Among the large bacterial sialidases with known substrate specificity shown in Figure 4, Vibrio cholerae sialidase requires Ca2+ for activity making it less preferred. More preferred sialidases include the 71 kDa enzyme from Clostridiumperfringens, the 113 kDa enzyme from Actinomyces viscosus and sialidase of Arthrobacter ureafaciens. A third sialidase, the 68 kDa enzyme from Micromonospora viridifaciens, has been known to destroy influenza viral receptor (Air, GM and Laver, WG. (1995) Virology 211:278-284), and is also a candidate. These enzymes have high specific activity (600 U/mg protein for C. perfringens (Corfield, AP, Veh, RW, Wember, M, Michalski, JC and Schauer, R. (1981) Bichem J 197:293-299) and 680 U/mg protein for A. viscosus (Teufel, M, Roggentin, P. and Schauer, R. (1989) Biol Chem Hoppe Seyler 370:435-443)), are fully active without divalent metal iron, and have been cloned and purified as recombinant proteins from E. coli (Roggentin, P, Kleineidam, RG and Schauer, R. (1995) Biol Chem Hoppe-Seyler 376:569-575, Teufel, M, Roggentin, P. and Schauer, R. (1989) Biol Chem Hoppe Seyler 370:435-443 , Sakurada, K, Ohta, T and Hasegawa, M. (1992) J Bacterial 174: 6896- 6903). In addition, C. perfringens is stable in solution at 2-8°C for several weeks, and at 4°C in the presence of albumin for more than two years (Wang, FZ, Akula, SM, Pramod, NP, Zeng, L and Chandran, B. (2001) J Virol 75:7517-27). A. viscosus is labile towards freezing and thawing, but is stable at 4°C in 0.1 M acetate buffer, pH 5 (Teufel, M, Roggentin, P. and Schauer, R. (1989) Biol Chem Hoppe Seyler 370:435-443). Although the chances of inducing immune reactions using bacterial sialidases is very low because the proteins will be used topically in the upper respiratory tract and will not be absorbed systemically a human enzyme would be more desirable for long-term use in human subjects. Four sialidase genes have been cloned from human so far: NEUl/G9/lysosomal sialidase (Pshezhetsky, A, Richard, C, Michaud, L, Igdoura, S, Wang, S, Elsliger, M, Qu, J, Leclerc, D, Gravel, R, Dallaire, L and Potier, M. (1997) Nature Genet 15: 316-320. , Milner, CM, Smith, SV, Carrillo MB, Taylor, GL, Hollinshead, M and Campbell, RD. (1997). JBio Chem 272:4549-4558); NEU3, a membrane-associated sialidase isolated from human brain (Wada, T, Yoshikawa, Y, Tokuyama, S, Kuwabara, M, Akita, H and Miyagi, T. (1999) Biochem Biophy Res Communi 261:21-27, Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. (2000) Bichem J349:343-351), NEU2 a 42 kDa sialidase expressed in human skeletal muscle at a very low level (Monti, E, Preti, A, Nesti, C, Ballabio, A and Borsani G. (1999) Glycobiol 9:1313-1321), and NEU4 a 497 amino acid protein (Genbank NM080741) expressed in all human tissues examined (Monti, E, Preti, A, Venerando, B and Borsani, G. (2002) Neurochem Res 27:646-663). Amino acid sequence comparison reveals NEU2 (SEQ ID NO:8) and NEU4 (SEQ ID NO:9) are both cytosolic sialidases. 9 out of 12 of the amino acid residues which form the catalytic site of S. typhimurium sialidase are conserved in both NEU2 and NEU4 (Monti, E, Preti, A, Nesti, C, Ballabio, A and Borsani G. (1999) Glycobiol 9:1313- 1321, Figure 3). In addition, NEU4 also shows a stretch of about 80 amino acid residues (aa 294-373) that appears unique among known mammalian sialidases (Monti, E, Preti, A, Venerando, B and Borsani, G. (2002) Neurochem Res 27:646-663). Unlike the selected large bacterial sialidases, the substrate specificity of NEU2 and NEU4 is unknown. It will need to be tested if NEU2 and NEU4 can effectively degrade the influenza virus receptors. Sialidase assay NEU2, NEU4 and M. viridifaciens enzymes will be stored in PBS and 50% glycerol at -20°C. C. perfringens and A. viscosus enzymes are stored in lOmM acetate buffer (pH5) at 4°C. Protein preps are characterized by HPLC and SDS-PAGE electrophoresis. Specific activities and stability of the enzymes will be monitored by sialidase assay. The enzymatic activity of sialidases are determined by fluorimetric 2'-(4- methylumbelliferyl)-alpha-D-N-acetylneuraminic acid) (4Mu-NANA) (Sigma) as the substrate. Specifically, reactions are set up in duplicate in 0.1 M Na citrate/phosphate buffer pH5.6, in the presence of 400 micrograms bovine serum albumin, with 0.2 mM 4MU-NANA in a final volume of 100 microliters, and incubated at 37°C for 5-10min. Reactions are stopped by addition of 1 ml of 0.2 M glycines/NaOH pH10.2. Fluorescence emission is measured on a fluorometer with excitation at 365 nm and emission at 445 nm, using 4-methylumbelliferone (4-MU) to obtain a calibration curve. Example 5: Comparing functions of the sialidases in vitro and selecting one sialidase for further studies. 1. Stocks of Influenza Viruses Influenza viral strains are obtained from the ATCC and the repository at St. Jude Children's Research Hospital.Viral stocks are grown on Madin-Darby canine kidney (MDCK) cells in minimal essential medium (MEM) supplemented with 0.3% bovine serum albumin and 0.5 micrograms of trypsin per ml. After incubating for 48 to 72 hours, the culture medium is clearified by low speed centrifugation. Viral particles are pelleted by ultracentrifugation through a 25% sucrose cushion. Purified viruses are suspended in 50% glycerol-O.lM Tris buffer (pH 7.3) and stored at -20°C. Viral titer is determined by plaque assay (Tobita, K, Sugiura, A, Enomoto, C and Furuyama, M. (1975) Med Microbiol Immnuol 162: 9-14), or TCIDso, which is the dose of virus required to infect 50% of the MDCK cells. Selected human and animal influenza A strains with specificity towards NeuSAc alpha(2,6)-Gal or NeuSAc alpha(2,3)-Gal and have high affinity to the receptors (measured by high hemagglutination activity) are chosen for in vitro tests: 1. Strains that recognize receptor NeuSAc alpha(2,6)-Gal include human isolates A/aichi/2/68, A/Udorn/307/72, A/Prot Chaimers/1/73 and A/Victoria/3/75, etc. (Connor, RJ, Kawaoka, Y, Webster, RG and Paulson JC. (1994) Virology 205:17- 23). 2. Strains that have NeuSAc alpha(2,3)-Gal specificity include animal isolates A/duckUkraine/1/63, A/duckMemphis/928/74, A/duckhokk/5/77, A/Eq/Miami/1/63, A/Eq/Ur/1/63, A/Eq/Tokyo/71, A/Eq/Prague/71, etc (Connor, RJ, Kawaoka, Y, Webster, RG and Paulson JC. (1994) Virology 205:17-23). 2; Hemagglutination Assay This assay is used to rapidly determine the efficiency of each enzyme to destroy receptors NeuSAc alpha(2,6)-Gal and NeuSAc alpha(2,3)-Gal. Specifically, 6 ml of Chicken red blood cells (SPAFAS Inc., Norwich, CT) are diluted in two times the volume of PBS, centrifuge for 5 min at 500 x g and re-suspended in PBS of original volume. Sialidases are added to the chicken erythrocytes at various concentrations and allowed to incubate at room temperature for 30 min. The cells are then washed three times to remove sialidase proteins, and then are resuspended in PBS to 6 ml. Control cells are incubated with BSA and washed. Various strains of influenza virus, which recognize either NeuSAc alpha(2,6)-Gal or NeuSAc salpha(2,3)-Gal as the receptor as listed above, are prepared in microtiter plates as serial dilutions in PBS (100 microliters) of the original viral stocks. Sialidase-treated or control chicken red blood cell suspensions (100 microliters of the 0.5% solution prepared above) are added to each well at 4°C. The plates are read after 2 h. The lowest concentration of virus that causes the blood cell to agglutinate is defined as one hemagglutination unit. We will be looking for enzymes that effectively abolish hemagglutination by all viral strains. 3. Viral Inhibition Assay Confluent monolayers of MDCK cells are treated with various concentrations of sialidases for 1 h, washed twice with buffer, then infected with various strains of influenza virus. After incubation for 1 hr, the cells are washed again to remove unbound virus. To estimate the decrease in viral binding sites on cell surface, the cells are overlaid with agar and incubated at 37°C. The number of plaques in the sialidase treated cells will be compared against those in control cells. Alternatively, the cells will be cultured in regular medium at 37°C, and viral titers in the culture media are measured at various time during culture as TCID5o. To demonstrate that sialidase treatment can inhibit a pre-existing infection, MDCK monolayers are first infected with a low titer of virus. After washing off the unbound virus, the cells are then cultured in the presence of a sialidase. Fresh sialidase is added to cell culture very 24 h. Viral titer in the cultured medium is measured over a 72- hour period. 4. Cytotoxicity assay Primary human bronchial epithelial cells are purchased (Clonetics) and cultured in supplemented minimal medium following manufacture's instruction. Sialidases are added to the culture medium at various concentrations. Cell growth over a period of 7-10 days will be measured. Cells will also be observed regularly for microscopic cytopathic effects. Example 6: Constructing and testing sialidase fusion proteins. 1. Choosing a GAG-binding sequence as the anchoring domain. One sialidase is selected for its best overall properties, including anti-viral activity, toxicity, stability, ease of production, etc. We will then genetically link it to a GAG-binding sequence, sub-clone the fusion genes into pQE vector, express and purify the fusion proteins from E. coli. We have selected six possible human GAG-binding sequences: PF4 (aa 47-70) (SEQ ID NO:2), IL-8 (aa 46-72) (SEQ ID NO:3), AT III (aa 118-151) (SEQ ID NO:4), ApoE (aa 132-165) (SEQ ID NO:5), amphiregulin (aa 25-45) (SEQ ID NO:6), and human angio-associated migratory cell protein (AAMP) (aa 14-25) (SEQ ID NO:7) (Figure 2). These sequences generally bind to heparin with nanomolar-level affinities; however, their affinities may vary from one another by an order of magnitude (Table 1). Since it is not clear which anchoring domain will enable the most effective functioning of the sialidase, all four GAG-binding sequences are fused with the sialidase gene either on the N terminus or the C terminus via a generic linker sequence GGGGS as the following constructs: (GAG binding domain— GGGGS(SEQ ID NO:10) —Sialidase); or (Sialidase—GGGGS(SEQ ID NO: 10)—GAG binding domain) Different fusion proteins are compared by a modified viral inhibition assay. Specifically, confluent monolayers of MDCK cells are treated with same amount of each fusion protein for a limited duration, such as 30 min. The cells are then washed twice with buffer to remove unbound sialidase fusion proteins, and incubated in culture medium for an additional 1 hour. Afterwards, strains of influenza virus are added to the cells for 1 hr and then cells are washed again to remove unbound virus. Viral titers in the culture media are measured during 72-h cultures as TCIDjo. The un-fused sialidase protein will be used to compare against the fusion proteins in this assay. If the results are too close to rank all fusion proteins, we will make the assay more stringent by shortening treatment window for the fusion proteins, lowering protein concentrations and increasing the level of viral challenge. 2. Optimizing the fusion protein construct After selecting the best fusion protein from the earlier experiments, the construct is further optimized by testing different linker length. In this regard, the following constructs are made: (Sialidase— (GGGGS(SEQ ID NO:10))n (n=0, 1, 2, 3, or 4) —GAG binding domain) The proteins are expressed and purified and compared in the modified viral protection assay as described above. In addition, if earlier data indicate that higher affinity of the fusion protein towards heparan sulfate brings better potency, we also plan to test if the potency can be further improved by increasing the GAG-binding affinity. This can be achieved by creating a multivalent GAG binding mechanism in the fusion protein in constructs like these: (Sialidase—(GGGGS(SEQ ID NO:10))n—HS binding domain—GAG binding domain); or: (GAG binding domain—(GGGGS(SEQ ID NO :10))n—Sialidase— (GGGGS(SEQ ID NO:10))n—GAG binding domain) The purified fusion proteins are ranked based on their activities in the modified viral protection assay as described above. 3. Cytotoxicity assay The effects of the fusion proteins on normal cell growth and morphology are monitored by culturing primary human bronchial epithelial cells with various concentrations of the fusion proteins and following growth curve of the cells and observing any microscopic cytopathic effects. Example 7: Fusion Proteins against Other Infectious Microbes Fusion proteins composed of a functional domain and an anchorage domain are designed for many more different applications. For example, a sialidase fusion protein as proposed here can also be used as a therapeutic/prophylatictic agent against infections by other viruses and bacteria besides influenza viruses, because many other infectious microbes, such as paramyxoviruses (Wassilewa, L. (1977) Arch Virol 54:299-305), coronaviruses (Vlasak, R., Luytjes, W., Spaan, W. and Palese, P. (1988) ProcNatl Acad Sci USA 85:4526-4529), rotaviruses (Fukudome, K., Yoshie, O. and Konno, T. (1989) Virology 172:196-205) and Pseudomonas aeruginosa (Ramphal, R. and Pyle, M. (1983) Infect Immun 41:339-44) etc, are also known to use sialic acid as cellular receptors. For example, aprotinin fused with a heparin-binding domain can make a fusion protein that be used to prevent/treat infection of other viruses besides influenza that require host serine proteases for activation, such as parainfluenza virus. Example 8: Cloning Sialidase Catalytic Domain Fusion Proteins According to the published literature on the large bacterial sialidases, the 51 kDa Arthrobacter ureafaciens sialidase, the 71 kDa sialidase from Clostridium perfringens and the 113 kDa sialidase from Actinomyces viscosus seem to have similar specific activities and broad substrate specificity toward various sialic acid conjugates (Biology of the Sialic Acids (1995) , 270-273; Corfield et al., Biochem. 1,(1981) 197(2), 293-299; Roggentin et al., Biol. Chem. Hoppe Seyler, (1995) 376(9), 569-575; Teufel et al., Biol. Chem. Hoppe Seyler, (1989) 370(5), 435-443). A third sialidase, the 68 kDa enzyme from Micromonospora viridifaciens, was also known to destroy the influenza viral receptor (Air and Laver, Virology, (1995) 211(1), 278-284; (1995) , 270-273). A. viscosus is part of the normal flora of human oral cavity and gastrointestinal tract (Sutler, Rev. Infect. Dis., (1984) 6 Suppl 1, S62-S66). Since the sialidase from A. viscosus is normally secreted by the bacterium hosted on human mucosal surface, it should be tolerated by the human mucosal immune system. Therefore, it is unlikely that A. viscosus sialidase will be immunogenic when delivered topically to the human airway surface. We think that this feature makes A. viscosus sialidase a good candidate for a therapeutic agent. We determined that a fragment of the A. viscosus sialidase, extending from amino acid 274 to amino acid 667, should contain the catalytic domain (referred to as AvCD) of the sialidase and should be fully active on it own. We later cloned the AvCD fragment and demonstrated that this AvCD fragment and other A. viscosus sialidase fragments comprising at least amino acids 290-666 of the A. viscosus sialidase protein sequence (SEQ ID NO:12), such as the fragment extending from amino acid 274 to amino acid 681, the fragment extending from amino acid 274 to amino acid 666, the fragment extending from amino acid 290 to amino acid 666, and the fragment extending from amino acid 290 to amino acid 681, have sialidase activity. The complete sequence of A. viscosus sialidase protein and gene were obtained from GenBank (A49227 and L06898). Based on homology with sialidases with known 3D structures (M. viridifaciens and S. typhimurium), we assigned the catalytic domain (CD) sequence to be located between amino acids 274-667 (SEQ ID NO:16). To clone the catalytic domain of A. viscosus sialidase (AvCD), this region of the A. viscosus sialidase gene was engineered with codons optimized for expression in E.coli (SEQ ID NO: 15). The codon-optimized AvCD nucleotide sequence encoding amino acids 274-667 of the A. viscosus sialidase (SEQ ID NO: 15) was produced by chemical synthesis of overlapping oligonucleotides which were annealed, amplified by PCR and cloned into the expression vector pTrc99a (Amersham, New Jersey, USA). Sialidase fusion constructs were made using standard molecular cloning methods. The Hise-AR construct was made by fusing six histidines (Hisg) to the N-terminal residue of the AvCD sequence. The Hise-AvCD construct has the nucleotide sequence of SEQ ID NO: 17 and translated amino acid sequence of SEQ ID NO: 18. These sequences are depicted in Figure 7. To make the AR-AvCD construct, an anchoring domain was directly fused with the N-terminal residue of the AvCD sequence. The anchoring domain, referred to as AR, was derived from the GAG binding sequence of human amphiregulin precursor (GenBank # AAH09799). Nucleotide sequences encoding amino acids 125 to 145 (Figure 2, SEQ ID NO:7) of the human amphiregulin precursor were synthesized chemically as two overlapping oligonucleotides. The AR-AvCD construct has the nucleotide sequence of SEQ ID NO:19 and translated amino acid sequence of SEQ ID NO:20. Another construct, AR-G4S-AvCD, was made by fusing the same AR-encoding sequence used in the AR-AvCD construct with a sequence encoding a five-amino-acid linker (GGGGS; SEQ ID NO: 10) which then was fused with the AvCD sequence such that in a translation product, the linker was fused to N-terminus of the catalytic domain of the A. viscosus sialidase. The nucleotide sequence (SEQ ID NO:34) and translated amino acid sequence (SEQ ID NO:35) of this construct are depicted in Figure 9. All constructs were cloned into the pTrc99a expression vector. In addition, four constructs were made in which the catalytic domain of the A. viscosus sialidase was fused to the N-terminus of the AR (GAG-binding domain of human amphiregulin; SEQ ID NO:7). In Construct #4 (SEQ ID NO:27), the catalytic domain of the A. viscosus sialidase consisted of amino acids 274-666 of SEQ ID NO:12 fused to the GAG-binding domain of amphiregulin (SEQ ID NO:7). In Construct #5 (SEQ ID NO:29), the catalytic domain of the A. viscosus sialidase consisted of amino acids 274- 681 of SEQ ID NO: 12 fused to the GAG-binding domain of amphiregulin (SEQ ID NO:7). In Construct #6 (SEQ ID NO:31), the catalytic domain of the A. viscosus sialidase consisted of amino acids 290-666 of SEQ ID NO:12 fused to the GAG-binding domain of amphiregulin (SEQ ID NO:7). In Construct #7 (SEQ ID NO:33), the catalytic domain of the A. viscosus sialidase consisted of amino acids 290-681 of SEQ ID NO:12 fused to the GAG-binding domain of amphiregulin (SEQ ID NO:7). All of these constructs displayed comparable sialidase activity in assays. Example 9: Production of Sialidase Catalytic Domain Fusion Proteins To produce the sialidase fusion proteins, the expression constructs were transformed into E.coli BL21. A single colony was inoculated into 2.5 ml of LB broth and grown overnight at 37°C with shaking. In the morning 2 ml of overnight culture was inoculated into 500 ml of TB medium in a 2 liter shake flask and the culture was allowed to grow to OD6oo=4.0 (2-4 hours) at 37°C with shaking. Protein expression was induced by addition of IPTG to a final concentration of 1 mM and continued for 3 hr with shaking. Cells were harvested by centrifugation at 5,000xg for 10 min. Cell were washed once (resuspended in PBS and recentrifuged) and resuspended in 15 ml of Lysis buffer. Compositions of media and buffers used in protein expression and purification. TB medium for protein expression Solution 1 Bacto-tryptone - 12 g Yeast extract - 24 g H2O to 800 ml Solution 2 KH2PO4 (anhydrous) - 2.3 g K2HPO4 (anhydrous) - 12.5 g H20tol00ml Autoclave solutions 1 and 2 separately, cool, mix and add the following: 60 ml of 20% glycerol (filter sterilized) 20 ml of 20% glucose (filter sterilized) Lysis buffer 50 mM phosphate, pH 8.0 10% glycerol 300 mM NaCl Bacterial cells suspended in lysis buffer were lysed by sonication and cell debris was removed by centrifugation. Clarified lysate was passed through an SP-Sepharose column (bed volume 15 ml, flow rate 120 cm/hour). The column was reconditioned to lower pH and salt with one volume of PBS to ensure good retention of Fludase during endotoxin removal. Endotoxin was removed by washing the column with 5 volumes of PBS containing 1% Triton X-100, 0.5% Sodium Deoxycholate and 0.1% SDS. The detergents were washed away with 3 volumes of PBS and 3 volumes of lysis buffer. Proteins were eluted from the column with lysis buffer that contained 0.8 M NaCl. The fraction eluted from SP-Sepharose was adjusted to 1.9 M (NH^SC^ (most contaminating proteins are salted out at this step) and clarified by centrifugation. The supernatant was loaded onto Butyl-Sepharose column (flow rate 120 cm/hour). The column was washed with 2 volumes of 1.3 M (NH4)2SO4 and the fusion was eluted with 0.65 M (NH4)2SO4. For the final step, size exclusion chromatography was performed on Sephacryl S-200 equilibrated with PBS buffer at a flow rate of 25 cm/hour. Sialidase activity was determined against 4-MU-NANA as described in the following paragraph. Protein concentration was determined using Bio-Rad's Bradford kit. Protein purity was assessed by SDS-PAGE and estimated to be >98%. Specific activity of the enzyme was about 937 U/mg. Endotoxin in final preparations was measured using LAL test (Cambrex) and estimated to be For purification of His6 containing fusion protein, cation exchange on SPSepharose was replaced with Metal Chelate Affinity Chromatography on Ni-NTA. All buffers remained the same with the exception that elution from Ni-NTA was performed by 0.25 M imidazole in lysis buffer. Example 10: Sialidase Assay to Measure Activity of Sialidase Catalytic Domain Fusion Proteins The sialidase activity of the AR-AvCD protein encoded by Construct #2 was assayed and compared with that of native sialidases purfied from C. perfringens (Sigma, St. Louis, MO) and A. ureafaciens (Prozyme, San Leandro, CA). In addition, a fusion protein produced from a construct in which the amphiregulin GAG sequence (SEQ ID NO: 7) was fused to the Neu 2 human sialidase (SEQ ID NO:8) was also assayed for sialidase activity. The sialidase activity expressed as units per mg sialidase was measured by the sialidase assay using the artificial fluorogenic substrate 4-MU-NANA (Sigma). One unit of sialidase is defined as the amount of enzyme that releases 10 nmol of MU from 4-MUNANA in 10 min at 37°C (50 mM CH3COOH - NaOH buffer, pH 5.5) in reaction that contains 20 nmol of 4-MU-NANA in a 0.2 ml volume. Reactions are stopped by addition of 1 ml of 0.2 M glycine/NaOH pH 10.2. Fluorescence emission is measured on a fluorometer with excitation at 365 nm and emission at 445 nm, using 4- methylumbelliferone (4-MU) to obtain a calibration curve (Potier et al., Anal. Biochem., (1979) 94(2), 287-296). (Table Removed) Our results show that the AvCD fusion protein (AR-AvCD) has the highest specific activity among all the tested sialidases (Table 2). The specific activity of ARAvCD is over 100 times higher than that of a human sialidase fusion (AR-NEU2), and over two times higher than that of C. perfringens sialidase. Experimental results comparing the stability of the sialidases indicate very high stability of AR-AvCD: No loss of activity for AR-AvCD was detected after 20 weeks at 25°C or 4°C in solution. By comparison, AR-NEU2 solution exhibited a half-life of 5 and 2 weeks when stored at 25°C and 37°C, respectively. Example 11: Optimization of the N-terminus ofSialidase Catalytic Domain Fusion Proteins The N-terminus of the AR-AvCD fusion protein was partially cleaved under certain conditions that resulted in small degrees of protein heterogeneity in the purified AR-AvCD prep. To solve this problem, we designed an approach to optimize the Nterminus of the sialidase fusion construct. A library containing AR-AvCD with random amino acids at the N-terminus was constructed as follows. AR-AvCD was amplified by PCR using a primer pair in which the primer annealing on 5'-end of the gene contained a randomized sequence in positions corresponding to amino acids 2 and 3. The nucleotide sequence of the primer and the encoded amino acid sequence are shown below. ttttcgtctcccatgvnnvnnaagcgcaaaaaaaaaggcggca (SEQ ID NO:21) MetXxxXxxLysArgLysLysLysGlyGly (SEQ ID NO:22) In SEQ ID NO:21, "n" stands for any nucleotide (a, c, g, or t) and "v" stands for nucleotides a, g or c. By designing the sequence in such a way (disallowing the nucleotide t in the first position of codons) we avoided introduction of stop codons as well as aromatic amino acids (Phe, Tyr, Trp) and Cys. The Espll restriction endonuclease site (shown in bold) was introduced to allow generation of Ncol compatible overhang. The primer annealing to 3'-end of the gene carried Hindlll site following the stop codon. The PCR product was digested with Esp3l - Hindlll was ligated into pTrc99a expression vector digested with Ncol - Hindlll. The ligation mix was transformed into E.coli and the cells were grown overnight in liquid culture containing Ampicillin. The next day the culture was diluted with fresh medium, grown to ODeoo-O.S and induced with IPTG for 2 hours. Cells were harvested, homogenized and the fusions were subjected to two-step purification by liquid chromatography. Clarified lysate was loaded onto SP-Sepharose equilibrated with lysis buffer (50 mM HEPES, pH 8.0, 0.3 M NaCl, 10% glycerol). The column was washed with 0.45 M NaCl and the fusions were eluted with 0.9 M NaCl. The eluate was diluted with 10% glycerol to bring the concentration of NaCl to 0.2 M and loaded onto Heparin-Sepharose column. The column was developed with a linear gradient of NaCl. The fractions that contained sialidase activity were resolved on SDS-PAGE, electroblotted onto PVDF membrane and the 43 kDa band was subjected to amino-terminal sequencing. The predominant N-terminal residues of the isolated sialidase fusion protein were either Val or Gly followed by the N-terminal residues of the AR tag. We then synthesized new sialidase fusion constructs, Constructs #2 and #3, by introducing a Val in front of the AR sequence such that the first six amino acids encoded by Constructs #2 and #3 were (Met-Val-Lys-Arg-Lys-Lys (SEQ ID NO:23)). N-terminal sequencing of proteins made from these new fusion constructs showed 100% homogeneity with the initiation Met being completely removed (which is desirable for therapeutic proteins) and Val being the first N-terminal residue followed by the AR tag sequence. These data are consistent with earlier publications that reported the common rules of N-terminal processing and protein stability as function of protein's N-terminal amino acid residue (Hirel et al., PfOC. Natl. Acad. Sci. U. S. A, (1989) 86(21), 8247-8251; Varshavsky, Proc. Natl. Acad. Sci. U. S. A, (1996) 93(22), 12142-12149). The nucleotide sequences of new fusion Construct #2 (AR-AvCD with optimized N-terminus) (SEQ ID NO:24) and its amino acid sequence translation (SEQ ID NO:25) is depicted in Figure 10. The nucleotide sequences of new fusion Construct #3 (ARG4S- AvCD with optimized N-terminus) (SEQ ID NO:36) and its amino acid sequence translation (SEQ ID NO:37) is depicted in Figure 11. The amino acid sequence of processed proteins isolated from E. coli infected with Construct #2 is provided herein as SEQ ID NO:38 and the amino acid sequence of processed proteins isolated from E. coli infected with Construct #3 is provided herein as SEQ ID NO:39. Example 12: Comparing Activities of Sialidase Constructs with or without an Anchoring Domain To evaluate if the AR sequence indeed improves the cell-surface activity of a sialidase fusion protein, we incubated proteins purified from E. coli that were transformed with Construct #2; SEQ ID NO:24, depicted in Figure 7) or Construct #1 (Hise-AvCD; SEQ ID NO: 17, depicted in Figure 5) with primary human bronchial epithelial cells and measured cell-bound sialidase activity after extensive washing. For cells incubated with Construct #2 protein (SEQ ID NO:25), up to 10% of the sialidase was found to be cell-bound, and the cell-bound sialidase activity increased in a dosedependent manner with the input concentration of Construct #2 protein. However, Construct #1 protein (SEQ ID NO: 18) incubated cells only exhibited background level of sialidase activity. Furthermore, we treated MDCK cells with either Construct #2 protein or Construct #1 protein and measured the level of residual a( 2,6)-linked sialic acid on the surface of the cells (Figure 8). At equal levels of enzymatic activity below 100 mU per well, Construct #2 protein demonstrated significantly higher potency than Construct #1 protein. These results indicate that the AR domain indeed enhances the function of sialidase. Example 13: In vitro Activities of Sialidase Fusion Proteins Stocks of Influenza Viruses Influenza viral strains are obtained from ATCC and the repository at St. Jude Children's Research Hospital. All experiments involving influenza viruses are conducted at Bio-safety level II. Viruses are propagated on Madin-Darby canine kidney (MDCK) cells in minimal essential medium (MEM) supplemented with 0.3% bovine serum albumin and 0.5 micrograms of trypsin per ml. After incubating for 48 to 72 hours, the culture medium is clarified by low speed centrifugation. Viral particles are pelleted by ultracentrifugation through a 25% sucrose cushion. Purified viruses are suspended in 50% glycerol-O.lM Tris buffer (pH 7.3) and stored at -20°C. Cell protection assay To evaluate the ability of the Construct #2 AR-AvCD protein to protect cells against influenza viruses, we first treated MDCK cells with AR-AvCD made from Construct #2 or a broad-spectrum bacterial sialidase isolated from A. ureofaciens, and challenged the cells with a broad selection of human influenza viruses (IFV), including human IFV A of HI, H2 and H3 subtypes, human IFV B as well as an avian IFV strain. As shown in Figure 9, the fusion protein made from Construct #2 demonstrated 80 to 100% of cell protection that was comparable to the effect of A. ureafaciens sialidase. To perform the assay, MDCK cells were treated with 10 mU of AR-AvCD protein (made using Construct #2) or the isolated sialidase of A. ureafaciens at 37°C for 2 hrs. The cells were subsequently challenged with influenza viruses at MOI 0.1 for 1 hr. The cells were washed and incubated in fresh DMDM:F12 supplemented with 0.2% ITS (GIBCO) and 0.6 ug/ml acetylated trypsin (Sigma). The cells were stained with 0.5% crystal violet and 20% methanol for 5 min and rinsed with tap water. The level of viable cells in each well was quantitated by extracting crystal violet by 70% ethanol and reading at 570 nM. Cell protection was calculated by 100 x {(sialidase treated sample - virus only)/(uninfected sample-virus only)}. IFV inhibition assay We evaluated inhibition of IFV amplification by AR-AvCD protein (made using Construct #2) and AR-G4S-AvCD protein (made using Construct #3) using a cell-based ELISA method (Belshe et al., J Virol., (1988) 62(5), 1508-1512). To perform the assay, MDCK monolayers in 96 well plates were treated with 16 mU of the sialidases AR-AvCD made from Construct #2 or AR-G4S-AvCD made from Construct #3 in EDB/BSA buffer (10 mM Sodium Acetate, 150 mM NaCl, 10 mM CaCl2, 0.5 mM MgCl2, and 0.5% BSA) for 2 hrs at 37 °C. Both the sialidase treated and the untreated control cells (treated with only EDB/BSA buffer) were infected with 0.1 MOI of virus. After 1 hour, the cells were washed two times with PBS and incubated in DMEM:F12 supplemented with 0.2% ITS (Gibco) and 0.6 ug/ml acetylated trypsin (Sigma). Forty to 48 hours post-infection, the levels of cell-bound virus were determined by using a cell-based ELISA assay. Specifically, cells were fixed in 0.05% glutaraldehyde in PBS and were incubated with 50 |ol of 103 dilution of either antiinfluenza A NP antiserum or anti-influenza B (Fitzgerald Inc.) in 0.5% BSA and PBS at 37°C for 1 hr. After washing, each well was incubated with HRP-protein G in 0.5% BSA and PBS for 1 hr. After final washes, 50ul of 25 mM sodium citrate (pH 4.5) containing 0.02% 3,3',5,5'-tetramethylbenzidine dihydrochloride (Sigma) and 0.01% hydrogen peroxide was allowed to react with the cells at room temperature for 5 min. The reactions were stopped by adding 50 ul of 1M t^SO^ and quantitated by measuring optical densities at 450 nM. Percentage viral replication inhibition is calculated by 100% x {(virus only samples - sialidase treated samples)/(virus only samples - uninfected samples)}. Data on inhibition of viral replication and cell protection ECSO's and selective indexes for recombinant sialidase fusion proteins AR-AvCD made from Construct #2 and AR-G4S-AvCD made from Construct #3 for a variety of human influenza A and influenza B viruses, as well as equine viruses are shown in Figure 12. As shown in Figure 10, sialidase fusion proteins strongly inhibited amplification of a broad selection of influenza viruses. Notably, 80-100% viral inhibition (Figure 10) as well as cell protection (Figure 9) was achieved although a maximum of 70-80% of cell surface sialic acid was removed by the sialidase treatment (Figure 8). This finding demonstrates that it is unnecessary to completely eliminate cell surface sialic acid in order to achieve the desired therapeutic effect of treating with the sialidase fusion proteins of the present invention. The residual 20-30% of the surface sialic acid, while being inaccessible for the sialidase fusion proteins, is probably inaccessible for influenza viruses as well. Cvtotoxicity of sialidase fusion proteins To evaluate the cytotoxicity of AR-AvCD or AR-G4S-AvCD proteins (made from Constructs #2 and #3), MDCK cells were seeded at low density in 96-well plates and cultured for 5 days in DMEM containing 10% FBS and up to 20 U of AR-AvCD protein or AR-G4S-AvCD protein per well (both sialidases remained fully active during the entire experiment). Cell density in AR-AvCD or AR-G4S-AvCD treated or control wells were determined every day by staining the cells with crystal violet and measuring absorption at 570 nM. No inhibition of cell growth was observed even at the highest concentration of AR-AvCD or AR-G4S-AvCD (100 U/ ml) in the culture. Therefore IC50, which is the drug concentration that inhibits cell growth by 50%, for AR-AvCD or AR-G4S-AvCD is above 100 U/ml. Example 14: In vivo Activities ofSialidase Catalytic Domain Fusion Protein Ferrets can be infected with human unadapted influenza viruses and produce signs of disease comparable to those of humans, which can be treated by antiviral compounds, such as zanamivir (Relenza). (Mendel et al., Antimicrob Agents Chemother, (1998) 42(3), 640-646; Smith and Sweet, Rev. Infect. DiS., (1988) 10(1), 56-75; Reuman et al., 1 Virol. Methods, (1989) 24(1-2), 27-34). To evaluate in vivo efficacy of our compounds, we tested AR-AvCD protein (made from Construct #2) in the ferret model. Specifically, 24 young female ferrets (0.5-0.8 kg) (Marshall Farms, North Rose, NY) that tested negative for the presence of anti-hemagglutinin antibodies in sera were included in the study. Two animals were placed in each cage and allowed to acclimate for 3 days before the experiment. The animals were randomly divided into three groups: 8 animals were treated with drug dilution buffer and viral challenge, 12 animals were treated with AR-AvCD and viral challenge, and 4 animals were treated with AR-AvCD only. A preparation of AR-AvCD dissolved in phosphate buffered saline (PBS) that contains 500 U/ml in sialidase activity and 0.7 mg/ml in protein concentration was used in the study. Animals in the drug treatment groups received 1 ml of AR-AvCD at each dose, which amounts to about 1 mg/kg in dosage level. Ferrets were anesthetized and inoculated intranasally (0.5 ml into each nostril) with AR-AvCD or PBS twice (8 am and 6pm) and daily for a total of 7 days (2 days prior to the viral challenge and 5 days post virus inoculation). The ferrets were observed following the drug application for signs of intolerance. Viral inoculation was carried out on day 3 between 10-11 am. The viral challenge was done with human A/Bayern/7/95 (HlNl)-like virus at dose 105 TCIDso (>104 ferret IDso). The nasal washes were collected from all animals starting day 2 post AR-AvCD treatment and continued until day 7. To collect nasal washes, 1 ml of sterile PBS was administered intranasally, the sneezed liquid was harvested and its volume was recorded. The nasal washes were centrifuged. The pelleted cells were re-suspended and counted in a hemacytometer under a microscope. The supernatants were collected, aliquoted and stored at -80°C. The protein concentration in cell-free nasal washes was determined by using the Bio-Rad protein reagent according to manufacturer's protocol (Bio-Rad, Hercules, CA). For virus titration of the nasal washes, inoculated MDCK cells were incubated for 3 days at 36°C in a CO2 incubator. The monolayers were inspected visually for cytopathic effect (CPE) and aliquots of the cell culture supernatants from each well were tested for the virus presence by a standard hemagglutination assay with guinea pig red blood cells. Viral liter was determined by the Spearman Karber method ( (1996) ). In uninfected animals given intranasal AR-AvCD (n=4), no apparent effect on the inflammatory cell counts and protein concentrations in the nasal washes was observed (Figure 15 A and B). Nasal washes from these animals were followed for 7 days and were all negative for viral shedding. No signs of drug-related toxicity were detected in these animals at the drug dose used in this study. In the vehicle-treated group, virus replicated in the nasal epithelium of all 8 ferrets. Viral shedding reached peak values of 4.4 to 5.9 logioTCIDso (mean peak titer of 4.9) on day 1 or 2 post challenge, diminished over time and became negative by day 5 (Figure 13). By contrast, only 3 of 12 ARAvCD- treated ferrets were positive for viral shedding on day 1 post challenge (Figure 13), and their nasal viral titers were about 100 times lower than those in the vehicletreated animals (mean 2.4+0.3 vs. 4.4+0.4 logi0TCID50) (Figure 13). After day 1, the response to the AR-AvCD treatment varied substantially. Three animals were completely protected against infection, signs of illness, and inflammatory response (Figure 13), ferret tag # 803, 805, 806). The protection was also confirmed by a lack of seroconversion on day-14 post challenge. One ferret (tag #780) did not shed virus during the first three days post challenge, but it died on day 4 post infection from an unrelated injury. The shedding in the remaining 8 ferrets varied during the course of infection, ranging from ferret #812 that shed virus for a day only, to the ferret #791 that shed virus for 5 days. Infection in the ferrets that shed virus for at least one day was confirmed by more than a 16-fold rise in the post-challenge anti-HA antibody titer (seroconversion). There was no apparent effect of AR-AvCD treatment on the anti-HA titers in post-challenge sera (320-1280, vs. 160-1280, vehicle- and drug-treated group, respectively). In ferrets that shed the virus despite the AR-AvCD treatment (n=8), the inflammatory response was reduced and animals appeared to be more alert and active compared to the untreated ferrets that were invariably lethargic and feverish. For this group of 8 infected, AR-AvCD-treated animals, the mean AUC (area under the curve) 81 value calculated for the nasal protein concentrations was reduced by approximately 40% (2.68 vs. 4.48, arbitrary units) compared to the vehicle-treated infected animals (Figure 11B). In vehicle-treated infected animals, the number of inflammatory cells in nasal washes was increased to approximately 100-fold above those in uninfected animals on day 2 post challenge. These levels were sustained for 4 additional days. The AR-AvCDtreated animals exhibited a significant reduction in the number of inflammatory cells in the nasal washes. Specifically, the AUC value for cell counts was reduced by approximately 3-fold in the AR-AvCD-treated animals compared to the vehicle-treated infected animals (1965 vs. 674, arbitrary units, Figure 11 A). The observed reduction in the inflammatory response indicates the importance of inhibiting viral replication at the early stage of infection. Example 15. Inhibition of Bacterial Cell Adhesion bySialidase Fusion Proteins Bacteria S. pneumoniae: 10 encapsulated strains of different serotypes are selected from the clinical isolates deposited at ATCC. Bacteria are maintained as frozen stocks and passaged on tryptic soy agar plates containing 3% sheep blood (Difco & Micropure Medical Inc.) for 18 hr at 37°C in 5% CC>2. To label pneumococci with radioisotope, an inoculum is taken from a 1- to 2-day plate culture, added to lysine-deficient tryptic soy broth containing 70 uCi of [3H] lysine per ml and incubated at 37°C in 5% CO2. The growth of each culture is monitored by light absorbance at 595 nm. At late logarithmic phase, the bacteria are harvested, washed twice by centrifugation (13,000rpm x 3min), and resuspended in L-15 medium (without phenol red) plus 0.1% BSA (L-15-BSA) (Cundell and Tuomanen, Microb. Pathog., (1994) 17(6), 361-374) (Barthelson et al., Infect. Immun., (1998) 66(4), 1439-1444). H. influenzae: 5 strains of type b (Hib) and 10 nontypable strains (NTHi) are obtained from the clinical isolates deposited at ATCC. All strains are stocked in brain heart infusion (BHI, Difco) containing hemin (ICN) and NAD (Sigma) and kept frozen until use; then they are cultured on BHI agar supplemented with hemin and NAD and grown for 14 hr at 37°C with 5% CO2. (Kawakami et al., Microbiol. Immunol., (1998) 42(10), 697-702). To label the bacteria with [3H], H. influenzae cells are inoculated in BHI broth containing hemin, NAD and [3H]leucine at 250 uCi/ml and allowed to grow until late logarithmic phase and then harvested, washed and resuspended in L-15-BSA (Barthelson et al., Infect. Immun., (1998) 66(4), 1439-1444). Cell Adhesion Assay All [3H]-labeled bacteria are suspended in L-15-BSA after washing, the bacterial concentration is determined by visual counting with a Petroff-Hausser chamber, radioactivity is determined by scintillation counting, and the specific activity of the [3H]- labeled cells is calculated. Preparations of bacteria with 7cpm/1000 cells or greater are used. The bacteria are diluted to 5x 108 cells/ml. BEAS-2B cell monolayers are incubated with [3H]-labeled bacterial suspension containing 5 x 107 bacteria at 37°C in 5% CO2. After 30 min, unbound bacteria are removed by washing with L-15-BSA for 5 times. Bacteria attached to the WD-HAE tissue samples are quantitated by scintillation counting. Desialylation of BEAS-2B cells by sialidase fusion proteins and effects on cell adhesion by H. influenzae and S. pneumoniae. BEAS-2B cells are incubated with 1-50 mU of AR-AvCD for 2 hours. Cell adhesion assay will be carried out using H. influenzae and 5. pneumoniae strains as described above. Mock treated cells are used as positive control. Efficacy of AR-AvCD is quantitated as the ECso, which is the amount of enzyme to achieve 50% inhibition on bacterial adhesion. Example 16. Improving Transduction Efficiency of AAV Vector using Sialidase Fusion Proteins In vitro Experiments An experiment demonstrating effect of AR-AvCD is performed in a way similar to the procedure published (Bals et al., J Virol., (1999) 73(7), 6085-6088). A monolayer of Well-Differentiated Airway Epithelium (WDAE) cells is maintained in transwells (Karp et al., Methods Mol. Biol., (2002) 188, 115-137; Wang et al., J Virol., (1998) 72(12), 9818-9826). In order to eliminate sialic acid from the cell surface the culture medium is replaced with serum free medium in which 0.5-10 units of AR-AvCD are dissolved. The cells are treated for 30 min to 6 hours. The cell monolayers are washed, transduced with AAV, and transduction efficiency is estimated using standard procedures. Several transwells are treated with medium only (without AR-AvCD) to serve the purpose of control (basal transduction efficiency). Additional controls may include the transwells treated with AR-AvCD only to assess cytotoxic effect of desialylation. A reporter virus is used for facile detection of transduced cells. Examples of reporter AAV and their use have been described in literature and include AAV-CMVeGFP, AAV2LacZ (Bals et al., J Virol., (1999) 73(7), 6085-6088; Wang et al., Hum. Gene Ther., (2004) 15(4), 405-413) and alkaline phosphatase (Halbert et al., Nat. Biotechnol., (2002) 20(7), 697-701). The efficiency is estimated by light microscopy of the cells that were fixed and treated with appropriate substrate (if lacZ or AP containing virus is used) or fluorescent microscopy of live cells (if GFP is used). According to the experiments conducted at NexBio with NHBE primary epithelial cells (Cambrex, Walkersville, MD) the maximum amount of removal of sialic acid is achieved in less than one hour when 10 units of AR-AvCD per transwell are used. Other cell lines used (e.g. MDCK) become desialylated with much less AR-AvCD administered (0.1 U for 1 hour). It is therefore our estimate that a treatment of WDAE with 10 U of AR-AvCD for 2 hours will be sufficient to remove accessible sialic acid and provide significant enhancement of transduction of WDAE cells with AAV. Testing Effect of AR-AvCD Treatment on AAV Transduction in an Animal Model. To demonstrate effect of AR-AvCD treatment in animal model an experiment similar to previously described is conducted (Flotte et al., Proc. Natl. Acad. Sci. U. S. A, (1993) 90(22), 10613-10617; Halbert et al., Nat. Biotechnol., (2002) 20(7), 697-701). Several hours (1-6) prior to administration of AAV AR-AvCD is delivered to mice lungs by nasal aspiration of aerosole or lyophilized AR-AvCD powder according to previously published protocol (Flotte et al., Proc. Natl. Acad. Sci. U. S. A, (1993) 90(22), 10613- 10617). AAV carrying reporter gene (alkaline phosphatase) is delivered by nasal aspiration, mice are euthanized 4 weeks later and transduced cells are detected in fixed lungs as previously described (Halbert et al., J ViroL, (1998) 72(12), 9795-9805). Example 17. Sialidase Treatment Inhibits Mast Cell Functions and Smooth Muscle Contraction in the Trachea. Using experimental methods described previously (Cocchiara et al., J Neuroimmunol., (1997) 75(1-2), 9-18), it will be demonstrated that treatment by compounds of the present invention prevents substance P (SP) induced histamine release by mast cells. Using another set of experiments (Stenton et al., J Pharmacol. Exp. Ther., (2002) 302(2), 466-474), treatment by compounds of the present invention will inhibit p-hexosaminidase release by mast cells stimulated by two PAR-activating peptides (PAR stands for proteinase-activated receptors). Compounds of the present invention will be administered intratracheally in guinea pigs and the airway reactivity will be assessed in the animals as described previously (Jarreau et al., Am. Rev. Respir. Dis., (1992) 145(4 Pt 1), 906-910; Stenton et al., J Pharmacol. Exp. Ther., (2002) 302(2), 466-474). Sialidase treatment should not induce nonspecific airway hyperreactivity judged by the reaction to multiple inducers. In addition, sialidase treatment should reduce substance P-induced bronchoconstriction. Similarly, compounds of the present invention will be used to treated the isolated guinea pig and rat trachea and lung (Kai et al., Eur. J. Pharmacol., (1992) 220(2-3), 181-185; Stenton et al., J Pharmacol. Exp. Ther., (2002) 302(2), 466-474). Again recombinant sialidase treatment will have no effect on smooth muscle contractions induced by acetylcholine, histamine and 5-hydroxytryptamme. In addition, it will inhibit tracheal contraction induced by antigen (ovalbumin) or compound 48/80. Bibliography Achyuthan, KE and Achyuthan AM. 2001. Comparative enzymology, biochemistry and pathophysiology of human exo-a-sialidases (neuraminidases). Comparative Biochem & Physiol part 8129:29-64. Air, GM and Laver, WG. 1995. Red cells bound to influenza virus N9 neuraminidase are not released by the N9 neuraminidase activity. Virology 211:278-284. Auerswald EA, Horlein D, Reinhardt G, Schroder W and Schnabel E. 1988. Expression, isolation and characterization of recombinant [Arg15, Glu52] Aprotinin. Biol Chem Hoppe-Seyler Vol 369, Suppl., pp27-35. Barbey-Morel CL, Oeltmann TN, Edwards KM and Wright PF. 1987. Role of respiratory tract proteases in infectivity of influenza A virus. J Infect Dis 155:667-672. Bessette PH, Aslund F, Beckwith J and Georgiou G. 1999. Efficient folding of proteins with multiple disulfide bonds in the Escherichia coli cytoplasm. Pro Natl Acad Sci USA 96:13703-13708. Callan RJ, Hartmann FA, West SE and Hinshaw VS. 1997. Cleavage of influenza A virus HI hemagglutinin by swine respiratory bacterial proteases. J Virol 71:7579-7585. Connor, RJ, Kawaoka, Y, Webster, RG and Paulson JC. 1994. Receptor specificity in human, avian, and equine H2 and H3 influenza virus isolates. Virology 205:17-23. Copley, RR, Russell, RB and Ponting, CP. 2001. Sialidase-like Asp-boxes: sequencesimilar structures within different protein folds. Prot Sci 10:285-292. Corfield, AP, Veh, RW, Wember, M, Michalski, JC and Schauer, R. 1981. The release of N-acetyl- and N-glycolloyl-neuraminic acid from soluble complex carbohydrates and erythrocytes by bacterial, viral and mammalian sialidases. Bichem J 197:293-299. Crennell, SJ, Garman, E, Laver, G, Vimr, E and Taylor, G. 1994. Crystal structure of Vibrio Cholerae neuraminidase reveals dual lectin-like domains in addition to the catalytic domain. Structure 2:535-544. Drzeniek, R. Substrate specificity of neuraminidases. 1973. Histochem J 5:271-290. Endo Y, Carroll KN, Ikizler MR and Wright PF. 1996. Growth of influenza virus in primary, differentiated epithelial cells derived from adenoids. J Virol 70:2055-2058. Fritz H and Wunderer G. 1983. Biochemistry and applications of aprotinin, the kallikrein inhibitor from bovine organs. Arzneim-Forsch 33:479-494. Fukudome, K., Yoshie, O. and Konno, T. 1989. Comparison of human, simian, and bovine rotaviruses for requirement of sialic acid in hemagglutination and cell adsorption. Virology 172:196-205. Garten W, Bosch FX, Linder D, Rott R and Klenk HD. 1981. Proteolytic activation of the influenza virus hemagglutinin: the structure of the cleavage site and the enzymes involved in cleavage. Virology 115:361-374. Goger, B, Halden, Y, Rek, A, Mosl, R, Pye, D, Gallagher, J and Kungl, AJ. 2002. Different affinities of glycosaminoglycan oligosaccharides for monomeric and dimeric interleukin-8: a model for chemokine regulation at inflammatory sites. Bichem 41:1640- 1646. Gotoh B, Ogasawara T, Toyoda T, Inocencio N, Hamaguchi M and Nagai Y. 1990. An endoprotease homologous to the blood clotting factor X as a determinant of viral tropism in chick embryo. EMBO J 9:4189-4195. Granoff, A. & Webster, R. G., ed. Encyclopedia of Virology, 2nd Edition, Vol 2. Gust, ID, Hampson, AW. and Lavanchy, D. 2001. Planning for the next pandemic. Rev MedVirol 11:59-70. Hayden, FG. 1996. Amantadine and rimantadine-mechanisms. In Antiviral drug resistance (ed. D. D. Richman), pp. 59-77. Chichester, UK: John Wiley & Sons Ltd. Hosoya M, Matsuyama S, Baba M, Susuki H and Shigeta S. 1992. Effects of protease inhibitors on replication of various myxoviruses. Antimicrobial Agents and Chemotherapy 36:1432-1436. Ito, T. 2000. Interspecies transmission and receptor recognition of influenza a virus. Microbiol Immunol 44(6):423-430. Janakiraman, MN, White, CL, Laver, WG, Air, GM and Luo, M. 1994. Structure of influenza virus neuraminidase B/lee/40 complexed with sialic acid and a dehydro analog at 1.8-A resolution: implications for the catalytic mechanism. Biochemistry 33:8172- 8179. Kido, H, Niwa, Y, Beppu, Y and Towatari, T. 1996. Cellular proteases involved in the pathogenicity of enveloped animal viruses, human immunodeficiency virus, influenza virus A and sendai virus. Advan Enzyme Regul 36:325-347. Kido H, Chen Y and Murakami M. 1999. Cellular proteinases and viral infection: influenza virus, sendai virus and HIV-1, p.205-217. In B. Dunn (ed.), Proteases of infectious agents. Academic Press, New York, N.Y. 88 Klenk, HD and Rott, R. 1988. The molecular biology of influenza virus pathogenicity. AdvVir Res 34:247-281. Klenk, HD and Garten W. 1994. Host cell proteases controlling virus pathogenicity. Trend Micro 2:39-43. Kreisel, W, Volk, BA, Buchsel, R. and Reutter, W. 1980. Different half-lives of the carbohydrate and protein moieties of a 110,000-dalton glycoproteins isolated from plasma membranes of rat liver. Proc Natl Acad Sci USA 77:1828-1831. Krunkosky TM, Fischer BM, Martin LD, Jones N, Akley NJ and Adler KB. 2000. Effects of TNF-P on expression of 1C AM-1 in human airway epithelial cells in vitro. Am J Respir Cell Mol Biol 22:685-692. Lazarowitz SG, Goldberg AR and Choppin PW. 1973. Proteolytic cleavage by plasmin of the HA polypeptide of influenza virus: host cell activation of serum plasminogen. Virology 56:172-180. Lee, MK and Lander, AD. 1991. Analysis of affinity and structural selectivity in the binding of proteins to glycosaminoglycans: development of a sensitive electrophoretic approach. Pro Natl Acad Sci USA 88:2768-2772. Meltzer, MI, Cox, NJ and Fukuda, K. 1999. The economic impact of pandemic influenza in the United States: priorities for intervention. Emerg Infect Dis 5:659-671. Meyer, FA, King, M and Gelman, RA., 1975. On the role of sialic acid in the rheological properties of mucus. Biochimica et Biophysica Acta 392: 223-232. Milner, CM, Smith, SV, Carrillo MB, Taylor, GL, Hollinshead, M and Campbell, RD. 1997. Identification of a sialidase encoded in the human major histocompatibility complex. JBio Chem 272:4549-4558. Monti, E, Preti, A, Venerando, B and Borsani, G. 2002. Recent development in mammalian sialidase molecular biology. Neurochem Res 27:646-663. Monti, E, Preti, A, Nesti, C, Ballabio, A and Borsani G. 1999. Expression of a novel human sialidase encoded by the NEU2 gene. Glycobiol 9:1313-1321. Monti, E, Bassi, MT, Papini, N, Riboni, M, Manzoni, M, Veneranodo, B, Croci, G, Preti, A, Ballabio, A, Tettamanti, G and Borsani, G. 2000. Identification and expression of NEU3, a novel human sialidase associated to the plasma membrane. Bichem J349:343- 351. Murakami M, Towatari T, Ohuchi M, Shiota M, Akao M, Okumura Y, Parry MA and Kido H. 2001. Mini-plasmin found in the epithelial cells of bronchioles triggers infection by broad-spectrum influenza A viruses and Sendai virus. Eur J Biochem 268: 2847-2855. Nakayama, K. 1997. Furin: a mammalian subtilisin/kex2p-like endoprotease involved in process of a wide variety of precursor proteins. Biochem 327:625-635. Ovcharenko AV and Zhirnov OP. 1994. Aprotinin aerosol treatment of influenza and paramyxovirus bronchopneumonia of mice. Antiviral Res 23:107-118. Pshezhetsky, A, Richard, C, Michaud, L, Igdoura, S, Wang, S, Elsliger, M, Qu, J, Leclerc, D, Gravel, R, Dallaire, L and Potier, M. 1997. Cloning, expression and chromosomal mapping of human lysosomal sialidase and characterization of mutations in sialidosis. Nature Genet 15: 316-320. Ramphal, R. and Pyle, M. 1983. Evidence for mucins and sialic acid as receptors for Pseudomonas aeruginosa in the lower respiratory tract. Infect Immun 41:339-44. 90 Roggentin, P, Kleineidam, RG and Schauer, R. 1995. Diversity in the properties of two sialidase isoenzymes produced by Clostridium perfringens spp.. Biol Chem Hoppe-Seyler 376:569-575. Roggentin, P, Schauer, R, Hoyer, LL and Vimr, ER. 1993. The sialidase superfamily and its spread by horizontal gene transfer. Mol Microb 9:915-921. Rosenberg A. ed. Biology of the Sialic Acids. 1995. pp270-273. Sakurada, K, Ohta, T and Hasegawa, M. 1992. Cloning, expression and characterization of the Micromonospora viridifaciens neuraminidase gene in Streptomyces lividans. J Bacteriol 174:6896-6903. Schauer, S. ed., pp233. Sialic Acids Chemistry, Metabolism and Function. Springer- Verlag, 1982. Schauer, R. 1982. Chemistry, metabolism, and biological functions of sialic acids. Adv. Carbohydrate Chem &Biochem 40:131-235. Scheiblauer H, Reinacher M, Tashiro M and Rott R. 1992. Interactions between bacteria and influenza A virus in the development of influenza pneumonia. J Infec Dis 166:783- 791. Sinn PL, Williams G, Vongpunsawad S, Cattaneo R and McCray PB. 2002. Measles virus preferentially transduces the basolateral surface of well-differentiated human airway epithelia. J Virol 76:2403-2409. Skehel, JJ and Wiley, DC. 2000. Receptor binding and membrane fusion in virus entry: the influenza hemagglutinin. Annu Rev Biochem 69:531 -569. Tashiro M, Klenk HD and Rott R. 1987. Inhibitory effect of a protease inhibitor, leupeptin, on the development of influenza pneumonia, mediated by concomitant bacteria. J Gen Virol 68:2039-2043. Tashiro M, Ciborowski P, Reinacher M, Pulverer G, Klenk HID and Rott R. 1987. Synergistic role of staphylococcal proteases in the induction of influenza virus pathogenecity. Virology 157:421-430. Teufel, M, Roggentin, P. and Schauer, R. 1989. Properties of isialidase isolated from Actinomyces viscosus DSM43798. Biol Chem Hoppe Seyler 370:435-443. Tobita, K, Sugiura, A, Enomoto, C and Furuyama, M. 1975. Plaque assay and primary isolation of influenza A viruses in an established line of canine kidney cells (MDCK) in the presence of trypsin. Med Microbiol Immnuol 162:9-14. Venturi M, Seifert C and Hunte C. 2001. High level production of functional antibody Fab fragments in an oxidizing bacterial cytoplasm. J Mol Biol 315:1-8. Vimr, DR. 1994. Microbial sialidases: does bigger always mean better? Trends Microbiol 2: 271-277. Vlasak, R., Luytjes, W., Spaan, W. and Palese, P. 1988. Human and bovine coronaviruses recognize sialic acid-containing receptors similar to those of influenza C viruses. Proc Natl Acad Sci USA 85:4526-4529. Wada, T, Yoshikawa, Y, Tokuyama, S, Kuwabara, M, Akita, H and Miyagi, T. 1999. Cloning, expression, and chromosomal mapping of a human ganglioside sialidase. Biochem Biophy Res Communi 261:21-27. Wang, FZ, Akula, SM, Pramod, NP, Zeng, L and Chandran, B. 2001. Human herpesvirus 8 envelope glycoproteins K8.1A interaction with the target cells involves heparan sulfate. JVirol 75:7517-27 Wassilewa, L. 1977. Cell receptor for paramyxoviruses. Arch Virol 54:299-305. Weisgraber, KH, Rail, SC, Mahley, RW, Milne, RW and Marcel, Y. 1986. Human apoliproprotein E, determination Witt, DP and Lander AD. 1994. Differential binding of chemokines to glycosaminoglycan subpopulations. Curr Bio 4:394-400. Wood, J. 2001. Developing vaccines against pandemic influenza. Phil Trans R Soc Land B 356:1953-1960. Xiang Y and Moss B. 2003. Molluscum contagiosum virus interleukin-18 (IL-18) binding protein is secreted as a full-length form that bind cell surface glycosaminoglycans through the C-terminal tail and a furin-cleaved form with only the IL-18 binding domain. J Virol 77:2623-2630. Zambon, M. 2001. The pathogenesis of influenza in humans. Rev Med Virol 11:227- 241. Zhang L, Peeples ME, Boucher RC, Collins PL and Pickles RJ. 2002. Respiratory syncytial virus infection of human airway epithelial cells is polarized, specific to ciliated cells, and without obvious cytopathology. J Virol 76:5654-5666. Zhirnov OP, Ovchartenko AV and Bukrinskaya AG. 1982. Protective effect of protease inhibitors in influenza virus infected animals. Arch Virol 73:263-272 Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. 1982. A modified plaque assay method for accurate analysis of infectivity of influenza viruses with uncleaved hemagglutinin. Arch Virol 71:177-183. Zhirnov OP. 1983. Proteolytic activation of myxo viruses and a new strategy in the treatment of viral diseases. Problems Virol. 4:9-12. (In Russian). Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. 1984. Suppression of influenza virus replication in infected mice by protease inhibitors. J Gen Virol 65:191-196. Zhirnov OP, Ovcharenko AV and Bukrinskaya AG. 1985. Myxovirus replication in chicken embryos can be suppressed by aprotinin due to the blockage of viral glycoprotein cleavage. J Gen Virol 66:1633-1638. Zhirnov OP. 1987. High protection of animals lethally infected with influenza virus by aprotinin-rimantadine combination. J Med Virol 21:161-167. Zhirnov OP, Ikizler MR and Wright PF. 2002. Cleavage of influenza A virus hemagglutinin in human respiratory epithelium is cell associated and sensitive to exogenous antiproteases. J Virol 76:8682-8689. Bartlett J.G., Breiman R.F., Mandell L.A., & File T.M., Jr. (1998) Community-acquired pneumonia in adults: guidelines for management. The Infectious Diseases Society of America. Clin.Infect.Dis. 26, 811-838. Andrews J., Nadjm B., Gant V., & Shetty N. (2003) Community-acquired pneumonia. Curr.Opin.Pulm.Med. 9, 175-180. File T.M. (2000) The epidemiology of respiratory tract infections. Semin.Respir.Infect. 15, 184-194. iviacfarlane J. (1994) An overview of community acquired pneumonia with lessons learned from the British Thoracic Society Study. Semin.Respir.Infect. 9, 153-165. Matsushima T., Miyashita N., & File T.M., Jr. (2002) Etiology and management of community-acquired pneumonia in Asia. Curr.Opin.Infect.Dis. 15, 157-162. Ball P. (1995) Epidemiology and treatment of chronic bronchitis and its exacerbations. Chest 108, 43S-52S. Faden H. (2001) The microbiologic and immunologic basis for recurrent otitis media in children. Eur.JPediatr. 160, 407-413. Garcia-Rodriguez, JA and Martinez, MJF. Dynamics of nasopharyngeal colonization by potential respiratory pathogens. J Antimicrob Chemother 50[Suppl S2], 59-73. 2002. Soriano F. & Rodriguez-Cerrato V. (2002) Pharmacodynamic and kinetic basis for the selection of pneumococcal resistance in the upper respiratory tract. J Antimicrob Chemother 50 Suppl S2, 51 -58. Mbaki N., Rikitomi N., Nagatake T., & Matsumoto K. (1987) Correlation between Branhamella catarrhalis adherence to oropharyngeal cells and seasonal incidence of lower respiratory tract infections. Tohoku J Exp.Med. 153, 111-121. Zopf D. & Roth S. (1996) Oligosaccharide anti-infective agents. Lancet 347, 1017-1021. Cundell D.R., Weiser J.N., Shen J., Young A., & Tuomanen E.I. (1995) Relationship between colonial morphology and adherence of Streptococcus pneumoniae. Infect.Immun. 63, 757-761. Karlsson K.A. (1998) Meaning and therapeutic potential of microbial recognition of host glycoconjugates. Mol.Microbiol. 29, 1-11. Andersson B., Porras O., Hanson L.A., Lagergard T., & Svanborg-Eden C. (1986) Inhibition of attachment of Streptococcus pneumoniae and Haemophilus influenzae by human milk and receptor oligosaccharides. J Infect.Dis. 153, 232-237. Bals R., Xiao W., Sang N., Weiner D.J., Meegalla R.L., & Wilson J.M. (1999) Transduction of well-differentiated airway epithelium by recombinant adeno-associated virus is limited by vector entry. J Virol. 73, 6085-6088. Barthelson R., Mobasseri A., Zopf D., & Simon P. (1998) Adherence of Streptococcus pneumoniae to respiratory epithelial cells is inhibited by sialylated oligosaccharides. Infect.Immun. 66, 1439-1444. Cundell D.R. & Tuomanen E.I. (1994) Receptor specificity of adherence of Streptococcus pneumoniae to human type-II pneumocytes and vascular endothelial cells in vitro. Microb.Pathog. 17, 361-374. Fakih M.G., Murphy T.F., Pattoli M.A., & Berenson C.S. (1997) Specific binding of Haemophilus influenzae to minor gangliosides of human respiratory epithelial cells. Infect.Immun. 65, 1695-1700. Kawakami K., Ahmed K., Utsunomiya Y., Rikitomi N., Hori A., Oishi K., & Nagatake T. (1998) Attachment of nontypable Haemophilus influenzae to human pharyngeal epithelial cells mediated by a ganglioside receptor. Microbiol.Immunol. 42, 697-702. Solzbacher D., Hanisch F.G., van Alphen L., Gilsdorf J.R., & Schroten H. (2003) Mucin in middle ear effusions inhibits attachment of Haemophilus influenzae to mucosal epithelial cells. Eur.Arch.Otorhinolaryngol. 260, 141-147. van Alphen L., Geelen-van den Broek L., Blaas L., van Ham M., & Dankert J. (1991) Blocking of fimbria-mediated adherence of Haemophilus influenzae by sialyl gangliosides. Infect.Immun. 59, 4473-4477. Ahmed K., Matsumoto K., Rikitomi N., & Nagatake T. (1996) Attachment of Moraxella catarrhalis to pharyngeal epithelial cells is mediated by a glycosphingolipid receptor. FEMS Microbiol.Lett. 135, 305-309. Hazlett L.D., Moon M, & Berk R.S. (1986) In vivo identification of sialic acid as the ocular receptor for Pseudomonas aeruginosa. Infect.Immun. 51, 687-689. Baker N., Hansson G.C., Leffler H., Riise G., & Svanborg-Eden C. (1990) Glycosphingolipid receptors for Pseudomonas aeruginosa. Infect.Immun. 58, 2361-2366. Schultze B., Gross H.J., Brossmer R., & Herrler G. (1991) The S protein of bovine coronavirus is a hemagglutinin recognizing 9-O-acetylated sialic acid as a receptor determinant. J Virol. 65, 6232-6237. Wuppermann F.N., Hegemann J.H., & Jantos C.A. (2001) Heparan sulfate-like glycosaminoglycan is a cellular receptor for Chlamydia pneumoniae. J'Infect.Dis. 184, 181-187. Beswick E.J., Travelstead A., & Cooper M.D. (2003) Comparative studies of glycosaminoglycan involvement in Chlamydia pneumoniae and C. trachomatis invasion of host cells. JInfect.Dis. 187, 1291-1300. Martinez I. & Melero J.A. (2000) Binding of human respiratory syncytial virus to cells: implication of sulfated cell surface proteoglycans. J Gen. Virol. 81, 2715-2722. Thomas R.J. & Brooks T.J. (2004) Oligosaccharide receptor mimics inhibit Legionella pneumophila attachment to human respiratory epithelial cells. Microb.Pathog. 36, 83-92. Hirmo S., Kelm S., Schauer R., Nilsson B., & Wadstrom T. (1996) Adhesion of Helicobacter pylori strains to alpha-2,3-linked sialic acids. Glycoconj.J 13, 1005-1011. Simon P.M., Goode P.L., Mobasseri A., & Zopf D. (1997) Inhibition of Helicobacter pylori binding to gastrointestinal epithelial cells by sialic acid-containing oligosaccharides. Infect.Immun. 65, 750-757. Miller-Podraza H., Bergstrom J., Milh M.A., & Karlsson K.A. (1997) Recognition of glycoconjugates by Helicobacter pylori. Comparison of two sialic acid-dependent specificities based on haemagglutination and binding to human erythrocyte glycoconjugates. Glycoconj.J 14, 467-471. Crocker P.R. & Varki A. (2001) Siglecs, sialic acids and innate immunity. Trends Immunol. 22, 337-342. Angata T. & Brinkman-Van der Linden E. (2002) I-type lectins. Biochim.Biophys.Acta 1572,294-316. Lyczak J.B., Cannon C.L., & Pier G.B. (2002) Lung infections associated with cystic fibrosis. Clin.Microbiol.Rev. 15, 194-222. Flotte T.R. & Carter BJ. (1998) Adeno-associated virus vectors for gene therapy of cystic fibrosis. Methods Enzymol. 292, 717-732. Wagner J.A., Reynolds T., Moran M.L., Moss R.B., Wine J.J., Flotte T.R., & Gardner P. (1998) Efficient and persistent gene transfer of AAV-CFTR in maxillary sinus. Lancet 351, 1702-1703. Martinez I. & Melero J.A. (2000) Binding of human respiratory syncytial virus to cells: implication of sulfated cell surface proteoglycans. J Gen. Virol. 81, 2715-2722. Park P.W., Pier G.B., Hinkes M.T., & Bernfield M. (2001) Exploitation of syndecan-1 shedding by Pseudomonas aeruginosa enhances virulence. Nature 411, 98-102. Monti E., Preti A., Venerando B., & Borsani G. (2002) Recent development in mammalian sialidase molecular biology. Neurochem.Res. 27, 649-663. (1995) Biology of the Sialic Acids, 270-273. Roggentin P., Kleineidam R.G., & Schauer R. (1995) Diversity in the properties of two sialidase isoenzymes produced by Clostridium perfringens spp. Biol.Chem.Hoppe Seyler 376, 569-575. Sutler V.L. (1984) Anaerobes as normal oral flora. Rev.Infect.Dis. 6 Suppl 1, S62-S66. Gaskell A., Crennell S., & Taylor G. (1995) The three domains of a bacterial sialidase: a beta-propeller, an immunoglobulin module and a galactose-binding jelly-roll. Structure. 3, 1197-1205. Alvarez P., Buscaglia C.A., & Campetella O. (2004) Improving protein pharmacokinetics by genetic fusion to simple amino acid sequences. J.Biol.Chem. 279, 3375-3381. Potier M., Mameli L., Belisle M., Dallaire L., & Melancon S.B. (1979) Fluorometric assay of neuraminidase with a sodium (4-methylumbelliferyl-alpha-D-Nacetylneuraminate) substrate. Anal.Biochem. 94, 287-296. Hirel P.H., Schmitter M.J., Dessen P., Fayat G., & Blanquet S. (1989) Extent of Nterminal methionine excision from Escherichia coli proteins is governed by the side-chain length of the penultimate amino acid. Proc.Natl.Acad.Sci.U.S.A 86, 8247-8251. Varshavsky A. (1996) The N-end rule: functions, mysteries, uses. Proc.Natl.Acad.Sci.U.S.A 93, 12142-12149. Belshe R.B., Smith M.H., Hall C.B., Belts R., & Hay A.J. (1988) Genetic basis of resistance to rimantadine emerging during treatment of influenza virus infection. J Virol. 62, 1508-1512. Mendel D.B., Tai C.Y., Escarpe P.A., Li W., Sidwell R.W., Huffman J.H., Sweet C., Jakeman K.J., Merson J., Lacy S.A., Lew W., Williams M.A., Zhang L., Chen M.S., Bischofberger N., & Kim C.U. (1998) Oral administration of a prodrug of the influenza virus neuraminidase inhibitor GS 4071 protects mice and ferrets against influenza infection. Antimicrob Agents Chemother42, 640-646. Smith H. & Sweet C. (1988) Lessons for human influenza from pathogenicity studies with ferrets. Rev.Infect.Dis. 10, 56-75. Reuman P.D., Keely S., & Schiff G.M. (1989) Assessment of signs of influenza illness in the ferret model. /. Virol.Methods 24, 27-34. Virology Methods Manual. 1996. London, San Diego, New York, boston, Sydney, Todyo, Toronto: Academic Press, Harcourt Brace & Company. Karp P.H., Moninger T.O., Weber S.P., Nesselhauf T.S., Launspach J.L., Zabner J., & Welsh M.J. (2002) An in vitro model of differentiated human airway epithelia. Methods for establishing primary cultures. Methods Mol.Biol, 188, 115-137. Wang G., Davidson B.L., Melchert P., Slepushkin V.A., van Es H.H., Bodner M., Jolly D.J., & McCray P.B., Jr. (1998) Influence of cell polarity on retrovirus-mediated gene transfer to differentiated human airway epithelia. J Virol. 72, 9818-9826. Wang A.Y., Peng P.D., Ehrhardt A., Storm T.A., & Kay M.A. (2004) Comparison of adenoviral and adeno-associated viral vectors for pancreatic gene delivery in vivo. Hum.Gene Ther. 15, 405-413. Halbert C.L., Allen J.M., & Miller A.D. (2002) Efficient mouse airway transduction following recombination between AAV vectors carrying parts of a larger gene. Nat.Biotechnol. 20, 697-701. Flotte T.R., Afione S.A., Conrad C., McGrath S.A., Solow R., Oka H., Zeitlin P.L., Guggino W.B., & Carter B.J. (1993) Stable in vivo expression of the cystic fibrosis transmembrane conductance regulator with an adeno-associated virus vector. Proc.NatlAcad.Sci.U.S.A 90, 10613-10617. Halbert C.L., Standaert T.A., Wilson C.B., & Miller A.D. (1998) Successful readministration of adeno-associated virus vectors to the mouse lung requires transient immunosuppression during the initial exposure. J Virol. 72, 9795-9805. Cocchiara R., Bongiovanni A., Albeggiani G., Azzolina A., Lampiasi N., Di Blasi F., & Geraci D. (1997) Inhibitory effect of neuraminidase on SP-induced histamine release and TNF-alpha mRNA in rat mast cells: evidence of a receptor-independent mechanism. J Neuroimmunol. 75, 9-18. Stenton G.R., Nohara O., Dery R.E., Vliagoftis H., Gilchrist M., Johri A., Wallace J.L., Hollenberg M.D., Moqbel R., & Befus A.D. (2002) Proteinase-activated receptor (PAR)- 1 and -2 agonists induce mediator release from mast cells by pathways distinct from PAR-1 andPAR-2.JPharmacol.Exp.Ther. 302,466-474. Jarreau P.H., Harf A., Levame M., Lambre C.R., Lorino H., & Macquin-Mavier I. (1992) Effects of neuraminidase on airway reactivity in the guinea pig. Am.Rev.Respir.Dis. 145, 906-910. Kai H., Makise K., Matsumoto S., Ishii T., Takahama K., Isohama Y., & Miyata T. (1992) The influence of neuraminidase treatment on tracheal smooth muscle contraction. Eur.J.Pharmacol. 220, 181-185. All publications, including patent documents, Genbank sequence database entries including nucleotide and amino acid sequences and accompanying information, and scientific articles, referred to in this application and the bibliography and attachments are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication were individually incorporated by reference. All headings are for the convenience of the reader and should not be used to limit the meaning of the text that follows the heading, unless so specified. CLAIMS We Claim: 1. A sialidase catalytic domain protein comprising a catalytic domain of a sialidase, wherein: a) the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that is identical to or substantially homologous to an amino acid sequence that begins at any one of the amino acid residues from amino acid 270 to amino acid 290 of the Actinomyces viscosus sialidase protein sequence set forth in SEQ ID NO:12, and ends at any one of the amino acid residues from amino acid 665 to amino acid 901 of the Actinomyces viscosus sialidase protein sequence set forth in SEQ ID NO:12; b) the sialidase catalytic domain protein lacks amino acid residues extending from amino acid 1 to amino acid 269 of the sequence of amino acids set forth in SEQ ID NO: 12; and c) the sialidase catalytic domain protein has sialidase activity. 2. The sialidase catalytic domain protein of claim 1, wherein the sequence of the protein comprises the sequence of amino acids set forth in SEQ ID NO:14. 3. The sialidase catalytic domain protein of claim 1, wherein the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that begins at any of the amino acid residues from amino acid 270 to amino acid 290 of the sequence of amino acids set forth in SEQ ID NO: 12. and ends at any of amino acid residues 665 to 681 of the sequence of amino acids set forth in SEQ ID NO:12. 4. The sialidase catalytic domain protein of claim 3, wherein the sequence of the protein comprises the sequence of amino acids set forth in SEQ ID NO:16. 5. The sialidase catalytic domain protein of claim 4, wherein the sequence of the protein comprises the sequence of amino acid residues from 1 to 393 of the sequence of amino acids set forth in SEQ ID NO: 16. 6. The sialidase catalytic domain protein of claim 3, wherein the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that begins at amino acid residue 274 of the sequence of amino acids set forth in SEQ ID NO: 12 and ends at amino acid residue 681 of the sequence of amino acids set forth in SEQ ID NO:12. 7. The sialidase catalytic domain protein of claim 3, wherein the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that begins at amino acid residue 290 of the sequence of amino acids set forth in SEQ ID NO: 12 and ends at amino acid residue 666 of the sequence of amino acids set forth in SEQ ID NO:12. 8. The sialidase catalytic domain protein of claim 3, wherein the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that begins at amino acid residue 290 of the sequence of amino acids set forth in SEQ ID NO: 12 and ends at amino acid residue 681 of the sequence of amino acids set forth in SEQ ID NO:12. 9. The sialidase catalytic domain protein of claim 1, wherein the sequence of the sialidase catalytic domain protein comprises an amino acid sequence that begins at amino acid residue 274 of the sequence of amino acids set forth in SEQ ID NO: 12 and ends at amino acid residue 666 of the sequence of amino acids set forth in SEQ ID NO: 12. 10. A nucleic acid molecule, comprising a nucleotide sequence encoding the sialidase catalytic domain protein of any of claims 1-9. 11. An expression vector, comprising the nucleic acid molecule of claim 10. 12. A fusion protein, comprising: a) at least one domain comprising a catalytic domain of a sialidase, wherein: the catalytic domain of the sialidase comprises an amino acid sequence that is identical to or substantially homologous to an amino acid sequence that begins at any one of the amino acid residues from amino acid 270 to amino acid 290 of the Actinomyces viscosus sialidase protein sequence set forth in SEQ ID NO: 12, and ends at any one of the amino acid residues from amino acid 665 to amino acid 901 of the Actinomyces viscosus sialidase protein sequence set forth in SEQ ID NO:12; the catalytic domain of the sialidase lacks amino acid residues extending from amino acid 1 to amino acid 269 of the sequence of amino acids set forth in SEQ ID NO: 12; and the catalytic domain of the sialidase has sialidase activity; and b) at least one other domain, wherein the at least one other domain is selected from among a purification domain, a protein tag, a protein stability domain, a solubility domain, a protein size-increasing domain, a protein folding domain, a protein localization domain, an anchoring domain, an N-terminal domain, a C-terminal domain, a catalytic activity domain, a binding domain, or a catalytic activity-enhancing domain 13. The fusion protein of claim 12, further comprising at least one peptide linker. 14. The fusion protein of claim 12, wherein the sequence of the catalytic domain of the sialidase comprises the sequence of ammo acids set forth in SEQ ID NO:16. 15. The fusion protein of claim 12, wherein the sequence of the catalytic domain of the sialidase comprises an amino acid sequence that begins at amino acid residue 274 of the sequence of amino acids set forth in SEQ ID NO:12 and ends at amino acid residue 666 of the sequence of amino acids set forth in SEQ ID NO:12. 16. The fusion protein of claim 14 or claim 15, comprising at least one protein purification domain. 17. The fusion protein of claim 16, wherein the at least one protein purification domain is a His tag, a calmodulin binding domain, a maltose binding protein domain, a streptavidin domain, a streptavidin binding domain; an intein domain, or a chitin binding domain. 18. The fusion protein of claim 17, wherein the protein purification domain is a His tag. 19. The fusion protein of claim 18 whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:29. 20. The fusion protein of claim 12, comprising at least one anchoring domain. 21. The fusion protein of claim 20, wherein the anchoring domain is a glycosaminoglycan (GAG)-binding domain. 22. The fusion protein of claim 21, wherein the GAG-binding domain is substantially homologous to the GAG-binding domain of human platelet factor 4 (SEQ ID NO:2), substantially homologous to the GAG-binding domain of human interleukin 8 (SEQ ID NO:3), substantially homologous to the GAG-binding domain of human antithrombin III (SEQ ID NO:4), substantially homologous to the GAG-binding domain of human apoprotein E (SEQ ID NO:5), substantially homologous to the GAG-binding domain of human angio-associated migratory protein (SEQ ID NO:6), or substantially homologous to the GAG-binding domain of human amphiregulin (SEQ ID NO:7). 23. The fusion protein of claim 22, wherein the GAG-binding domain is substantially homologous to the human amphiregulin GAG-binding domain (SEQ ID NO:7). 24. The fusion protein of claim 22, wherein the GAG-binding domain comprises the human amphiregulin GAG-binding domain (SEQ ID NO:7). 25. The fusion protein of claim 24, wherein the sequence of the catalytic domain of the sialidase comprises the sequence of amino acids set forth in SEQ ID NO:16. 26. The fusion protein of claim 25, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO: 19. 27. The fusion protein of claim 25, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:38. 28. The fusion protein of claim 25, further comprising a peptide linker connecting the human amphiregulin GAG-binding domain to the domain comprising the catalytic domain of the sialidase. 29. The fusion protein of claim 28, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:35. 30. The fusion protein of claim 28, whose sequence comprises the sequence of amino acdis set forth in SEQ ID NO:37. 31. The fusion protein of claim 28, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:39. 32. The fusion protein of claim 24, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:21. 33. The fusion protein of claim 24, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:23. 34. The fusion protein of claim 24, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:25. 35. The fusion protein of claim 24, whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:27. 36. A nucleic acid molecule encoding the fusion protein of any of claims 19, 26, or 29-35. 37. An expression vector comprising the nucleic acid molecule of claim 36. 38. A nucleic acid molecule, wherein the sequence of the nucleic acid molecule comprises a sequence of nucleotides selected from among the sequences set forth in SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32 and SEQ ID NO:36. 39. A pharmaceutical formulation comprising a sialidase whose sequence comprises the sequence of amino acids set forth in SEQ ID NO:12. 40. A pharmaceutical formulation comprising a sialidase whose sequence is substantially homologous to the sequence of amino acids set forth in SEQ ID NO: 12. 41. A pharmaceutical formulation comprising the protein of claim 1. 42. A pharmaceutical formulation comprising the protein of claim 3 43. A pharmaceutical formulation comprising the fusion protein of claim 13. 44. A pharmaceutical formulation comprising the fusion protein of claim 15. 45. A pharmaceutical formulation comprising the fusion protein of claim 26. 46. A pharmaceutical formulation comprising the composition of claim 32. 47. The pharmaceutical formulatiofi of any of claims 39-46 that is formulated as a spray. 48. The pharmaceutical formulation of any of claims 39-46 that is formulated as an inhalant.. 49. The pharmaceutical formulation of any of claims 39-46 that is formulated as a solution for injection. 50. The pharmaceutical formulation of any of claims 39-46 that is formulated as a solution for eye drops. 51. The pharmaceutical formulation of any of claims 39-46 that is formulated as a cream, salve, gel, or ointment. 52. The pharmaceutical formulation of any of claims 39-46 that is formulated as a pill, tablet, lozenge, suspension, or solution for oral administration. 53. A method of treating or preventing viral infection by influenza, parainfluenza, or respiratory syncytial virus, comprising: applying a therapeutically effective amount of the formulation of any of claims 39-52 to epithelial cells of a subject. 54. The method of claim 53, wherein the applying is by use of a nasal spray. 55. The method of claim 53, wherein the applying is by use of an inhaler. 56. The method of claim 53, wherein the applying is performed from once to four times a day. 57. A method of treating or preventing infection by a bacterial pathogen, comprising: administering a therapeutically effective amount of the formulation of any of claims 39- 52 to a subject. 58. The method of claim 57, wherein the pathogen is selected from among Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Moraxella catarrhalis , Pseudomonas aeruginosa, and Heliobacter pylori. 59. The method of claim 57, wherein the administering is by use of a nasal spray. 60. The method of claim 57, wherein the administering is by use of an inhaler. 61. The method of claim 57, wherein the administering is by topical application. 62. The method of claim 57, wherein said administering is by oral administration. 63. The method of claim57, wherein the administering is performed from once to four times a day. 64. A method of treating or preventing allergy or inflammation, comprising: administering a therapeutically effective amount of the formulation of any of claims 39-52 to a subject. 65. The method of claim 64, wherein the inflammation is associated with asthma, allergic rhinitis, eczema, psoriasis, exposure to plant or animal toxins, or autoimmune conditions. 66. The method of claim 64, wherein the administering is by use of a nasal spray. 67. The method of claim 64, wherein the administering is by use of an inhaler. 68. The method of claim 64, wherein the administering is by use of eye drops. 69. The method of claim 64, wherein the administering is by topical application. 70. The method of claim 64, wherein the administering is by local or intravenous injection. 71. The method of claim 64, wherein the administering is performed from once to four times a day. 72. A method of enhancing gene delivery by a recombinant viral vector, comprising: administering, to epithelial cells of a subject, a recombinant viral vector comprising a gene for delivery to the subject; and administering an effective amount of the formulation of any of claims 39-52 to the epithelial cells of the subject, wherein the administration of the formulation is performed prior to or concomitant with the administration of the recombinant viral vector. 73. The method of claim 72, wherein the recombinant viral vector is selected from among a retro viral vector, a Herpes viral vector, an adeno viral vector and an adenoassociated viral vector. 74. The method of claim 73, wherein the recombinant viral vector is a recombinant adeno-associated viral vector. 75. The method of claim 74, wherein the recombinant adeno-associated viral vector comprises a gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). 76. The method of claim 74, wherein the administering is by use of an inhaler. 77. The method of claim 74, wherein the administering is performed from once to four times a day.

Documents:

2576-delnp-2007-1-Claims-(22-08-2014).pdf

2576-delnp-2007-1-Correspondence Others-(22-08-2014).pdf

2576-delnp-2007-1-Description (Complete)-(22-08-2014).pdf

2576-delnp-2007-1-Form-2-(22-08-2014).pdf

2576-delnp-2007-1-GPA-(22-08-2014).pdf

2576-delnp-2007-2-Correspondence Others-(22-08-2014).pdf

2576-delnp-2007-Abstract-(11-10-2013).pdf

2576-delnp-2007-abstract.pdf

2576-delnp-2007-Assingment-(02-04-2013).pdf

2576-delnp-2007-Claims-(11-10-2013).pdf

2576-delnp-2007-claims.pdf

2576-delnp-2007-correspondece-others.pdf

2576-delnp-2007-Correspondence Others-(02-04-2013).pdf

2576-delnp-2007-Correspondence Others-(03-10-2013).pdf

2576-delnp-2007-Correspondence Others-(07-10-2013).pdf

2576-delnp-2007-Correspondence Others-(11-10-2013).pdf

2576-delnp-2007-Correspondence Others-(15-05-2013).pdf

2576-delnp-2007-Correspondence Others-(18-10-2013).pdf

2576-delnp-2007-Correspondence Others-(22-08-2014).pdf

2576-delnp-2007-Correspondence Others-(28-10-2013).pdf

2576-delnp-2007-Correspondence Others-(29-10-2013).pdf

2576-delnp-2007-Description (Complete)-(22-08-2014).pdf

2576-delnp-2007-description (complete).pdf

2576-delnp-2007-Drawings-(03-10-2013).pdf

2576-delnp-2007-drawings.pdf

2576-delnp-2007-form-1.pdf

2576-delnp-2007-Form-13-(22-08-2014).pdf

2576-delnp-2007-Form-2-(02-04-2013).pdf

2576-delnp-2007-Form-2-(29-10-2013).pdf

2576-delnp-2007-form-2.pdf

2576-delnp-2007-Form-3-(15-05-2013).pdf

2576-delnp-2007-Form-3-(18-10-2013).pdf

2576-delnp-2007-form-3.pdf

2576-delnp-2007-form-5.pdf

2576-delnp-2007-GAP-(02-04-2013).pdf

2576-delnp-2007-Petition-137-(28-10-2013).pdf