Title of Invention

A COMBINATION COMPRISING BACHTERIAL VECTOR AND INDUCTOR SACCHARIDE

Abstract A combination of compounds for producing a combination of pharmaceutical preparation comprising a first compound, a bacterial vector comprising a transgene under the control of a saccharide inducible promoter, and as a second compounds, an inductor saccharide for induction of the saccharide inducible promoter while the bacterial vector is present within an animal or a human patient to be treated.
Full Text The present invention relates to a combination of compounds for introducing nucleic acids
and/or protein into animal cells, tissue, organs or organisms in vitro, extracorporal, or in
vivo. This combination or system comprises preparations suitable for administration to an
animal or human, comprising as one component a bacterial vector genetically manipulated
to contain nucleic acid sequences comprising a transgene, and a second component
allowing the subsequent transcription, possibly translation of the transgene by controlled
induction of the transgene activity within the bacterial vector as it is present within the
animal or human.
Applications of the system according to the invention are medical uses, e.g. immunization,
tumor treatment, and release of pharmaceutically active compounds, e.g. hormones,
immunomodulating compounds and pro-drug converting enzymes.
Background state of art
For traditional vaccination, attenuated pathogens are in use to elicit an immune response
from the recipient organism that is also active against wild type pathogens. An example
for the use of attenuated invasive bacteria as a vaccine is the use of attenuated
enteropathogenic salmonella, providing protection against salmonellosis.
Depending on the disease against which immunoprotection is intended, it is desired to
elicit a variety of the immune responses such as the stimulation of antibody production
and/or T-cell mediated immunity, systemically and/or mucosally. As the quality of these
immunoreactions is at least in part dependent on the route of administration, a vector
according to the invention can be designed to preferentially elicit a cellular and/or humoral
immune response.
Although effective in recognising antigens and marking antigen for subsequent removal,
antibodies cannot bind to intracellular antigens, for example to bacteria which are
contained within the phagosome of infected cells, or to cytosolic antigens of malignant
cells, i.e. tumor cells. This part of the immune response is provided by the cellular immune
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response, i.e. T-cells recognizing foreign peptide displayed on the outer surface of infected
cells in conjunction with MHC-I and/or MHC-II complexes. However, in relation to tumor
cells, the cellular immune response against these is often hampered by self-tolerance of the
immune system against homologous constituents.
In general, antigen specific cytotoxic T-lymphocytes (CTL), which are one sub-group of
T-cells, are activated by interaction with antigen presented on the cell surface in a complex
with MHC I, which is the presentation pathway for cytosolic protein of mammalian cells.
Accordingly, antigen synthesized by invasive pathogens in the cytoplasm, or antigen
synthesized by bacterial vectors based on attenuated invasive bacteria which liberate
antigen into the cytoplasm, is efficient in eliciting the cellular immune response by CTL.
Following this activation, CTL are immediately directed against infected cells that display
the relevant antigenic peptides in complex with MHC I.
Some invasive bacteria, e.g. salmonella, are able to specifically target professional antigen
presenting cells (APC) in the infected organism. In the case of salmonella, the bacteria
invade the mammalian organism mainly by passage through the M cells of Peyer patches
within the small intestiny. Subsequent to passaging M cells, invasive bacteria infect
dendritic cells and macrophages present in Peyer patches which are part of the mucosa
associated lymphoid tissue. Peyer patches contain an increased number of APC of the gut
associated lymphoid tissue, wherein bacteria can persist for days up to several weeks,
depending on the degree of their attenuation. APC infected with salmonella can migrate
into mesenteric lymph nodes, spleen and liver, effectively transporting invaded bacteria
into these tissues. Macrophages which are lysed after infection by invasive bacteria are
phagocytosed by dendritic cells.
Some invasive bacteria, e.g. salmonella, are able to replicate within the phagosome of
mammalian cells, e.g. macrophages, by secreting a range of proteins and further effector
molecules. These secreted molecules for example prohibit the import of NADPH oxidase
into the phagosome, effectively preventing an immediate antibacterial response by the
macrophages. As a further result of the infection with salmonella, caspase 1 is activated,
leading to the secretion of inflammatory cytokines (IL-1 beta, IL-18) and initiating
apoptosis of infected cells. Material of apoptotic macrophages which are phagocytosed by
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dendritic cells enter the presentation pathway of MHCI and MHC II, in turn initiating
specific T-cell responses.
Some invasive bacteria, e.g. Listeria monocytogenes and Shigella spp., are able to
replicate within the cytoplasm of mammalian cells. Upon lysis, the bacterial content can
be released directly into the cytosol of infected cells, providing access to the MHC-I
presentation pathway.
It is known that bacterial vaccine strains can induce mucosal and systemic immune
responses, e.g. Salmonella administered orally.
Attracted by the efficiency of invasive bacteria to elicit an immune response, attenuated
invasive bacteria have been investigated to serve as bacterial vectors for vaccines eliciting
an immune response against a peptide foreign to the bacterial vector.
In addition, attenuated invasive bacteria have been used for genetic vaccination and gene
therapeutic purposes as carrier vehicles to introduce eukaryotic expression plasmids into
mammalian cells. In order to allow transcription of DNA sequences introduced into a
mammalian cell, the DNA needs to be transported into the cellular nucleus. One
prerequisite for efficient DNA transfer is an efficient invasion of host cells by the bacterial
carrier vehicle. After invasion of the host cell, lysis of the bacterial vector to release its
contents into the cytoplasm and a subsequent effective translocation of DNA into the
nucleus are essential steps for transcription of the eukaryotic expression plasmid.
When using attenuated invasive bacteria as bacterial vectors for the transfer of protein
and/or nucleic acid into mammalian cells, it is desirable to control the level of expression
of said peptide and/or the copy number of nucleic acids. Up to now most attempts to
control the expression of a foreign peptide by bacterial vectors rely on constitutive
promoter sequences. Recently, also in vivo inducible promoters isolated from invasive
bacteria, e.g. Salmonella, and have been used for this purpose. These promoters are
regulated depending on the stage of the infectious cycle of said bacteria. Accordingly,
such promoter sequences automatically respond to specific phases of the infectious cycle
of the bacterium, so that they cannot be regulated by exerting an external influence. For
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Objects of the invention
The present invention seeks to overcome shortcomings of the known state of art in respect
of bacterial vectors, especially their disadvantage of being essentially uncontrolled.
In a first embodiment, it is an object of the present invention to provide a system of
Pharmaceuticals for medical use as live vaccines. In this respect, the present invention
especially seeks to provide a system of Pharmaceuticals, which are applicable
systemically, nasally, orally, rectally and/or otherwise mucosally and which can be used to
elicit a systemic immune response and/or one that is present within the mucosa associated
lymphoid tissue of the intestiny and/or mucosa of the respiratory organs and/or of the
genitals.
For the development of potent vaccines, especially against infections transmitted via
mucosal tissue, like infectious microorganisms, parasites, and viral infections like HIV, it
is desirable for the vaccine to elicit cellular immune responses and/or antibody responses.
The design of the bacterial vector, e.g. choice of the appropriate bacterial strain, allows to
induce immune responses in the mucosa and/or systemically. Accordingly, the present
invention also seeks to provide bacterial vectors for vaccines eliciting a humoral and/or
cellular immune response both within mucosa and systemically based on non-invasive as
well as on invasive bacteria, preferably attenuated strains.
In order to control the activity of genetically manipulated attenuated invasive bacteria
during their presence adjacent target cells and/or during their infection of target cells,
which may be cultivated cells, cultivated or extracorporal tissue or extracorporal organs,
preferably specific tissue or organs within an animal, the present invention seeks to
provide a regulatory component acting in combination with the vector component to
provide control by exertion of an influence external to the bacterial vector as well as
external to the target cell and at will to regulate the activity of functionally linked nucleic
acid sequences, e.g. of a transgene forming part of an expression cassette.
In a second embodiment, it is an object of the present invention to provide a combination
of pharmaceutical preparations for medical use for the delivery of peptide and/or nucleic
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acid sequences for immunization, gene therapy, or other biologically active compounds,
e.g. probiotic or functional food applications, e.g. for the delivery of beneficial factors
within the intestiny of an animal, hormones, antibody, immunomodulating substances, or
pro-drug converting enzymes.
In a third and fourth embodiment, it is an object of the present invention to provide a
combination of pharmaceuticals for medical use in tumor therapy and for diagnostic
purposes, respectively.
In a fifth embodiment, it is an object of the present invention to provide a combination of
compounds acting as an insecticide or vermicide realizing a tight control system which
allows the arbitrary activation of the insecticidal and vermicidal activity, respectively.
Apart from the need for the regulatory system to be responsive to an external inductor or
repressor substance, a very tight control of the activity is preferred. Tight regulation by a
regulatory element has the desired effect to substantially eliminate any activity of the
transgene sequences functionally linked downstream in order to substantially avoid the
presence of ribonucleic acid sequences and/or peptide and/or minimize the presence of
plasmid DNA within the bacterial vector which can be detrimental to the vector's
infectivity or detrimental to its transfer rate of the functionally linked gene product and/or
nucleic acid sequence into the mammalian cell.
In this respect, it has been found in preliminary experiments that expression of a
heterologous peptide within a bacterial vector, for example under control of a constitutive
promoter sequence, decreases its infectivity. Furthermore, high copy number plasmids
encoding the desired peptide for transfection into a mammalian cell, although in principle
preferable due to the higher content of the desired sequences, also result in a decreased
infectivity of the bacterial vector in addition to being unstable within the vector in the
absence of a selective pressure.
General description of the invention
The present invention achieves the above-mentioned objects by making use of the
surprising finding that induction of RNA transcription and/or translation of protein from
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the transgene under the control of a saccharide inducible promoter within bacterial vectors
can be induced even when the bacterial vector is present in an animal like a mammalian
organism, e.g. when the bacterial vector has been introduced to the animal or human being
by concurrent or later introduction of the inductor saccharide to the animal or human
being.
For achieving the above-mentioned objects, the present invention provides the use of a
bacterial vector, genetically manipulated to contain at least one transgene under the control
of a saccharide inducible promoter, for administration to an animal for medical purposes,
including the use as a functional food and/or for probiotic food applications, in
combination with the use of the inductor saccharide for administration to an animal for
medical purposes in order to induce the saccharide inducible promoter by separate
administration to the animal. Preferably, the administration of inductor saccharide is
carried out concurrent or subsequent to the administration of the bacterial vector.
Accordingly, the present invention can make use of the property of bacterial vectors to
preferentially migrate to and replicate in specific body regions, tissues or organs, e.g.
professional antigen presenting cells or tumor tissue. By administration of the inductor
saccharide to the animal or human simultaneously with the introduction of the bacterial
vector, but preferably some time past the introduction of the bacterial vector, and without
the necessity to apply the inductor saccharide within the vicinity of the bacterial vector,
induction of the saccharide inducible promoter is arbitrarily controllable.
In relation to the invention, reference to arbitrary activation of the saccharide inducible
promoter, i.e. transgene activation, refers to the property of the invention to provide
control of transgene activation essentially independent from the environment of the
bacterial vector at the desired site of transgene activation, e.g. controllability by
application of an inductor substance by an arbitrary act.
It has been found surprisingly that the administration of the inductor saccharide to an
animal that has concurrently or previously received a bacterial vector containing a
transgene under the control of a saccharide inducible promoter is a feasible way to control
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activity, i.e. transcription and/or translation of the transgene, essentially independent from
the localization of the bacterial vector within the animal.
In addition to overcoming the previously accepted necessity to directly apply the inductor
saccharide within the immediate vicinity to a bacterium containing a transgene under the
control of a saccharide inducible promoter, the present inventors have found that
administration of the inductor saccharide in a distinct manner, and separately from the
bacterial vector, i.e. without a close co-localization within a limited space to the bacterial
vector, can still be used to induce the saccharide inducible promoter within the bacterial
vector. Accordingly, oral, mucosal or systemic administration of the inductor saccharide to
an animal that concurrently or previously has received bacterial vectors, independently by
oral, mucosal or systemic administration, can be used to deliver nucleic acid and/or protein
from the bacterial vector to cells, tissue or organs, e.g. tumor tissue, within the animal.
Further, it has been found that the present invention advantageously allows to induce
transcription and/or translation of the transgene under the control of a saccharide inducible
promoter in a concentration dependent manner, i.e. by varying the amount of inductor
saccharide that is administered to the animal that has received the bacterial vector.
Accordingly, the present invention uses a bacterial vector and an inductor saccharide
suitable for inducing an activity from the bacterial vector for producing a system or a
combination of pharmaceutical preparations, comprising as a first compound a bacterial
vector for administration for medical purposes, genetically manipulated to contain a
transgene under the control of a saccharide inducible promoter and, as a second
component, the inductor saccharide for administration for medical purposes for induction
of the saccharide inducible promoter while the bacterial vector is present within an animal,
e.g. within a mammal or a human patient to be treated.
Generally, the pharmaceutical combination according to the invention is used for
transcribing and/or translating the transgene contained in the bacterial vector concurrent to
or, preferably, after its administration to an animal by the use of the inductor saccharide
for administration to the animal for inducing the saccharide inducible promoter. In the
present invention, the use of bacterial vectors for medical purposes is comprised in the
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combination with the use of the inductor saccharide as a pharmaceutical compound for
induction of the saccharide inducible promoter in a controlled manner, preferably by
administration of the bacterial vector separate from the administration of the inductor
saccharide. Bacterial vectors can be administered systemically, nasally, orally, rectally
and/or otherwise mucosally in combination with the concurrent or subsequent
administration of the inductor saccharide, essentially without limitations to the route or
point in time of the administration in relation to the administration of the bacterial vector,
in order to transcribe the transgene functionally linked to the saccharide inducible
promoter.
In a preferred embodiment, the combination of compounds according to the present
invention is used firstly for the administration of the bacterial vector and, at a second, later
point of time, for the administration of the inductor saccharide to the same animal. In this
embodiment, the properties of the bacterial vector to migrate to and/or replicate in certain
tissues or organs within the mammalian body is utilized to deliver nucleic acids and/or
protein to the region, where the bacterial vector accumulates. Surprisingly, it has been
found that induction of the saccharide inducible promoter is possible by administration of
the inductor saccharide to the animal, e.g. orally or systemically, is effecitve and
essentially independent from the localization, that the bacterial vector has reached.
In the embodiments of the invention, a pharmaceutical system or combination comprising
two compounds for concurrent, preferably for subsequent administration is provided,
namely a first component comprising a bacterial vector which is genetically manipulated
to contain a transgene functionally linked to a saccharide inducible promoter and, as a
second component, comprising the inductor saccharide. Accordingly, the present invention
provides the use of a bacterial vector for production of a first component of a
pharmaceutical system of compositions and the use of the inductor saccharide for
production of a second component of the pharmaceutical system of compositions. In this
pharmaceutical system or combination of compositions, the first component serves to
introduce the nucleic acid sequences encoding the transgene under the control of the
saccharide inducible promoter into the animal according to the route of administration and,
predominantly, according to migration and accumulation of the vector within the animal;
the second component serves for activation, e.g. induction of the first component by its
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administration to the animal that contains, e.g. by concurrent, preferably by previous
administration, the first component.
Controlled induction of the transgene activity by the second component allows to regulate
transcription of the transgene at the desired localization and time. A bacterial vector used
as the first component for vaccination can introduce a transgene encoding an antigenic
peptide into target cells and/or by using a very low copy number plasmid encoding the
antigenic peptide, also bearing a high copy number origin of replication under the control
of the saccharide inducible promoter.
In a first embodiment, the pharmaceutical combination according to the invention can be
used to elicit a systemic immune response and/or one that is present within the mucosa
associated lymphoid tissue of the intestiny and/or mucosa of the respiratory organs or of
the genitals.
In a second embodiment, the pharmaceutical combination according to the invention can
be used for the delivery of pharmaceutically active compounds to specified tissue regions
within an animal, e.g. nucleic acid sequences, e.g. for gene therapy, or hormones,
immuno-modulating substances, reactive RNA species or other biologically active
compounds, e.g. immuno-reactive peptides for immunization, antibody, apoptose-inducing
factors, or pro-drug converting enzymes.
The combination of a bacterial vector component with the inductor component can
advantageously be used for producing pharmaceutical preparations for use in tumor
therapy, by itself or in combination with known pharmaceuticals or methods for tumor
treatment, e.g. in combination with chemotherapy and/or with irradiation. For use in tumor
therapy, several bacterial species are suitable for generation of the bacterial vector
component, e.g. non-pathogenic obligate anaerobic or facultative anaerobic bacteria which
invade and selectively replicate within tumor, preferably solid tumors. However,
attenuated strains of originally pathogenic bacteria can also be used for generating the
bacterial vector component. The bacterial vector component of the invention in this
embodiment is efficient to deliver peptide and/or nucleic acid sequences to tumor tissue
upon application of the inductor saccharide because the properties of the vector to
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preferentially, preferably selectively, colonize tumor tissue are realized during this use of
the bacterial vector component for medical purposes.
Accordingly, in a third embodiment, the pharmaceutical combination according to the
invention is used for the treatment of tumors like cancer or other neoplastic tissue. In this
embodiment, the natural preference of some bacteria that are used as bacterial vectors
according to the invention for accumulation in and/or around tumor tissue is utilized, e.g.
of Salmonella, E.coli and Clostridium, even to colonize tumor tissue. Preferably,
subsequent to the localization of bacterial vector in the vicinity of tumor tissue, e.g. the
colonization of a tumor, administration of the inductor saccharide by a route independent
from the localization of the bacterial vector and at a later point in time, e.g. after
colonization of tumor tissue by bacterial vector, is used.
According to the fourth embodiment of the present invention for use in diagnostics and/or
treatment of tumors, e.g. cancer, the bacterial vector component is provided with a
monitoring transgene, characterized by encoding a product which can be monitored by
detection of its activity using spectroscopical analysis. As monitoring transgenes, genes
for luminescent and/or fluorescent proteins, e.g. GFP, eGFP, lux gene products, e.g.
obtainable from Photorhabdus luminescens, luciferase as well as enzymes converting a
pro-compound to a compound resulting in an increased signal in analytical expression can
be used. As a result, presence and localization of bacterial vector can be followed, e.g. for
identification of localization of tumor tissue and metastatic carcinoma, and for an
assessment of localization and of the number of bacterial vector distributing in and
colonizing the tissue, organ or animal, optionally also over the course of administration of
inductor saccharide.
In this embodiment, the bacterial vector may in addition to the monitoring transgene
contain a transgene that provides anti-tumor activity, e.g. cytokines, antibody or toxic
products, wherein the transgene is under the control of a saccharide inducible promoter,
which is a different or the same as the saccharide inducible promoter controlling the
monitoring transgene.
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For the purpose of this disclosure, the term "animal" refers to vertebrates, e.g. to fish and
to mammals, e.g. to farm and pet animals like dogs, cats, sheep, cattle, horses, camels,
goats, preferably to humans, as well as to wild animals like vermin and insects.
In relation to vermin and insects, which are regarded as pests, the combination according
to the invention can be used as an insecticide and vermicide, respectively. In this fifth
embodiment, the transgene to be induced within the animal after uptake of the bacterial
vector by administration of the inductor saccharide is chosen to act as a poison, preferably
specific poison to the vermin and insects, respectively.
For constructing bacterial vectors, non-invasive or invasive bacteria can be used,
genetically manipulated to comprise a saccharide inducible promoter controlling a nucleic
acid sequence encoding the transgene. Induction of the saccharide inducible promoter
causes transcription of the transgene, producing an RNA, e.g. an inhibitory RNA (iRNA),
small interfering RNA (siRNA), or an mRNA, translatable into protein. As induction of
the transcription of the transgene according to the invention within an animal or a human
being is essentially independent from the localization which the bacterial vector has
reached within the animal, transcription occurs at the site of accumulation of the bacterial
vector, transcription and/or translation of the transgene occurs at the site of localization of
the bacterial vector, i.e. extracellularly and/or intracellularly within the animal tissue.
Depending on the transgene, the bacterial vector serves as a transport vehicle for the
nucleic acid encoded by the transgene and/or for peptide translated from the transgene.
Release of nucleic acid and/or peptide synthesized by the vector can also be obtained by
partial or complete lysis of the bacterial vector, controlled by a saccharide inducible
promoter and/or by secretion of peptide translated from the transgene.
The bacterial vectors for use in the pharmaceutical combination according to the invention
are based on non-invasive, e.g. commensal bacteria or on invasive bacteria, which are
preferably attenuated, and which are useful for introducing peptide and/or nucleic acids
into or adjacent to target cells or organisms. These bacterial vectors comprise a transgene,
for example containing an expression cassette for a peptide and/or an expression cassette
regulating an origin of replication and/or an expression cassette encoding untranslated
RNA, wherein the expression cassette is operably linked to and under the control of a
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saccharide inducible promoter as the specific regulatory element. As a further
embodiment, the transgene may in addition to nucleic acid sequences functionally linked
to the saccharide inducible promoter comprise protein encoding nucleic acid sequences,
which are linked in one operon encoding two or more proteins, e.g. synthetic pathway
enzymes. Further, different transgenes may be comprised in the bacterial vector,
functionally linked to different saccharide inducible promoters to allow for separate
induction of transgene activity by administration of the respective inductor saccharide.
The transgene is operably linked to the saccharide inducible promoter, forming an
expression cassette within the genome of the bacterial vector or, alternatively, on one
plasmid replicable or maintainable within said bacterial vector. The transgene may be
present within an expression cassette under the control of the saccharide inducible
promoter, or its expression may be controlled indirectly by regulating the copy number of
the transgene under the control of the saccharide inducible promoter. In the latter case, the
saccharide inducible promoter indirectly controls the activity of the transgene by directly
controlling the activation factor (e.g. a replicase) acting on an inducible origin of
replication linked to the transgene.
According to the invention, the saccharide inducible promoter originates from operator
regions of bacterial origin, which are regulatable by saccharides, for instance inducible by
increasing concentrations of a saccharide. In its preferred form, the inventive saccharide
inducible promoter is gradually inducible, responding gradually to increasing
concentrations of the saccharide.
Examples for the saccharide inducible promoters to be used according to the invention are
regulatory regions controlling catabolic enzymes of the bacterial degradation pathway of
saccharides, for example the promoters encoding catabolic enzymes of the rhamnose or
xylulose pathway, and, most preferably the arabinose promoter element PBAD from E. coli
or a promoter from the ara-operon of Bacillus subtilis. The inductor substance for the
saccharide inducible promoters to be used in connection with the invention are the
corresponding saccharides, i.e. rhamnose in the case of the promoter element from the
rhamnose operon, xylulose in the case of the promoter element from the xylulose operon,
and L-arabinose in the case of the arabinose promoter. Activation of the saccharide
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inducible promoter is obtained by adding the respective saccharide inductor to the culture
medium of cells, tissue, organs or to an organism, respectively.
The preferred saccharide inducible promoter to be used within the bacterial vectors
according to the present invention is the promoter PBAD of the L-arabinose operon of E.
coli regulating the transcription of the gene product araB (ribulokinase), araA (isomerase)
as well as araD (epimerase). This promoter is regulated by the gene product araC, whose
transcription is repressed by AraC itself. In the absence of L-arabinose, AraC forms a
homodimer, binding to the initiator region 1 (II) and the operator region 2 (02), forming a
DNA loop upstream of the PBAD resembling a termination loop which represses PBAD-
When L-arabinose is present, AraC accepts L-arabinose into its binding pocket, changes
its conformation and releases the DNA loop formation. Further, AraC as a homodimer
with L-arabinose bound then binds to the initiator regions 1 and 2 (II, 12) upstream of
PBAD, allowing both binding of the activating complex formed by cyclic AMP (cAMP) and
cAMP receptor protein upstream of the regions II and 12 as well as allowing the binding
of RNA polymerase downstream from the regions II and 12, thus effectively starting
transcription from the promoter element PBAD- For a detailed description of the L-
arabinose operon in E. coli, see Schleif, BioEssays 25.3, pp. 274-282 (2003).
As an alternative to using saccharides which are metabolizable by the bacterial vector
and/or by the recipient animal for induction of the saccharide inducible promoter,
analogons and derivatives of the saccharide can be used as inductor saccharides.
Analogons and derivatives of the saccharides are e.g. sugar alcohols, sugar isomers, as
well as esterification, amidation, alkylation or alkoxylation products of sugar, which are
included in the term inductor saccharide for the purposes of the invention.
One of the considerable advantages of the saccharide inducible promoters to be used
according to the present invention, especially of the preferred promoter element PBAD, is
their tight regulation in the absence of inductor. Therefore, also structural genes encoding
peptides which are potentially toxic to the bacterial vector, for instance the gene E of
bacteriophage bacterial vector according to the invention. Similarly, tight control of expression of a
replicase acting on an inducible origin of plasmid replication is required. The tight
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regulation of the promoter activity allows to create bacterial vectors containing DNA
sequences, the activation of which would be detrimental to the viability or to the
infectivity of the bacterial vector or would result in the loss of the plasmid containing
these sequences.
A further advantage of the promoter element PBAD is its response to gradually increasing
concentrations of the inductor substance L-arabinose in the form of gradually increasing
activity.
The inductor saccharides used as inductors for the saccharide inducible promoters have the
advantage of being non-toxic to the host cells and organisms targeted by the bacterial
vector, e.g. to animals, and non-toxic to other cells of a target organism. Furthermore,
saccharides can be administered by one of several routes (e.g. orally or systemically, i.e.
intravenously, peritoneally, parenterally or intramuscularly) to spread through an animal
or human organism to reach the bacterial vector according to the invention. Therefore,
induction of the saccharide inducible promoter contained in the bacterial vector to
transcribe the functionally linked expression cassette, e.g. to activate the pre-determined
activity encoded by the vector, is feasible in a very simple manner. Especially the
preferred inductor substance L-arabinose is in wide use for dietary purposes as well as a
formulation agent for pharmaceutical preparations and, accordingly, its harmlessness in
view of mammalian cells, for example cultured cells, tissue, organs or mammalian
organisms is proven.
Furthermore, a saccharide to be used as an inductor substance offers the advantages of
being readily available at low cost and of administration by established routes, for
example orally or intravenously.
In a first aspect, the present invention provides a pharmaceutical combination for
controlled peptide delivery into an animal organism, e.g. into the vicinity of target cells in
vivo. For this use, vectors that form the first component of the pharmaceutical system are
based on non-invasive bacteria or on invasive bacteria. Synthesis of an antigenic peptide
encoded by said bacterial vector is induced by application of the inductor saccharide, e.g.
the pharmaceutical combination of the invention resulting in the effect of a live vaccine
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for animals including humans. The use as vaccines can be directed to preferentially induce
a cellular and/or humoral immune response, by appropriate choice of the bacterium used
for the vector and on the peptide encoded by the transgene.
It is a specific advantage of the present invention that the bacterial vector component of
the pharmaceutical combination according to the invention can be chosen to preferentially
induce a cellular and/or humoral immune response, depending on the properties of the
bacterium used and/or on the properties of the peptide encoded by the transgene. In detail,
it has been found that both non-invasive bacteria and invasive bacteria lead to or can be
adapted to preferentially direct the immune response to a cellular or a humoral one.
However, a person skilled in the art can easily determine which bacterium constitutes a
suitable component for a bacterial vector in combination with the peptide encoded by the
transgene in the pharmaceutical system to achieve the desired cellular and/or humoral
immune response.
An example for an analytical method to determine the induction of humoral immune
responses in serum of recipient animals is an ELISA for antigen-specific antibodies. An
example for an analytical method to determine the induction of cellular immune responses
in different locations of recipient animals is the analysis of cytokine production by
antigen-specific immune cells.
Here, bacterial vectors that are based on non-invasive bacteria like e.g. commensal
bacteria, are used for the delivery of peptide encoded under the control of the saccharide
inducible promoter. Bacteria commensal to animals or humans can be used to express
and/or release peptide or synthetic pathway enzymes to produce effector molecules.
Effector molecules can be provided by the pharmaceutical combination of the invention
using bacterial vectors expressing synthetic pathway enzymes for e.g. interleukins,
leukotrienes as well as drugs obtainable from pro-drugs by enzymatic conversion. An
exemplary enzyme for the conversion of a pro-drug to a more potent drug is cytosine
deaminase, e.g. from E. coli.
Not only are these activities of the vector induced at will by applying the inductor
saccharide to the animal or human having received said vector, but further, repeated
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activation of the transgene is possible by application of the inductor saccharide, as long as
bacterial vector is present.
For introducing peptide into the cells of animals treated with the pharmaceutical
combination of the invention, its vector component is preferably based on attenuated
invasive bacteria. Target cells are tissue or organs within an animal, i.e. in vivo, cultivated
animal cells or extracorporal tissue or organs. Herein, attenuated invasive bacteria serve as
a transport vehicle for introducing transgene sequences into animal cells, which transgene
sequences are transcribed and/or translated by the bacterial component. Dependent on the
nature of the peptide encoded by the vector, the vector is for medical use or for technical
use, e.g. for manipulating cultivated target cells, e.g. for the extracorporal treatment of
organs.
Additionally or in the alternative, the bacterium on which the bacterial vector component
is based serves to enhance the specific immune response desired against the peptide
expressed, e.g. the bacterium acts as an adjuvant for antigenic peptides. In accordance with
the antigenic properties of the peptide encoded by the transgene and depending on the
cellular and humoral components of the immune response elicited, such a bacterial vector
can constitute the first component of the pharmaceutical combination used as a vaccine
against viral or bacterial infection or against parasites, tumor cells, or factors involved in
autoimmunity or allergy, against Alzheimer plaques and other malignancies.
Alternatively, the transgene may encode a suicide gene whose synthesis leads to lysis of
the bacterial vector and subsequent release of its constituents, predominantly into the
vicinity of target cells in the case of vectors based on non-invasive bacteria, and
predominantly within target cells in the case of vectors based on attenuated invasive
bacteria, respectively.
In a further aspect, the bacterial vector component is based on non-invasive or on
attenuated invasive bacteria for delivery of nucleic acids, which can be transcribed and/or
translated by the recipient mammalian cell. This can be used for introducing a desired
nucleic acid sequence into the vicinity of or into target cells within an animal or within an
extracorporal organ. In one aspect, the vector component is used as a transport vehicle for
18

introducing exogenous nucleic acid sequences into animal organisms or cells, for example
DNA comprising an expression cassette encoding a peptide homologous to the recipient
mammalian cell or encoding a heterologous peptide, for example having antigenic
properties to elicit an immune response from the recipient organism. The transfer of an
expression cassette encoding an immunogenic peptide instead of the direct transfer of the
antigen is also termed DNA vaccination.
For use in vaccination, the pharmaceutical combination according to the invention allows
the advantageous delivery of a transgene because the transgene can be maintained within
the vector component until delivery of peptide and/or nucleic acid to the vicinity of or into
the target cell essentially without activity of the transgene previous to the administration of
its second component. The advantage of induction of trangene activity by administration
of the inductor saccharide becomes evident when looking at the energetic burden to the
bacterial vector for maintenance of a transgene within a plasmid or for continued peptide
synthesis during the course of infection, reducing the efficiency of the vector component.
As target cells reached by the vector component, Peyer plaques and further
immunoreactive tissues of animals have been identified to contain bacterial vector after
oral and systemic administration of the vector, respectively. Activation of the transgene
could be achieved in these immunoreactive target cells by subsequent oral or systemic
administration of the inductor saccharide.
A further medical use of the pharmaceutical combination, which preferably contains a
bacterial vector component, using a vector generated on the basis of non-invasive or
invasive bacteria, which in the case of pathogenic bacteria are preferably attenuated, is
marking, identification and/or killing of tumor cells. Here, the transgene may be a peptide
which is recognized by the recipient animal as an antigen when available for presentation
in complex with MHC molecules. The antigen may be heterologous peptide or a self-
antigen to break self-tolerance. Marking or identification of tumor cells for subsequent
elimination by CTL is an efficient way of surmounting the self-tolerance which is an
obstacle to the attack of CTL against tumor cells. The complex of antigen delivered by the
bacterial vector component and MHC I is then recognisable by cytotoxic T-lymphocytes.
This leads to the generation of cytotoxic T-lymphocytes, directed against cells presenting
the immunogenic peptide on their superficial MHC I complex. When used in connection
19

with the preference of some enteropathogenic bacteria, for example salmonella or E. coli,
to invade tumor tissue and replicate therein, the bacterial vector component of the
pharmaceutical system directs the cellular immune response involving cytotoxic T-
lymphocytes against identified cells, preferably against tumor tissue.
For use in tumor therapy, the transgene contained within the bacterial vector component
can be selected from nucleic acids encoding factors that suppress the expression and/or
activity of oncogenes, e.g. iRNA, pro-drug converting enzymes, e.g. E. coli deaminase,
cytotoxic proteins, e.g. colicin E3, immunomodulating factors, e.g. cytokines, the tumor
necrosis factor alpha (TNFalpha), and/or anti-angiogenic factors, e.g. endostatin.
Synchronizing the time of administration of the inductor component with the infectious
cycle or migration of the bacterial vector component within the target organism that has
been administered the vector component to specific or non-specific tissues, cells and/or
cellular compartments, e.g. after completion of migration into tumor tissue is expected or
determined, allows to start the desired activity from the saccharide inducible promoter at
desired locations.
This desired activity may be the synthesis of an antigen intended for presentation on the
surfaces of specific target cells, i.e. on the outside of tumor cells to mark them for
recognition by T-cells. Another example for the desired activity is the synthesis of an
apoptose-inducing factor, or of a peptide catalyzing the conversion of a pro-drug to a drug,
resulting for example in an increased cytotoxicity of the drug compared to the pro-drug. A
further desired transgene activity may be the synthesis of bacterial toxins, e.g. cytotoxins.
These bacterial vector components preferentially comprise a transgene encoding a peptide,
the expression of which within the infected tumor cell induces apoptosis or lysis by
cytotoxic T-cells. For diagnostic or research purposes, tumor tissue can be identified by
introduction of an expression cassette containing a product that can be identified
spectrometrically, for example a fluorescent or bioluminescent peptide or peptide
catalyzing the conversion of a compound to generate a detectable signal, e.g. a
magnetosome or luminescence.
20

As a further embodiment of the invention, the bacterial vector component is genetically
manipulated for enhanced expression of the inductor saccharide transporter system
importing the inductor saccharide into the vector. This genetic manipulation can be
effected by enhancement of the basal promoter activity controlling expression of the
inductor saccharide transporter system or, alternatively, by introduction of the expression
cassette encoding the inductor saccharide transporter system, e.g. into bacteria used as
vectors that originally are devoid of an inductor saccharide transporter system for the
inductor saccharide suitable for inducing activity of the saccharide inducible promoter
controlling activity of the transgene. For example, the expression cassette encoding the L-
arabinose transporter of E. coli is used to transform a bacterium lacking an L-arabinose
transporter.
As a result, increased uptake of the inductor saccharide by bacterial vectors is observed,
leading to enhanced induction of transgene activity. Further, the percentage of bacterial
vector present that is induced is increased, reducing the effect of the so-called all-or-
nothing effect that is observed at inductor saccharide concentrations in tissue below a
saturating level, e.g. at medium range concentrations, leading to a considerable proportion
of bacterial vector without inductor saccharide, i.e. essentially without transgene activity.
As an example, chromosomal or plasmid-based integration of a mutant lacY gene into a
bacterial vector that is deficient for L-arabinose transport and/or degradation (e.g.
according to Morgan-Kiss et al., PNAS 99, 7373-7377 (2002)) can be used as a genetic
manipulation to enhance L-arabinose uptake and, hence, induction of the saccharide
inducible promoter, in this example PBAD-
In addition or in the alternative to the embodiment of using a genetically manipulated
bacterial vector having increased activity of the inductor saccharide transporter, the
bacterial vector is genetically manipulated for reduction of the metabolic pathway activity
of inductor saccharide degradation. In these embodiments, genetic manipulation of the
bacteria used as the bacterial vector component leads to reduction or inactivation of
transcription and/or translation and/or activity of metabolic enzymes. For example,
synthesis of metabolic enzymes of the L-arabinose degradation pathway (ara operon) is
inactivated in the bacterial vector component.
21

The genetic manipulation to increase uptake of inductor saccharide and/or to reduce
inductor saccharide metabolism is preferred in bacterial vectors that are not intended for
repeated administration of inductor saccharide., e.g. when complete and intense induction
of transgene activity is desired, e.g. lysis of the vector component when using gene E as
the transgene for termination of presence of the vector.
The specificity of the bacterial vector component originates from the properties of the
bacterium utilized as the first component of the pharmaceutical combination, whereas it is
the second component that achieves controlled induction of the presence and, hence,
activity of the transgene. Making use of the control of the vector component by
administration of the inductor saccharide allows to determine, if desired repeatedly, the
point of time of activation, e.g. transcription and, depending on the transgene, translation
of the transgene. On the basis of identification of vector component within the animal or
after lapse of a period of time the vector component needs for reaching a desired location,
the spatial localisation of the vector component is utilized to achieve a spatial, i.e. a
localized effect from the transgene. In this embodiment, a bacterial vector component may
be used to direct the cellular immune response towards target cells displaying the antigen
by MHC I, e.g. tumor cells containing the antigenic peptide originally encoded by the
bacterial vector. In this regard, the bacterial component of the vector can provide adjuvant
activity and serves for identification of tumor cells and localisation of the transgene
activity.
The saccharide inducible promoter contained within the bacterial vector component allows
for an infection of animal cells unhampered by transcription and/or translation of
structural sequences and/or by a high copy number of the plasmid, due to the tight
regulation exerted by this promoter in the absence of inductor saccharide. It is only after
the external administration of the inductor saccharide at any desired point of time that the
desired transgene activity commences, e.g. transcription starts from the promoter.
An example for the second embodiment is the use of the pharmaceutical combination
against inflammatory bowel disease, comprising a vector component based on commensal
bacteria containing a transgene encoding for example interleukins, leukotrienes etc., or
synthetic pathway enzymes to produce effector molecules. This bacterial vector
22

component may be introduced into the target organism by ingestion and the synthesis of
effector molecules may be induced repeatedly by subsequent ingestion of the relevant
inductor component.
The transgene may encode structural genes (antigenic or immunomodulating peptide,
antibody or bioluminescent peptide, toxins, e.g. bacteriostatics and/or cytostatics, enzymes
modifying bacterial nucleic acids, e.g. bacterial recombinases, e.g. for altering the
transgene sequence), reactive RNA species (ribozyme, antisense RNA, siRNA), a
replicase for the amplification of plasmids (the trfA gene product of E. coli, acting on
oriV) and/or lysis determinant of a bacteriophage (lytic peptide from suicide gene, e.g.
protein E of 0X174).
Alternatively or additionally, the transgene under the control of a saccharide inducible
promoter may be used to control the copy number of the bacterial plasmid on which it is
contained. For example, the transgene may encode a replicase acting on a high copy
number origin of replication. Presence of the inductor saccharide leads to the synthesis of
the transgene, which in turn acts on its specific origin of replication, leading to the
amplification of the entire plasmid sequence. Due to the tight regulation of the inventive
promoter element, such a plasmid furthermore comprises a very low copy number origin
of replication in order to maintain at least one copy of the plasmid within the bacterial
vector in the absence of inductor. The plasmid may comprise a further nucleic acid
sequence, for example an expression cassette, optionally also under the control of a
saccharide inducible promoter, encoding a structural gene or a reactive RNA species.
In order to enhance the import of nucleic acid sequences into the cellular nucleus,
enhancer elements for nuclear import can be present on such nucleic acid sequences, for
example the cPPT region, (poly purine tract, a genetic element enhancing nuclear import).
Further transgenes which can be encoded by bacterial vector components may additionally
or alternatively encode a suicide gene under the control of the saccharide inducible
promoter. Such a suicide gene catalyzes the lysis of the bacterial vector component and
may be represented for example by the lysis gene of phage OX 174, gene E. The presence
of a transgene encoding a suicide gene is only possible under the control of a tightly
23

regulated promoter as the lysis of the bacterial vector is induced by the synthesis of only a
few molecules, for example of less the 100 molecules of gene E product. Therefore,
presence of the inductor saccharide leading to the synthesis of the suicide gene product
results in the rapid destruction of the bacterial vector component and in the release of its
contents into the phagosome, the cellular cytosol and/or into the intercellular space.
Accordingly, a suicide gene under control of a saccharide inducible promoter can be used
for genetically manipulated bacterial vector components as a safety feature for aborting
their presence and for the release of the bacterial content.
In order to destroy the phagosome in the case of intracellular bacteria replicating therein,
the bacterial vector component may be genetically manipulated to comprise a transgene
for secretion of a peptide leading to the destruction of the phagosome, for example
listeriolysin O (LLO). The peptide leading to the destruction of the phagosome may be
activated by administration of the inductor component. This phagosomal lysis facilitates
the liberation of the bacterial vector's contents into the cytosol, which allows access of
peptides for presentation via MHC-I and/or the nuclear import of nucleic acid sequences
into the cellular nucleus.
A further example for a structural gene to be used as the transgene are sequences encoding
peptides useful for research, monitoring and diagnostic purposes, for example green
fluorescent protein and its homologues or derivatives, luciferase or the lux operon (lux
CD ABE) ofPhotorhabdus luminescens for detection of luminescence, for example by a
CCD camera, or via enzymatic activity generating a dye, e.g. beta-galactosidase.
Further examples of transgenes are secretory proteins, conjugational DNA-protein
complexes, bacteriolytic determinants or bacteriophage for release of macromolecules
from the vector within the tissue, organ or animal upon induction by administration of
inductor saccharide. Secretion systems usable for secretion of transcription and/or
translation products of the transgene or of DNA, respectively, are for example bacterial
secretion systems and, alternatively, bacteriophages and lysis systems, modified for the
transfer and/or release of macromolecules from the bacterial vector. Secretion systems
comprise type I secretion systems like the E.coli hemolysin secretion system, which be
adapted to the saccharide regulated secretion of peptide by generation of transgene
24

encoding a fusion peptide containing the secretory recognition sequence. Similarly, the
general secretion pathway (Sec) of E. coli, classified as type II secretion system, and type
III secretion systems, e.g. E.coli flagella type III secretion system or pathogenicity related
type III secretion systems of Salmonella can be adapted by the generation of a transgene
encoding a fusion peptide with the respective signal peptide. One specific use of the type
III secretion systems is the translocation of peptide from extracellular bacteria into target
cells or from bacteria residing in intracellular compartments of the host cell into the
cytosol. Further, type IV secretion systems, also refered to as conjugational apparatuses,
e.g. the VirB/VirD4 type IV secretion system of Agrobacterium tumefaciens, can be
adapted for secretion and/or translocation of peptide and/or DNA by providing the
transgene with a nucleic acid sequence encoding the respective signal sequence specific to
the secretion system. One specific use of type IV secretion systems is the translocation of
peptide and/or DNA from extracellular bacteria into target cells or from intracellular
bacteria across cellular compartmental borders, according to the invention within the
animal after induction by administration of the inductor saccharide. Alternatively or
additionally, autotransporter and other surface-display systems, e.g. the E.coli AID A
autotransporter, can be used as transgene. Bacteriophages, e.g. phages Lambda or Ml3,
can be used as a transgene, effecting their release from the bacterial cell upon induction by
the inductor saccharide. Whereas the release of Lambda phage requires bacterial cell lysis,
the filamentous phage Ml3 can be secreted by the viable bacterial cell. Lysis
determinants, e.g. protein E of bacteriophage phiX174 or protein Hok of plasmid Rl, can
be used as transgenes for lysis of the bacterial vector giving rise to the release of peptide
and/or nucleic acid from the bacterial vector.
In one embodiment of the present invention, the bacterial vector component is genetically
manipulated to enhance the activity of its intrinsic secretory system to increase secretion
of a transcription or translation product of the transgene upon administration of the
inductor saccharide. Alternatively, the bacterial vector component is genetically
manipulated to comprise a chromosomal or plasmid-based expression cassette encoding a
secretory system for the enhancement of secretion of the transcription or translation
product of the transgene. For these purposes, the above mentioned secretion systems type I
to IV can be used.
25

Bacteria that can form the basis for the vector component of the pharmaceutical
combination according to the invention comprise artificial bacteria carrying substantial
deletions in comparison to wild-type strains and/or comprising genetic determinants of
several different bacteria as long as they still provide for the function of the bacterial
vector component in the combination according to the present invention, and attenuated
strains of non-pathogenic or pathogenic gram-positive and gram-negative bacteria which
may be invasive or non-invasive to animal cells, or commensal bacteria. The gram-
negative bacteria are for example E. coli, Salmonella spp., e.g. Salmonella enterica
serovar Typhimurium, like strain SL7207, e.g. Salmonella enterica serovar Typhi, like
strain Ty21a, Shigella spp., Yersinia spp., and Vibrio cholerae. Examples for gram-
positive bacteria are Bacillus spp., e.g. Bacillus subtilis, Clostridium spp., Listerium
monocytogenes, and Mycobacterium spp., e.g. strain BCG. Commensal bacteria are for
example E. coli, Lactobacillus spp., Lactococcus spp., and Streptococcus gordonii.
Within the terms of this disclosure, the expression "attenuated invasive bacteria"
especially refers to attenuated strains of E. coli, Listerium monocytogenes, Salmonella
enterica var. typhimurium, Shigella flexneri, Yersinia pseudotuberculosis, and attenuated
strains of further invasive bacteria as well as of the non-invasive bacterium Vibrio
cholerae. The reason for including Vibrio cholerae for the purposes of this disclosure
within the term "invasive bacteria" is that for Vibrio cholerae attenuated strains exist,
which have been demonstrated to accumulate within tumor tissue (Nature Biotechnology,
Volume 22, No 3, March 2004). With reference to the affinity of Vibrio cholerae to
tumors this is a property shared with at least some invasive bacteria, making them useful
within the present invention.
In the context of this disclosure, the classification of bacteria useful as the bacterial vector
components of the invention as invasive or non-invasive includes the possibility for some
bacteria to colonize organ specific tissue intracellularly and extracellularly. This applies
for example to Salmonella, that colonize tumor tissue also in an extracellular state.
Further, invasive bacteria can be used to generate the vector component of the invention
which originally are non-invasive bacteria but which have been rendered invasive by
genetic manipulation, e.g. by introduction of coding sequences for invasion promoting
26

factors, e.g. the invasin gene (inv) derived from Yersinia pseudotuberculosis, e.g. by
expression in E. coli.
Further exemplary bacteria suitable for producing the bacterial vector component of the
pharmaceutical combination according to the invention are: Agrobacterium e.g.
Agrobacterium tumefaciens; Bacillus e.g. Bacillus cereus, Bacillus subtilis, Bacillus
thuringiensis, Bacillus weihenstephanensis; Bartonella e.g. Bartonella henselae,
Bartonella schoenbuchensis; Bdellovibrio e.g. Bdellovibrio bacteriovorus, Bdellovibrio
starrii, Bdellovibrio stolpii; Bifidobacterium e.g. Bifidobacterium adolescentis,
Bifidobacterium bifidum, Bifidobacterium lactis, Bifidobacterium longum; Bordetella e.g.
Bordetellapertussis; Borrelia e.g. Borrelia burgdorferi; Brucella e.g. Brucella abortus,
Brucella bronchiseptica; Burkholderia e.g. Burkholderia cenocepacia, Burkholderia
fungorum, Burkholderia mallei, Burkholderia pseudomallei; Campylobacter e.g.
Campylobacter fecalis, Campylobacter pylori, Campylobacter sputorum; Chlamydia e.g.
Chlamydia pneumoniae, Chlamydia psittaci, Chlamydia trachomatis; Clostridium e.g.
Clostridium difficile, Clostridium novyi, Clostridium oncolyticum, Clostridium
perfringens, Clostridium sporogenes, Clostridium tetani; Corynebacterium e.g.
Corynebacterium diphtheriae, Corynebacterium glutamicum, Corynebacterium jeikeium;
Edwardsiella e.g. Edwardsiella hoshinae, Edwardsiella ictaluri, Edwardsiella tarda;
Enterobacter e.g. Enterobacter aerogenes, Enterobacter cloacae, Enterobacter sakazakii;
Enterococcus e.g. Enterococcus avium, Enterococcus faecalis, Enterococcus faecium,
Enterococcus gallinarum; Escherichia e.g. Escherichia coli; Eubacterium e.g.
Eubacterium lentum, Eubacterium nodatum, Eubacterium timidum; Helicobacter e.g.
Helicobacterpylori; Klebsiella e.g. Klebsiella oxytoca, Klebsiellapneumoniae;
Lactobacillus e.g. Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus
delbrueckii, Lactobacillus plantarum; Lactobacterium e.g. Lactobacterium fermentum;
Lactococcus e.g. Lactococcus lactis, Lactococcus plantarum; Legionella e.g. Legionella
pneumophila; Listeria e.g. Listeria innocua, Listeria ivanovii, Listeria monocytogenes;
Microbacterium e.g. Microbacterium arborescens, Microbacterium lacticum;
Mycobacterium e.g. Bacille Calmette-Guerin (BCG), Mycobacterium avium,
Mycobacterium bovis, Mycobacterium paratuberculosis, Mycobacterium tuberculosis;
Neisseria e.g. Neisseria gonorrhoeae, Neisseria lactamica, Neisseria meningitidis;
Pasteurella e.g. Pasteurella haemolytica, Pasteurella multocida; Salmonella e.g.
27

Salmonella bongori, Salmonella enterica ssp.; Shigella e.g. Shigella dysenteriae, Shigella
flexneri, Shigella sonnei; Staphylococcus e.g. Staphylococcus aureus, Staphylococcus
lactis, Staphylococcus saprophyticus; Streptococcus e.g. Streptococcus gordonii,
Streptococcus lactis, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus
salivarius; Treponema e.g. Treponema denticola, Treponema pallidum; Vibrio e.g. Vibrio
cholerae; Yersinia e.g. Yersinia enterocolitica, Yersiniapseudotuberculosis, including Si-
strains devoid of Hfr factors and of pili of these bacteria, especially SI-strains of E. coli.
A further advantage of the promoter elements according to the invention are the absence
of side effects of the inductor component, which saccharide is furthermore non-toxic,
reaches cells and tissue within an animal organism, is not immunogenic, can be
administered via separate routes, for example orally, intravenously or otherwise
systemically, its concentration within the recipient organism or cell culture can be adjusted
and it is available at low cost.
Brief description of the figures
The present invention will now be described by way of examples, taking reference to the
accompanying figures, wherein
- Figure 1 schematically depicts expression plasmid pHL238, wherein GFP is
operably linked to PBAD,
- Figure 2 shows the results of flow cytometric analysis of Salmonella enterica
serovar typhimurium SL7207 bearing a plasmid according to Figure 1 under
induced and non-induced conditions,
- Figure 3 the results of flow cytometric analysis of Salmonella enterica serovar
typhimurium SL7207 bearing a plasmid according to Figure 1, re-isolated from
infected macrophage cells J774A1, after induction with varying concentrations of
L-arabinose.
- Figure 4 shows the flow cytometric analysis of Salmonella enterica serovar
Typhimurium strain SL7207 bearing the plasmid according to Figure 1, re-isolated
from the spleen of infected mice, after induction with varying amounts of L-
arabinose.
28

- Figure 5 depicts single copy plasmid pAENl 7, containing the inducible replicon of
RK2, having a constitutive expression cassette for GFP.
- Figure 6 shows the flow cytometric analysis of Salmonella enterica serovar
Typhimurium strain SL7207 bearing a plasmid according to Figure 5 under
induced and non-induced conditions.
- Figure 7 shows the flow cytometric analysis of Salmonella enterica serovar
Typhimurium strain SL7207 cells bearing the plasmid according to Figure 5, re-
isolated from infected macrophage cells J774A1, after induction with varying
concentrations of L-arabinose.
- Figure 8 schematically depicts plasmid bearing gene E of bacteriophage O XI74
under the control of PBAD>
- Figure 9 gives the number of bacterial vector cells re-isolated from cultured
macrophage cells J774A1, infected with the Salmonella enterica serovar
Typhimurium strain SL7207 bearing the plasmid according to Figure 8 after
induction with various amounts of L-arabinose,
- Figure 10 shows the number of viable bacterial vector re-isolated from the spleen
of a mouse infected with the Salmonella enterica serovar Typhimurium strain
SL7207 bearing the plasmid according to Figure 8 after administration of various
amounts of L-arabinose
- Figure 11 schematically shows a plasmid harbouring the luciferase gene (luc) as a
transgene,
- Figure 12 A shows colony forming units (cfu) re-isolated from the tissues indicated
at time intervals (h) after administration of inductor saccharide to an animal
containing bacterial vector comprising the plasmid according to Figure 11,
- Figure 12 B shows transgene activity (relative luminescence units, RLU) of the
reporter gene in different tissue homogenates obtained from animals treated with
bacterial vector and, subsequently, with inductor saccharide as for Figure 12 A,
- Figure 12 C shows transgene activity per bacterial vector (RLU/cfu) of the reporter
gene in different tissue homogenates obtained from animals treated with bacterial
vector and, subsequently, with inductor saccharide as for Figure 12 A,
Figures 13 A, B and C show cfu, RLU and relative RLU (RLU/cfu), respectively,
for Peyer patches obtained from animals treated with bacterial vector of Figure 12
29

A by oral administration and, subsequently, with inductor saccharide administered
in solution as drinking water,
- Figure 14 schematically shows a plasmid comprising a lysis gene as the transgene
for Tn-7 mediated chromosomal integration into the bacterial vector's genome,
- Figure 15 shows cfu determined for indicated tissue homogenates obtained from an
animal administered with a vector harbouring the lysis gene according to Figure 14
and, subsequently, with inductor saccharide,
- Figures 16 A and B show cfu and transgene activity (RLU), respectively,
determined in the tissues indicated of animals administered with bacterial vectors
based on different bacteria, each harbouring the plasmid according to Figure 11,
after administration of inductor saccharide, and
- Figure 17 schematically shows a bacterial vector, forming the first component of
the pharmaceutical combination according to the invention.
Examples
In the examples, the promoter element PBAD from the L-arabinose operon of E. coli, is
present on one plasmid and/or on a DNA segment integrated at least in single copy into
the bacterial vector's chromosome in combination with the structural gene for its regulator
protein AraC under control of its own promoter Pc. However, the promoter element PBAD
is only representative for saccharide inducible promoters to be used according to the
invention in genetically manipulated bacterial vectors.
An arrangement of the saccharide inducible promoter PBAD with an expression cassette for
its specific regulator AraC is shown in the Figure 1, wherein the saccharide inducible
promoter is arranged in a back to back relationship with the promoter Pc controlling the
structural gene for its regulator AraC. This arrangement is not obligatory, however, it is
essential that the expression cassette for the regulator gene is physically linked to the
saccharide inducible promoter, and the arrangement of the operator elements should allow
for the insertion of the desired DNA sequences downstream, i.e. in an operably linked
fashion.
30

Example 1: Expression of peptide from a plasmid contained in the bacterial vector after
induction
As an example for a structural gene, plasmid pHL238 (schematically depicted in Figure 1)
comprising the structural gene for green fluorescent protein (GFP) under the control of
PBAD was cloned, further comprising the structural gene for the regulator of PBAD, araC
under the control of its own promoter Pc, along with the Ampicillin resistance gene as a
selection marker, and a high copy number origin of replication from pUC. Regulatory
elements originate from plasmid pBAD18 (Guzman et al., J. Bacteriol 1995 Jul;
177(14):4121-30)
This bacterial vector is based on Salmonella enterica serovar Typhimurium, strain
SL7207, which is a known attenuated invasive salmonella strain in use for experimental
vaccination.
The salmonella strain was transformed with plasmid pHL238 by electroporation,
transformed colonies were selected on LB-medium agar plates containing streptomycin at
30 ug/mL and ampicillin at 100 ug/mL. The resultant transformed strain was bacterial
vector SL7207[pHL238]. At 3 hours after addition of 0.1 % w/vol L-arabinose to the
bacterial culture in liquid LB medium (30 ug/mL streptomycin, 100 ug/mL ampicillin) at
logarithmic growth phase, strong induction of GFP expression was monitored using a
FACScalibur flow cytometer (Becton Dickinson). Results are shown in Figure 2, the thick
line for addition of L-arabinose, the thin line without L-arabinose.
These measurements demonstrate that the synthesis of the gene product under the control
of a saccharide inducible promoter by addition of the saccharide acting as its specific
inductor substance leads to the bacterial expression of the structural gene. In this example,
the expression of GFP leads to fluorescence values more than two orders above the
background fluorescence obtained for the infected cells without induction by L-arabinose.
31

Example 2: in vitro expression of peptide from a bacterial vector after induction within
infected animal cells
The murine macrophage cell line J774A1 was infected with bacterial vector
SL7207[pHL238] of Example 1. Before infection, cells were seeded to 2 x 106 cells per
well in a 6-well plate in antibiotic-free medium (IMDM with 10% inactivated fetal calf
serum, 2 mM glutamine) and grown for one day in a 5% CO2 atmosphere at 37°C. For
infection, SL7207[pHL238] were grown from a glycerol stock overnight at 37°C on a LB
plate supplemented with anitibiotics, followed by cultivation in liquid LB medium
supplemented with antibiotics for approximately 2 hours at 37°C, shaking at 60 rpm.
Bacteria were harvested by centrifugation, washed in PBS, resuspended in cell culture
medium and added at a ~MOI of 10. 30 min after start of infection cells were washed
twice with PBS before medium containing gentamycin (50 ug/mL) was added to kill
extracellular bacteria. 4 hours after infection different amounts of L-arabinose were added
into individual wells of infected J774A.1 cells up to final concentrations in of 800 uM, 4
mM, 40 mM, and 400 mM. 3 hours after addition of L-arabinose cells were treated with
0,25% Triton X-100. GFP expressing bacteria in the lysates were monitored by flow
cytometry. In order to differentiate fluorescence of GFP expressing bacteria from
autofluorescent cell fragments the so-called two colour flow cytometry method was used
(Bumann, Infect. Immun. (2001) 69,4618-4626.). The analytical results are depicted in
Figure 3, with unspecific background fluorescence substracted. Varying L-arabinose
concentrations are depicted for medium without L-arabinose (thin curve) and L-arabinose
at increasing concentrations at 4 mM, 40 mM and 400mM (curves with increasing
boldness).
It can be seen that the fluorescence intensity of GFP increases with increasing
concentrations of L-arabinose in the medium, demonstrating the gradual induction of the
saccharide inducible promoter, leading to the synthesis of GFP.
These measurements demonstrate that the introduction of a bacterial vector into
mammalian cells is obtained using the bacterial vector according to the invention, and
induction of the synthesis of the gene product under the control of a saccharide inducible
promoter by extracellular addition of the saccharide acting as its specific inductor
32

substance leads to the bacterial expression of the structural gene while contained in animal
cells.
Example 3: in vivo expression of peptide from a bacterial vector after induction within a
mammalian organism
Balb/c mice were infected intravenously with a dose of ca. 5 x 106 bacteria in PBS of
bacterial vector SL7207[pHL238]. After 2 days, different amounts of L-arabinose
dissolved in PBS were administered intravenously into mice. 4 hours after L-arabinose
administration mice were sacrificed, spleens were removed, homogenized in PBS
containing 0,1% Triton X-100 and lysates were analyzed by two colour flow cytometry.
It is demonstrated that expression of GFP by bacteria recovered from the infected animals
was induced by L-Arabinose in a dose-dependent manner, results are depicted in Figure 4.
It is seen that the fluorescence intensity due to GFP increases with increasing
concentrations of L-arabinose in the animal, demonstrating the gradual induction of the
saccharide inducible promoter, leading to the synthesis of GFP.
Example 4: In vitro regulation of copy number of a bacterial plasmid
In order to demonstrate the regulation of the copy number of a plasmid contained within a
bacterial vector, the plasmid according to Figure 5 was constructed. In the absence of L-
arabinose, just one copy of this plasmid per bacterial cell is maintained, regulated by the
origin of replication derived from the F plasmid of Escherichia coli. In addition, this
plasmid contains the inducible origin of replication of plasmid RK2, namely oriV. The
replicase gene trfA, acting on this origin, is placed under the control of PBAD, as an
example for a saccharide inducible promoter.
In order to allow for a convenient analysis of plasmid replication, GFP was placed under
control of the weak constitutive Pwa promoter derived from the bla gene, also contained on
said vector. The recombinant strain SL7207[pAEN17] was grown into logarithmic phase
and either no or 0,1% L-Arabinose was added into bacterial cultures. After 3 hours of
induction, plasmid replication was monitored by measuring increased GFP activity due to
33

increased expression, which in turn was caused by plasmid amplification containing gfp
gene copies, as depicted in Figure 6.
The results demonstrate that the addition of L-arabinose induces the PBAD, leading to the
synthesis of the trfA gene product, which in turn induces replication mediated by oriV,
resulting in an increased copy number of the plasmid pAEN17. The analytical results of
flow cytometry are shown in Figure 6 with background fluorescence as the left-hand peak,
representing the expression of GFP at low copy number under non-induced conditions.
The right-hand peak represents the activity of GFP under induced conditions, indicating
the effect of the increased copy number of the plasmid and of the expression cassette for
GFP, respectively. This demonstrates that a saccharide inducible promoter can be used to
control the copy number of a plasmid harboured by a bacterial vector when placing the
coding sequence for the gene acting on an inducible origin of replication functionally
linked under the control of a saccharide inducible promoter.
Example 5: In vitro induction of plasmid replication to control protein expression from a
bacterial vector within mammalian cells
J774A1 cells, a murine macrophage cell line, were infected with strain SL7207[pAEN17],
as described in Example 2. 4 hours after infection, different amounts of L-arabinose were
added into individual wells of infected J774A1 cells up to a concentration in the medium
of 4 mM, 40 mM and 400mM, respectively. 3 hours after addition of L-arabinose cells
were treated with 0,25% Triton X-100. Bacteria in the lysates were monitored for GFP
expression by flow cytometry as described in Example 2. The analytical results are
depicted in Figure 7, with unspecific background fluorescence substracted.
It is seen that the fluorescence intensity of GFP increases with increasing concentrations of
L-arabinose in the medium, demonstrating the gradual induction of the saccharide
inducible promoter, leading to induction of plasmid replication and in turn to an increase
in the synthesis of GFP due to elevated gene copy number.
These measurements demonstrate that the introduction of a bacterial vector into
mammalian cells is obtained using the bacterial vector according to the invention, and
34

induction of the synthesis of the replicase TrfA under the control of a saccharide inducible
promoter by extracellular addition of the saccharide acting as its specific inductor
substance leads to the amplification of the plasmid containing a constitutive expression
cassette of the structural gene while contained in animal cells.
Example 6: In vitro induction of lysis of bacterial vector within a mammalian organism
In order to demonstrate the lysis of bacterial vectors according to the invention,
controllable by addition of the inductor saccharide for the saccharide inducible promoter, a
plasmid according to Figure 8 was constructed. This plasmid carries the lysis gene E of
bacteriophage O XI74 under the control of the saccharide inducible promoter PBAD,
demonstrating the strict regulation of PBAD in the non-induced state. The plasmid pHL241
shown in Figure 8 was derived from plasmid pHL238 shown in Figure 1 by exchanging
gene gfp against gene E.
For infection, J774A1 cells were cultured and infected with SL7207 bearing the plasmid
of Figure 8 according to the procedure of Example 2. Induction was by addition of L-
arabinose to the final concentrations in cell culture medium as given in Figure 9, for an
induction period of 3 hours. Following induction, cells were harvested and lysed by
addition of Triton X-100 to a concentration of 1 g/L. For re-isolation, intracellular
bacterial vectors were plated on LB-agar containing ampicillin for quantification of viable
bacteria as colony forming units (CFU).
The results depicted in Figure 9 show that presence of the inductor saccharide L-arabinose
drastically decreases the number of viable bacterial vectors inside infected J774A1 cells.
The number of viable bacteria which can be re-isolated from infected J774A1 cells is
reduced by presence of L-arabinose as a result of lysis of the bacterial vector caused by
synthesis of the gene E product.
This example shows the effectiveness of bacterial vectors according to the invention,
based on attenuated invasive bacteria, containing a saccharide inducible promoter in
combination with a suicide gene as a system for terminating the infection of mammalian
cells with invasive attenuated bacteria by controlled lysis. This controlled termination of
35

the infection inevitably leads to the release of the bacterial vector contents into the
phagosome or cytosol of the infected cell, respectively.
Example 7: In vivo inducible lysis of bacterial vectors within an infected mammalian
organism
This example demonstrates the applicability of the attenuated invasive bacteria containing
a saccharide inducible promoter controlling a suicide gene for terminating the infection of
cells within a mammal, i.e. a mouse. The lysis gene E of bacteriophage 0X174 was
contained on the plasmid of Figure 8, harboured within Salmonella strain SL7207. This
bacterial vector was intravenously injected into Balb/c mice as described in Example 3.
Two days after infection of mice, L-arabinose was injected intravenously in amounts of 60
mg, 8 mg and 1.6 mg per animal, saline solution was used as background control (0).
Following 4 hours after induction, animals were sacrificed and the spleen was
homogenized for determination of the number of viable bacterial vectors. Viable bacterial
vectors were counted after plating according to Example 6.
The results depicted in Figure 10 demonstrate that the activity of the saccharide inducible
promoter contained in attenuated invasive bacteria according to the invention can be
induced in vivo by the systemic application of inductor substance. Injection of the inductor
saccharide leads to the activation of the saccharide inducible promoter PBAD, resulting in
expression of gene E and, subsequently, in an efficient lysis of the bacterial vector. Results
furthermore nicely demonstrate that the activity of the saccharide inducible promoter can
be regulated in a gradual manner by variation of the saccharide concentration acting as the
inductor.
Figures 9 and 10 further show that regulation of the toxic gene under the control of the
saccharide inducible promoter is sufficiently tight to allow for the maintenance of the
respective plasmid, encoding a toxic gene product, within bacterial vectors.
Example 8: In vivo induction of transgene activity from bacterial vector within a tumor of
an animal
36

This example demonstrates the use of a pharmaceutical combination of a bacterial vector
with the inductor saccharide to induce a transgene activity within an animal, with
preference to tumor tissue.
As a representative for a transgene, the luciferase gene from the firefly Photinus pyralis
was used as the reporter gene. As the saccharide inducible promoter element, PBAD from
the L-arabinose operon of E. coli was functionally linked to the luciferase gene, the
promoter element further being in conjunction with the structural gene for its regulator
protein araC under the control of its natural own promoter (Pc). The bacterial vector was
generated by transforming Salmonella enterica serovar Typhimurium, vaccine strain
SL7207, with the plasmid containing the transgene under the control of the saccharide
inducible promoter by electroporation. This plasmid, termed pHL259 is schematically
shown in Figure 11.
As an example for an animal having a tumor, Balb/c mice were subcutaneously inoculated
abdominally with 106 cells of the colon adenocarcinoma cell line CT26. After this tumor
generation treatment, mice bearing tumors of approximately 400-600 mm3 were
intravenously injected with 5 x 106 bacteria of the above bacterial vector
(SL7207[pHL259]), representing the first component of the pharmaceutical combination,
suspended in phosphate buffered saline (PBS). Three days post infection, L-arabinose as
the appropriate inductor saccharide, representing the second component of the
pharmaceutical combination, was administered intraperitoneally, dissolved in PBS.
Subsequently, mice were sacrificed and the tumors, spleens and livers dissected, then
transferred into 3 mL of sterile, ice-cold PBS containing 0.1% (vol/vol) Triton X-100.
In order to determine the distribution of the vector component within the animal organism
as well as the induction of the transgene activity due to the administration of the second
component, tumor tissue, spleens and livers were analysed.
Tissues were disrupted in a Polytron PG3000 homogenizer (Kinematica, Littau,
Switzerland). Homogenates were diluted in PBS and streaked on medium plates with
selective antibiotic (ampicillin). Colonies were counted after incubation of plates. As a
37

result, the number of bacteria in respective tissues could be calculated by counting the
resulting colony forming units (cfu) for each organ. The results are shown in Figure 12 A.
The induction of the transgene was determined by measurement of the reporter gene
(luciferase) activity from tissue homogenates after dilution (1:1) in 2x luciferase assay
lysis buffer (50 mM tris-HCl, 4 mM DTT, 20% (vol/vol) glycerol, 2% (vol/vol) Triton X-
100, 2 mg/mL lysozyme, pH 8.3), incubation at 25 °C for 10 minutes, centrifugation at
3,000 x g for 3 minutes, lOuL supernatant were added to lOOmL LARII reagent of the
luciferase assay system according to the manufacturer's instructions (Promega,
Mannheim, Germany). Luminescence intensity was measured spectrometrically in a
luminometer (Lumat LB9507, Berthold, Pforzheim, Germany). Dilution was taken into
account when calculating RLU per organ.
The transgene activity, represented by the luciferase activity (RLU) is shown in Figure 12
B, and relative transgene activity is shown in Figure 12 C, i.e. the relative luminescence
per colony forming units (RLU/cfu).
For all animals, the number of bacteria found in tumors by far exceeded the number of
bacteria detected in the spleen or liver, over the course of time. Here, the preference of the
bacterial vector component for accumulation in tumor tissue can be seen.
As can be taken from Figures 12 B and 12 C, the administration of the second component,
namely L-arabinose, induces transgene expression for all tissues tested. For the tissues
tested here, absolute transgene activity was greatest in tumor tissue, with the main activity
at about 6 hours past administration of the inductor saccharide. Note that transgene
activity in spleen and liver was very low to about background levels, and even presence of
the inductor saccharide did not cause significant activity levels.
Further, relative transgene activity, i.e. in relation to bacterial numbers in the tissues
tested, as shown in Figure 12 C, demonstrates that transgene activity was most effectively
induced in tumor tissue, whereas spleen and liver show considerably lower levels of
relative transgene expression at the intervals tested after administration of the inductor
saccharide.
38

Further, this example demonstrates that transgene induction is transient and, accordingly,
can be repeated by repetition of the administration of the inductor saccharide, and further
demonstrates that transgene induction can be modulated by the amount of inductor
saccharide and, i.e. transgene activity is inductor saccharide concentration dependent.
Example 9: In vivo induction of transgene activity from bacterial vector within a mammal,
using the pharmaceutical combination as a vaccine
Balb/c mice were orally inoculated with 5 x 108 cfu of recombinant strain
SL7207[pHL259], which was obtained as described in Example 8. At day 6 after
administration of the bacterial vector, mice were separated into groups, one group
receiving drinking water containing 250 mg/mL L-arabinose for 24 hours as the inductor
saccharide; a second group received drinking water, identically containing L-arabinose for
6 hours and a third group received a total of
120 mg L-arabinose, dissolved in PBS, intraperitoneally. 6 hours after administration of
the inductor saccharide, mice were sacrificed and Peyer patches were isolated and
homogenated.
From homogenates of Peyer patches, bacterial numbers and transgene activity (luciferase)
was determined as described in Example 8. Results are shown in Figures 13 A, 13 B, and
13 C, demonstrating that oral administration of the bacterial vector component, followed
by oral administration of the inductor saccharide is sufficient to induce transgene
expression in Peyer patches, representing an immune inductive site.
Example 10: Use of a pharmaceutical composition for the delivery of nucleic acid and/or
protein to tumor tissue within animals
As an example for a bacterial vector containing a transgene that can be activated to initiate
lysis of the bacterial vector within an animal, strain SL7207 was genetically manipulated
by integrating part of plasmid HL260a (schematically shown in Figure 14) by Tn7 mini-
transposon-mediated site specific integration into the bacterial chromosome, essentially
39

according to Bao et al. (Gene 109,167-168 (1991)), containing gene E of bacteriophage
phiX174 under the control of the PBAD promoter.
As an example for animals, mice were used that had been implanted subcutanously with a
CT26 tumor as described in Example 8. As the first component of the pharmaceutical
combination according to the invention, recombinant strain SL7207::HL260a, containing
the Tn7 mediated chromosomally integrated copy of the transgene (gene E), was
administered by intravenous injection (5 x 106 bacteria in PBS). At 3 days subsequent to
the administration of the bacterial vector, the second component, namely 120 mg L-
arabinose dissolved in PBS, was administered by intraperitoneal injection, followed by an
identical second injection 12 hours later. At 6 hours after the second administration of
inductor saccharide, mice were sacrificed and their tumor tissue, spleens and livers
isolated and homogenized as described in Example 8, including the determination of
bacterial numbers from homogenates. Results are shown in Figure 15, showing bacterial
counts of animals having received mock inductor, namely PBS (black columns) and
animals having received administration of the inductor saccharide (white columns), for
tumor tissue, spleen and liver, respectively. These results demonstrate that administration
of the inductor saccharide lead to lysis of the bacterial vector, especially in tumor tissue,
where bacterial vector had predominantly localized and/or increased in number, at least in
relation to spleen and liver.
This example demonstrates that a lysis gene as a transgene may be used for liberation of
bacterial vector's contents, e.g. nucleic acid, protein, for delivery to tissue within an
animal, controlled by administration of the second component of the pharmaceutical
combination. Further, a lysis gene as a transgene may be used for a drastic reduction of
bacterial vector concentration, even in most intensely populated tissue, e.g. tumor tissue.
In this respect, repeated lysis of the bacterial vector by repeated administration of the
inductor saccharide is feasible, as concentrations of inductor saccharide can be adjusted to
avoid lysis of the complete number of bacterial vector, i.e. leave some bacterial vectors for
repopulation of tissue, again, predominantly of tumor tissue.
Example 11: Genetic manipulation of bacterial vector component to enhance transgene
activity
40

The bacterial vector obtained in Example 10 was modified in a first alternative by T7-
mediated chromosomal integration of a mini-transposon comprising the mutant lacY gene
and, in a second alternative, by inactivating the ara operon by site-directed insertional
mutagenesis.
When using the alternatively manipulated vectors for the tumor treatment in mice
according to Example 10, both vector alternatives demonstrate a similar colonization of
tumor tissue in combination with an enhancement of reduction in residual vector counts
following administration of the inductor saccharide, i.e. increased efficiency in transgene
activity induction.
Example 12: Comparison of different bacteria for generating the bacterial vector
component in relation to the efficiency in colonizing a tumor of an animal
For an evaluation of the suitability of bacteria for generating the bacterial vector
component for use in the pharmaceutical composition according to the invention, the E.
coli SI laboratory strain Top 10 (Invitrogen, Karlsruhe, Germany), Salmonella enterica
serovar Typhimurium SL7207 (SL7207, described by Hoiseth et al, Nature 291 238-239
(1981)), and Salmonella enterica strains Salmoporc and Suisaloral (IDT, Rofllau,
Germany) were transformed by electroporation with plasmid pHL259, encoding luciferase
as a reporter gene.
Mice bearing CT26 tumors as described in Example 8 were administered the bacterial
vector by subcutaneous injection (5 x 106 bacteria) in PBS. 3 days later, the inductor
saccharide
(120 mg L-arabinose in PBS) was administered by intraperitoneal injection. 6 hours later,
mice were sacrificed and tumor tissue, spleen and liver removed and analyzed for bacterial
vector content and transgene activity after homogenization according to Example 8.
The results obtained for the different bacterial vectors under otherwise identical conditions
are shown in Figures 16 A and B for efficiency in colonizing the tissue (cfu) and
efficiency of transgene activity (RLU), respectively. The results show that different
41

bacterial strains can be used to generate the bacterial vector component of the
pharmaceutical combination according to the invention, yielding variations in the
efficiency of colonization (cfu) of tumor tissue in relation to spleen and liver, as well as
different efficiencies in transgene activity (RLU) in tumor tissue in relation to spleen and
liver.
It can be seen that all bacterial vectors predominantly colonized tumor tissue, although
with differing efficiency. Administration of inductor saccharide caused transgene activity,
again predominantly confined to tumor tissue. However, efficiency of colonization of
tumor tissue was not correlated to transgene activation for all vectors.
When monitoring the general health status of the animals tested, it was found that the
bacterial vector based on E. coli Top 10 caused the least pronounced impairment.
Accordingly, the present invention provides a choice of vectors for use in the
pharmaceutical combination of components to select a bacterial vector which
predominantly accumulates in tumor tissue, and the transgene activity can be regulated by
administration of the inductor saccharide, depending inter alia on the bacterium the vector
is based on.
Further, this example provides an assay for identification of bacteria suitable for
generating the bacterial vector component of the invention, using re-isolation of bacteria
from tissue samples of an animal having received the bacterial vector component for
assessing the efficiency of colonization of different tissue, and a reporter gene for
assessing induction of transgene activity by subsequent administration of the inductor
saccharide component.
Example 13: Bacterial vector comprising a combination of transgenes, each under the
control of a different saccharide inducible promoter
As an example for multifunctional bacterial vectors for use in the pharmaceutical
combination
42

according to the invention, vaccine strain SL7207 was genetically manipulated by Tn7
mediated chromosomal integration of the mini-transposon of a plasmid pHL260b,
modified from pHL260a by replacing the PBAD promoter by the L-rhamnose inducible
promoter (Prha), derived from plasmid pJOE2702 (Stumpp et al., Biospektrum 6, 33-
36(2000)). This strain chromosomally contains at least one copy of gene E of
bacteriophage phiX174 under the control of the rhamnose inducible promoter (Prha). The
resultant strain was then transformed with plasmid pTNFa-lux, containing the
bioluminescence operon of Photorhabdus luminescence under control of the PBAD
promoter in combination with the mouse TNFalpha gene under the control of the
constitutive promoter from beta-lactamase (Pbia). The resultant bacterial vector is
schematically shown in Figure 17.
As described in Example 8, Balb/c mice bearing a CT26 tumor were administered 5 x 106
bacterial vector, suspended in PBS by intravenous administration. 3 days after this
administration, the inductor saccharide, namely 120 mg L-rhamnose, dissolved in PBS,
was administered intraperitoneally. As a result, lysis of bacterial vector and release of
TNFalpha was observed. Upon administration of 120 mg L-arabinose dissolved in PBS
intraperitoneally, to the same mice 1 day later, as well as on consecutive days,
colonization of tumor tissue by bacterial vectors was monitored by spectrometry, more
specifically luminometric analysis of anesthesized mice using a CCD camera.
It could be shown that repeated administration of the inductor saccharides L-rhamnose
and, subsequently, of L-arabinose, results in bacterial lysis and release of TNFalpha in
combination with bioluminescence (RLU). Further, monitoring of tumor location and size
could be demonstrated by luminometric analysis of a monitoring transgene product,
exemplified here by bioluminescence operon of Photorhabdus luminescence, also
allowing observation of the effects of administration of inductor saccharide inducing the
therapeutic transgene, exemplified here by TNFalpha.
This example demonstrates that different transgene activities can be induced
independently and repeatedly at the site of localization of the bacterial vector, exemplified
here by tumor tissue.
43
WE CLAIM
1. Combination of compounds for producing pharmaceutical preparations comprising
as a first compound a bacterial vector for administration for medical purposes,
genetically manipulated to contain a transgene under the control of a saccharide
inducible promoter, and
as a second compound an inductor saccharide for induction of the saccharide inducible
promoter while the bacterial vector is present within an animal or a human patient to be
treated.
2. Combination of compounds as claimed in claim 1, wherein it is used firstly for the
administration of the bacterial vector and, at a second, later point of time, for the
administration of the inductor saccharide.
3. Combination of compounds as claimed in anyone of the preceding claims, wherein the
vector is based on bacteria selected from the group comprising attenuated invasive
bacteria which are invasive to animal cells and bacteria commensal to animal cells or to
animals.
4. Combination of compounds as claimed in anyone of the preceding claims, whereinin the
saccharide inducible promoter and the inductor saccharide are selected from the
combinations of the arabinose promoter and L-arabinose, the rhamnose promoter and
rhamnose, and the xylulose promoter and xylulose.
5. Combination of compounds as claimed in anyone of the preceding claims, whaein the
saccharide inducible promoter is the regulatory module of a bacterial L- trabinose
operon.
6. Combination of compounds as claimed in claim 4, wherein the bacterial L-
arabinoseoperon originates from E.coli.
7. Combination of compounds as claimed in anyone of the preceding claims, wherein the
transgene encodes a structural protein or a reactive RNA species.

8. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene encodes a structural protein or a reactive RNA species selected from the group of
ribozyme, antisense RNA, and siRNA.
9. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene encodes synthetic pathway enzymes for the synthesis of biologically or
pharmaceutically active effector molecules.
10. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene encodes a peptide catalyzing the conversion of a pro-drug to a drug.
11. Combination of compounds as claimed in any one of claims 1 to 9, where in the transgene
encodes the product of a suicide gene.
12. Combination of compounds as claimed in claim 11, where in the suicide gene is selected
from the group of bacteriotoxic and bacteriolytic genes.
13. Combination of compounds as claimed in any one of the preceding claims, wherein the
bacterial vector is genetically manipulated to express a heterologous inductor saccharide
transporter system or a mutant inductor saccharide transporter system.
14. Combination of compounds as claimed in any one of the preceding claims, wherein the
bacterial vector is genetically manipulated to express its intrinsic inductor saccharide
transporter system at increased levels.
15. Combination of compounds as claimed in any one of the preceding claims, wherein the
bacterial vector is genetically manipulated by inactivation of the metabolic pathway of the
inductor saccharide.
16. Combination of compounds as claimed in any one of the preceding claims, wherein the


bacterial vector is genetically manipulated to contain a heterologous secretion system.
17. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene encodes a signal sequence of a secretion system.
18. Combination of compounds as claimed in any one of the preceding claims, wherein the
medical use is immunization.
19. Combination of compounds as claimed in any one of claims 1 to 17, wherein the medical
use is the treatment of tumors.
20. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene comprises a coding sequence selected from sequences encoding synthetic pathway
enzymes for the production of an immunomodulating compound or a toxic compound,
sequences encoding an antibody, a heterologous peptide or a self-antigen.
21. Combination of compounds as claimed in any one of the preceding claims, wherein the
transgene comprises a monitoring transgene and the medical use is monitoring of tumor tissue
by spectroscopy or luminometric analysis.
22. Combination of preparations as an insecticide or a vermicide, comprising as a first component a
bacterial vector, genetically manipulated to contain a transgene under the control of a
saccharide inducible promoter, and,
as a second component an inductor saccharide for induction of the saccharide inducible
promoter, wherein the transgene to be induced within the insect or vermin after uptake
of the bacterial vector by administration of the inductor saccharide acts as a specific poison
to insects and vermin, respectively.
A combination of compounds for producing a combination of pharmaceutical preparation
comprising a first compound, a bacterial vector comprising a transgene under the control
of a saccharide inducible promoter, and as a second compounds, an inductor saccharide
for induction of the saccharide inducible promoter while the bacterial vector is present
within an animal or a human patient to be treated.



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01893-kolnp-2007-correspondence others 1.1.pdf

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1893-KOLNP-2007-(06-09-2011)-CORRESPONDENCE.pdf

1893-KOLNP-2007-(08-05-2012)-CORRESPONDENCE.pdf

1893-KOLNP-2007-(08-05-2012)-OTHERS.pdf

1893-KOLNP-2007-(20-10-2011)-ABSTRACT.pdf

1893-KOLNP-2007-(20-10-2011)-CLAIMS.pdf

1893-KOLNP-2007-(20-10-2011)-CORRESPONDENCE.pdf

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1893-KOLNP-2007-(20-10-2011)-FORM 2.pdf

1893-KOLNP-2007-(20-10-2011)-FORM 3.pdf

1893-KOLNP-2007-(20-10-2011)-OTHERS.pdf

1893-KOLNP-2007-ABSTRACT 1.1.pdf

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1893-KOLNP-2007-CORRESPONDENCE 1.4.pdf

1893-KOLNP-2007-CORRESPONDENCE OTHERS 1.3.pdf

1893-KOLNP-2007-CORRESPONDENCE-1.5.pdf

1893-KOLNP-2007-DESCRIPTION (COMPLETE) 1.1.pdf

1893-KOLNP-2007-FORM 1-1.1.pdf

1893-KOLNP-2007-FORM 13.pdf

1893-kolnp-2007-form 18.pdf

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1893-KOLNP-2007-OTHERS 1.1.pdf

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1893-KOLNP-2007-PETITION UNDER RULE 137.pdf

1893-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf


Patent Number 252031
Indian Patent Application Number 1893/KOLNP/2007
PG Journal Number 17/2012
Publication Date 27-Apr-2012
Grant Date 23-Apr-2012
Date of Filing 28-May-2007
Name of Patentee HELMHOLTZ-ZENTRUM FÜR INFEKTIONSFORSCHUNG GMBH
Applicant Address INHOFFENSTRASSE 7, 38124 BRAUNSCHWEIG
Inventors:
# Inventor's Name Inventor's Address
1 LÖSSNER, HOLGER DRESDENSTRASSE 119A, 38124 BRAUNSCHWEIG
2 LESCHNER, SARA LAFFERTSTRASSE 3, 38118 BRAUNSCHWEIG
3 WEISS, SIEGFRIED GUTENBERGSTRASSE 10, 38118 BRAUNSCHWEIG
4 ENDMANN, ANNE ALTEWIEKRING 1, 38102 BRAUNSCHWEIG
PCT International Classification Number C12N 15/63, 15/87
PCT International Application Number PCT/EP2005/054343
PCT International Filing date 2005-09-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 04105564.1 2004-11-05 EUROPEAN UNION