U.S. patent application number 11/859569 was filed with the patent office on 2008-05-29 for live bacterial vaccines for viral infection prophylaxis or treatment.
Invention is credited to David Gordon Bermudes.
Application Number | 20080124355 11/859569 |
Document ID | / |
Family ID | 39230778 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080124355 |
Kind Code |
A1 |
Bermudes; David Gordon |
May 29, 2008 |
LIVE BACTERIAL VACCINES FOR VIRAL INFECTION PROPHYLAXIS OR
TREATMENT
Abstract
The present invention provides a vaccine, method of use, and kit
employing genetically isolated and stabilized, live attenuated
bacterial strains including Salmonella that express one or more
avian influenza antigens for use in live vaccine compositions that
can be orally administered to an individual to protect against
avian influenza. Genetic stabilization may be achieved through
deletion of IS200 elements and bacteria phage and prophage
elements. The bacterial strains may be genetically isolated from
external phage infection by constitutive expression of a P22 phage
repressor. Nucleic acid sequences encoding antigenic hemagglutinin
and neuraminidase avian influenza proteins, having at least one
modified codon for optimum expression when transferred into a
prokaryotic microorganism for improved immunogenicity
Inventors: |
Bermudes; David Gordon;
(Vancouver, CA) |
Correspondence
Address: |
MILDE & HOFFBERG, LLP
10 BANK STREET, SUITE 460
WHITE PLAINS
NY
10606
US
|
Family ID: |
39230778 |
Appl. No.: |
11/859569 |
Filed: |
September 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60826542 |
Sep 22, 2006 |
|
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|
Current U.S.
Class: |
424/200.1 ;
435/252.3 |
Current CPC
Class: |
A61K 2039/542 20130101;
C12N 2760/16134 20130101; A61K 39/145 20130101; A61K 2039/523
20130101; A61K 2039/552 20130101; A61P 31/16 20180101; C12N 15/74
20130101; C12N 1/36 20130101; C12N 9/2402 20130101; C12Y 302/01018
20130101; A61K 2039/522 20130101; A61K 39/12 20130101 |
Class at
Publication: |
424/200.1 ;
435/252.3 |
International
Class: |
A61K 39/02 20060101
A61K039/02; C12N 1/21 20060101 C12N001/21 |
Claims
1. A live vaccine composition for protecting an animal against
avian influenza infection, comprising a live attenuated Salmonella
bacterium comprising: an attenuating mutation in a genetic locus of
the chromosome of said bacterium that attenuates virulence of said
bacterium; an antigen-expressing DNA construct comprising: a
nucleotide sequence coding for an immunogenic polypeptide
comprising an avian influenza H or N antigen, an immunogenic
portion of said H or N antigen, or a combination thereof, wherein
said nucleotide sequence is operably linked to a promoter that
permits expression of said immunogenic polypeptide from said DNA
construct; the gene encoding the immunogenic polypeptide has at
least one codon optimized for bacterial expression, and said live
vaccine composition elicits an immune response to at least one
avian influenza antigen when administered orally to an animal.
2. The live vaccine composition according to claim 1, wherein said
live attenuated Salmonella bacterium is selected from the group
consisting of Salmonella enterica serovar Typhimurium (S.
typhimurium), Salmonella enterica serovar Typhi (S. typhi), 34
Salmonella enterica serovar Paratyphi B (S. paratyphi B),
Salmonella enterica serovar Paratyphi C(S. paratyphi Q, Salmonella
enterica serovar Hadar (S. hadar), Salmonella enterica serovar
Enteriditis (S. enteriditis), Salmonella enterica serovar Kentucky
(S. kentucky), Salmonella enterica serovar Infantis (S. infantis),
Salmonella enterica serovar Pullorum (S. pullorum), Salmonella
enterica serovar Gallinarum (S. gallinarum), Salmonella enterica
serovar Muenchen (S. muenchen), Salmonella enterica serovar Anatum
(S. anatum), Salmonella enterica serovar Dublin (S. dublin),
Salmonella enterica serovar Derby (S. derby), and Salmonella
enterica serovar Choleraesuis var. kunzendorf, and Salmonella
enterica serovar Minnesota.
3. The live vaccine composition according to claim 2, wherein said
live attenuated Salmonella bacterium is S. enterica serovar
Typhimurium (S. typhimurium).
4. The live vaccine composition according to claim 1, wherein said
attenuating mutation is in a genetic locus selected from the group
consisting of phoP, phoQ, Mt, cya, crp, poxA, rpoS, htrA, nuoG,
pmi, gale, pabA, pts, damA, purA, purB, purl, zwf, gua, cadA, rfic,
rjb, rfa, ompR, Suwwan and combinations thereof
5. The live vaccine composition according to claim 4, wherein said
attenuating mutation is a deletion mutation.
6. The live vaccine composition according to claim 5, wherein said
attenuating mutation comprises at least a partial deletion mutation
of phoP.
7. The live vaccine composition according to claim 1, wherein said
Salmonella bacterium comprises a lethal mutation, comprising a
deletion in the asd gene, and said immunogenic polypeptide
comprises a fusion protein comprising a V antigen or an immunogenic
portion thereof, linked to an F1 antigen or an immunogenic portion
thereof, encoded on an antigen-expressing, multi-copy plasmid.
8. The live vaccine composition according to claim 7, wherein an
origin of replication of said multi-copy plasmid is a ColE1, pUC,
M15, or pBR322 plasmid origin of replication.
9. The live vaccine composition according to claim 1, wherein said
live vaccine composition comprises a plurality of live Salmonella
serovars.
10. The live vaccine composition according to claim 1, wherein said
live attenuated Salmonella bacterium is genetically stabilized with
respect to a wild type Salmonella of the same serovar.
11. The live vaccine composition according to claim 1, wherein said
live attenuated Salmonella bacterium is genetically stabilized
against genetic exchange with other organisms with respect to a
wild type Salmonella of the same serovar.
12. A live vaccine composition comprising a Salmonella bacteria
that expresses at least one of an avian influenza H or N antigen,
and an immunogenic portion of said H or N antigen.
13. The live vaccine composition according to claim 12, wherein the
Salmonella bacterium comprises S. typhirmurium.
14. The live vaccine composition according to claim 1, produced
from a kit comprising (a) a first container comprising a bacterial
expression codon optimized antigen from a pathogenic avian
influenza virus strain containing unique genetically engineered
restriction sites contained within at least one of a bacterial
protein expression plasmid or a bacterial chromosomal protein
expression vector which allows rapid exchange of small segments;
and (b) a second container comprising bacterial flagellar vectors
having at least one bacterial flagellar antigens, wherein the
Salmonella bacterium comprises multiple unique chromosomal
localization vectors targeting at least IS200s, phage elements and
metabolic genes for insertion of the expression codon.
15. A method of immunizing an animal against avian influenza,
comprising administering a live vaccine composition comprising a
Salmonella bacteria that expresses at least one of an avian
influenza H or N antigen, and an immunogenic portion of said H or N
antigen.
16. The method according to claim 15, wherein the live vaccine
composition is adapted to protect an animal against avian influenza
infection, wherein the Salmonella bacterium comprises an
attenuating mutation in a genetic locus of the chromosome of said
bacterium that attenuates virulence of said bacterium; an
antigen-expressing DNA construct comprising a nucleotide sequence
coding for an immunogenic polypeptide comprising an avian influenza
H or N antigen, an immunogenic portion of said H or N antigen, or a
combination thereof, wherein said nucleotide sequence is operably
linked to a promoter that permits expression of said immunogenic
polypeptide from said DNA construct; the gene encoding the
immunogenic polypeptide has at least one codon optimized for
bacterial expression, and said live vaccine composition elicits an
immune response to at least one avian influenza antigen when
administered orally to an animal.
17. The method according to claim 16, wherein the Salmonella
bacterium is selected from the group consisting of Salmonella
enterica serovar Typhimurium (S. typhimurium), Salmonella enterica
serovar Typhi (S. typhi), 34 Salmonella enterica serovar Paratyphi
B (S. paratyphi B), Salmonella enterica serovar Paratyphi C(S.
paratyphi Q, Salmonella enterica serovar Hadar (S. hadar),
Salmonella enterica serovar Enteriditis (S. enteriditis),
Salmonella enterica serovar Kentucky (S. kentucky), Salmonella
enterica serovar Infantis (S. infantis), Salmonella enterica
serovar Pullorum (S. pullorum), Salmonella enterica serovar
Gallinarum (S. gallinarum), Salmonella enterica serovar Muenchen
(S. muenchen), Salmonella enterica serovar Anatum (S. anatum),
Salmonella enterica serovar Dublin (S. dublin), Salmonella enterica
serovar Derby (S. derby), and Salmonella enterica serovar
Choleraesuis var. kunzendorf, and Salmonella enterica serovar
Minnesota.
18. The method according to claim 17, wherein the Salmonella
bacterium comprises S. enterica serovar Typhimurium (S.
typhimurium).
19. The method according to claim 16, wherein the attenuating
mutation is in a genetic locus selected from the group consisting
of phoP, phoQ, Mt, cya, crp, poxA, rpoS, htrA, nuoG, pmi, gale,
pabA, pts, damA, purA, purB, purl, zwf, gua, cadA, rfic, rjb, rfa,
ompR, Suwwan and combinations thereof
20. The method according to claim 19, wherein the attenuating
mutation comprises at least a partial deletion mutation of
phoP.
21. The method according to claim 16, wherein the Salmonella
bacterium comprises a lethal mutation, comprising a deletion in the
asd gene, and the immunogenic polypeptide comprises a fusion
protein comprising a V antigen or an immunogenic portion thereof,
linked to an F1 antigen or an immunogenic portion thereof, encoded
on an antigen-expressing, multi-copy plasmid.
22. The method according to claim 16, wherein the Salmonella
bacterium is genetically stabilized with respect to a wild type
Salmonella of the same serovar.
23. The method according to claim 16, wherein the live attenuated
Salmonella bacterium is genetic stabilized through deletion of
IS200 elements and bacteria phage and prophage elements, and
genetically isolated from external phage infection by a
constitutive expression of a P22 phage repressor.
24. A kit adapted to be used to produce a live vaccine composition
comprising a Salmonella bacteria that expresses at least one of an
avian influenza H or N antigen, and an immunogenic portion of said
H or N antigen, comprising (a) a first container comprising a
bacterial expression codon optimized antigen from a pathogenic
avian influenza virus strain containing unique genetically
engineered restriction sites contained within at least one of a
bacterial protein expression plasmid or a bacterial chromosomal
protein expression vector; and (b) a second container comprising
bacterial flagellar vectors having at least one bacterial flagellar
antigens.
25. The kit according to claim 23, further comprising a bacterial
strain; wherein the bacterial expression codon allows rapid
exchange of small segments, wherein the bacterial strain comprises
multiple unique chromosomal localization vectors targeting at least
IS200s, phage elements and metabolic genes for insertion of the
expression codon.
Description
FIELD OF THE INVENTION
[0001] This invention is generally in the field of live bacterial
vaccines for viral infection prophylaxis or treatment.
BACKGROUND OF THE INVENTION
[0002] Citation or identification of any reference herein, or any
section of this application shall not be construed as an admission
that such reference is available as prior art to the present
application.
[0003] There are three types of influenza viruses Influenza A, B,
and C. Influenza types A or B viruses cause epidemics of disease
almost every winter. In the United States, these winter influenza
epidemics can cause illness in 10% to 20% of people and are
associated with an average of 36,000 deaths and 114,000
hospitalizations per year. Influenza type C infections cause a mild
respiratory illness and are not thought to cause epidemics.
Influenza type A viruses are divided into subtypes based on two
proteins on the surface of the virus. These proteins are termed
hemagglutinin (H) and neuraminidase (N). Influenza A viruses are
divided into subtypes based on these two proteins. There are 16
different hemagglutinin subtypes H1, H2, H3, H4, H6, H7, H8,
H9H10H11H12, H13, H14, H15 or H16 and 9 different neuraminidase
subtypes N1 N2 N3 N4 N5 N6 N7 N8 or N9, all of which have been
found among influenza A viruses in wild birds. Wild birds are the
primary natural reservoir for all subtypes of influenza A viruses
and are thought to be the source of influenza A viruses in all
other animals. The current subtypes of influenza A viruses found in
people are A(H1N1) and A(H3N2). Influenza B virus is not divided
into subtypes.
[0004] In 1918, a new highly pathogenic influenza H1N1 pandemic
swept the world, killing an estimated 20 and 50 million people. The
H1N1 subtype circulated from 1918 until 1957 which then was
replaced by viruses of the H2N2 subtype, which continued to
circulate until 1968.
[0005] Since 1968, H3N2 viruses have been found in the population.
Because H1N1 viruses returned in 1977, two influenza A viruses are
presently cocirculating (Palese and Garcia-Sarstre J Clin Invest,
July 2002, Volume 110, Number 1, 9-13). The pathogenicity of the
initial 1918 H1N1 has not been equaled by any of the latter H1N1,
H2N2 or H3N2 subtypes, although infection from some subtypes can be
severe and result in death. By molecular reconstruction, the genome
of the 1918 flu including the amino acid sequences of the H1 and N1
antigens is now known (Kaiser, Science 310: 28-29, 2005; Tumpey et
al., Science 310: 77-81, 2005).
[0006] In 1997, 2003, and again in 2004, antigenically-distinct
avian H5N1 influenza viruses emerged as pandemic threats to human
beings. During each of these outbreaks there was concern that the
avian viruses would adapt to become transmissible from human to
human. Furthermore, oseltamivir (Tamiflu.RTM.) was ineffective in
50% of avian influenza patients in Thailand (Tran et al. N. Engl.
J. Med 350: 1179, 2004) and a new mutation in the neuraminidase has
been identified which causes resistance to oseltamivir. Sequence
analysis of the neuraminidase gene revealed the substitution of
tyrosine for histidine at amino acid position 274 (H274Y),
associated with high-level resistance to oseltamivir in influenza
(N1) viruses (Gubareva et al., Selection of influenza virus mutants
in experimentally infected volunteers treated with oseltamivir. J
Infect Dis 2001; 183:523-531; de Jong et al., Oseltamivir
Resistance during Treatment of Influenza A (H5N1) Infection. N.
Engl. J. Med. 353:2667-2672, 2005). Such changes may alter the
antigenic nature of the protein and reduce the effectiveness of
vaccines not matched to the new variant. Other avian influenza
strains of potential danger include H1N1, H7N7 and H9N2.
[0007] The optimum way of dealing with a human pandemic virus would
be to provide a clinically approved well-matched vaccine (i.e.,
containing the hemagglutinin and/or neuraminidase antigens of the
emerging human pandemic strain), but this cannot easily be achieved
on an adequate timescale because of the time consuming method of
conventional influenza vaccine production in chicken eggs.
2.1 Live Bacterial Vaccine Vectors
[0008] Live attenuated bacterial vaccine vectors offer an important
alternative to conventional chicken egg based vaccines. Growth on
embryonated hen eggs, followed by purification of viruses from
allantoic fluid, is the method by which influenza virus has
traditionally been grown for vaccine production. More recently,
viruses have been grown on cultured cell lines, which avoids the
need to prepare virus strains that are adapted to growth on eggs
and avoids contamination of the final vaccine with egg proteins.
However, because some of the vaccine virus may be produced in
canine tumor cells (e.g., MDCK), there is concern for contamination
of the vaccine by cancer causing elements. Moreover, both must
undergo a labor intensive and technically challenging purification
process, with a total production time of 3 to 6 months. Because of
the time factors and scale-up, these vaccines are produced in
large, but finite batches. Meeting a world-wide demand requires
stockpiling of multiple batches. Therefore, traditionally produced
vaccine produced before a pandemic, would likely be generated based
upon an avian influenza virus and its antigens more than a year
earlier and therefore may not be well matched to an emerging
variant and could result in only partial protection. Bacterial
vectors self replicate in simple growth media can be produced
extremely rapidly by virtue of exponential growth and require
minimal purification such as a single centrifugation and
resuspension in a pharmaceutically acceptable excipient.
[0009] Human studies have shown that antibody titres against
hemagglutinin of human influenza virus are correlated with
protection (a serum sample hemagglutination-inhibition titre of
about 30-40 gives around 50% protection from infection by a
homologous virus) (Potter & Oxford (1979) Br Med Bull 35:
69-75). Antibody responses are typically measured by enzyme linked
immunosorbent assay (ELISA), immunoblotting, hemagglutination
inhibition, by microneutralisation, by single radial
immunodiffusion (SRID), and/or by single radial hemolysis (SRH).
These assay techniques are well known in the art.
[0010] Salmonella bacteria have been recognized as being
particularly useful as live "host" vectors for orally administered
vaccines because these bacteria are enteric organisms that, when
ingested, can infect and persist in the gut (especially the
intestines) of humans and animals.
[0011] As a variety of Salmonella bacteria are known to be highly
virulent to most hosts, e.g., causing typhoid fever or severe
diarrhea in humans and other mammals, the virulence of Salmonella
bacterial strains toward an individual that is targeted to receive
a vaccine composition must be attenuated. Attenuation of virulence
of a bacterium is not restricted to the elimination or inhibition
of any particular mechanism and may be obtained by mutation of one
or more genes in the Salmonella genome (which may include
chromosomal and non-chromosomal genetic material). Thus, an
"attenuating mutation" may comprise a single site mutation or
multiple mutations that may together provide a phenotype of
attenuated virulence toward a particular host individual who is to
receive a live vaccine composition for avian influenza. In recent
years, a variety of bacteria and, particularly, serovars of
Salmonella enterica, have been developed that are attenuated for
pathogenic virulence in an individual (e.g., humans or other
mammals), and thus proposed as useful for developing various live
bacterial vaccines (see, e.g., U.S. Pat. Nos. 5,389,368; 5,468,485;
5,387,744; 5,424,065; Zhang-Barber et al., Vaccine, 17; 2538-2545
(1999); all expressly incorporated herein by reference). In the
case of strains of Salmonella, mutations at a number of genetic
loci have been shown to attenuate virulence including, but not
limited to, the genetic loci phoP, phoQ, cdt, cya, crp, poxA, rpoS,
htrA, nuoG, pmi, pabA, pts, damA, purA, purB, purl, zwf, aroA,
aroC, gua, cadA, rfc, rjb, rfa, ompR, msbB and combinations
thereof.
[0012] Bacterial flagella are known to be antigenic and subject to
antigenic or phase variation which is believed to help a small
portion of the bacteria in escaping the host immune response. The
bacterial flagellar antigens are referred to as the H1 and H2
antigens. To avoid confusion with the viral hemagglutinin H
antigen, the bacterial flagellar H antigen will be referred to as
fH henceforth. Because the Salmonella-based vaccination of a
heterologous antigen is dependent upon the bacteria's ability to
colonize the gut, which may be reduced do to the initial immune
response, the vaccination ability of the second immunization may be
diminished due to an immune response to the vector. In Salmonella
Hin invertase belongs to the recombinase family, which includes Gin
invertase from phage Mu, Cin invertase from phage P1, and
resolvases from Tn3 and the transposon (Glasgow et al. 1989, p.
637-659. In D. E. Berg, and M. M. Howe (ed.), Mobile DNA. American
Society for Microbiology, Washington, D.C.). Hin promotes the
inversion of a chromosomal DNA segment of 996 bp that is flanked by
the 26-bp DNA sequences of hixL and hixR (Johnson and Simon. 1985.
Cell 41:781-791). Hin-mediated DNA inversion in S. typhimurium
leads to the alternative expression of the all and fH2 flagellin
genes known as phase variation. Hin (21 kDa) exists in solution as
a homodimer and binds to hix sites as a dimer (Glasgow et al. 1989.
J. Biol. Chem. 264:10072-10082). In addition to Hin and the two hix
sites, a cis-acting DNA sequence (recombinational enhancer) and its
binding protein (F is, 11 kDa) are required for efficient inversion
in vitro (Johnson et al. 1986. Cell 46:531-539). Live Salmonella
vaccines have not had deletions of the hin gene nor defined all or
fH2 antigens, nor have they been constructed such that they lack fH
antigens altogether. Accordingly, live Salmonella vaccines have not
been constructed to maximize a prime-boost strategy which
alternates or eliminates the fH antigen whereby the immune response
of the fH antigen of the first immunization (prime) is not specific
for the anigen of the second immunization (boost). Therefore, the
boost immunization is not diminished by a rapid elimination by the
immune system, and is therefore able to persist longer and more
effectively present the immunizing antigen.
[0013] Introduction of viral genes into bacteria results in
genetically engineered microorganisms (GEMs) for which there may be
concern regarding containment of the introduced gene in the
environment and its ability to reassort. Such genes could in theory
provide virulence factors to non-pathogenic or less pathogenic
viral strains if allowed to recombine under circumstances were the
bacterial vaccine could co-occur at the same time in the same
individual as a wild type viral infection. Thus, methods that
reduce bacterial recombination and increase bacterial genetic
isolation are desirable.
[0014] Insertion sequences (IS) are genetic elements that can
insert copies of themselves into different sites in a genome. These
elements can also mediate various chromosomal rearrangements,
including inversions, deletions and fusion of circular DNA segments
and alter the expression of adjacent genes. IS200 elements are
found in most Salmonella species. S. typhimurium strain LT2 has six
IS200s. Salmonella typhimurium strain 14028 has been described to
possess an additional IS200 element at centisome 17.7 which is
absent in other commonly studied Salmonella strains LT2 and SL1344
(Murray et al., 2004 Journal of Bacteriology, 186: 8516-8523).
These authors describe a spontaneous hot spot (high frequency)
deletion of the Cs 17.7 to Cs 19.9 region. Live Salmonella vaccines
have not had deletions of IS200 elements which would limit such
recombination events.
[0015] Salmonella strains are known to possess phage and prophage
elements. Such phage are often capable of excision and infection of
other susceptible strains and are further capable of transferring
genes from one strain by a process known as transduction. Live
Salmonella vaccines have not had deletions in phage elements such
as phage recombinases which exist in Salmonella, such that the
phage are no longer capable of excision and reinfection of other
susceptible strains.
[0016] Salmonella strains are known to be capable of being infected
by bacteria phage. Such phage have the potential to carry genetic
elements from one Salmonella strain to another. Live Salmonella
vaccines have not comprised mechanisms to limit phage infection
such as the implantation and constitutive expression of the P22
phage repressor C2.
[0017] Bacterial expression of the viral hemagglutinin genes was
first described by Heiland and Gething (Nature 292: 581-582, 1981)
and Davis et al., (Proc. Natl. Acad. Sci. USA 78: 5376-5380). These
authors suggest that the recombinant protein could be used as a
vaccine without regard to the fact that the viral genetic loci are
not optimal for bacterial expression. These authors did not suggest
the use of live bacterial vectors as vaccine carriers, such as the
genetically stabilized and isolated vectors of the present
application, nor the use of defined flagellar antigens or no
flagellar antigens. Nor did these authors suggest the use of
secreted proteins.
[0018] Use of secreted proteins in live bacterial vectors has been
demonstrated by several authors. Holland et al. (U.S. Pat. No.
5,143,830, expressly incorporated herein by reference) have
illustrated the use of fusions with the C-terminal portion of the
hemolysin A (hlyA) gene. When co-expressed in the presence of the
hemolysin protein secretion channel (hlyBD), heterologous fusions
are readily secreted from the bacteria. Similarly, Galen et al.
(Infection and Immunity 2004 72: 7096-7106) have shown that a
heterologous fusions to the ClyA are secreted and immunogenic.
Other heterologous protein secretion systems include the use of the
autotransporter family. For example, Veiga et al. (2003 Journal of
Bacterilogy 185: 5585-5590) demonstrated hybrid proteins containing
the b-autotransporter domain of the immunogloulin A (IgA) protease
of Nisseria gonorrhoea.
[0019] Bacterial expression of the viral hemagglutinin genes was
first described by Heiland and Gething (Nature 292: 581-582, 1981)
and Davis et al., (Proc. Natl. Acad. Sci. USA 78: 5376-5380). These
authors teach that the antigens may be purified from the bacteria
in order to be used as vaccines and did not suggest the use of live
attenuated bacterial vectors. Furthermore, the codon usage of the
viral genome is not optimal for bacterial expression. Accordingly,
a gram-negative bacterium of the enterobacteraceae such as E. coli
and Salmonella will have a different codon usage preference
(National Library of Medicine, National Center for Biotechnology
Information, GenBank Release 150.0 [Nov. 25, 2005]) and would not
be codon optimized. Further, these authors used
antibiotic-containing plasmids and did not use stable chromosomal
localization. Nor did these authors suggest heterologous fusions in
order for the bacteria to secrete the antigens.
[0020] Kahn et al. (EP No. 0863211) have suggested use of a live
bacterial vaccine with in vivo induction using the E. coli nitrite
reductase promoter nirB. These authors further suggest that the
antigenic determinant may be an antigenic sequence derived from a
virus, including influenza virus. However, Khan et al. did not
describe a vaccine for avian influenza virus. They did not describe
the appropriate antigens for an avian influenza virus, the
hemagluttinin and neuraminidase, and did not describe how to
genetically match an emerging avian influenza virus. Furthermore,
it has become apparent that certain assumptions, and experimental
designs described by Khan et al. regarding live avian influenza
vaccines would not be genetically isolated or have improved genetic
stability in order to provide a live vaccine for avian influenza
that would be acceptable for use in humans. For example, Khan et
al. state that any of a variety of known strains of bacteria that
have an attenuated virulence may be genetically engineered and
employed as live bacterial carriers (bacterial vectors) that
express antigen polypeptides to elicit an immune response including
attenuated strains of S. typhimurium and, for use in humans,
attenuated strains of S. typhi (i.e., S. enterica serovar Typhi).
In support of such broad teaching, they point to the importance of
"non-reverting" mutations, especially deletion mutations which
provide the attenuation. However, non-reversion only refers to the
particular gene mutated, and not to the genome per se with its
variety of IS200, phage and prophage elements capable of a variety
of genetic recombinations and/or even transductions to other
bacterial strains. Khan et al. did not describe a bacterial strain
with improved genetic stability, nor methods to reduce genetic
recombination, such as deletion of the IS200 elements. Khan et al.
did not describe a bacterial strain with improved genetic stability
by deletion of the bacteria phage and prophage elements nor
limiting their transducing capacity. Neither did Khan et al.
describe methods to minimize bacterial genetic exchange, such as
constitutive expression of the P22 C2 phage repressor.
[0021] The above comments illustrate that Khan et al. have not
provided the field with an effective vaccine against avian
influenza. Clearly, needs remain for an genetically isolated and
genetically stable, orally administered vaccine against avian
influenza which is capable of rapid genetically matching an
emerging pathogenic variant.
SUMMARY OF THE INVENTION
[0022] The present invention provides live attenuated bacterial
strains that express one or more immunogenic polypeptide antigens
of a virus, preferably an avian influenza virus, that is effective
in raising an immune response in mammals.
[0023] In particular, one aspect of the invention relates to live
attenuated bacterial strains which may include Salmonella vectoring
avian influenza antigens that can be administered orally to an
individual to elicit an immune response to protect the individual
from avian influenza.
[0024] The preferred bacteria are serovars of Salmonella.
Preferably, the bacteria are genetically isolated from infecting
bacteria phage and have improved genetic stability by virtue of
deletion of IS200 and phage elements. The preferred Salmonella
strains of the invention are attenuated by mutations at genetic
loci which, alone or in combination, provides sufficient
attenuation, and defined flagellar antigens for improved an
improved prime/boost strategy. The attenuating mutations may be
those of strains known to exhibit a degree of safety in humans
including but not limited to Ty21a, CMV906, CMV908, CMV906-htr,
CMV908-htr, Ty800, holavax, M01ZH09 or VNP20009 or may be novel
combinations of mutations.
[0025] Whereas the current medical practice uses derivatives of
pathogenic avian strains in chicken eggs to provide vaccines that
generate an immune response including antibodies in humans or other
mammals against known pathogenic avian strains, the invention
provides methods and compositions comprising genetically isolated
bacterial vectors with enhanced genetic stability vectoring avian
influenza virus antigens to protect against emerging pathogenic
human strains.
[0026] Furthermore, whereas the prior art often fails to achieving
close antigenic match between the vaccine strain and the target
strain, the invention targets viruses for vaccine strains based on
their emerging pathogenicity, and produces an effective vaccine
more closely matched to the antigen profile of the emerging
pathogen. As the invention requires detailed knowledge of the
antigenic profile of an emerging strain, such a vaccine can be
produced at the time of need in order to reduce the risk of an
unmatched vaccine and potential effects of partial protection in a
human pandemic outbreak. Thus the invention provides vaccines for
protecting a human patient against infection by an emerging avian
influenza virus strain.
[0027] Preferably, the vaccines according to the present invention
comprise genetically stable bacterial vectors carrying one or more
antigen from an avian influenza virus strain that can cause highly
pathogenic avian influenza.
[0028] The invention further preferably provides for vaccines
against oseltamivir resistant strains.
[0029] Accordingly, when orally administered to an individual, a
live Salmonella bacterial vaccine, in accordance with the present
invention, that is genetically engineered to express one or more
avian influenza antigens as described herein have the inherent
ability to establish a population (infection) in the gut and, if
properly modified they could provide a desirable source of
immunogenic avian influenza antigen polypeptide(s) to elicit an
immune response in the mucosal tissue of the individual.
[0030] The antigen(s) can invoke an antibody response in the
patient that is capable of neutralizing the emerging avian
influenza vaccine strains with high efficiency, as well as emerging
heterologous avian influenza vaccine strains, with moderate
efficiency. Preferably, the emerging avian influenza vaccine will
be within the same hemagglutinin and or neuraminidase type (i.e.,
H1, H5, H5 (H274Y), H7 or H9 and/or N1, N2 or N7) as are the
current pathogenic avian influenza strains.
[0031] The live vaccine compositions are suitable for oral
administration to an individual to provide protection from avian
influenza. Preferably, a vaccine composition comprises a suspension
of a live bacterial strain described herein in a physiologically
accepted buffer or saline solution that can be swallowed from the
mouth of an individual. However, oral administration of a vaccine
composition to an individual may also include, without limitation,
administering a suspension of a bacterial vaccine strain described
herein through a nasojejunal or gastrostomy tube and administration
of a suppository that releases a live bacterial vaccine strain to
the lower intestinal tract of an individual. Vaccines of the
invention may be formulated for delivery by other various routes
e.g. by intramuscular injection, subcutaneous delivery, by
intranasal delivery (e.g. WO 00/47222, U.S. Pat. No. 6,635,246),
intradermal delivery (e.g. WO02/074336, WO02/067983, WO02/087494,
WO02/0832149 WO04/016281) by transdermal delivery, by
transcutaneous delivery, by topical routes, etc. Injection may
involve a needle (including a microneedle), or may be
needle-free.
[0032] Annual human influenza vaccines typically include more than
one influenza strain, with trivalent vaccines being normal (e.g.
two influenza A virus antigens, and one influenza B virus antigen).
In pandemic years, however, a single monovalent strain may be used.
Thus the pathogenic avian antigen(s) described above may be the
sole influenza antigen(s) in a vaccine of the invention, or the
vaccine may additionally comprise antigen(s) from one or more (e.g.
1, 2, 3, 4 or more) annual influenza virus strains. Specific
vaccines of the invention thus include: (i) a vaccine comprising
the pathogenic avian antigen(s) as the sole influenza antigen(s);
(ii) a vaccine comprising the pathogenic avian antigen(s) plus
antigen(s) from another pathogenic avian influenza strain (e.g.,
H1N1, H5N1, H7N7, H2N9, H9N2).
[0033] Vaccines of the invention use one or more avian antigens to
protect patients against infection by an influenza virus strain
that is capable of human-to-human transmission i.e. a strain that
will spread geometrically or exponentially within a given human
population without necessarily requiring physical contact. The
patient may also be protected against strains that infect and cause
disease in humans, but that are caught from birds rather than from
other humans (i.e., bird to human transmission). The invention is
particularly useful for protecting against infection by pandemic,
emerging pandemic and future pandering human strains e.g. for
protecting against H5 and N1 influenza subtypes. Depending on the
particular season and on the nature of the antigen included in the
vaccine, however, the invention may protect against any
hemagglutinin subtypes, including H1, H2, H3, H4, H5, H6, H7, H8,
H9, H10, H11, H12, H13, H14, H15 or H16 or various neuraminidase
subtypes, including N1, N2, N3, N4, N5, N6, N7, N8 or N9.
[0034] The characteristics of an influenza strain that give it the
potential to cause a pandemic outbreak may include: (a) it contains
a new or antigenically altered hemagglutinin compared to the
hemagglutinins in currently-circulating human strains i.e., one
that has not been evident in the human population for over a decade
(e.g. H2), or has not previously been seen at all in the human
population (e.g. H5, H6 or H9, that have generally been found only
in bird populations), such that the human population will be
immunologically naive to the strain's hemagglutinin or that is a
subtype which is antigenically altered by changes in amino acid
sequence or glycosylation; (b) it is capable of being transmitted
horizontally in the human population; (c) is capable of being
transmitted from animals (including birds, dogs, pigs) to humans;
and/or (d) it is pathogenic to humans.
[0035] As a preferred embodiment of the invention protects against
a strain that is capable of human-to-human or bird-to-human or
bird-to-bird transmission, one embodiment of the invention in
accordance with that aspect will generally include at least one
gene that originated in a mammalian (e.g. in a human) influenza
virus and one gene which originated in a bird or non-human
vertibrate. Vaccines in accordance with various aspects of the
invention may therefore include an antigen from an avian influenza
virus strain. This strain is typically one that is capable of
causing highly pathogenic avian influenza (HPAI). HPAI is a
well-defined condition (Alexander Avian Dis (2003) 47(3
Suppl):976-81) that is characterized by sudden onset, severe
illness and rapid death of affected birds/flocks, with a mortality
rate that can approach 100%. Low pathogenicity (LPAI) and high
pathogenicity strains are easily distinguished e.g. van der Goot et
al. (Epidemiol Infect (2003) 131(2):1003-13) presented a
comparative study of the transmission characteristics of low and
high pathogenicity H5N2 avian strains. For the 2004 season,
examples of HPAI strains are H.sub.5N1 influenza A viruses e.g.
A/Viet Nam/I 196/04 strain (also known as A Vietnam/3028/2004 or
A/Vietnam/3028/04). The skilled person will thus be able to
identify or predict future HPAI strains and the DNA sequence and
amino acid compositions of the H and N antigens as and when they
emerge. The avian influenza strain may be of any suitable
hemagglutinin subtype, including H1, H2, H3, H4, H5, H6, H7, H8,
H9, H10, H11, H12, H13, H14, H15 or H16. The avian influenza strain
may further be of any suitable neuraminidase subtype N1, N2, N3,
N4, N5, N6, N7, N8, or N9. The vaccines of the invention may
comprise two or more (i.e., two, three, four, or five) avian
influenza hemagglutinin and neuraminidase antigens. Such avian
influenza strains may comprise the same or different hemagglutinin
subtypes and the same or different neuraminidase subtypes.
[0036] A preferred vaccine composition will contain a sufficient
amount of live bacteria expressing the antigen(s) to produce an
immunological response in the patient. Accordingly, the attenuated
Salmonella strains described herein are both safe and useful as
live bacterial vaccines that can be orally administered to an
individual to provide immunity to avian influenza and, thereby,
protection from avian influenza.
[0037] Although not wishing to be bound by any particular
mechanism, an effective mucosal immune response to avian influenza
antigen(s) in humans by oral administration of genetically
engineered, attenuated strains of Salmonella strains as described
herein may be due to the ability of such mutant strains to persist
in the intestinal tract. Each bacterial strain useful in the
invention carries an antigen-expressing plasmid or chromosomally
integrated cassette that encodes and directs expression of one or
more avian influenza antigens of avian influenza virus when
resident in an attenuated Salmonella strain described hererin. As
noted above, avian influenza antigens that are particularly useful
in the invention include an H1, H5, H5 (H274Y), H7 or H9 antigen
polypeptide (or immunogenic portion thereof), a N1, N2 or N7
antigen polypeptide (or immunogenic portion thereof), and a fusion
polypeptide comprising a heterologous secretion peptide linked
in-frame to the antigenic peptide.
[0038] The serovars of S. enterica that may be used as the
attenuated bacterium of the live vaccine compositions described
herein include, without limitation, Salmonella enterica serovar
Typhimurium ("S. typhimurium"), Salmonella montevideo, Salmonella
enterica serovar Typhi ("S. typhi"), Salmonella enterica serovar
Paratyphi B ("S. paratyphi 13"), Salmonella enterica serovar
Paratyphi C ("S. paratyphi C"), Salmonella enterica serovar Hadar
("S. hadar"), Salmonella enterica serovar Enteriditis ("S.
enteriditis"), Salmonella enterica serovar Kentucky ("S.
kentucky"), Salmonella enterica serovar Infantis ("S. infantis"),
Salmonella enterica serovar Pullorurn ("S. pullorum"), Salmonella
enterica serovar Gallinarum ("S. gallinarum"), Salmonella enterica
serovar Muenchen ("S. muenchen"), Salmonella enterica serovar
Anatum ("S. anatum"), Salmonella enterica serovar Dublin ("S.
dublin"), Salmonella enterica serovar Derby ("S. derby"),
Salmonella enterica serovar Choleraesuis var. kunzendorf ("S.
cholerae kunzendorf`), and Salmonella enterica serovar minnesota
(S. minnesota).
[0039] By way of example, live avian influenza vaccines in
accordance with aspects of the invention include known strains of
S. enterica serovar Typhimurium (S. typhimurium) and S. enterica
serovar Typhi (S. typhi) which are further modified as provided by
the invention to form suitable vaccines for the prevention and
treatment of avian influenza. Such Strains include Ty21a, CMV906,
CMV908, CMV906-htr, CMV908-htr, Ty800, aroA-/serC-, holavax,
M01ZH09, VNP20009.
[0040] Novel strains are also encompassed that are attenuated in
virulence by mutations in a variety of metabolic and structural
genes. The invention therefore may provide a live vaccine
composition for protecting against avian influenza comprising a
live attenuated bacterium that is a serovar of Salmonella enterica
comprising, an attenuating mutation in a genetic locus of the
chromosome of said bacterium that attenuates virulence of said
bacterium and wherein said attenuating mutation is the Suwwan
deletion (Murray et al., 2004) or combinations with other known
attenuating mutations. Other attenuating mutation useful in the
Salmonella bacterial strains described herein may be in a genetic
locus selected from the group consisting of phoP, phoQ, edt, cya,
crp, poxA, rpoS, htrA, nuoG, pmi, pabA, pts, damA, purA, purB,
purl, zwf, purF, aroA, aroB, aroC, aroD, serC, gua, cadA, rfc, rjb,
rfa, ompR, msbB and combinations thereof.
[0041] The invention may also provide a process for preparing
genetically stable bacterial vaccines for protecting a human
patient against infection by a avian influenza virus strain,
comprising genetically engineering the avian antigen from an avian
influenza virus strain that can cause highly pathogenic avian
influenza to comprise a bacterially codon optimized expression
sequence within a bacterial plasmid expression vector or
chromosomal localization expression vector and further containing
engineered restriction endonuclease sites such that the bacterially
codon optimized expression gene contains subcomponents which are
easily and rapidly exchangeable in order to facilitate rapid
exchange of the genetic subcomponents to achieve a well matched
antigen to the emerging avian influenza pathogen. The plasmid
and/or chromosomal expression constructs may be further modified to
result in the secretion of the viral antigens. Administration of
the vaccine to the patient invokes an antibody response that is
capable of neutralizing said avian influenza virus strain.
[0042] The invention may also provide methods and compositions for
producing a bacterial vector expressing one or more avian influenza
antigens where said bacterial vector has one or more deletions in
IS200 elements which results in enhance genetic stability. The
composition and methods comprise a bacterial strain with a deletion
in the IS200 elements, such that the bacteria are no longer capable
of genetic rearrangement using IS200 elements. Such a deletion is
generated in any one or more IS200 element, which is then confirmed
using standard genetic techniques.
[0043] The invention may also provide methods and compositions for
producing a genetically stabilized bacterial vector expressing one
or more avian influenza antigens where said bacterial vector has
one or more deletions in bacteria phage or prophage elements which
enhanced genetic stability and prevent phage excision. The
composition and methods comprise a bacterial strain with one or
more deletions in bacteria phage or prophage elements, such that
the bacteria are no longer capable of genetic rearrangement using
bacteria phage or prophage elements. Such a deletion is generated
in any bacteria phage or prophage elements, which is then confirmed
using standard genetic techniques. Such strains have phage with
reduced capacity for transduction of genes to other strains.
[0044] The invention may also provide methods and compositions for
producing a bacterial vector expressing one or more avian influenza
antigens where said bacterial vector constitutively expresses the
P22 phage C2 repressor, thereby preventing new infections by
bacteria phage and further preventing subsequent phage
transductions by these phage. Live Salmonella vaccines have not had
deletions of the hin gene nor defined fH1 or fH2 antigens, nor have
they been constructed such that they lack fH antigens altogether.
Accordingly, prior live Salmonella vaccines have not been
constructed to maximize a prime-boost strategy which alternates or
eliminates the fH antigen whereby the immune response of the fH
antigen of the first immunization (prime) is not specific for the
anigen of the second immunization (boost). Therefore, the boost
immunization is not diminished by a rapid elimination by the immune
system, and is therefore able to persist longer and more
effectively present the immunizing heterologous avian influenza
antigen.
[0045] An embodiment of the present invention therefore may also
provide methods and compositions for producing a bacterial vector
expressing one or more avian influenza antigens where said
bacterial vector has a defined flagellar H antigen (fH). The
composition and methods comprise a bacterial strain with a deletion
in the Hin recombinase gene, such that the bacteria are no longer
capable of alternating between fH1 and fH2 antigens. Such a
deletion is generated in either an fH1 or fH2 serologically defined
strain, which is then reconfirmed following deletion or disruption
of the hin recombinase gene. The invention further provides methods
and compositions for producing a bacterial vector which lacks
flagellar antigens generated by deletion of the fliBC genes (i.e.,
fH0). Therefore, an improved composition for a prime/boost strategy
is provided where the second vaccination comprises administration
of a vaccine where the fH antigen composition is different from the
first vaccination.
[0046] The invention may also provide a method for protecting a
human patient against infection by an avian influenza virus strain
with an improved prime/boost strategy, comprising the step of
administering to the patient a vaccine that comprises an antigen
from an avian influenza virus strain that can cause highly
pathogenic avian influenza or 1918 influenza within a bacterial
vector expressing one or more avian influenza antigens where said
bacterial vector has a defined fH antigen or no fH antigen (i.e.,
fH1, fH2, or fH0). The invention may further provide a method of
administering a second bacterial vector expressing one or more
avian influenza antigens comprising a second step where the second
administration where said bacterial vector has a defined fH antigen
which is different fH antigen composition than the fH antigen of
the first administration or no fH antigen. The second
administration includes a bacterial vaccine where the first vaccine
administration is a bacterial vaccine of the present invention or
is another vaccine not encompassed by the present application,
e.g., another bacterial vaccine or an egg-based vaccine.
[0047] Similarly, the invention may also provide a kit comprising
(a) a first container comprising a bacterial expression codon
optimized antigen from a pathogenic avian influenza virus strain
containing unique genetically engineered restriction sites
contained within either a bacterial protein expression plasmid or a
bacterial chromosomal protein expression vector and (b) a second
container comprising bacterial vector(s) with one or more (e.g.,
fH1, fH2 or fH0) flagellar antigen(s). Component (a) will be
modifiable to genetically match an emerging avian influenza virus
using standard in vitro molecular techniques and can be combined
with component (b) to generate one or more bacterial strains with
defined flagellar antigens which constitute a live vaccine. The
variation(s) in flagellar antigens provided by the kit provide for
more than one live vaccine strain in which a first immunization
(prime) using one strain may be followed at an appropriate time
such as 2 to 4 weeks by a second immunization (boost) using a
second strain with a different fH antigen or no fH antigen. The
live vaccine compositions are suitable for oral administration to
an individual to provide protection from avian influenza.
[0048] Preferably, a vaccine composition comprises a suspension of
a live bacterial strain described herein in a physiologically
accepted buffer or saline solution that can be swallowed from the
mouth of an individual. However, oral administration of a vaccine
composition to an individual may also include, without limitation,
administering a suspension of a bacterial vaccine strain described
herein through a nasojejunal or gastrostomy tube and administration
of a suppository that releases a live bacterial vaccine strain to
the lower intestinal tract of an individual.
4. DEFINITIONS
[0049] In order that the invention may be more fully understood,
the following terms are defined.
[0050] As used herein, "attenuated", "attenuation", and similar
terms refer to elimination or reduction of the natural virulence of
a bacterium in a particular host organism, such as a mammal.
"Virulence" is the degree or ability of a pathogenic microorganism
to produce disease in a host organism. A bacterium may be virulent
for one species of host organism (e.g., a mouse) and not virulent
for another species of host organism (e.g., a human). Hence,
broadly, an "attenuated" bacterium or strain of bacteria is
attenuated in virulence toward at least one species of host
organism that is susceptible to infection and disease by a virulent
form of the bacterium or strain of the bacterium. As used herein,
the term "genetic locus" is a broad term and comprises any
designated site in the genome (the total genetic content of an
organism) or in a particular nucleotide sequence of a chromosome or
replicating nucleic acid molecule (e.g., a plasmid), including but
not limited to a gene, nucleotide coding sequence (for a protein or
RNA), operon, regulon, promoter, regulatory site (including
transcriptional terminator sites, ribosome binding sites,
transcriptional inhibitor binding sites, transcriptional activator
binding sites), origin of replication, intercistronic region, and
portions therein. A genetic locus may be identified and
characterized by any of a variety of in vivo and/or in vitro
methods available in the art, including but not limited to,
conjugation studies, crossover frequencies, transformation
analysis, transfection analysis, restriction enzyme mapping
protocols, nucleic acid hybridization analyses, polymerase chain
reaction (PCR) protocols, nuclease protection assays, and direct
nucleic acid sequence analysis. As used herein, the term
"infection" has the meaning generally used and understood by
persons skilled in the art and includes the invasion and
multiplication of a microorganism in or on a host organism ("host",
"individual", "patient") with or without a manifestation of a
disease (see, "virulence" above). Infectious microorganisms include
pathogenic viruses, such as avian influenza, that can cause serious
diseases when infecting an unprotected individual. An infection may
occur at one or more sites in or on an individual. An infection may
be unintentional (e.g., unintended ingestion, inhalation,
contamination of wounds, etc.) or intentional (e.g., administration
of a live vaccine strain, experimental challenge with a pathogenic
vaccine strain). In a vertebrate host organism, such as a mammal, a
site of infection includes, but is not limited to, the respiratory
system, the alimentary canal (gut), the circulatory system, the
skin, the endocrine system, the neural system, and intercellular
spaces. Some degree and form of replication or multiplication of an
infective microorganism is required for the microorganism to
persist at a site of infection. However, replication may vary
widely among infecting microorganisms. Accordingly, replication of
infecting microorganisms comprises, but is not limited to,
persistent and continuous multiplication of the microorganisms and
transient or temporary maintenance of microorganisms at a specific
location. Whereas "infection" of a host organism by a pathogenic
microorganism is undesirable owing to the potential for causing
disease in the host, an "infection" of a host individual with a
live vaccine comprising genetically altered, attenuated Salmonella
bacterial strain as described herein is desirable because of the
ability of the bacterial strain to elicit a protective immune
response to antigens of avian influenza virus that cause avian
influenza in humans and other mammals.
[0051] As used herein, the terms "disease" and "disorder" have the
meaning generally known and understood in the art and comprise any
abnormal condition in the function or well being of a host
individual. A diagnosis of a particular disease or disorder, such
as avian influenza, by a healthcare professional may be made by
direct examination and/or consideration of results of one or more
diagnostic tests.
[0052] A "live vaccine composition", "live vaccine", "live
bacterial vaccine", and similar terms refer to a composition
comprising a strain of live Salmonella bacteria that expresses at
least one antigen of avian influenza, e.g., the H antigen, the N
antigen, or a combination thereof, such that when administered to
an individual, the bacteria will elicit an immune response in the
individual against the avian influenza antigen(s) expressed in the
Salmonella bacteria and, thereby, provide at least partial
protective immunity against avian influenza. Such protective
immunity may be evidenced by any of a variety of observable or
detectable conditions, including but not limited to, diminution of
one or more disease symptoms (e.g., respiratory distress, fever,
pain, diarrhea, bleeding, inflammation of lymph nodes, weakness,
malaise), shorter duration of illness, diminution of tissue damage,
regeneration of healthy tissue, clearance of pathogenic
microorganisms from the individual, and increased sense of well
being by the individual. Although highly desired, it is understood
by persons skilled in the art that no vaccine is expected to induce
complete protection from a disease in every individual that is
administered the vaccine or that protective immunity is expected to
last throughout the lifetime of an individual without periodic
"booster" administrations of a vaccine composition. It is also
understood that a live vaccine comprising a bacterium described
herein may be, at the discretion of a healthcare professional,
administered to an individual who has not presented symptoms of
avian influenza but is considered to be at risk of infection or is
known to already have been exposed to avian influenza virus, e.g.,
by proximity or contact with avian influenza patients or virally
contaminated air, liquids, or surfaces.
[0053] The terms "oral", "enteral", "enterally", "orally",
"non-parenteral", "non-parenterally", and the like, refer to
administration of a compound or composition to an individual by a
route or mode along the alimentary canal. Examples of "oral" routes
of administration of a vaccine composition include, without
limitation, swallowing liquid or solid forms of a vaccine
composition from the mouth, administration of a vaccine composition
through a nasojejunal or gastrostomy tube, intraduodenal
administration of a vaccine composition, and rectal administration,
e.g., using suppositories that release a live bacterial vaccine
strain described herein to the lower intestinal tract of the
alimentary canal.
[0054] The term "recombinant" is used to describe non-naturally
altered or manipulated nucleic acids, cells transformed,
electroporated, or transfected with exogenous nucleic acids, and
polypeptides expressed non-naturally, e.g., through manipulation of
isolated nucleic acids and transformation of cells. The term
"recombinant" specifically encompasses nucleic acid molecules that
have been constructed, at least in part, in vitro using genetic
engineering techniques, and use of the term "recombinant" as an
adjective to describe a molecule, construct, vector, cell,
polypeptide, or polynucleotide specifically excludes naturally
existing forms of such molecules, constructs, vectors, cells,
polypeptides, or polynucleotides.
[0055] Cassette, or expression cassette is used to describe a
nucleic acid sequence comprising (i) a nucleotide sequence encoding
a promoter, (ii) a first unique restriction enzyme cleavage site
located 5' of the nucleotide sequence encoding the promoter, and
(iii) a second unique restriction enzyme cleavage site located 3'
of the nucleotide sequence encoding the promoter. The cassette may
also contain a multiple cloning site (MCS) and transcriptional
terminator within the 5' and 3' restriction endonuclease cleavage
sites. The cassette may also contain cloned genes of interest.
[0056] As used herein, the term "salmonella" (plural,
"salmonellae") and "Salmonella" refers to a bacterium that is a
serovar of Salmonella enterica. A number of serovars of S. enterica
are known. Particularly preferred salmonella bacteria useful in the
invention are attenuated strains of Salmonella enterica serovar
Typhimurium ("S. typhimurium") and serovar Typhi ("S. typhi") as
described herein. As used herein, the terms "strain" and "isolate"
are synonymous and refer to a particular isolated bacterium and its
genetically identical progeny. Actual examples of particular
strains of bacteria developed or isolated by human effort are
indicated herein by specific letter and numerical designations
(e.g. strains Ty21a, CMV906, CMV908, CMV906-htr, CMV908-htr, Ty800,
holavax, M01ZH09, VNP20009).
[0057] The definitions of other terms used herein are those
understood and used by persons skilled in the art and/or will be
evident to persons skilled in the art from usage in the text. This
invention provides live vaccine compositions for protecting against
avian influenza comprising live Salmonella enterica serovars that
are genetically engineered to express one or more avian influenza
antigen polypeptides, such as the H1, H5, H5 (H274Y), H7 or H9 and
N1, N2 and N7 antigens of avian influenza virus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] FIG. 1 shows a modified ptrc99a plasmid.
[0059] FIGS. 2A and B show a plasmid vectors capable of expressing
the H5 or N1 antigens cytoplasmically.
[0060] FIG. 3 shows modified ptrc99a plasmid with unique
restriction sites engineered into the coding sequence of the N1
gene for rapid exchange of mutations such as the H274Y.
[0061] FIG. 4A shows a plasmid vectors expressing the H5 or N1
antigens in a secreted form as fusions with the hlyA protein. FIG.
4B shows a plasmid vector expressing HlyB and HlyD genes necessary
for secretion of HlyA and HlyA fusion proteins.
[0062] FIG. 5 shows a plasmid vector for expression of an antigen
(e.g., H5 or N1) as a ClyA fusion.
[0063] FIG. 6 shows a plasmid vector for expression of an antigen
(e.g., H5 or N1) as a autotransporter fusion.
[0064] FIG. 7 shows a plasmid vector for expression of an antigen
(e.g., H5 or N1) as a colicin E3 fusion.
[0065] FIG. 8A shows selection of 5' and 3' DNA segments for
constructing a pCVD442 chromosomal integration vector. 8B shows the
vector for disrupting chromosomal genes and capable of integration
of new genes into the chromosome.
[0066] FIG. 9 shows a cloning sequence, from A) synthetic gene
expression vector to B) chromosomal localization vector.
[0067] FIG. 10 shows a PCR method for determination of IS200 17.7
and 19.9 rearrangement/deletion.
[0068] FIG. 11 shows a method to achieve the Suwwan deletion in
strains lacking the 17.7 Cs IS200.
DETAILED DESCRIPTION OF THE INVENTION
[0069] The present invention is based upon a combination of
bacterial vector and protein expression technology which results in
a unique vaccine which is rapidly constructed in response to
emerging avian influenza and their highly pathogenic derivatives.
The present invention is directed to the construction bacterially
codon optimized avian and human influenza genes and their
incorporation into a Salmonella strain for therapeutic use in the
prevention of avian influenza and highly pathogenic derivatives. An
antigen-expressing plasmid or chromosomal construct in the
bacterial strains described herein may also contain one or more
transcriptional terminators adjacent to the 3' end of a particular
nucleotide sequence on the plasmid to prevent undesired
transcription into another region of the plasmid or chromosome.
Such transcription terminators thus serve to prevent transcription
from extending into and potentially interfering with other critical
plasmid functions, e.g., replication or gene expression. Examples
of transcriptional terminators that may be used in the
antigen-expressing plasmids described herein include, but are not
limited to, the T1 and T2 transcription terminators from 5S
ribosomal RNA bacterial genes (see, e.g., FIGS. 1-5; Brosius and
Holy, Proc. Natl. Acad. Sci. USA, 81: 6929-6933 (1984); Brosius,
Gene, 27(2): 161-172 (1984); Orosz et al., Eur. J. Biochem., 20
(3): 653-659 (1991)).
[0070] The mutations in an attenuated bacterial host strain may be
generated by integrating a homologous recombination construct into
the chromosome or the endogenous Salmonella virulence plasmid
(Donnenberg and Kaper, 1991; Low et al. (Methods in Molecular
Medicine, 2003)). In this system, a suicide plasmid is selected for
integration into the chromosome by a first homologous recombination
event, followed by a second homologous recombination event which
results in stable integration into the chromosome. The
antigen-expressing chromosomal integration constructs described
herein comprise one or more nucleotide sequences that encode one or
more polypeptides that, in turn, comprise one or more avian
influenza antigens, such as the hemagglutinin and neuraminidase
polypeptide antigens, or immunogenic portions thereof, from avian
influenza virus and highly pathogenic derivatives. Such coding
sequences are operably linked to a promoter of transcription that
functions in a Salmonella bacterial strain even when such a
bacterial strain is ingested, i.e., when a live vaccine composition
described herein is administered orally to an individual. A variety
of naturally occurring, recombinant, and semi-synthetic promoters
are known to function in enteric bacteria, such as Escherichia coli
and serovars of S. enterica (see, e.g., Dunstan et al., Infect.
Immun., 67(10): 5133-5141 (1999)). Promoters (P) that are useful in
the invention include, but are not limited to, well known and
widely used promoters for gene expression such as the naturally
occurring Plac of the lac operon and the semi-synthetic Ptrc (see,
e.g., Amman et al., Gene, 25 (2-3): 167-178 (1983)) and Ptac (see,
e.g., Aniann et al., Gene, 69(2): 301-315 (1988)), as well as PpagC
(see, e.g., Hohmann et al., Proc. Natl. Acad. Sci. USA, 92.
2904-2908 (1995)), PpmrH (see, e.g., Gunn et al., Infect. Immun.,
68: 6139-6146 (2000)), PpmrD (see, e.g., Roland et al., J.
Bacteriol., 176: 3589-3597 (1994)), PompC (see, e.g., Bullifent et
al., Vacccine, 18: 2668-2676 (2000)), PnirB (see, e.g., Chatfield
et al., Biotech. (NY), 10: 888-892 (1992)), PssrA (see, e.g., Lee
et al., J. Bacteriol. 182. 771-781 (2000)), PproU (see, e.g.,
Rajkumari and Gowrishankar, J. Bacteriol., 183. 6543-6550 (2001)),
Pdps (see, e.g., Marshall et al., Vaccine, 18: 1298-1306 (2000)),
and PssaG (see, e.g., McKelvie et al., Vaccine, 22: 3243-3255
(2004)), Some promoters are known to be regulated promoters that
require the presence of some kind of activator or inducer molecule
in order to transcribe a coding sequence to which they are operably
linked. However, some promoters may be regulated or inducible
promoters in E. coli, but function as unregulated promoters in
Salmonella. An example of such a promoter is the well known trc
promoter ("Ptrc", see, e.g., Amman et al., Gene, 25(2-3): 167-178
(1983); Pharmacia-Upjohn). As with Plac and Ptac, Ptrc functions as
an inducible promoter in Escherichia coli (e.g., using the inducer
molecule isopropyl-p-D-1 8 thio-galactopyranoside, "IPTG"),
however, in Salmonella bacteria having no Lacd repressor, Ptrc is
an efficient constitutive promoter that readily transcribes avian
influenza antigen-containing polypeptide coding sequences present
on antigen-expressing plasmids described herein. Accordingly, such
a constitutive promoter does not depend on the presence of an
activator or inducer molecule to express an antigen-containing
polypeptide in a strain of Salmonella.
[0071] The avian influenza antigen-expressing chromosomal
integration constructs which integrate into the live vaccine
strains also contain an origin of replication (ori) that enables
the precursor plasmids to be maintained as multiple copies in
certain the bacterial cells which carry the lamda pir element. For
the process of cloning DNA, a number of multi-copy plasmids that
replicate in Salmonella bacteria are known in the art, as are
various origins of replications for maintaining multiple copies of
plasmids. Preferred origins of replications for use in the
multi-copy antigen-expressing plasmids described herein include the
origin of replication from the multi-copy plasmid pBR322 ("pBR
ori"; see, e.g., Maniatis et al., In Molecular Cloning: A
Laboratoly Manual (Cold Spring Harbor Laboratory, Cold Spring
Harbor, 1982), pp. 479-487; Watson, Gene, 70: 399-403, 1988), the
low copy origin of replication from pACYC177, and the origin of
replication of pUC plasmids ("pUC ori"), such as found on plasmid
pUC1 8 (see, e.g., Yanish-Perron et al., Gene, 33: 103-119 (1985)).
Owing to the high degree of genetic identity and homology, any
serovar of S. enterica may be used as the bacterial host for a live
vaccine composition for avian influenza, provided the necessary
attenuating mutations and antigen-expressing plasmids as described
herein are also employed. Accordingly, serovars of S. enterica that
may be used in the invention include those selected from the group
consisting of Salmonella enterica serovar Typhimurium ("S.
typhimurium"), Salmonella montevideo, Salmonella enterica serovar
Typhi ("S. typhi"), Salmonella enterica serovar Paratyphi B ("S.
paratyphi B"), Salmonella enterica serovar Paratyphi C ("S.
paratyphi C"), Salmonella enterica serovar Hadar ("S. hadar"),
Salmonella enterica serovar Enteriditis ("S. enteriditis"),
Salmonella enterica serovar Kentucky ("S. kentucky"), Salmonella
enterica serovar Infantis ("S. infantis"), Salmonella enterica
serovar Pullorum ("S. pullorum"), Salmonella enterica serovar
Gallinarum ("S. gallinarum"), Salmonella enterica serovar Muenchen
("S. muenchen"), Salmonella enterica serovar Anaturn ("S. anatum"),
Salmonella enterica serovar Dublin ("S. dublin"), Salmonella
enterica serovar Derby ("S. derby"), Salmonella enterica serovar
Choleraesuis var. kunzendorf ("S. cholerae kunzendorf`), and
Salmonella enterica serovar minnesota (S. minnesota).
[0072] The vaccine compositions described herein may be
administered orally to an individual in any form that permits the
Salmonella bacterial strain of the composition to remain alive and
to persist in the gut for a time sufficient to elicit an immune
response to one or more avian influenza antigens of avian influenza
virus and highly pathogenic derivatives expressed in the Salmonella
strain. For example, the live bacterial strains described herein
may be administered in relatively simple buffer or saline solutions
at physiologically acceptable pH and ion content. By
"physiologically acceptable" is meant whatever is compatible with
the normal functioning physiology of an individual who is to
receive a live vaccine composition described herein. Preferably,
bacterial strains described herein are suspended in otherwise
sterile solutions of bicarbonate buffers, phosphate buffered saline
(PBS), or physiological saline, that can be easily swallowed by
most individuals. However, "oral" routes of administration may
include not only swallowing from the mouth a liquid suspension or
solid form comprising a live bacterial strain described herein, but
also administration of a suspension of a bacterial strain through a
nasojejunal or gastrostorny tube, and rectal administration, e.g.,
by using a suppository comprising a live bacterial strain described
herein to establish an infection by such bacterial strain in the
lower intestinal tract of the alimentary canal. Accordingly, any of
a variety of alternative modes and means may be employed to
administer a vaccine composition described herein to the alimentary
canal of an individual if the individual cannot swallow from the
mouth.
[0073] In a preferred embodiment of the invention, the bacteria
have genetic modifications which result in the expression of at
least one hemagglutinin and one neuraminidase, where each gene is
optimized for bacterial expression in at least one codon. In a most
preferred embodiment, the hemagglutinin and neuraminidase genes are
further modified to be secreted by the bacteria as heterologous
fusion proteins. In a most preferred embodiment, the neuraminidase
and hemagglutinin heterologous fusion proteins are integrated into
the chromosome in delta IS200 sites.
[0074] In a preferred embodiment, the bacterial strains are
genetically stabilized by deletion of IS200 elements, which reduces
their genetic recombination potential.
[0075] In another embodiment, the bacterial strains are genetically
stabilized by deletion of phage and prophage elements, which
reduces their genetic recombination and transduction potential.
[0076] In another embodiment, the bacterial strains are genetically
isolated from phage infection by constitutive expression of the P22
C2 repressor, which reduces their ability to be infected by phage
and the subsequent transduction of genes by such phage.
[0077] In another embodiment, the bacterial strains have
genetically defined flagellar antigens, or no flagellar antigens,
which reduces the immune system elimination of the vector,
enhancing its immunization potential in second immunizations.
[0078] In a preferred embodiment, the genetically modified bacteria
are used in animals, including humans, birds, dogs and pigs, for
protection against avian influenza and highly pathogenic
derivatives.
[0079] In another embodiment, a kit allows for rapid construction
of a bacterial vaccine which is closely matched to an emerging
avian influenza or its highly pathogenic derivative.
[0080] FIG. 1 shows a modified ptrc99a plasmid. The SphI site
within the multiple cloning site has been deleted making the
upstream SphI site unique and useful for subcloning into pCVD
vectors. In addition, NotI and PacI sites are added downstream of
the t.sub.1t.sub.2 terminators also for use in subcloning into pCVD
vectors.
[0081] FIGS. 2A and B show a plasmid vectors capable of expressing
the H5 or N1 antigens cytoplasmically. "Ptrc" refers to a
functional trc promoter operably linked to a structural coding
sequence for an H5 antigen fusion polypeptide. "T1 T2" refers to
the T1 and T2 transcriptional terminators of the 5S bacterial
ribosomal RNA gene. "bla" refers to the beta-lactamase gene for
ampicillin and carbenicillin resistance. Arrows indicate direction
of transcription. See text for details.
[0082] FIG. 3 shows modified ptrc99a plasmid with unique
restriction sites engineered into the coding sequence of the N1
gene for rapid exchange of mutations such as the H274Y.
[0083] FIG. 4A shows a plasmid vectors expressing an antigen (H5 or
N1) in a secreted form as fusions with the hlyA protein. Numbers
after names of restriction endonucleases indicate specific
restriction sites in the plasmid. "Ptrc" refers to a functional trc
promoter operably linked to a structural coding sequence for an
antigen fusion polypeptide. "ColE1 ori" refers to the colicin E1
origin of replication. 4B shows the hemolysin secretion HlyB and
HlyD proteins in a plasmid vector with a different origin of
replication, the "M15ori", which refers the M15 origin of
replication. See text for details.
[0084] FIG. 5 shows ClyA fusion. A plasmid vector for expression of
an antigen (e.g., H5 or N1) as a ClyA fusion is shown. The modified
trc99a vector of FIG. 1 is used as a cloning and expression vector
for a ClyA:antigen fusion.
[0085] FIG. 6 shows Autotransporter fusion. A plasmid vector for
expression of an antigen (e.g., H5 or N1) as a autotransporter
(translocator) fusion is shown. The modified trc99a vector of FIG.
1 is used as a cloning and expression vector for the
autotransporter:antigen fusion. "S" refers to a hydrophobic signal
sequence.
[0086] FIG. 7 shows Colicin E3 (ColE3) fusion. A plasmid vector for
expression of an antigen (e.g., H5 or N1) as a colicin E3 fusion is
shown. The modified trc99a vector of FIG. 1 is used as a cloning
and expression vector for the ColE3:antigen fusion.
[0087] FIG. 8 shows pCVD knockout constructs. A. Selection of 5'
and 3' DNA segments for constructing a pCVD442 chromosomal
integration vector for disrupting chromosomal genes and integration
of new genes into the chromosome. The 5' and 3' segments may be
selected completely within the gene (a), partly within and partly
outside (b) or completely outside (c) or any combination of the
above so long as in each case there is a gap of at least one
nucleotide such that the recombination event results in such gap
introduced into the gene as a deletion resulting in inactivation of
the gene. When a foreign gene is inserted such as in FIG. 8B, then
the inserted gene also results in a gene disruption following
integration and resolution. B. A localization vector with 5' and 3'
sequence flanking a multiple-cloning sites (SphI/NotI) into which
an expression cassette containing a gene of interest (e.g., an
antigen such as H5 or N1, or another gene of interest such as the
P22 phage C2 phage repressor protein).
[0088] FIG. 9 shows a cloning sequence, from A) synthetic gene
within the expression vector to B) chromosomal localization vector.
First, a synthetic gene is generated using standard molecular
techniques, the gene is then cloned into an expression vector and
then subcloned into a pCVD vector for chromosomal localization.
"H274Y" refers to the histidine to tyrosine mutation that confers
oseltamivir resistance.
[0089] FIG. 10 shows a determination of IS200 17.7 and 19.9
rearrangement/deletion. The Suwwan deletion is a recombination
event between two IS200 elements located at 17.7 and 19.9 Cs. If
oligonucleotide primers are generated (P1; forward) to unique
sequences before the 17.7 and (P2; reverse) after the 19.9, no PCR
product will be generated under standard short PCR conditions
(typically 500 bp to 10,000 bp) because the distance between the
two points is too long (greater than 20,000 bp). However, following
a Suwwan deletion, the two points are in relative close proximity
and a PCR product will readily be generated.
[0090] FIG. 11 shows a method to generate strains capable of
undergoing the Suwwan deletion in strains lacking the 17.7 Cs
IS200. In strains which lack the 17.7 Cs IS200, an IS200 can be
introduced in order to generate the potential to undergo such a
deletion. As depicted in FIG. 8, a chromosomal localization vector
derived from pCVD442 can be generated with an cloning sites
(SphI/NotI) into which will accommodate foreign DNA. In order to
insert an IS200 in the DNA sequence in the homologous location to
that of Salmonella typhimurium ATCC 14028 is identified (A) between
the genes ybjL (1) and ybjM (2) and the DNA flanking that region is
cloned as 5' and 3' regions into pCVD442 together with the SphI and
NotI cloning sites (B) and the IS200 from ATCC 14028 is cloned in
between the 5' and 3' regions (C). Recombination with the
chromosome results in the insertion of the IS200 at the appropriate
location (D) allowing for the potential to spontaneously recombine
as shown in FIG. 10.
1.1 Cloning Avian Influenza Antigens for Bacterial Expression.
[0091] As described in the present invention, avian influenza genes
can be cloned as a codon-optimized synthetic DNA construct and
expressed in bacteria including but not limited to Salmonella.
Cloning and expression of the avian influenza genes uses standard
molecular techniques (Sambrook et al., Molecular Cloning, Cold
Spring Harbor Laboratory Press, 1989) and conventional bacterial
expression plasmids such as pTrc99a (Pharmacia-Upjohn). This
results in a plasmid-based, cytosolic expression of the antigen.
For an example, see Section 2.1. The avian influenza antigens can
be further modified for secretion as heterologous fusions. Such
fusions can be with previously described for hlyA, clyA, SPATE
autotransporter proteins or a novel composition of a fusion with
colicin E3 (colE3). For example, see Section 2.10. These cytosolic
and secreted constructs can be further modified by integration into
the bacterial chromosome using standard techniques of targeted
homologous recombination (Donnenberg and Kaper, 1991) where the
bacterial expression cassette is inserted in between the 5' and 3'
flanking sequences as further described below.
1.2 Improvement of Genetic Stability
[0092] Bacterial strains such as Salmonella contain a variety of
phage and prophage elements. Activation of such phage elements can
result in genetic rearrangements and/or liberate such phage as
Gifsy and Fels which are capable of transducing other bacterial
strains. Such phage elements are known by DNA sequence of entire
genomes. If the genome sequence is unknown, such elements may be
determined by low stringency DNA:DNA hybridization. In the present
invention, DNA sequences associated with phage and prophage
elements are disrupted to improve genetic stability and reduce the
potential for transduction. Genetic stability is improved by
deletion of IS200 and phage/prophage elements. Deletion of IS200
and phage/prophage elements on the bacterial chromosome is
accomplished using standard techniques of targeted homologous
recombination (Donnenberg and Kaper, 1991) where 5' and 3' flanking
sequences of the deletion target (IS200 or phage/prophage elements)
are cloned into the pCVD442 vector.
[0093] Improvement of genetic stability can be determined by assay
of phenotypic or genotypic properties such as spontaneous
rearrangement of IS200 elements resulting in chlorate resistance
(Murray et al., 2004). The ability to rearrange IS200 elements and
cause a spontaneous deletion may be determined by assay of
spontaneous chlorate resistant bacterial colonies on LB media
containing chlorate. These colonies are then subjected to PCR
analysis of the genome, combined with DNA sequencing, which is thus
definitive in respect to a particular IS200-based deletion in the
17.7 to 19.9 Cs region (See FIG. 8). This and other DNA
rearrangements, duplications and deletions are also determined by
pulse-field gel electrophoresis which compares the DNA banding
pattern of the parent strain (control strain) to strains in which
rearrangements are to be determined (test strains).
1.3 Genetic Isolation of the Bacterial Vectors from Phage
[0094] The bacterial strains which vector the avian influenza
antigens can be altered to genetically isolate them from phage.
Genetic isolation is accomplished by limiting the phage integration
through constitutive expression of the P22 phage repressor. When
exogenous phage enter the repressor inhibits their integration into
the chromosome. Under certain circumstances, the repressor may be
proteolyticly cleaved by the RecA protein. This may be circumvented
by eliminating the RecA protein cleavage site through site-directed
mutagenesis (Sambrook et al., Molecular Cloning, Cold Spring Harbor
Laboratory Press, 1989). The P22 repressor is cloned into a
bacterial expression vector, such as the trc99a vector and results
in constitutive expression. The expression cassette may be further
modified to be integrated into the chromosome using standard
techniques of targeted homologous recombination (Donnenberg and
Kaper, 1991) where the trc99a expression cassette is cloned between
the 5' and 3' flanking sequences of a deletion target (e.g., IS200
or phage/prophage elements) within a pCVD442 vector. Genetic
isolation is tested by experimental infection with phage to which
the bacteria are normally susceptible. Successful construction of a
genetically isolated strain is recognized by substantially lower
infection rates (e.g., 10 fold lower or more) compared to the
parent strain, where infection rates are determined by plaque
forming units (PFU) of phage, such as P22 phage. Moreover, the
transduction potential of such bacteria is also assayed using
standard techniques know to those skilled in the arts, such as the
comparison of transducing potential for a metabolic gene (e.g.,
purl) from the parent strain compared to the modified strain to an
identical recipient strain deficient in the same metabolic gene
(e.g., delta purl). The genetically isolated strains shows
substantially lower (e.g., 10 fold lower or more) ability to have a
representative gene transduced to another strain compared to the
parent strain.
1.4 Construction of bacteria with genetically defined flagellar
(fH) Antigens or No fH Antigens.
[0095] In another embodiment, the bacterial strains have
genetically defined flagellar antigens, or no flagellar antigens,
which reduces the immune system elimination of the vector,
enhancing its immunization potential in second immunizations.
Strains with defined flagellar antigens are constructed by first
selecting substrains that express either the fH1 or fH2 antigens
which the bacteria spontaneously generate by inversion of a portion
of the gene mediated by the hin recombinase. To select strains
expressing either fH1 or fH2, the bacteria are plated to standard
growth media and subjected to a colony lift using nitrocellulose or
equivalent membrane binding matrix, followed by lysis and blocking
of the membrane. fH1 and fH2 are selected using fH1 and fH2
antibodies. The corresponding clone is then purified. These clones
are further subjected to deletion of the hin recombinase gene using
standard homologous recombination techniques including lamda red
recombinase or pCVD vectors specific for disrupting hin, thus
fixing their flagellar antigen expression. Furthermore, strains
without any flagellar antigens may be constructed by deletion of
the fliBC genes using standard homologous recombination. These
genetically altered strains with stable expression of either fH1,
fH2 or no flagellar antigens (fH0) have reduced elimination by the
immune system when they are used for second immunizations where the
first immunization is a bacterial strain with a different flagellar
antigen or no flagellar antigen or where the first immunization is
a non-bacterial vaccine including an egg-based vaccine.
1.5 Use of Genetically Modified Bacteria for Protection Against
Avian Influenza and Highly Pathogenic Derivatives.
[0096] As described in the present invention, the bacterial strains
which vector the H and N antigens of avian influenza and highly
pathogenic derivatives are useful as vaccines, resulting protection
against infection by influenza strains.
1.6 A Kit for Rapidly Producing Genetically Modified Bacteria for
Protection Against Avian Influenza and Highly Pathogenic
Derivatives.
[0097] A kit according to one embodiment of the invention comprises
1) a bacterial strain, 2) pTrc99a expression vectors containing A)
neuraminidase and B) hemagglutinin antigens with unique restriction
endonuclease enzymes within the sequence which allows rapid
exchange of small segments (such as the N1 amino acid 274) and 3)
multiple unique chromosomal localization vectors targeting a
variety of genes including IS200s, phage elements (especially Gifsy
and Fels) and metabolic genes (such as purl, AroA, etc) for
insertion of the pTrc99a expression cassettes with the modified H
and N antigens.
[0098] In order to more fully illustrate the invention, the
following non-limiting examples are provided.
Examples of Bacterial Expression of H and N Antigens and
Incorporation in Genetically Stabilized and Isolated Strains with
Defined Flagellar Antigens and their Use in Protection Against
Avain Influenza and Highly Pathogenic Derivatives.
2.1 Example of Methods for Obtaining Bacterial Strains of the
Appropriate Genetic Background.
[0099] Bacterial strains useful in the invention include strains of
known safety when administered to humans including but not limited
to Ty21a, CMV906, CMV908, CMV906-htr, CMV908-htr, Ty800, holavax,
M01ZH09, VNP20009. These strains contain defined mutations within
specific serotypes of bacteria. The invention also includes the use
of these same mutational combinations contained within alternate
serotypes or strains. Each of the mutations can be generated by
chromosomal deletion techniques known to those skilled in the arts.
Generally, the mutational combination includes at least two
mutations. Such mutations are made sequentially and generally
involve the elimination of antibiotic resistance markers. The
process therefore consists of a first step in selection of an
appropriate serotype based upon the known species specificity (e.g,
S. typhi is human specific and S. typhimurium has broad species
specificity including humans, birds, pigs and many other
vertebrates). Thus, if the target species for immunization were
limited to humans, S. typhi would be appropriate. If more species
are desired to be immunized including humans, birds, pigs, dogs,
horses and many other vertebrates, then other serotypes may be
used. In a preferred embodiment, as S. typhimurium and S. motevidio
which have non-overlapping O-antigen presentation (e.g., S.
typhimurium is 0-1,4,5,12 and S. typhi is Vi, S. montevideo is 0-6,
7) may be used. Thus, S. S. typhimurium is a suitable serotype for
a prime/boost strategy where S. typhimurium is either the primary
vaccine, or the booster vaccine where the primary vaccine is
another serotype such as S. typhi or S. montivideo. Furthermore, S.
typhimurium is suitable for humans, pigs or birds. A second step
follows serotype selection where the first genetic mutation is
introduced which may involve the use of antibiotic resistance
markers and where any antibiotic resistance makers are then
eliminated, followed by a third step where a second genetic
mutation is introduced which may involve the use of antibiotic
resistance markers and where any antibiotic resistance makers are
then also eliminated. Reiteration of genetic deletion and
antibiotic marker elimination can be used to supply additional
mutations. Methods for reiterative chromosomal deletion and
elimination of antibiotic resistance markers are known to those
skilled in the arts, including TN10 transposon deletion followed by
Bochner selection for elimination of the tetracycline antibiotic
resistance marker, lamda red recombinase deletion followed by flip
recombinase elimination of the antibiotic resistance marker, and
suicide vectors such as those containing sucrasgene (e.g., pCVD442,
Donnenberg and Kaper, 1991). By way of example, the pCVD442 vector
is used in the following manner to create specific genetic
deletions. First, the desired bacterial serotype is selected, such
as Salmonella typhimurium. Second, the desired genetic background
to be utilized is selected, such as AroA-, AroD-, htrA- which has
been shown to be a safe mutational combination. The genes are then
deleted in sequence using the pCVD442 vector as described by
Donnenberg and Kaper 1991. The construction of the deletion vector
uses DNA sequence for the gene of interest and/or the flanking 5'
and 3' DNA. Such DNA may be known and previously deposited in a
database, or new sequence obtained by methods known to those
skilled in the arts such as low stringency hybridization. The
isolation genes such as AroA, AroD, htrA or any other known
attenuating mutation from Salmonella serotypes where the DNA
sequence is not known is accomplished by low-stringency DNA/DNA
hybridization of a Salmonella genomic DNA library carried in either
E. coli or Salmonella LT2 5010 (e.g., Sambrook et al., 1989
Molecular Cloning: A laboratory manual (2 d Ed.), Cold Spring
Harbor Laboratory Press; Low et al., 1999 Nature Biotechnology). A
probe for the desired gene such as AroA, AroD, htrA or any other
known attenuating mutation is generated from a known homologous
gene and its corresponding DNA sequence of such as AroA, AroD, htrA
or any other known attenuating mutation respectively, by PCR. This
fragment is labeled using .sup.32P-dCTP and used to probe the
Salmonella library at low-stringency conditions consisting of
6.times. sodium chloride/sodium citrate (SSC), 0.1% sodium
dodecylsulfate (SDS), 2.times.Denhardts, 0.5% non-fat dry milk
overnight at 55.degree. C. Those skilled in the art will understand
that higher or lower stringency can be achieved using variation in
the 55.degree. C. (higher temperature is a higher stringency used
when excessive binding occurs) combined with higher or lower SSC
concentration (lower buffer concentration is higher stringency used
when excessive binding occurs; higher concentration is lower
stringency used when insufficient binding occurs to generate a
signal). Strongly hybridizing colonies are purified, and plasmids
extracted and subjected DNA sequencing. DNA sequence flanking novel
homologue is used to generate the 5' and 3' regions of a sucrase
vector which can then be used to specifically delete that genetic
element.
[0100] Flanking DNA representing 5' and 3' regions is then cloned
into the sucrase vector using standard techniques such that the
unification of these regions represents a genetic deletion within
the desired gene of at least one nucleotide. Preferably, most or
all of entire gene is deleted (See FIG. 8). The vector is
transformed to the desired strain and selected for antibiotic
(ampicillin) resistance. The ampicillin resistance is then
eliminated by selection of deletion of the sucrase gene by plating
the bacteria to agar plates containing sucrase as described by
Donnenberg and Kaper, 1991. Reiteration of these steps targeted at
additional genes results in multiple mutations within the desired
genetic background.
2.2 Example of Generation of Novel Mutational Combinations.
[0101] Strains useful in the invention also include novel
combinations of mutations including phoP, phoQ, cdt, cya, crp,
poxA, rpoS, htrA, nuoG, pmi, pabA, pts, damA, purA, purB, purl,
zwf, aroA, aroC, aroD, gua, cadA, rfc, rjb, rfa, ompR, msbB and the
Suwwan deletion. Novel combinations are selected by experimental
analysis of two factors, attenuation and immunogenicity.
Attenuation, where the LD50 by administration in normal
immunocompetent mice (e.g., CD1) is greater than 10.sup.5, but not
more than 10.sup.9, and/or the LD50 by IV injection is more than
10.sup.4 but not more than 10.sup.8 is desirable, since this is
expected to translate into a dose in humans which will neither be
too potent and prone to potential overdosing and/or side effects,
nor over-attenuated which would result in use of very large doses
necessitating vastly greater manufacturing capability. A safe dose
(LD.sub.0) is first determined in mice, and may be extrapolated to
other species on a per weight basis or on a basis of surface area
(e.g., meters2). A safe dose is the non-lethal dose determined by a
toxicity study using standard methods (Welkos and O'Brian Taylor et
al., Proc. Natl. Acad. Sci. USA 84: 2833-2837). In non-experimental
animals including humans, a dose 1:100 or 1:1000 of the LD.sub.0
may first be tested and then escalated to a maximum tolerated dose
(MTD) defined as the maximum dose having acceptable toxicities
which are not life threatening. A dose below or up to the MTD may
be used. Immunogenicity is determined by methods know to those
skilled in the art including wild type strain challenge and/or
analysis for immune response to specific antigens, e.g., ELISA for
LPS (e.g., FLOCKTYPE.RTM. Labor Diagnostik, Leipzig, Germany) or to
the genetically engineered antigens as described further in
examples 2.15 and 2.16. Strains which fall into the attenuation
range and have the comparatively highest immune response as
determined by ELISA and wild type immune challenge using methods
known to those skilled in the arts are preferred. By way of
example, the following three combinations are generated 1) aroA and
purl, 2) aroA and Suwwan, and 3) aroA, purl and Suwwan are
generated. DNA sequences for aroA and purl are known for S.
typhimurium. The Suwwan deletion is described by Murray et al.,
2004. The Suwwan deletion is selected for in ATCC strain 14028
using agar plates containing chlorate. Approximately one in three
resistant stains contain the Suwwan deletion, which is confirmed by
PCR using primers outside of the two IS200 elements (FIG. 8). The
introduction of the Suwwan deletion is not followed by restoring
antibiotic sensitivity, since chlorate is not clinically relevant
and there is no antibiotic resistance gene inserted in the process.
Thus, using the methods described by Donnenberg and Kaper 1991 as
described in Example 2.1 and the derivation of the Suwwan deletion,
the combined three mutations are generated: 1) aroA and purl, 2)
aroA and Suwwan, and 3) aroA, purl and Suwwan. These combinations
are then determined for LD.sub.50 using standard methods (Welkos
and O'Brian Taylor et al., Proc. Natl. Acad. Sci. USA 84:
2833-2837) and those with the desired attenuation profile described
above are selected for further analysis. In a wild type challenge
experiment, the mice are first administered the individual
bacterial strain orally at a safe dose (i.e., an LD.sub.0 or less
than the LD.sub.10 as defined from the same LD.sub.50 experiment
previously performed). Sub-lethal doses of the attenuated strains
are expected to immunize the mice against the lethal wild type
strain. At a suitable time period (for example, 2 to 6 weeks, 1 to
12 weeks, or 1 to 53 weeks) following a single administration of a
dose less than the LD.sub.10, either a booster dose also less than
the LD.sub.10 may be administered and staged for two additional
weeks, or the challenge experiment may be performed. The challenge
is performed in the form of an oral administration of a lethal dose
of the wild type, usually 10 colony forming units (CFU) or greater,
and a survival is monitored over time. Strains with the greatest
immunization potential result in immunized mice with the longest
survival. Immunization can also be determined by immune response to
Salmonella antigens, such as the O-antigens, H-antigens or LPS. A
determination of anti-LPS is performed using a commercially
available ELISA kit. Bacterial strains with the appropriate
attenuation and highest level of demonstrated immunization are used
for vaccine carriers.
2.3 Example of Construction of the Suwwan Deletion in Strains
Lacking the 17.7 IS200 Element.
[0102] The method for selection of the Suwwan deletion has been
described by Murray et al., 2004 for the Salmonella typhimurium
strain ATCC 14028. Since other Salmonella strains lack the
additional IS200 element at Cs. 17.7, they do not undergo this
specific chromosomal deletion. The invention further provides a
method to allow the Suwwan deletion to occur in other Salmonella
strains, by using a sucrase deletion construct as described above
which contains the 3' and 5' flanking regions which occur in other
strains, isolated using analogous primers and providing a multiple
cloning site. The IS200 Cs 17.7 is then cloned by PCR into the
multiple cloning site of the sucrase vector containing the flanking
sequence of the empty IS200 site. Subsequent homologous
recombination results in the addition of the IS200 to the site
where it was previously absent. Subsequent selection for the Suwwan
deletion is then performed, resulting in a strain with the
analogous Cs 17 Cs 19 deletion.
2.4 Example of Construction of Synthetic, Codon Optimized
Hemagglutinin Genes for Bacterial in a Cytosolic Form in
Salmonella.
[0103] Codon optimized genes generated by reverse translation
(a.k.a., back-translation) of the avian influenza genes or their
highly pathogenic derivatives using Salmonella optimized codons and
the synthetic gene constructed by annealing overlapping plus and
minus strand oligonucleotides. For cytoplasmic expression, a second
codon GCT is added following the ATG start site, the two codons
together with an upstream CC constitute the restriction
endonuclease site NcoI (CCATGG). Following the final codon TGA, the
restriction endonuclease site HindIII has been added, thus, a
nucleic acid containing this sequence can be restriction digested
with NcoI and HindIII and cloned into the NcoI/HindIII sites of the
bacterial expression plasmid trc99a (Pharmacia/Upjohn). For
convenience, the trc99a vector is modified to remove the sphI and
pstI sites and addition of NotI and PacI sites (FIG. 1). This
allow, for example, directional subcloning of the expression
cassette consisting of the trc promoter and its ribosomal binding
site, any given cloned gene within the multiple cloning site, and
the downstream ribosomal rna termination signals. SphI and PstI are
removed from trc99a by restriction digestion with PstI and HindIII,
agarose gel analysis and gel purification of the restriction
digested plasmid minus the small DNA seq cleaved by the restriction
enzymes, and ligation of a synthetic oligonucleotide
TABLE-US-00001 AGCTTGCA. SEQ ID NO: 001
[0104] Clones may be further confirmed by restriction endonuclease
analysis or DNA sequencing. The NotI and PacI sites are added by
inverse PCR, where the primers consist of INVNOTF1
TABLE-US-00002 SEQ ID NO: 002
5'-GATCGCGGCCGCTTAATTAACATTCAAATATGTATCCGCTCATGA G-3' and INVNOTR1
SEQ ID NO: 003 5'-GATCGCGGCCGCGTATTTAGAAAAATAAACAAAAAGAGTTTG-3'
[0105] The forward primer introduces the NotI and PacI sites, and
the reverse primer provides a second NotI site. The linear PCR
product is then restriction digested with NotI and self-ligated,
and transformed to E. coli. Confirmation of the correct clones is
obtained by restriction analysis, where the isolated plasmids now
contain NotI and PacI sites or by DNA sequencing.
[0106] Bacterial expression is tested by any applicable technique
known to those skilled in the arts such as ELISA or immunoblot.
Such plasmid can be transferred to a suitable Salmonella strain by
standard transformation techniques to comprise a Salmonella strain
which expresses the H5 antigen cytoplasmically and is capable of
eliciting an immune response.
TABLE-US-00003 TABLE 1 Salmonella typhimurium LT2 [gbbct]: 4696
CDS's (1477317 codons) fields: [triplet] [frequency: per thousand]
([number]) UUU 23.3 (34407) UCU 7.2 (10665) UAU 17.1 (25288) UGU
4.8 (7154) UUC 15.3 (22562) UCC 10.1 (14953) UAC 11.6 (17079) UGC
6.6 (9817) UUA 13.2 (19499) UCA 6.2 (9186) UAA 1.9 (2781) UGA 1.0
(1466) UUG 12.4 (18352) UCG 9.5 (14062) UAG 0.3 ( 452) UGG 15.2
(22479) CUU 11.8 (17442) CCU 7.2 (10564) CAU 13.3 (19643) CGU 18.8
(27700) CUC 10.4 (15425) CCC 6.9 (10235) CAC 9.6 (14171) CGC 23.3
(34474) CUA 4.9 (7257) CCA 5.8 (8501) CAA 12.7 (18796) CGA 3.6
(5268) CUG 53.6 (79180) CCG 24.7 (36447) CAG 31.0 (45726) CGG 6.9
(10266) AUU 29.3 (43251) ACU 6.7 (9935) AAU 17.8 (26263) AGU 7.3
(10831) AUC 24.4 (36114) ACC 23.3 (34480) AAC 20.1 (29752) AGC 17.4
(25762) AUA 5.3 (7886) ACA 5.8 (8515) AAA 31.7 (46882) AGA 2.3
(3451) AUG 27.4 (40490) ACG 18.8 (27756) AAG 11.3 (16630) AGG 1.6
(2422) GUU 15.5 (22914) GCU 12.8 (18891) GAU 31.6 (46740) GGU 17.4
(25643) GUC 18.2 (26821) GCC 29.1 (42983) GAC 20.3 (30060) GGC 35.3
(52100) GUA 11.4 (16792) GCA 13.0 (19160) GAA 35.4 (52232) GGA 8.7
(12841) GUG 25.2 (37210) GCG 42.5 (62843) GAG 20.7 (30586) GGG 12.0
(17784) Coding GC 53.36% 1st letter GC 59.34% 2nd letter GC 41.20%
3rd letter GC 59.53%
TABLE-US-00004 TABLE 2 Salmonella typhi [gbbct]: 397 CDS's (116164
codons) fields: [triplet] [frequency: per thousand] ([number]) UUU
23.8 (2767) UCU 11.8 (1372) UAU 18.9 (2192) UGU 6.3 (727) UUC 15.5
(1804) UCC 10.4 (1209) UAC 13.2 (1538) UGC 5.6 (652) UUA 15.3
(1783) UCA 14.3 (1656) UAA 1.7 (193) UGA 1.3 (155) UUG 12.3 (1434)
UCG 9.6 (1119) UAG 0.4 (49) UGG 12.8 (1491) CUU 15.8 (1834) CCU
10.0 (1165) CAU 11.4 (1319) CGU 15.2 (1765) CUC 10.7 (1247) CCC 6.7
(783) CAC 7.2 (839) CGC 12.5 (1456) CUA 6.5 (754) CCA 8.7 (1012)
CAA 13.9 (1618) CGA 6.3 (729) CUG 35.4 (4110) CCG 14.5 (1689) CAG
27.4 (3183) CGG 7.8 (908) AUU 27.7 (3214) ACU 14.2 (1647) AAU 26.6
(3086) AGU 12.6 (1467) AUC 20.5 (2382) ACC 20.5 (2377) AAC 22.6
(2629) AGC 16.5 (1921) AUA 9.5 (1107) ACA 13.5 (1568) AAA 35.8
(4156) AGA 5.7 (666) AUG 26.1 (3037) ACG 15.9 (1845) AAG 17.1
(1989) AGG 4.5 (520) GUU 20.1 (2339) GCU 17.5 (2036) GAU 34.0
(3947) GGU 19.7 (2286) GUC 15.6 (1817) GCC 22.0 (2559) GAC 20.1
(2332) GGC 22.5 (2612) GUA 12.8 (1484) GCA 20.5 (2382) GAA 35.1
(4080) GGA 12.2 (1414) GUG 19.6 (2274) GCG 21.2 (2461) GAG 21.1
(2446) GGG 13.2 (1532) Coding GC 48.16% 1st letter GC 53.73% 2nd
letter GC 40.62% 3rd letter GC 50.14%
[0107] A codon optimized sequence is generated by reverse or back
translation, i.e., the conversion of the amino acid sequence into
the appropriate DNA sequence. Because of redundancy of the genetic
code, many amino acids have more than one possible codon set which
will translate to the appropriate amino acid. Recognition sequences
representations use the standard abbreviations (Eur. J. Biochem.
150:1-5, 1985) to represent ambiguity. [0108] R=G or A [0109] Y=C
or T [0110] M=A or C [0111] K=G or T [0112] S=G or C [0113] W=A or
T [0114] B=not A (C or G or T) [0115] D=not C (A or G or T) [0116]
H=not G (A or C or T) [0117] V=not T (A or C or G) [0118] N=A or C
or G or T
[0119] Based upon the codon usage table which indicates preferences
as higher percentages of usage and therefore optimal codons, a
complete sequence can be back translated.
[0120] The H5 hemagglutinin gene has a number of known sequence,
see e.g., Genbank LOCUS NC.sub.--007362, isolated from a goose in
Guangdong, China in 1996, or a more preferably, a recent isolate
such as CY019432, obtained from a 26 year old female human infected
with avian influenza in Indonesia in 2006, expressly incorporated
herein by reference.
[0121] The result of the reverse translation of CY019432 into a
Salmonella codon optimized sequence is shown below (SEQ ID NO:
004).
TABLE-US-00005 GATCCCATGGCTGAGAAAATTGTGCTGCTGCTGTCCATTGTGTCGCTGGT
CAAAAGCGATCAGATCTGCATTGGCTACCATGCGAACAATAGCACCGAAC
AGGTTGATACCATTATGGAGAAAAACGTCACCGTGACCCATGCGCAGGAC
ATCCTGGAAAAAACCCATAATGGCAAACTGTGCGATCTGGATGGCGTCAA
ACCGCTGATCCTGAAAGATTGCAGCGTGGCGGGTTGGCTGCTGGGCAACC
CGATGTGCGATGAATTTATCAATGTTCCGGAATGGAGCTATATTGTGGAA
AAAGCGAATCCGACCAACGATCTGTGTTATCCGGGTTCGTTTAACGATTA
CGAAGAACTGAAACACCTGCTGAGCCGTATTAATCATTTTGAAAAAATCC
AGATTATTCCGAAATCGAGCTGGTCGGACCACGAGGCGAGCTCGGGCGTT
TCCTCCGCCTGCCCGTATCTGGGTAGCCCGAGCTTTTTTCGTAATGTGGT
CTGGCTGATCAAAAAAAATTCCACGTACCCGACCATTAAAAAAAGCTATA
ACAACACCAACCAGGAAGATCTGCTGGTGCTGTGGGGCATTCATCATCCG
AACAATGAAGAAGAACAGACCCGCCTGTACCAGAATCCGACCACCTATAT
TAGCATTGGCACCAGCACCCTGAATCAGCGTCTGGTTCCGAAAATTGCGA
CCCGCAGCAAAGTGAACGGCCAGTCCGGTCGTATGGAATTTTTTTGGACC
ATTCTGAAACCGAATGATGCCATCAACTTTGAATCCAATGGCAATTTTAT
CGCGCCGGAATACGCGTATAAAATCGTGAAAAAAGGCGATAGCGCCATTA
TGAAAAGCGAACTGGAATACTCCAACTGCAATACGAAATGTCAGACGCCG
ATGGGCGCGATCAACAGCTCGATGCCGTTTCACAACATCCATCCGCTGAC
CATTGGCGAGTGTCCGAAATATGTCAAAAGCAGCCGCCTGGTGCTGGCCA
CCGGCCTGCGCAATTCGCCGCAGCGTGAAAGCCGTCGCAAAAAACGTGGC
CTGTTTGGCGCGATTGCGGGCTTCATTGAAGGCGGCTGGCAGGGTATGGT
CGACGGCTGGTACGGTTATCATCATAGCAACGAACAGGGTAGCGGCTATG
CGGCGGATAAAGAATCCACCCAGAAAGCCATCGATGGTGTCACGAATAAA
GTGAATAGCATTATTGACAAAATGAACACCCAGTTCGAGGCGGTCGGCCG
CGAGTTTAATAATCTGGAACGCCGCATTGAAAATCTGAATAAAAAAATGG
AAGATGGCTTTCTGGACGTTTGGACCTATAACGCGGAACTGCTGGTCCTG
ATGGAGAACGAACGCACGCTGGACTTTCATGATTCCAACGTGAAAAATCT
GTACGATAAAGTTCGTCTGCAGCTGCGCGACAATGCCAAAGAACTGGGCA
ACGGCTGTTTCGAGTTTTATCATAAATGTGATAACGAATGCATGGAATCC
ATTCGTAACGGTACCTACAACTATCCGCAGTATAGCGAAGAAGCGCGCCT
GAAACGTGAAGAGATTTCGGGTGTGAAACTGGAATCCATTGGCACCTATC
AGATTCTGTCCATTTATAGCACCGTCGCCAGCTCCCTGGCCCTGGCCATT
ATGATTGCGGGCCTGAGCCTGTGGATGTGCTCCAACGGCTCCCTGCAGTG
TCGCATCTGCATCTGAAAGCTTGATC
[0122] The sequence begins with four spacer codons for restriction
digestion and cloning. The Genbank sequence had a second codon
inserted (GCT), which is a strong translational second codon in
gram negative bacteria. The initiating codon ATG is underlined as
well as the stop codon TGA which is followed by the nucleotides for
the restriction site HindIII and four spacer codons.
2.5 Example of Construction of Synthetic, Codon Optimized
Neuraminidase Genes for Bacterial in a Cytosolic Form in
Salmonella.
[0123] Codon optimized N1 orf (SEQ ID NO: 005) is generated by
reverse translation of the avian influenza gene using Salmonella
optimized codons and the synthetic gene constructed by annealing
overlapping plus and minus strand oligonucleotides as described in
the example above. For cytoplasmic expression, a second codon GCT
encoding alanine is added following the ATG start site encoding the
initiating methionine, the two codons together with an upstream CC
constitute the restriction endonuclease site NcoI. Further upstream
the nucleotides GACT are added to increase the distance of the
restriction site from the end, enhancing the abiligy of the enzyme
to cut close to the end. Following the final amino acid codon a TGA
stop codon, the restriction endonuclease site HindIII has been
added, thus, a nucleic acid containing this sequence can be
restriction digested with NcoI and HindIII and cloned into the
NcoI/HindIII sites of the bacterial expression plasmid trc99a
(Pharmacia/Upjohn). Bacterial expression is tested by any
applicable technique known to those skilled in the arts such as
ELISA or immunoblot. Such plasmids can be transferred to a suitable
Salmonella strain by standard transformation techniques to comprise
a Salmonella strain which expresses the H5 antigen cytoplasmically
and when administered to an animal is capable of eliciting an
immune response as described in example 7.15.
[0124] The N1 neuraminidase gene has a known sequence, see Genbank
LOCUS NC.sub.--007361, expressly incorporated herein by
reference.
[0125] Reverse translation using Salmonella codon preferences
results in the following DNA sequence. (SEQ ID NO: 005)
TABLE-US-00006 GATC cc ATG (GCT) AAT CCG AAC CAG AAA ATT ATC ACC
ATT GGC TCT ATT TGC ATG GTG GTA GGG ATC ATT TCC CTG ATG TTA CAG ATC
GGC AAC ATT ATC TCG ATC TGG GTG TCC CAT TCT ATT CAG ACC GGC AAC CAG
CAT CAG GCC GAA CCG TGC AAT CAA AGC ATT ATC ACC TAC GAA AAT AAC ACC
TGG GTA AAT CAG ACC TAT GTT AAT ATT TCA AAC ACC AAC TTC CTG ACC GAA
AAA GCG GTG GCA AGT GTA ACC CTC GCC GGT AAC AGC TCG CTG TGT CCT ATT
TCT GGC TGG GCG GTA CAC AGC AAA GAT AAT GGC ATT CGC ATC GGC TCT AAA
GGC GAC GTT TTT GTG ATC CGC GAA CCC TTT ATT TCG TGT AGC CAT CTG GAG
TGC CGT ACC TTT TTC TTG ACC CAG GGG GCG CTG CTT AAC GAT AAG CAT TCG
AAT GGC ACG GTT AAA GAT CGC AGT CCG CAC CGC ACG CTG ATG AGC TGC CCA
GTG GGG GAG GCC CCA TCC CCA TAC AAC TCG CGC TTC GAA TCC GTC GCT TGG
AGC GCC AGC GCG TGC CAC GAT GGT ACG TCT TGG CTG ACG ATC GGC ATT AGC
GGT CCG GAC AAC GGT GCG GTT GCT GTC CTG AAA TAT AAT GGT ATT ATC ACG
GAC ACC ATT AAA TCG TGG CGC AAC AAT ATC TTA CGG ACC CAG GAG TCA GAA
TGC GCC TGC GTG AAT GGC TCT TGC TTT ACG GTC ATG ACC GAT GGC CCG AGT
AAT GGC CAA GCG TCC TAT AAA ATT TTT AAA ATG GAA AAA GGG AAA GTT GTG
AAG TCA GTG GAA CTT AAC GCC CCG AAC TAT CAC TAT GAA GAG TGT TCG TGT
TAC CCT GAC GCA GGC GAA ATC ACG TGT GTC TGC CGT GAT AAC TGG CAT GGC
AGC AAC CGC CCG TGG GTG TCC TTT AAC CAG AAT TTG GAA TAT CAG ATC GGC
TAT ATT TGT TCT GGG GTC TTC GGC GAT AAC CCG CGT CCT AAT GAC GGC ACC
GGC AGC TGT GGC CCG GTA TCC CCC AAT GGT GCG TAT GGC GTT AAG GGT TTC
AGT TTC AAA TAC GGT AAT GGC GTG TGG ATT GGT CGC ACC AAA TCA ACC AAC
TCG CGG TCG GGT TTT GAA ATG ATC TGG GAT CCG AAT GGC TGG ACC GGT ACC
GAT AGC TCA TTC TCC GTG AAG CAA GAC ATC GTC GCA ATT ACG GAT TGG TCC
GGC TAC AGT GGC AGC TTT GTG CAA CAT CCG GAG CTG ACC GGG CTG GAT TGC
ATT CGC CCC TGT TTT TGG GTT GAA CTG ATT CGT GGG CGT CCG AAG GAG TCA
ACG ATC TGG ACG AGC GGC AGC AGT ATT AGC TTT TGC GGC GTC AAC AGC GAC
ACG GTC GGC TGG AGT TGG CCG GAT GAC GCG GAG CTC CCT TTT ACC ATT GAT
AAA TAG AAGCTT GATC
[0126] The sequence is further optimized for bacterial expression
by addition of the appropriate restriction sites for cloning. An
NcoI site is engineered using the start codon together with second
codon GCT and a stop codon is added after the final amino acid
codon together with an engineered HindIII site and end spacer. Such
a synthetically derived DNA sequence can then be cloned into the
NcoI/HindIII sites of the bacterial expression plasmid pTrc99a and
transformed into the Salmonella strain to result in a vaccine
strain expressing the viral antigen.
2.6 Example of Construction of Synthetic, Codon Optimized Genes
with Unique Restriction Endonuclease Sites for Rapidly Matching an
Emerging Pathogen.
[0127] Oseltamivir-resistant neuraminidase is an example of an
antigen with an altered amino acid sequence which could change
antigenicity. The above synthetic construct in Example 2.5 above
which contains restriction sites is further modified, where the
synthetic sequence contains mutations representing resistance to
osetlamivir, such as the histadine to tyrosine mutation at amino
acid position 274 (H274Y). First the trc99a N1 expression construct
is restriction endonuclease digested with appropriate sequences. A
synthetic DNA construct containing the N1 sequence bearing the
H274Y variation is obtained through synthetic construction and
ligated into the restriction endonuclease target sites of the
previously prepared gene. The plasmid is transfected into a
suitable bacterial vector. Thus, the new construct is more rapidly
generated and when expressed in the bacterial vector, results in a
vaccine antigenically matched to the emerging oseltamivir resistant
strain.
2.7 Example of Secretion of Avian Influenza Antigens and Highly
Pathogenic Derivatives using HlyA fustion.
[0128] Avian influenza antigen polypeptides expressed from
antigen-expressing plasmids or chromosomal constructs in the
vaccine strains described herein need not be linked to a signal
peptide or other peptide for membrane localization or secretion
across the cell membrane. However, by way of further example of a
preferred embodiment, a nucleotide sequence that encodes an H5-HlyA
fusion polypeptide useful in the invention is known in the art, and
the corresponding encoded H5-HlyA fusion polypeptide has the
corresponding amino acid sequence. The antigen-expressing plasmids
useful in the invention may be engineered to express an avian
influenza antigen polypeptide intracellularly in a host Salmonella
strain. Preferably, antigen-expressing plasmids or chromosomal
expression constructs useful in the invention are engineered to
express secreted forms of avian influenza antigen polypeptide
extracellularly. Accordingly, avian influenza antigen polypeptides
expressed from antigen-expressing plasmids in the vaccine strains
described herein, are preferably linked to a signal peptide or
other peptide for membrane localization or secretion across the
cell membrane.
[0129] Construction of hemolysin A (hlyA) fusions with H5
nucleotide sequence to result in an hlyA secreted fusion peptide.
HlyA fusions are generated using plasmids that provide the 60 C
terminal amino acids of HLYA [(Gentschev, et al., 1994. Synthesis
and secretion of bacterial antigens by attenuated Salmonella via
the Escherichia coli hemolysin secretion system. Behring Inst.
Mitt. 95:57-66; Holland et al. U.S. Pat. No. 5,143,830) by methods
known to those skilled in the arts and ligated into the hlyA fusion
vector to generate a nucleic acid sequence encoding an H5::HLYA
fusion peptide. The fusion may also be generated as a completely
synthetic DNA construct as described for the hemagglutinin and
neuraminidase genes.
[0130] An example of the CY019432 codon optimized H5 gene operably
fused to the 60 C-terminal amino acids of HlyA is shown below. (SEQ
ID NO: 006)
TABLE-US-00007 GATCCCATGGCTGAGAAAATTGTGCTGCTGCTGTCCATTGTGTCGCTGAA
GCGATCAGATCTGCATTGGCTACCATGCGAACAATAGCACCGAACAGGTT
GATACCATTATGGAGAAAAACGTCACCGTGACCCATGCGCAGGACATCCT
GGAAAAAACCCATAATGGCAAACTGTGCGATCTGGATGGCGTCAAACCGC
TGATCCTGAAAGATTGCAGCGTGGCGGGTTGGCTGCTGGGCAACCCGATG
TGCGATGAATTTATCAATGTTCCGGAATGGAGCTATATTGTGGAAAAAGC
GAATCCGACCAACGATCTGTGTTATCCGGGTTCGTTTAACGATTACGAAG
AACTGAAACACCTGCTGAGCCGTATTAATCATTTTGAAAAAATCCAGATT
ATTCCGAAATCGAGCTGGTCGGACCACGAGGCGAGCTCGGGCGTTTCCTC
CGCCTGCCCGTATCTGGGTAGCCCGAGCTTTTTTCGTAATGTGGTCTGGC
TGATCAAAAAAAATTCCACGTACCCGACCATTAAAAAAAGCTATAACAAC
ACCAACCAGGAAGATCTGCTGGTGCTGTGGGGCATTCATCATCCGAACAA
TGAAGAAGAACAGACCCGCCTGTACCAGAATCCGACCACCTATATTAGCA
TTGGCACCAGCACCCTGAATCAGCGTCTGGTTCCGAAAATTGCGACCCGC
AGCAAAGTGAACGGCCAGTCCGGTCGTATGGAATTTTTTTGGACCATTCT
GAAACCGAATGATGCCATCAACTTTGAATCCAATGGCAATTTTATCGCGC
CGGAATACGCGTATAAAATCGTGAAAAAAGGCGATAGCGCCATTATGAAA
AGCGAACTGGAATACTCCAACTGCAATACGAAATGTCAGACGCCGATGGG
CGCGATCAACAGCTCGATGCCGTTTCACAACATCCATCCGCTGACCATTG
GCGAGTGTCCGAAATATGTCAAAAGCAGCCGCCTGGTGCTGGCCACCGGC
CTGCGCAATTCGCCGCAGCGTGAAAGCCGTCGCAAAAAACGTGGCCTGTT
TGGCGCGATTGCGGGCTTCATTGAAGGCGGCTGGCAGGGTATGGTCGACG
GCTGGTACGGTTATCATCATAGCAACGAACAGGGTAGCGGCTATGCGGCG
GATAAAGAATCCACCCAGAAAGCCATCGATGGTGTCACGAATAAAGTGAA
TAGCATTATTGACAAAATGAACACCCAGTTCGAGGCGGTCGGCCGCGAGT
TTAATAATCTGGAACGCCGCATTGAAAATCTGAATAAAAAAATGGAAGAT
GGCTTTCTGGACGTTTGGACCTATAACGCGGAACTGCTGGTCCTGATGGA
GAACGAACGCACGCTGGACTTTCATGATTCCAACGTGAAAAATCTGTACG
ATAAAGTTCGTCTGCAGCTGCGCGACAATGCCAAAGAACTGGGCAACGGC
TGTTTCGAGTTTTATCATAAATGTGATAACGAATGCATGGAATCCATTCG
TAACGGTACCTACAACTATCCGCAGTATAGCGAAGAAGCGCGCCTGAAAC
GTGAAGAGATTTCGGGTGTGAAACTGGAATCCATTGGCACCTATCAGATT
CTGTCCATTTATAGCACCGTCGCCAGCTCCCTGGCCCTGGCCATTATGAT
TGCGGGCCTGAGCCTGTGGATGTGCTCCAACGGCTCCCTGCAGTGTCGCA
TCTGCATCCCCGGGTCAACTTATGGGAGCCAGGACTATCTTAATCCATTG
ATTAATGAAATCAGCAAAATCATTTCAGCTGCAGGTAATTTGGATGTTAA
GGAGGAAAGATCTGCCGCTTCTTTATTGCAGTTGTCCGGTAATGCCAGTG
ATTTTTCATATGGACGGAACTCAATAACTTTGACAGCATCAGCATAAAAG CTTGATC
[0131] The sequence begins with four spacer codons for restriction
digestion and cloning. The Genbank sequence had a second codon
inserted (GCT) in the H5 gene, which is a strong translational
second codon in gram negative bacteria. The initiating codon ATG is
underlined. A SmaI restriction endonuclease site has been added in
place of the H5 stop codon to facilitate cloning and the fusion of
the peptides, followed by in-frame coding sequence for the 60
C-terminal amino acids of the HlyA gene, which ends with the stop
codon TAA (underlined) which is followed by the nucleotides for the
restriction site HindIII and four spacer codons. A naturally
occurring PacI restriction endonuclease site occurring within HlyA
has been conservatively altered to facilitate the potential use of
PacI as a restriction site outside of the coding sequence.
[0132] The secretion of the hlyA fusion requires the presence of
the HlyBD gene products. In order to provide for the presence of
the HlyBD genes, a plasmid containing the genes may be used (FIG.
4), or preferably, the HlyBD genes are cloned within a sucrase
vector such as an IS200 phage recombinase, flagellar, or hin pCVD
deletion vector. The entire export cassette can be excised from
pVDL9.3 as a NotI-digested fragment and cloned into the NotI site
of a sucrase vector, which when recombined with the chromosome,
results in deletion of the IS200 phage recombinase, flagellar, or
hin and insertion of the HlyBD genes into the chromosome.
2.8 Example of Secretion of Avian Influenza Antigens and Highly
Pathogenic Derivatives Using ClyA Fusion.
[0133] Construction of clyA fusions with hemagglutinin and
neuraminidase antigens are generate according to the methods of
Galen et al. (2004 Infection and Immunity 72: 7096-7106).
2.9 Example of Secretion of Avian Influenza Antigens and Highly
Pathogenic Derivatives using autotransporter fusions.
[0134] Construction of autotransporter fusions with hemagglutinin
and neuraminidase antigens. Autotransporter chimeric proteins are
capable of self-transportation/secretion outside the bacterial
cell. Hemagglutinin and neuraminidase fusions with the IgA protease
autotranported protein of Nisseria gonorrhoeae are constructed
according to the methods of Veiga et al., 2003 J. Virol. 2003 77:
13396-13398) and Oomen et al., 2004 EMBO Journal 23: 1257-1266. The
resulting fusion construct, when transfected into a bacterial
vector, results in a vaccine strain which secretes the
neuraminidase and hemagglutinin antigens.
2.10 Example of Secretion of Avian Influenza Antigens and Highly
Pathogenic Derivatives using colicin E3 fusions.
[0135] Colicin E3 (ColE3) is a bacterial ribosomal RNA inactivating
toxin. ColE3 is neutralized within the cells that express it by an
antitoxin which inhibits is anti-ribosomal activity. An inactivated
ColE3 is cloned from a colE3 containing bacterial strain (e.g.,
ColE3-CA38). PCR primers consist of a forward primer which clones
the start codon with a second added codon and providing an NcoI
cloning site and a reverse primer which contains a SmaI (blunt end)
cloning site. The PCR primer is situated sufficiently far down the
sequence, such that the C-terminal portion of the protein is
absent, thus inactivating the toxic activity while retaining the
secretion activity. The hemagglutinin and neuraminidase antigens
are cut with NcoI and HindIII, blunt end polished and ligated
in-frame into the SmaI site of the truncated ColE3 protein. The DNA
orientation is then confirmed by restriction analysis and DNA
sequencing. When transformed into the bacterial vector, the DNA
construct results in secreted hemagglutinin or neuraminidase
antigens.
2.11 Example of Genetic Stabilization by Deletion of IS200
Elements.
[0136] Using the generalized pCVD442 method homologous
recombination technique using the vector pCVD442 (Donnenberg and
Kaper, 1991), IS200 elements can be deleted. Such elements in the
Salmonella typhimurium strain LT2 includes LOCUS NC.sub.--003197,
having a sequence well known in the art. The IS200 elements contain
a transposase with a well known amino acid sequence.
[0137] Additional IS200 elements, if not known by DNA sequence, can
be isolated by low stringency hybridization. The isolation IS200
elements from Salmonella by low-stringency DNA/DNA hybridization of
a Salmonella genomic DNA library carried in Salmonella LT2 5010
(e.g., Low et al., 1999 Nature Biotechnology). A probe for IS200 is
generated from a known IS200 element by PCR. This fragment is
labeled using .sup.32P-dCTP and used to probe the Salmonella
library at low-stringency conditions consisting of 6.times. sodium
chloride/sodium citrate (SSC), 0.1% sodium dodecylsulfate (SDS),
2.times.Denhardts, 0.5% non-fat dry milk overnight at 55.degree. C.
Strongly hybridizing colonies are purified, and plasmids extracted
and subjected DNA sequencing. DNA sequence flanking novel IS200
elements is used to generate the 5' and 3' regions of a sucrase
vector which can then be used to specifically delete that IS200
element.
[0138] By way of specific example, the IS200 located in 17.7 Cs.
can be deleted using a 5' section generated using the PCR primers
2415F1 (IS200 5.degree. F. with SacI)
TABLE-US-00008 SEQ ID NO: 007
GATCGAGCTCGGCTTAATTATTGCCCAGCTTGCGCTGG and 2415R1 (IS200 5'R with
poly linker) SEQ ID NO: 008
CCCCGCATGCGGGGCTCGAGGGGGCCATATAGGCCGGGGATTTAAATGGG
GCGGCCGCAAAAAAAATCCTGGCGCAGGGCCAGG and a 3' section using the
primers 2413F1 (IS200 3'F with poly) SEQ ID NO: 009
CCCCGCATGCGGGGAGATCTGGGGTTAATTAAGGGGTCTAGAGGGGGCGG
CCGCAGGACTATATTTAGGGCGAAACAGC and 2413R1 (IS200 3'R with SalI) SEQ
ID NO: 010 GATCGTCGACGACTAAACATGATTCCAACAATCACG.
[0139] The 5' section is cloned into the pCVD442 vector using SacI
and SphI, and subsequently, after isolation and identification of
the appropriate clone, the 3' section is added using the
restriction endonuclease enzymes SphI and SalI. The primers also
provide a multiple cloning site containing NotI, PacI, BstY1, SphI,
SfiI, Swa1, which can be used to deliver exogenous genes such as
the H5 and N1, the lamda repressor C1, or the hlyBD (protein
channel) described further below.
2.12 Example of Genetic Stabilization by Deletion of Phage
Elements.
[0140] Bacterial strains containing phage or prophage elements may
have the phage enter a lytic cycle in which they may undergo
recombination inversion. Bacterial strains such as Salmonella
contain Fels and Gifsy prophage. The Fels prophage
recombinase/invertases can be deleted using the pCVD442 homologous
recombination system as described above for IS200 elements.
Deletion results in the inability to excise the phage DNA and
therefore is unable to undergo the lytic cycle or genetic
recombination.
[0141] The Fels-1 invertase has a well known amino acid and DNA
sequence. The Fels-2 recombinase/invertases also have known amino
acid sequences, and DNA sequences.
2.13 Example of Genetic Isolation by Constitutive Expression of the
P22 Phage C2 Repressor.
[0142] See: Donnenberg and Kaper, 1991; Low et al. (Methods in
Molecular Medicine, 2003), expressly incorporated herein by
reference.
2.14 Example of Chromosomal Integration of a Synthetically
Constructed avian Influenza Hemagglutinin Gene and Neuraminidase
gene.
[0143] See: Donnenberg and Kaper, 1991; Low et al. (Methods in
Molecular Medicine, 2003), expressly incorporated herein by
reference.
2.15 Example of Determining Immune Response to H5N1 Expressing
Bacteria.
[0144] Experimental determination of vaccine activity is known to
those skilled in the arts. By way of non-limiting example,
determination of an antibody response is demonstrated.
[0145] 1) Vertibrate animals including mice, birds, dogs, cats,
horses, pigs or humans are selected for not having any known
current or recent (within 1 year) influenza infection or
vaccination. Said animals are pre-bled to determine background
binding to, for example, H5 and N1 antigens.
[0146] 2) The Salmonella expressing H5 and N1 are cultured on LB
agar overnight at 37.degree.. Bacteria expressing other H and or N
antigens may also be used.
[0147] 3) The following day the bacteria are transferred to LB
broth, adjusted in concentration to OD.sub.600=0.1
(.about.2.times.10.sup.8 cfu/ml), and subjected to further growth
at 37.degree. on a rotator to OD.sub.600=2.0, and placed on ice,
where the concentration corresponds to approx. 4.times.10.sup.9
cfu/ml.
[0148] 4) Following growth, centrifuged and resuspended in 1/10 the
original volume in a pharmacologically suitable buffer such as PBS
and they are diluted to a concentration of 104 to 10.sup.9
c.f.u./ml in a pharmacologically suitable buffer on ice, warmed to
room temperature and administered orally or intranasally in a
volume appropriate for the size of the animal in question, for
example 50 .mu.l for a mouse or 10 to 100 ml for a human. The
actual dose measured in total cfu is determined by the safe dose as
described elsewhere in this application.
[0149] 5) After 2 weeks, a blood sample is taken for comparison to
the pretreatment sample. A booster dose may be given. The booster
may be the same as the initial administration, a different species,
a different serotype, or a different flagellar antigen (H1 or H2)
or no flagellar antigen.
[0150] 6) After an additional 2 to 4 weeks, an additional blood
sample may be taken for further comparison with the pretreatment
and 2 week post treatment.
[0151] 7) A comparison of preimmune and post immune antibody
response is preformed by immunoblot or ELISA. A positive response
is indicated by a relative numerical value 2.times. greater then
background/preimmune assay.
2.16 Example of Immunization with H5N1 Bacterial Vaccine
Strains.
[0152] An experiment to determine if H5N1 strains of Salmonella are
capable of providing protection from challenge with the wildtype
strain. Ducks are immunized orally with 5.times.10.sup.9 cfu of
bacteria when 4 weeks old, then challenged with the standard
challenge model of avian influenza at 6 weeks age.
[0153] Birds in Group A are immunized with empty vector. Group B
receive Salmonella H.sub.5N.sub.1. Group C is immunized with
Salmonella expressing the Tamiflu resistant neuraminidase
mutations. Birds in Group D are not immunized. Each group is
further divided into +/-Tamiflu treatment. Results of these
experiments can be used to demonstrate the effectiveness of the
vaccine on Tamiflu resistant strain, with and without Tamiflu
treatment.
OTHER EMBODIMENTS
[0154] Other embodiments are within the claims set forth below. For
example, the host bacterium (the bacterium the chromosome of which
is engineered to encode a heterologous antigen) can be E. coli or
any other enteric bacterium, including Salmonella, Bordetella,
Shigella, Yersenia, Citrobacter, Enterobacter, Klebsiella,
Morganella, Proteus, Providencia, Serratia, Plesiomonas, and
Aeromonas, all of which are known or believed to similar to the
promoters of E. coli and Salmonella. Also potentially useful would
be a bacille Calmette-Guerin (BCG) vaccine strain engineered to
encode a heterologous antigen. The promoter used can be native to
the species of the host bacterium, or can be a heterologous
promoter (i.e., from a species other than that of the host
bacterium) engineered into the host bacterium along with the
heterologous antigen coding sequence, using standard genetic
engineering techniques. Multiple heterologous antigen coding
sequences linked to the same or different promoter sequences can be
inserted into a given chromosome, using techniques analogous to
those set forth above, to produce a multivalent vaccine strain.
[0155] Those who practice in the field of prokaryotic gene
expression will realize that, while naturally-occurring promoter
sequences are preferred, synthetic sequences or a hybrid of two or
more sequences would also be expected to be useful in the
chromosomes of the invention. Alteration, addition or deletion of
one or a few nucleotides within a naturally-occurring promoter
sequence would generally not affect its usefulness. The invention
therefore encompasses promoters having such inconsequential
changes.
Sequence CWU 1
1
1018DNAUnknownSynthetic Oligonucleotide 1agcttgca 8246DNAUnknownPCR
Primer 2gatcgcggcc gcttaattaa cattcaaata tgtatccgct catgag
46342DNAUnknownPCR Primer 3gatcgcggcc gcgtatttag aaaaataaac
aaaaagagtt tg 4241726DNAInfluenza A virus 4gatcccatgg ctgagaaaat
tgtgctgctg ctgtccattg tgtcgctggt caaaagcgat 60cagatctgca ttggctacca
tgcgaacaat agcaccgaac aggttgatac cattatggag 120aaaaacgtca
ccgtgaccca tgcgcaggac atcctggaaa aaacccataa tggcaaactg
180tgcgatctgg atggcgtcaa accgctgatc ctgaaagatt gcagcgtggc
gggttggctg 240ctgggcaacc cgatgtgcga tgaatttatc aatgttccgg
aatggagcta tattgtggaa 300aaagcgaatc cgaccaacga tctgtgttat
ccgggttcgt ttaacgatta cgaagaactg 360aaacacctgc tgagccgtat
taatcatttt gaaaaaatcc agattattcc gaaatcgagc 420tggtcggacc
acgaggcgag ctcgggcgtt tcctccgcct gcccgtatct gggtagcccg
480agcttttttc gtaatgtggt ctggctgatc aaaaaaaatt ccacgtaccc
gaccattaaa 540aaaagctata acaacaccaa ccaggaagat ctgctggtgc
tgtggggcat tcatcatccg 600aacaatgaag aagaacagac ccgcctgtac
cagaatccga ccacctatat tagcattggc 660accagcaccc tgaatcagcg
tctggttccg aaaattgcga cccgcagcaa agtgaacggc 720cagtccggtc
gtatggaatt tttttggacc attctgaaac cgaatgatgc catcaacttt
780gaatccaatg gcaattttat cgcgccggaa tacgcgtata aaatcgtgaa
aaaaggcgat 840agcgccatta tgaaaagcga actggaatac tccaactgca
atacgaaatg tcagacgccg 900atgggcgcga tcaacagctc gatgccgttt
cacaacatcc atccgctgac cattggcgag 960tgtccgaaat atgtcaaaag
cagccgcctg gtgctggcca ccggcctgcg caattcgccg 1020cagcgtgaaa
gccgtcgcaa aaaacgtggc ctgtttggcg cgattgcggg cttcattgaa
1080ggcggctggc agggtatggt cgacggctgg tacggttatc atcatagcaa
cgaacagggt 1140agcggctatg cggcggataa agaatccacc cagaaagcca
tcgatggtgt cacgaataaa 1200gtgaatagca ttattgacaa aatgaacacc
cagttcgagg cggtcggccg cgagtttaat 1260aatctggaac gccgcattga
aaatctgaat aaaaaaatgg aagatggctt tctggacgtt 1320tggacctata
acgcggaact gctggtcctg atggagaacg aacgcacgct ggactttcat
1380gattccaacg tgaaaaatct gtacgataaa gttcgtctgc agctgcgcga
caatgccaaa 1440gaactgggca acggctgttt cgagttttat cataaatgtg
ataacgaatg catggaatcc 1500attcgtaacg gtacctacaa ctatccgcag
tatagcgaag aagcgcgcct gaaacgtgaa 1560gagatttcgg gtgtgaaact
ggaatccatt ggcacctatc agattctgtc catttatagc 1620accgtcgcca
gctccctggc cctggccatt atgattgcgg gcctgagcct gtggatgtgc
1680tccaacggct ccctgcagtg tcgcatctgc atctgaaagc ttgatc
172651429DNAInfluenza A virus 5gatcccatgg ctaatccgaa ccagaaaatt
atcaccattg gctctatttg catggtggta 60gggatcattt ccctgatgtt acagatcggc
aacattatct cgatctgggt gtcccattct 120attcagaccg gcaaccagca
tcaggccgaa ccgtgcaatc aaagcattat cacctacgaa 180aataacacct
gggtaaatca gacctatgtt aatatttcaa acaccaactt cctgaccgaa
240aaagcggtgg caagtgtaac cctcgccggt aacagctcgc tgtgtcctat
ttctggctgg 300gcggtacaca gcaaagataa tggcattcgc atcggctcta
aaggcgacgt ttttgtgatc 360cgcgaaccct ttatttcgtg tagccatctg
gagtgccgta cctttttctt gacccagggg 420gcgctgctta acgataagca
ttcgaatggc acggttaaag atcgcagtcc gcaccgcacg 480ctgatgagct
gcccagtggg ggaggcccca tccccataca actcgcgctt cgaatccgtc
540gcttggagcg ccagcgcgtg ccacgatggt acgtcttggc tgacgatcgg
cattagcggt 600ccggacaacg gtgcggttgc tgtcctgaaa tataatggta
ttatcacgga caccattaaa 660tcgtggcgca acaatatctt acggacccag
gagtcagaat gcgcctgcgt gaatggctct 720tgctttacgg tcatgaccga
tggcccgagt aatggccaag cgtcctataa aatttttaaa 780atggaaaaag
ggaaagttgt gaagtcagtg gaacttaacg ccccgaacta tcactatgaa
840gagtgttcgt gttaccctga cgcaggcgaa atcacgtgtg tctgccgtga
taactggcat 900ggcagcaacc gcccgtgggt gtcctttaac cagaatttgg
aatatcagat cggctatatt 960tgttctgggg tcttcggcga taacccgcgt
cctaatgacg gcaccggcag ctgtggcccg 1020gtatccccca atggtgcgta
tggcgttaag ggtttcagtt tcaaatacgg taatggcgtg 1080tggattggtc
gcaccaaatc aaccaactcg cggtcgggtt ttgaaatgat ctgggatccg
1140aatggctgga ccggtaccga tagctcattc tccgtgaagc aagacatcgt
cgcaattacg 1200gattggtccg gctacagtgg cagctttgtg caacatccgg
agctgaccgg gctggattgc 1260attcgcccct gtttttgggt tgaactgatt
cgtgggcgtc cgaaggagtc aacgatctgg 1320acgagcggca gcagtattag
cttttgcggc gtcaacagcg acacggtcgg ctggagttgg 1380ccggatgacg
cggagctccc ttttaccatt gataaataga agcttgatc 142961912DNAInfluenza A
virus 6gatcccatgg ctgagaaaat tgtgctgctg ctgtccattg tgtcgctggt
caaaagcgat 60cagatctgca ttggctacca tgcgaacaat agcaccgaac aggttgatac
cattatggag 120aaaaacgtca ccgtgaccca tgcgcaggac atcctggaaa
aaacccataa tggcaaactg 180tgcgatctgg atggcgtcaa accgctgatc
ctgaaagatt gcagcgtggc gggttggctg 240ctgggcaacc cgatgtgcga
tgaatttatc aatgttccgg aatggagcta tattgtggaa 300aaagcgaatc
cgaccaacga tctgtgttat ccgggttcgt ttaacgatta cgaagaactg
360aaacacctgc tgagccgtat taatcatttt gaaaaaatcc agattattcc
gaaatcgagc 420tggtcggacc acgaggcgag ctcgggcgtt tcctccgcct
gcccgtatct gggtagcccg 480agcttttttc gtaatgtggt ctggctgatc
aaaaaaaatt ccacgtaccc gaccattaaa 540aaaagctata acaacaccaa
ccaggaagat ctgctggtgc tgtggggcat tcatcatccg 600aacaatgaag
aagaacagac ccgcctgtac cagaatccga ccacctatat tagcattggc
660accagcaccc tgaatcagcg tctggttccg aaaattgcga cccgcagcaa
agtgaacggc 720cagtccggtc gtatggaatt tttttggacc attctgaaac
cgaatgatgc catcaacttt 780gaatccaatg gcaattttat cgcgccggaa
tacgcgtata aaatcgtgaa aaaaggcgat 840agcgccatta tgaaaagcga
actggaatac tccaactgca atacgaaatg tcagacgccg 900atgggcgcga
tcaacagctc gatgccgttt cacaacatcc atccgctgac cattggcgag
960tgtccgaaat atgtcaaaag cagccgcctg gtgctggcca ccggcctgcg
caattcgccg 1020cagcgtgaaa gccgtcgcaa aaaacgtggc ctgtttggcg
cgattgcggg cttcattgaa 1080ggcggctggc agggtatggt cgacggctgg
tacggttatc atcatagcaa cgaacagggt 1140agcggctatg cggcggataa
agaatccacc cagaaagcca tcgatggtgt cacgaataaa 1200gtgaatagca
ttattgacaa aatgaacacc cagttcgagg cggtcggccg cgagtttaat
1260aatctggaac gccgcattga aaatctgaat aaaaaaatgg aagatggctt
tctggacgtt 1320tggacctata acgcggaact gctggtcctg atggagaacg
aacgcacgct ggactttcat 1380gattccaacg tgaaaaatct gtacgataaa
gttcgtctgc agctgcgcga caatgccaaa 1440gaactgggca acggctgttt
cgagttttat cataaatgtg ataacgaatg catggaatcc 1500attcgtaacg
gtacctacaa ctatccgcag tatagcgaag aagcgcgcct gaaacgtgaa
1560gagatttcgg gtgtgaaact ggaatccatt ggcacctatc agattctgtc
catttatagc 1620accgtcgcca gctccctggc cctggccatt atgattgcgg
gcctgagcct gtggatgtgc 1680tccaacggct ccctgcagtg tcgcatctgc
atccccgggt caacttatgg gagccaggac 1740tatcttaatc cattgattaa
tgaaatcagc aaaatcattt cagctgcagg taatttggat 1800gttaaggagg
aaagatctgc cgcttcttta ttgcagttgt ccggtaatgc cagtgatttt
1860tcatatggac ggaactcaat aactttgaca gcatcagcat aaaagcttga tc
1912738DNAUnknownPCR Primer 7gatcgagctc ggcttaatta ttgcccagct
tgcgctgg 38884DNAUnknownPCR Primer 8ccccgcatgc ggggctcgag
ggggccatat aggccgggga tttaaatggg gcggccgcaa 60aaaaaatcct ggcgcagggc
cagg 84979DNAUnknownPCR Primer 9ccccgcatgc ggggagatct ggggttaatt
aaggggtcta gagggggcgg ccgcaggact 60atatttaggg cgaaacagc
791036DNAUnknownPCR Primer 10gatcgtcgac gactaaacat gattccaaca
atcacg 36
* * * * *