WO2001034190A2 - Live bacterial vaccines against escherichia coli o157:h7 - Google Patents
Live bacterial vaccines against escherichia coli o157:h7 Download PDFInfo
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- WO2001034190A2 WO2001034190A2 PCT/CA2000/001321 CA0001321W WO0134190A2 WO 2001034190 A2 WO2001034190 A2 WO 2001034190A2 CA 0001321 W CA0001321 W CA 0001321W WO 0134190 A2 WO0134190 A2 WO 0134190A2
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- A61K39/00—Medicinal preparations containing antigens or antibodies
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- A—HUMAN NECESSITIES
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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- A61K2039/522—Bacterial cells; Fungal cells; Protozoal cells avirulent or attenuated
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- A—HUMAN NECESSITIES
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- A61K39/00—Medicinal preparations containing antigens or antibodies
- A61K2039/51—Medicinal preparations containing antigens or antibodies comprising whole cells, viruses or DNA/RNA
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Definitions
- the invention relates to live bacterial vaccines against pathogenic strains of enteric bacteria, in particular to novel Salmonella- and C/Yrobac-er-based live vaccines against Escherichia coli strain 0157:H7, for preventing, reducing or eliminating the colonization of the gastrointestinal tract of cattle by E. coli 0157:H7.
- Escherichia coli strain 0157:H7 is an enteric bacterial pathogen that can cause severe local and systemic disease in susceptible humans, especially young children and the elderly (reviewed in: Su et al, Ann. Intern. Med., 123: 698 - 714 (1995)). Unusually for an enteric pathogen, the organism can cause severe infection even when ingested in very small numbers (Neill, M.A., Curr. Opin. Infect. Dis., 7: 295 - 303 (1994)).
- Cattle are considered to be a major reservoir for this organism, which appears to be widely disseminated amongst North American cattle herds. Cattle can harbour E. coli 0157:H7 in their intestinal tracts asymptomatically, and they can shed it in their feces for prolonged periods (Hancock et al., in: Escherichia coli 0157:H7 and other shiga toxin-producing E. coli, pp. 85 - 91 , Kaper, J.B. and O'Brien, A.D. (editors), American Society for Microbiology, Washington D.C. (1998)). Fecal contamination of meat during slaughter, and the use of contaminated feces as fertilizer are two ways by which this organism can enter the human food supply.
- Contamination of the potable water supply by contaminated farm yard run-off is another major way by which this pathogen disseminates from cattle to humans.
- E. coli 0157:H7 attaches to the intestinal mucosa wherein it triggers an inflammatory response that can develop into a severe, sometimes fatal hemorrhagic colitis (Su et al, supra).
- this pathogen elaborates toxins, including shiga-like toxins and endotoxin (Wadolkowski et al, Infect. Immun., 58: 3959 - 3965 (1990); Fujii et al, Infect. Immun., 62: 3447 - 3453 (1994); Karpman et al, J. Infect. Dis., 175: 611 - 620 (1997)), which can disseminate from the gut to cause systemic pathology including hemolytic uremic syndrome (HUS) which may progress to kidney failure and death.
- HUS hemolytic uremic syndrome
- E. coli 0157:H7 O-antigen is considered a good vaccination target because it is abundantly expressed and exposed at the bacterial surface.
- others Konadu et al, supra (1994); Konadu et al, supra (1998) have demonstrated that antibodies directed against this antigen can kill E. coli 0157:H7 in vitro in a complement- dependent manner.
- antibodies directed against lipopolysaccharides of other enteric bacterial pathogens afford protection against the respective organisms in vivo (Michetti et al, Infect.
- the 0157 antigen was chemically identified as a polysaccharide composed of repeating tetrasaccharide units (Perry et al, Biochem. Cell Biol., 64: 21 - 28 (1985) having the structure:
- Salmonellae are well suited for this purpose because being enteric pathogens themselves they naturally elicit a robust mucosal immunity.
- the present invention provides a novel Salmonella-based live vaccine against Escherichia coli strain 0157:H7, for preventing, reducing or eliminating the colonization of the gastrointestinal tract of vertebrates, in particular cattle, by the pathogen.
- the present invention provides a live vaccine for the immunization of a vertebrate against a first Gram-negative enteric bacteria, said vaccine comprising a live non-pathogenic second Gram-negative enteric bacteria naturally expressing an antigen of the first gram-negative enteric bacteria or a structural mimic thereof.
- the present invention provides a method for inducing in a vertebrate an immune response to a first Gram-negative enteric bacteria, said method comprising administering to said vertebrate an effective amount of a live, non-pathogenic second Gram-negative bacteria naturally expressing an antigen of the first Gram-negative enteric bacteria or a structural mimic thereof.
- the present invention provides a method for preventing or treating carriage of a first Gram-negative enteric bacteria by a vertebrate, said method comprising administering to said vertebrate an effective amount of a live, non-pathogenic second Gram-negative enteric bacteria naturally expressing an antigen of the first Gram-negative enteric bacteria or a structural mimic thereof.
- the first Gram-negative enteric bacteria is a strain of Escherichia coli, in particular the strain E. coli 0157:H7
- the second Gram-negative enteric bacteria is a bacterial strain of the genus Salmonella or Citrobacter, in particular a wild strain of Salmonella landau, Citrobacter sedlakii or Citrobacter freundii naturally expressing the 0157:H7 antigen or a structural mimic thereof as part of its lipopolysaccharide.
- the vaccine and the methods of the present invention are particularly useful in maintaining cattle herds free of E. coli 0157:H7 and in reducing carriage and fecal shedding of E. coli 0157:H7 prior to slaughter, thus potentially reducing the clinical incidence of E. coli 0157:H7 infections in humans.
- Figure 1 is a graph showing fecal shedding period of S. landau by mice. Mice were gavaged with 2.84 x 10 10 CFU (group A), 2.84 x 10 9 CFU (group B), 2.84 x 10 8 CFU (group C), or 2.84 x 10 7 CFU (group D) of S. landau, and their feces were monitored for the presence of the organism.
- Figure 2 is a graph showing levels of 0157-antigen-specific antibodies in serum and feces of mice following primary exposure to S. landau.
- Sera and feces were collected from a group of unexposed control mice (group E) and from the mice shown in Fig. 1 (groups A - D) on day 15 post gavage with S. landau, and serum IgG (O), serum IgA ( ⁇ ), and fecal IgA ( ⁇ ) antibody titres against 0157 antigen were determined by ELISA. Data points below the horizontal broken line depict negative samples (serum titre ⁇ 25; fecal titre ⁇ 4).
- Figure 3 is a graph showing fecal shedding of S. landau by mice following secondary challenge. Mice shown in Fig. 1 were all regavaged with 8 x 10 9 CFU of S. landau, and their feces were monitored for the presence of the organism.
- Figure 4 is a graph showing levels of 0157-antigen-specific antibodies in the sera and feces of mice following secondary exposure to S. landau.
- Sera and feces were collected from mice shown in Fig. 3 on day 11 of secondary exposure to S. landau, and serum IgG (O), serum IgA ( ⁇ ), and fecal IgA ( ⁇ ) antibody titres against 0157 antigen were determined by ELISA.
- Data points below the horizontal broken line depict negative samples (serum titre ⁇ 25; fecal titre ⁇ 4).
- Figure 6 is a graph showing fecal shedding of E. coli 0157:H7 by mice previously exposed to S. landau, and by unexposed control mice. Mice exposed twice by gavage to S. landau (groups A - C), and control mice (Group E) never exposed to this organism were all gavaged with 2.9 x 10 10 CFU of a test isolate of E. coli 0157:H7, and the presence of the latter organism in the feces was monitored. The fecal shedding period was calculated as the last day on which E. coli 0157:H7 was recovered by culture from the feces. Fecal shedding periods were analysed statistically by log- rank test of survival curves.
- Figure 7 is a graph showing levels of 0157-antigen-specific serum and fecal antibodies in control and vaccinated mice following challenge with E. coli 0157:H7.
- Sera and feces were collected from mice shown in Fig. 5 on day 8 post-exposure to a challenge gavage of 2.9 x 10 10 CFU of an isolate of E. coli 0157:H7, and serum IgG (O), serum IgA ( ⁇ ), and fecal IgA ( ⁇ ) antibody titres against 0157 antigen were determined by ELISA.
- Data points below the horizontal broken line depict negative samples (serum titre ⁇ 25; fecal titre ⁇ 4).
- Figure 8 is a graph showing fecal loads of E.
- mice depicted in Table 1 ( ⁇ ), and a group of control mice (O) were challenged by gavage with 3.94 x 10 10 CFU of a test isolate of E. coli 0157:H7. Feces were collected from both groups on days 3, 7, 9, 14, 18 post challenge with E. coli 0157:H7, and were examined for the presence of this organism by bacteriological culture.
- Figure 9 is a graph showing levels of anti-0157-antigen serum and coproantibodies in mice exposed to multiple inocula of S. landau.
- Sera and feces were collected from both the mice vaccinated with S. landau (group A), and the control mice (group B) depicted in Fig. 8, on day 8 and 18 post challenge with E. coli 0157:H7, and serum IgG (O), serum IgA ( ⁇ ), and fecal IgA ( ⁇ ) antibody titres against 0157 antigen were determined by ELISA.
- Data points below the horizontal broken line depict negative samples (serum titre ⁇ 25; fecal titre ⁇ 4).
- Figure 10 is a graph showing the 1 H - 13 C-NMR correlation spectrum and 1 D 1 H-NMR spectrum of the LPS O-polysaccharide of Citrobacter sedlakii (NRCC 6070).
- Figure 1 1 is a graph showing the 1 H - 13 C-NMR correlation spectrum and 1 D 1 H-NMR spectrum of the LPS O-polysaccharide of Citrobacter freundii (NRCC 6052).
- Figure 12 is a graph showing the serological response of cattle to S. landau immunization.
- Groups of eight calves were vaccinated per os with either placebo or 10 6 cfu (low), 10 8 cfu (medium), and 10 10 cfu (high) doses of S. landau on days 0 (Sep 01 ), 21 (Sep 22), and 42 (Oct 06), then challenged 14 days later (Oct 20) with 10 8 cfu of a test isolate of E. coli 0157:H7. Animals were bled on each of these days to generate sera in which levels of antibody specific to S. landau LPS were determined by ELISA or titration.
- Figure 13 is a graph showing the total number of days in which animals of each group of Fig. 12 shed detectable levels of E. coli 0157:H7, after being challenged with a 10 8 cfu dose of E. coli 0157:H7. Shedding was monitored on a daily basis, between days 4 and 14 post challenge, using enrichment culture and direct planting of fecal samples on Rainbow Agar. The total number of eligible days was 88 per group.
- Figure 14 is a graph showing the number of animals of each group of Fig. 12 shedding greater than 100,000 cfu of E. coli 0157:H7 per gram of feces between days 4 and 14 post challenge.
- non-pathogenic enteric bacteria refers to bacteria which do not cause pathological conditions in an animal when administered to the animal in the amount necessary to elicit the desired immunological reaction.
- structural mimic of an antigen refers to an antigen which is not chemically identical with the antigen it mimics but which shows cross- reaction with a monoclonal antibody specific to the mimicked antigen.
- Konadu et al, supra (1994) have developed a conjugate vaccine consisting of the O- specific carbohydrate moiety of E. coli 0157 lipopolysaccharide (LPS) coupled to a protein from Pseudomonas aeruginosa.
- LPS lipopolysaccharide
- This vaccine elicits systemic IgG and IgA antibodies to the 0157 antigen when administered parenterally to mice and humans (Konadu et al, supra (1994); Konadu et al, supra (1998)).
- these antibodies proved to be bactericidal for E. coli 0157:H7 in vitro.
- these antibodies must be available at foci of E.
- the immunogenicity of many orally fed antigens can be improved by various measures including admixing with cholera toxin which acts as a potent mucosal adjuvant (Jackson et al, Infect. Immun., 62: 3594 - 3597 (1993)).
- oral vaccination of mice with 0157:H7-antigen glycoconjugate admixed with cholera toxin failed to elicit a local immune response to 0157 antigen, despite eliciting a robust systemic and local immune response to the toxin adjuvant (Conlan et al, Can. J. Microbiol, 46: 283-290.).
- Live Salmonella-based vaccines have proven to be highly suitable for eliciting mucosal immune responses in the gut (Curtiss, supra (1990); hackett, supra (1990)). Live Salmonella-based vaccines are now being used in the poultry industry, and it is likely that they will ultimately gain acceptance elsewhere in the veterinary and medical arena. Usually the Salmonella strains employed for this purpose are deliberately attenuated by selective mutagenesis of bacterial genes crucial for the expression of virulence. According to the present invention, inventors used a wild type Salmonella landau strain that naturally expresses the 0157 antigen as part of its lipopolysaccharide, because its rarity as a clinical entity suggests that innately it might not be particularly virulent.
- mice gavaged with S. landau developed high titres of systemic and local antibodies to the 0157 antigen. These antibodies persisted for several months post-vaccination. Moreover, mice exposed to S. landau displayed some evidence of protection from colonization, measured as decreased fecal shedding, against a subsequent challenge with an isolate of E. coli 0157:H7. This protection could be due to immunity elicited against shared antigens other than the 0157 antigen. However, this seems unlikely given that the normal flora of mice includes benign strains of E. coli (Miller et al, J. Infect. Dis., 113: 59 - 60 (1963)) which might be expected to share greater non-O- antigen-based antigenicity with E.
- the protection results of this study might be a reflection of the inadequacies of the mouse model rather than of the vaccine used.
- the E. coli 0157:H7 isolate used only colonizes the intestinal tracts of nonimmune mice for up to two weeks, making it difficult to assess the meaningfulness of any vaccine induced immunity that might reduce this period by only a day or so.
- cattle can harbour and excrete the pathogen for several months (Hancock et al., supra). If vaccination could reduce this colonization period to only a week or so it would be considered a significant achievement.
- An additional caveat of the mouse model is that the inoculum size needed to ensure that mice become colonized is of the order of 10 8 fold higher than that required to initiate severe infection in susceptible humans.
- the LPS O-PS of C. freundii strain which showed strong cross-reactivity with E. coli 0157 O-antigen had its own unique structure differing from that of the E. coli 0157 antigen and surprisingly, unlike other investigated crossreacting LPS O-PS antigens, did not contain a 2-substituted 4-amino-4,6-dideoxy-D- mannopyranosyl residue which has been implicated as the epitope involved in previously examined Gram-negative bacteria. It is possible that the 2- substituted K-D-Rhap residue in the C.
- freundii O-PS structurally mimics the 2-substituted 4-acetamido-4,6-dideoxy-K-D-mannopyranosyl residue (K-D- Rhap4Nac residue) in the E. coli 0157 O-PS; however, modeling and oligosaccharide inhibition experiments will be required to establish this point.
- mice were inoculated with 2.8 x 10 10 CFU of S. landau (group A) or serial ten-fold dilutions thereof (groups B - D). Monitoring showed that mice rapidly ceased shedding this organism in their feces at all test doses (Fig. 1 ). Serological testing of mice 11 days following initial gavage with S. landau showed that the majority of mice receiving the highest doses of the organism had developed detectable levels of 0157 antigen-specific copro-antibodies, but not circulating antibodies by this time (Fig. 2). By contrast, the group of mice (group D) that received the smallest inoculum of S. landau and a group of control mice (group E) that were not exposed to S. landau were uniformly negative for 0157 antigen-specific fecal and circulating antibodies at this time. None of the mice became ill following primary exposure to S. landau at any dose tested.
- mice were rechallenged with 0.8 x 10 10 CFU of S. landau. All mice had stopped shedding S. landau by 11 days of rechallenge (Fig. 3). Moreover, all but one of the mice that had been exposed to high inocula of S. landau initially (Group A and B in Fig. 1 ) had already stopped shedding the secondary inoculum of the organism by day 4 of rechallenge. This was a shorter fecal shedding period than observed for mice initially gavaged with a comparable inoculum (groups A and B in Fig. 1 ), suggesting that these mice acquired immunity against recolonization by S. landau as a result of initial exposure to a large bolus of the organism.
- mice One group of mice (group D) was killed on day 11 following secondary challenge with S. landau and their Peyer's patches, livers, and spleens were removed, homogenized, and plated on SBHI agar to check for evidence of enteroinvasion (Carter et al, J. Exp. /Wed., 139: 1189 - 1203 (1974)). Trace quantities of S. landau were found in the Peyer's patches (150 CFU/tissue) of one mouse and in the spleen of another (200 CFU/tissue). All other tissues examined were sterile. Again, no mice died as a result of re-exposure to S. landau.
- mice On day 15 post re-exposure to S. landau, the aforementioned mice (groups A - C) and a group of control mice (group E) that had never been exposed to this organism were all challenged by gavage with an inoculum (2.9x10 10 CFU/mouse) of a test isolate of E. coli 0157:H7. Subsequently, the feces of all mice were monitored for the presence of E. coli 0157:H7 by bacteriology coupled with confirmatory slide agglutination test of random colonies. The results of this examination are shown by Fig 5. Compared to control mice (group E), all groups (group A - C) of mice previously exposed to S. landau exhibited lower mean fecal loads of E.
- mice compared to control (group E) mice, the mean period over which E. coli 0157:H7 was detectable in the feces was reduced in all groups (groups A - C) of mice previously exposed to S. landau (Fig. 6). However, this decrease was only statistically significant in the case of group C versus group E, implying that none of the observed reductions in fecal shedding period among the test groups were biologically meaningful.
- mice Eight days after gavage with E. coli 0157:H7, serum and copro-antibody levels against 0157 antigen were determined, and the results are shown in Fig. 7. All mice previously exposed to S. landau (groups A - C) had circulating anti-0157 antigen IgA and IgG antibodies, whereas the control group (group E) had no detectable systemic antibodies to this antigen. In contrast, most group E mice had detectable levels of fecal IgA against the 0157 antigen, however the mean level of these was significantly lower (P ⁇ 0.05) than those found in the feces of mice in groups A - C. No 0157-antigen specific IgG was detected in the feces of any mouse (data not shown). Immune status of mice following multiple exposures to S. landau.
- mice In a complementary experiment, a group of mice was gavaged a total of four times with approximately 2.5 x 10 10 CFU of S. landau at weekly intervals. The fecal burdens of S. landau were assessed three days following each gavage and the results are shown in Table 1.
- mice showed that the bacterial burden as measured by the proportion of mice shedding the organism in feces, fell following each exposure implying that the initial exposures to S. landau generated protective immunity against colonization by subsequent inocula of the organism.
- Mice developed 0157- specific IgA copro-antibodies following primary exposure to S. landau, and this titre rose significantly (p ⁇ 0.05) following secondary exposure, but not in response to subsequent exposures (Table 2).
- mice Two weeks following the final exposure to S. landau the aforementioned mice, and a group of five control mice that had never been exposed to this organism, were challenged by gavage with an inoculum of 3.94 x 10 10 CFU/mouse of E. coli 0157:H7. Subsequently, the fecal burden of E. coli 0157:H7 in both groups of mice was monitored (Fig. 8). At each period examined the mean fecal burden was slightly lower in group A versus group B mice, however all these differences were statistically insignificant. There was no significant difference either in the mean fecal shedding period between the two groups.
- Control mice had not developed a detectable humoral immune response to 0157 antigen by day 8 post gavage with E. coli 0157:H7. The latter mice had developed a weak fecal IgA anti-0157 antigen titre by day 18 post gavage. However, these control mice essentially failed to mount a systemic antibody response to this antigen.
- mice exposed four times to S. landau were left unchallenged with E. coli 0157:H7.
- sera and feces from these mice, and a group of five control mice were examined for the presence of 0157-antigen specific antibodies. Additional feces collected at these times were cultured for the presence of S. landau.
- Table 3 show that 0157 antigen specific antibodies persisted for at least 15 weeks following the final exposure to S. landau. No 0157-specific antibodies were detected in the feces or sera of control mice. No S. landau -like colonies were recovered from the feces of any mice at any of these extended time points.
- mice received 4 inocula of S. landau as detailed in Table 1.
- the O-PS from the LPS of the C. sedlakii strain had [ ⁇ ] D +35.2° (c 1.3, water), gave chemical analysis composition and structural data identical with the data from E. coli 0157 O-PS. Furthermore, 1 H- and 13 C-NMR analysis of the O-PS gave spectra (Fig. 10) consistent with published data and indistinguishable from those given by the E. coli 0157 O-PS.
- the C. freundii O-PS had [ ⁇ ] D +15.5° (c 1.6, water) and preparative paper chromatographic separation of the O-PS hydrolysate (4 M TFA, 105°C, 4 h) gave only two glycoses which were identified as D-glucose and D-rhamnose (1 :2).
- Methylation analysis by GLC-MS showed the hydrolysis products of the methylated O-PS to be 3,4-di-O-methyl-D-rhamnose, 2,4-di-O-methyl-D- rhamnose and 2,3,6-tri-O-methyl-D-glucose (1 :1 :1 ) thus identifying the structural units -2)-D-Rhap-(1-, -3)-D-Rhap-(1-, and -4)-D-Glcp-(1- in the O- PS.
- the linkage sequence and anomeric configurations of the glycose units present in the C. freundii O-PS trisaccharide repeating unit were determined by NMR spectroscopy.
- the 1 D 1 H- and 13 C-NMR spectra of the O-PS were consistent with a trisaccharide repeating unit.
- Two-dimensional NMR spectra 2D correlation spectroscopy (DQF COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), and H-detected heteronuclear H, 13 C single-quantum coherence (HSQC) (Fig. 11 ) were used for the assignment of proton and carbon signals as recorded in Table 4.
- the three O-PS component glycose units were given the designations A, B, and C in order of decreasing anomeric proton chemical shifts (Fig. 10).
- the two component D-Rhap residues (A and B) were identified on the basis of vicinal proton coupling constants and the D-Glcp residue (C) anomeric configuration was determined as ⁇ - from its J 1>2 coupling constant (8 Hz).
- residue B The ⁇ -D-configu ration of residue B was confirmed from the observation of intraresidue NOEs between H-1 B and H-3B and H-5B.
- sequence of the residues was determined from NOE data: correlations were observed between proton H-1 A and H-3B, H-1 B and H-4C, and H-1 C and H-1 A and H-2A, thus indicating a residue linkage order ⁇ A ⁇ B ⁇ C -» and the structure of the O-PS to be an unbranched linear polymer of the repeating unit:
- Fig. 12 shows the serological response of animals to immunization, as a function of time and the vaccine dose.
- the levels of antibodies developed as a result of immunization were measured by titration and are shown as a mean optical density of a 100-fold serum dilution.
- the serological response is clearly stronger in animals of the medium and high dose vaccine groups.
- these results indicate that cattle can tolerate even multiple high doses of S. landau applied for immunization purposes.
- the observed seroconversion was used only as a convenient marker for immunogenecity, as there is no known correlation between the level of the circulating antibody and the protective immunity against E. coli 0157:H7.
- This data shows a trend towards a decreased shedding with increasing S. landau vaccine dose, as reflected by a lower number of total days shedding.
- Salmonella landau (LCDC Strain # S-1358) originated as a clinical isolate. It was obtained in a frozen state from a culture collection maintained at the
- a streptomycin-resistant variant was obtained by natural selection by re-plating heavy inocula of the revived organism onto BHl agar containing 50 g/ml streptomycin sulphate (Sigma
- a single streptomycin-resistant colony identified as S. landau as above, was used to seed a flask of BHl broth containing 50 g/ml streptomycin sulphate (SBHI broth). This culture was incubated at 37°C with shaking for 5 h, then sterile glycerol was added to a final concentration of 20% (v/v) and dispersed by shaking. This stock culture was then dispensed in 1.5 ml aliquots and frozen at -80°C until required.
- a stock of a streptomycin-resistant isolate of Escherichia coli 0157:H7 was similarly prepared, as described previously (Conlan et al, Can. J.
- E. coli 0157:H7 (NRCC 4125) was obtained from the NRC culture collection, C. freundii (CDC 3488-90, NRCC 6052) kindly supplied by Dr. N.A. Strockbine and C. sedlakii (NRCC 6070) was kindly supplied by Dr. CH. Park.
- the bacteria were cultivated in 3.7% brain-heart infusion broth (Difco) for 18 h at 37°C in a 75-I fermenter with stirring and air aeration and killed cells (2% phenol) were harvested (yield ca. 450 g wet weight each).
- mice Female Balb/c mice were obtained from Charles Rivers Laboratories (St.- Constant, Quebec) when they were 7 to 9 weeks old. Groups of 5 mice, including appropriate control groups were used throughout. Mice were maintained and used in accordance with the recommendations of the current edition of the Canadian Council on Animal Care Guide to the Care and Use of Experimental Animals (1993). Mice entered experiments within two weeks of receipt. Mice were inoculated by gavage with freshly grown cultures of S. landau or E. coli 0157:H7. Briefly, for each experiment, vials of frozen bacteria were thawed and the entire contents of each vial used to inoculate a flask containing 200 ml fresh SBHI broth.
- Flasks were incubated as above to an absorbance at 600 nm of approximately 1.1. Next, the cultures were harvested by centrifugation at 7200 g at ambient temperature and resuspended in phosphate buffered saline (PBS) to a concentration of approximately 10" CFU/ml for inoculation into mice. In each case, the viability of the inoculum was determined by plating serial dilutions of it on SBHI agar. Mice received approximately 2 x 10 10 CFU of either organism in a volume of 0.2 ml delivered using a 1 ml tuberculin syringe fitted with a 20 g gavage needle. Mice were observed to ensure that they did not regurgitate or aspirate the inoculum.
- PBS phosphate buffered saline
- Bacterial burdens per unit weight of feces were compared among various groups of mice using the Mann Whitney Rank Sum Test to assess statistically significant (P ⁇ 0.05) differences. Fecal shedding periods between groups were also compared for statistically significant differences. For individual mice, the fecal shedding period was calculated as the last day of examination on which the pathogen was cultured from the feces. For each group, fecal shedding periods were plotted as survival curves which were then compared for statistical differences by log-rank test.
- mice were inoculated with two doses of S. landau administered 14 days apart, or four doses administered 7 days apart. Two weeks after the final exposure to S. landau, mice were challenged with the test isolate of E. coli 0157:H7. Feces were monitored for the presence of either pathogen as detailed above. Additionally, sera and feces were collected at intervals for antibody determinations. Sera were prepared from venous blood obtained from a lateral tail vein. For copro-antibody determinations, freshly expressed fecal pellets were homogenized in PBS containing 0.05 % w/v sodium azide and 10 % v/v fetal calf serum as exogenous protein to quench proteolytic degradation of specific antibody (Elson et al, J.
- Sera and feces were screened for the presence of specific IgA and IgG isotype antibodies by ELISA using purified E. coli 0157 LPS, or delipidified 0157 LPS, or E. coli O70 LPS as antigen. Briefly, microtitre plates (Dynatech Immunlon II) were coated with antigen (100 ⁇ /well), diluted to 10 ⁇ g/ml in carbonate buffer by incubating them overnight at 4°C Excess antigen was removed by washing the wells three times with PBS containing 0.05 % v/v Tween 20 using an automated plate washer.
- Bacterial cells ( V400 g wet weight) were extracted with 50% aqueous phenol as described by Johnson and Perry (Can. J. Microbiol, 22: 29 - 34 (1976)) and the water diluted (2 vols). Dialyzed solutions were subjected to ultracentrifugation (105 000 x g, 10 h, at 4°C) to yield precipitated LPS gels which were lyophilised from water solutions (yields 4.7 - 5.2 g). LPSs (1 g) dissolved in 2% (v/v) acetic acid (150 ml) were heated in a boiling water bath (2 h), precipitated lipid A (ca.
- ELISAs were performed as described previously (Perry et al, supra) using E. coli 0157:H7 LPS or O-PS, C. freundii LPS or O-PS, C. sedlakii LPS or O-PS, or E. coli O70 LPS as coating antigens at a concentration of 5 g ml "1 .C. freundii- specific polyclonal antiserum was prepared by vaccinating 10-week-old female CD1 mice subcutaneously with purified C. freundii LPS admixed with incomplete Freund's adjuvant. Mice were inoculated subcutaneously with 12.5 g of LPS in a volume of 0.1 ml three times at 14-day intervals.
- Antisera were prepared from blood collected 1 week following the final immunization.
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP00975694A EP1227839A2 (en) | 1999-11-10 | 2000-11-10 | Live bacterial vaccines against escherichia coli o157:h7 |
CA002390304A CA2390304A1 (en) | 1999-11-10 | 2000-11-10 | Live bacterial vaccines against escherichia coli o157:h7 |
AU13739/01A AU1373901A (en) | 1999-11-10 | 2000-11-10 | Live bacterial vaccines against escherichia coli O157:H7 |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US16456499P | 1999-11-10 | 1999-11-10 | |
US60/164,564 | 1999-11-10 | ||
US19093400P | 2000-03-21 | 2000-03-21 | |
US60/190,934 | 2000-03-21 |
Publications (2)
Publication Number | Publication Date |
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WO2001034190A2 true WO2001034190A2 (en) | 2001-05-17 |
WO2001034190A3 WO2001034190A3 (en) | 2001-11-08 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CA2000/001321 WO2001034190A2 (en) | 1999-11-10 | 2000-11-10 | Live bacterial vaccines against escherichia coli o157:h7 |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1227839A2 (en) |
AU (1) | AU1373901A (en) |
CA (1) | CA2390304A1 (en) |
WO (1) | WO2001034190A2 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0564689A1 (en) * | 1992-04-10 | 1993-10-13 | SCHWEIZERISCHES SERUM- & IMPFINSTITUT BERN | Recombinant live vaccines against Gram-negative enteric pathogens |
-
2000
- 2000-11-10 CA CA002390304A patent/CA2390304A1/en not_active Abandoned
- 2000-11-10 EP EP00975694A patent/EP1227839A2/en not_active Withdrawn
- 2000-11-10 WO PCT/CA2000/001321 patent/WO2001034190A2/en not_active Application Discontinuation
- 2000-11-10 AU AU13739/01A patent/AU1373901A/en not_active Abandoned
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0564689A1 (en) * | 1992-04-10 | 1993-10-13 | SCHWEIZERISCHES SERUM- & IMPFINSTITUT BERN | Recombinant live vaccines against Gram-negative enteric pathogens |
Non-Patent Citations (5)
Title |
---|
BETTELHEIM K A ET AL: "Isolation of a Citrobacter freundii strain which carries the Escherichia coli O157 antigen." JOURNAL OF CLINICAL MICROBIOLOGY, vol. 31, no. 3, 1993, pages 760-761, XP001002899 ISSN: 0095-1137 cited in the application * |
CONLAN J WAYNE ET AL: "Salmonella landau as a live vaccine against Escherichia coli O157:H7 investigated in a mouse model of intestinal colonization." CANADIAN JOURNAL OF MICROBIOLOGY, vol. 45, no. 9, September 1999 (1999-09), pages 723-731, XP001002870 ISSN: 0008-4166 * |
PARK C H ET AL: "Isolation of a nonpathogenic strain of Citrobacter sedlakii which expresses Escherichia coli 0157 antigen." JOURNAL OF CLINICAL MICROBIOLOGY, vol. 36, no. 5, May 1998 (1998-05), pages 1408-1409, XP002169822 ISSN: 0095-1137 * |
ROLAND K ET AL: "CONSTRUCTION AND EVALUATION OF A DELTACYA DELTACRP SALMONELLA TYPHIMURIUM STRAIN EXPRESSING AVIAN PATHOGENIC ESCHERICHIA COLI O78 LPS AS A VACCINE TO PREVENT AIRSACCULITIS IN CHICKENS" AVIAN DISEASES,US,AMERICAN ASSOCIATION OF AVIAN PATHOLOGISTS, KENNET SQ., PA, vol. 43, no. 3, 1999, pages 429-441, XP000874569 ISSN: 0005-2086 * |
WANG L ET AL: "IMMUNIZATION OF MICE WITH LIVE ORAL VACCINE BASED ON A SALMONELLA ENTERICA (SV TYPHIMURIUM) AROA STRAIN EXPRESSING THE ESCHERICHIA COLI 0111 0 ANTIGEN" MICROBIAL PATHOGENESIS,US,ACADEMIC PRESS LIMITED, NEW YORK, NY, vol. 27, no. 1, July 1999 (1999-07), pages 55-59, XP000867891 ISSN: 0882-4010 * |
Also Published As
Publication number | Publication date |
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CA2390304A1 (en) | 2001-05-17 |
AU1373901A (en) | 2001-06-06 |
WO2001034190A3 (en) | 2001-11-08 |
EP1227839A2 (en) | 2002-08-07 |
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