• Vaccine Name: Avirulent Salmonella vaccine strain carrying C. jejuni cjaA gene
• Target Pathogen: Campylobacter jejuni
• Target Disease: Campylobacterosis
• Vaccine Ontology ID: VO_0004121
• Type: Recombinant vector vaccine
• Antigen: Three C jejuni genes [cjaA ( cj0982c ) , cjaC ( cj0734c ) and cjaD ( cj0113 )] encoding highly immunogenic proteins which are conserved among different Campylobacter serotypes have been introduced into avirulent Salmonella enterica sv. Typhimurium (chi 4550 and chi 3987) strains of two different serotypes (UK-1 and SR) (Wyszynska et al., 2004). C. jejuni 72Dz/92 cjaA gene encodes a highly immunogenic protein which is conserved among different Campylobacter serotypes (Wyszynska et al., 2004). The surface antigen CjaA of Campylobacter jejuni is supported by the presence of an upstream gene with significant homology to ATP binding proteins (Martin et al., 1999).
• cjaA gene engineering:
  • Type: Recombinant vector construction
  • Description: pUWA10A plasmid carrying CjaA was ligated into the pYA3341 plasmid and then transformed into E. coli χ6097 competent cells. It was later introduced by electroporation into two S. enterica sv. Typhimurium (χ3987 and χ4550) strains (Wyszynska et al., 2004).
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0001322
  • Description: The heat-labile enterotoxin of Escherichia coli as an oral adjuvant ( OA ) has been used (Baqar et al., 1995a)
• Preparation: Three gene libraries of Campylobacter jejuni 72Dz/92 DNA were prepared using lambda gt11, pSupercos and pWSK129 cloning vectors. Screening of the libraries revealed several immunoreactive clones (Pawelec et al., 1997).
• Virulence: The vaccine vector is avirulent Salmonella enterica sv. Typhimurium (chi 4550 and chi 3987) strains of two different serotypes (UK-1 and SR) (Wyszynska et al., 2004).
• Description: The constitutive expression of all analysed genes as measured by Western immunoblot technique was independent of the particular host strain. Specific rabbit anti-rCjaA antibody reacted not only with CjaA but also with other solute-binding proteins, components of the ABC transport system (CjaC protein), chosen as the protective antigen for animal experiments. Chickens orally immunized with Salmonella expressing Campylobacter cjaA gene developed serum IgG and mucosal IgA antibody responses against Campylobacter membrane proteins and Salmonella OMPs. Protection experiments show that chicken immunization with avirulent Salmonella carrying Campylobacter cjaA gene greatly reduces ability of heterologous wild type C. jejuni strain to colonize the bird cecum (Wyszynska et al., 2004).

Chicken Response

• Host Strain: Commercial broiler chickens (Gallus gallus)
• Vaccination Protocol: Commercial broiler chickens were obtained from the local hatchery on the day of hatch. Briefly, chickens deprived of food and water for 4 h were immunized orally with 100 μl of 109 CFU/ml of Salmonella χ3987 carrying pUWM251 (cjaA). Booster doses were administrated 2 weeks after primary immunization. Following vaccination, chickens were observed for the development of diarrhoea and other potential adverse side effects (Wyszynska et al., 2004).
• Persistence: There was high anti-Campylobacter IgG titer present at the first time point (week 0), dropping at weeks 2 and 4. A moderate increase of Campylobacter specific IgG level was observed at week 6 followed by significant increase of anti-Campylobacter IgG level at week 8. Serum IgG titers to Campylobacter whole cell lysates followed a similar pattern, as those measured with membrane antigens, with respect to time, although the increase of anti-Campylobacter IgG titer at week 8 was not so significant. The results suggest that high IgG titer observed at the 0 week reflects maternally derived immunity while increasing serum IgG titers at 6 and 8 weeks is a consequence of vaccination (Wyszynska et al., 2004).
• Immune Response: Mucosal anti-Salmonella and anti-Campylobacter IgA antibodies were present in samples taken from chickens inoculated with Salmonella/pUWM251 at every tested time point. In contrast to serum IgG, the kinetics of IgA responses to both antigens were similar. In intestinal secretions the level of the antibodies dropped at week 2 and then peaked 2 weeks after the booster. During the next 2 weeks, IgA titers decreased and maintained at almost the same level during the remainder of the experiment. Since IgA antibodies directed towards both antigens were present in the intestinal fluids of 1-day-old birds, similarly to IgG antibodies, IgA present at 0 week were maternally derived. In intestinal secretions, taken from different parts of chicken gut (rectum and jejunum), levels of IgA antibodies to Campylobacter and Salmonella antigens also peaked 2 weeks after the secondary immunization. Intestinal IgA titers to Campylobacter whole cell lysates followed the similar patterns as those measured with membrane antigens (Wyszynska et al., 2004).
• Side Effects: No adverse side effects were observed (Wyszynska et al., 2004).
• Challenge Protocol: Two weeks after booster, all chicks received a dose containing approximately 2×10^9 CFU/ml of the wild type C. jejuni/pUOA18 strain in 0.1 ml PBS with gelatine. Campylobacter colonization was confirmed on days 3, 6, 9 and 12 after the challenge. In each instance, four chicks were euthanized, the intestine was excised and the C. jejuni present in chicken cecal contents were enumerated by plating (Wyszynska et al., 2004).
• Efficacy: Protection experiment showed that chicken immunization with avirulent Salmonella carrying Campylobacter cjaA gene greatly reduced the ability of heterologous wild type C jejuni strain to colonize the bird cecum (Wyszynska et al., 2004).
• Description: It is well documented that poultry and poultry products are the major source of human campylobacteriosis and salmonellosis. The avirulent Salmonella vaccine strains expressing Campylobacter antigen can be potentially used as a bivalent chicken vaccine (Wyszynska et al., 2004).