Efficacy of an oral recombinant attennated Salmonella vaccine encoding cjaA in turkeys colonized with Campylobacter jejuni

Abstract

Abstract Campylobacter jejuni spp. jejuni, (C. jejuni) is a commensal bacterium in the lower gastrointestinal tract of poultry (e.g., chickens and turkeys), where it causes no clinical disease. Consumption of C. jejuni-contaminated poultry products is the most likely route of transmission to humans. Strategies previously attempted in chickens to reduce intestinal C. jejuni colonization include administration of probiotics, non-antibiotic feed additives, vaccines and bacteriophages. These interventions have not been evaluated in turkeys. Recombinant attenuated Salmonella vaccines (RASV) encoding C. jejuni cjaA are reported to reduce cecal C. jejuni colonization in chickens. The goal of this study was to evaluate the efficacy of a RASV encoding cjaA in turkey poults experimentally colonized with C. jejuni. The cjaA gene from C. jejuni was cloned into RASV strain χ8133 (RASV-cjaA). A control RASV χ8133 (RASV-control) was generated lacking a cjaA insert. At different dates of age, poults received either one or two doses of RASV-cjaA. Other poults received 2 doses of RASV-control. Intestinal colonization by RASV-cjaA was evaluated and was detectable up to 6 days after oral inoculation. Poults were orally challenged with C. jejuni and euthanized at days 3, 7, 14 and 28 days post-challenge to evaluate cecal colonization (cfu/g content) and histopathological changes. Poults vaccinated with 2 doses of RASV-cjaA showed significant reduction (P<0.01) in C. jejuni cecal colonization and histopathological lesion scoring, as compared to those receiving a single dose of RASV-cjaA or RASV-control. These data demonstrate that oral RASV-cjaA significantly reduced C. jejuni colonization in turkeys, which may enhance food safety.