Infectious bursal disease virus-induced immunosuppression exacerbates Campylobacter jejuni colonization and shedding in chickens

Campylobacter jejuni is the leading cause of food-borne bacterial gastroenteritis in humans in the United States. Infectious bursal disease virus (IBDV) causes an immunosuppressive disease in young chickens. To analyze a possible role of IBDV-induced immunosuppression in colonization and shedding of C. jejuni, two experiments were conducted. In both experiments, group I consisted of noninoculated control chickens, groups 2 and 3 were inoculated with varying doses of C jejuni, and groups 4 and 5 were inoculated initially with IBDV followed by doses of C jejuni similar to groups 2 and 3. Campylobacter jejuni was recovered from the cloaca and cecum, but not the small intestines, from all chickens in groups 2 and 3. In groups 4 and 5, C jejuni was recovered from the small intestines, cecum, and cloaca from all chickens. The amount (colony-forming units/sample) of C jejuni recovered from chickens in groups 4 and 5 was significantly greater (P < 0.05) than the amount recovered from chickens in groups 2 and 3; and C jejuni was also present sooner in these groups than in groups 2 and 3. Bursa samples from chickens in groups 4 and 5 were significantly smaller (P < 0.05) than in the other groups. Additionally, real-time polymerase chain reaction results for IBDV were positive in groups 4 and 5 and negative in all other groups. This study indicated that IBDV infection exacerbated colonization and shedding of C jejuni, presumably through the immune suppression this virus causes in chickens. It highlights the need for further investigation into the role of immunosuppression in preharvest control strategies for food-borne disease-causing agents.