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 1 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.