Irrelevance between the Induction of Anti-Campylobacter Humoral Response by a Bacterin and the Lack of Protection against Homologous Challenge in Japanese Jidori Chickens

Abstract

On-farm vaccination of chickens against Campylobacter jejuni is considered a potentially effective countermeasure to decrease campylobacteriosis via consumption of contaminated chicken meat, but is not yet available. In this study, 2 groups of Jidori chicks were immunized subcutaneously with a formalin-killed C. jejuni with 2 different adjuvants. Other chicks served as the unvaccinated control group. Both vaccines induced high levels of anti-Campylobacter IgG but did not decrease bacterial excretion in cecal droppings and bacterial load in the liver and spleen after oral challenge with 10⁵ CFU of the homologous strain. Further study is needed to address the observed irrelevance and to develop a novel effective vaccine against C. jejuni.