Comparative Effectiveness of Various Multi-Antigen Vaccines in Controlling Campylobacter jejuni in Broiler Chickens

This study was undertaken to evaluate and compare the efficacy of different multi-antigen vaccines, including heat-inactivated, whole lysate, and subunit (outer membrane proteins [OMPs]) <i>C. jejuni</i> vaccines along with the immunostimulant CpG ODN in controlling <i>Campylobacter</i> colonization in chickens. In the first trial, 125 μg of <i>C. jejuni</i> OMPs and 50 μg of CpG ODN were administered individually or in combination, either in ovo to chick embryos or subcutaneously (SC) to one-day-old chicks. In the second trial, different concentrations of <i>C. jejuni</i> antigens (heat-killed, whole lysate, and OMPs) were administered SC to one-day-old chicks. The results of the first trial revealed that SC immunization with the combination of CpG ODN and <i>C. jejuni</i> OMPs elevated interferon (IFN)-γ, interleukin (IL)-1β, and IL-13 gene expression in the spleen, significantly increased serum IgM and IgY antibody levels, and reduced cecal <i>C. jejuni</i> counts by approximately 1.2 log₁₀. In contrast, in ovo immunization did not elicit immune responses or confer protection against <i>Campylobacter</i>. The results of the second trial showed that SC immunization with <i>C. jejuni</i> whole lysate or 200 μg OMPs reduced <i>C. jejuni</i> counts by approximately 1.4 and 1.1 log₁₀, respectively. In conclusion, <i>C. jejuni</i> lysate and OMPs are promising vaccine antigens for reducing <i>Campylobacter</i> colonization in chickens.