Evaluation of passive immunotherapeutic efficacy of hyperimmunized egg yolk powder against intestinal colonization of Campylobacter jejuni in chickens

Campylobacter jejuni is a leading cause of foodborne bacterial gastroenteritis in human. Chickens are the reservoir host of C. jejuni, and contaminated chicken meat is an important source of human infection. Therefore, control of C. jejuni in chickens can have direct effect on human health. In this study we tested the passive immunotherapeutic efficacy of the chicken egg-yolk-derived antibodies, in the form of hyperimmunized egg yolk powder (HEYP), against 7 colonization-associated proteins of C. jejuni, namely, CadF (Campylobacter adhesion to fibronectin), FlaA (flagellar proteins), MoMP (major outer membrane protein), FlpA (fibronectin binding protein A), CmeC (Campylobacter multidrug efflux C), Peb1A (Campylobacter putative adhesion), and JlpA (Jejuni lipoprotein A). Three chicken experiments were performed. In each experiment, chickens were treated orally via feed supplemented with 10% (wt/wt) egg yolk powder. In experiment 1, chicken groups were experimentally infected with C. jejuni (10⁸ cfu) followed by treatment with 5 HEYP (CadF, FlaA, MoMP, FlpA, CmeC) for 4 d either individually or as a cocktail containing equal parts of each HEYP. In experiment 2, chickens were treated for 21 d with cocktail containing equal parts of 7 HEYP before and after experimental infection with C. jejuni (10⁸ cfu). In experiment 3, chickens were treated with feed containing a cocktail of 7 HEYP before and after (prophylaxis), and after (treatment) experimental infection with C. jejuni (10⁵ cfu). Intestinal colonization of C. jejuni was monitored by culturing cecal samples from chickens euthanized at the end of each experiment. The results showed that there were no differences in the cecal colonization of C. jejuni between HEYP treated and nontreated control chickens, suggesting that use of HEYP at the dose and the regimens used in the current study is not efficacious in reducing C. jejuni colonization in chickens.