Improving chicken responses to glycoconjugate vaccination against Campylobacter jejuni

Campylobacter jejuni is a common cause of diarrheal disease worldwide. Human infection typically occurs through the ingestion of contaminated poultry products. We previously demonstrated that an attenuated Escherichia coli live vaccine strain expressing the C. jejuni N-glycan on its surface reduces the Campylobacter load in more than 50% of vaccinated leghorn and broiler birds to undetectable levels (responder birds), whereas the remainder of the animals were still colonized (non-responders). To understand the underlying mechanism, we conducted 3 larger scale vaccination and challenge studies using 135 broiler birds and found a similar responder/non responder effect. Subsequent genome-wide association studies (GWAS), sex of the birds and level of vaccine induced IgY-responses did not correlate with the responder versus non-responder phenotypes. In contrast, antibodies isolated from responder birds displayed a higher Campylobacter-opsonophagocytic activity when compared to antisera from non-responder birds, however, no differences in the N-glycome of the sera, or specifically the IgY, could be detected. As reported before, the composition of the microbiome, particularly levels of Clostridium spp., Ruminococcaceae and Lachnospiraceae are associated with response. Transplantation of the Cecal Microbiota of responder bids into non-responders in combination with vaccination resulted in a significant reduction in C. jejuni colonization and increases in vaccine-induced antigen-specific IgY responses when compared to birds that did not receive microbiota transplants. Improving the efficacy of the E. coli live vaccine to levels that would eliminate C. jejuni colonization in poultry would produce a safer food product that leads to decreased cases of foodborne illness and GBS induction, and reduced antimicrobial resistance development in birds.