Evaluation of N-glycan-decorated live attenuated Escherichia coli and outer membrane vesicles as vaccines against Campylobacter jejuni colonisation in chickens

Abstract

Campylobacter jejuni is a leading global cause of bacterial gastroenteritis in humans, and poultry are a major reservoir. Glycoconjugate vaccines containing the conserved C. jejuni N-glycan have previously been reported to be effective at reducing caecal colonisation of chickens by C. jejuni. These include recombinant subunit vaccines, live E. coli strains expressing the N-glycan on the surface as well as outer membrane vesicles (OMVs) derived from these E. coli strains. In this study, we evaluated the efficacy of live E. coli expressing the C. jejuni N-glycan from a plasmid and glycosylated OMVs (G-OMVs) derived from them against colonisation by different C. jejuni strains. Despite the C. jejuni N-glycan being expressed on the surface of the live strain and the OMVs, no reduction in caecal colonisation by C. jejuni was observed and N-glycan-specific responses were not detected.