Recombinant Lactococcus lactis multicomponent mucosal vaccine reduces Campylobacter jejuni colonization and shifts poultry gut microbiota (microbiomejournal.biomedcentral.com)

• Bioengineered food-grade L. lactis expresses three C. jejuni antigens (CadF, Hcp, JlpA) as a live mucosal vaccine.
• Chitosan coating improves gut retention of non-colonizing LAB vector.
• Oral vaccination in chickens reduced cecal C. jejuni load by ~1.54 log10 with significant sIgA and cytokine upregulation.
• Metagenomic sequencing revealed decrease in Campylobacterota and increase in Bacteroidota, suggesting beneficial microbiota shift.

"Researchers engineered Lactococcus lactis to express three Campylobacter jejuni colonization proteins (CadF, Hcp, JlpA) and used chitosan microencapsulation to create an oral vaccine for chickens. Vaccination elicited strong mucosal IgA and cytokine responses, reducing cecal C. jejuni by ~1.54 log10. Gut metagenomic analysis showed a ~2-fold decrease in Campylobacterota and increased Bacteroidota, indicating a healthier microbial balance. The study was funded by BactiVac and UK-India partnerships, suggesting a cost-effective strategy to reduce foodborne transmission in poultry."