Oral vaccination of young broilers with a live Salmonella Typhimurium vaccine reduces caecal and internal organ colonization following a Salmonella Infantis challenge in a seeder-bird model

ABSTRACT

Poultry products are an important source of foodborne Salmonella infections in humans. Amongst these, the prevalence of S. Infantis is rising. In this study, the protection efficacy of an authorized live-attenuated S. Typhimurium vaccine against S. Infantis, was examined using a seeder-bird model in broilers. Vaccinated birds displayed a significantly lower colonization of S. Infantis bacteria in the caeca compared to the non-vaccinated counterparts (P = 0.017), with no significant differences observed in the spleen among the groups, three days post-infection. Thirty-two days post-infection, the disparity in average S. Infantis concentration between all-vaccinated and non-vaccinated birds was significant in both caeca (P = 0.0003) and spleen (P = 0.0002). Interestingly, a third group, consisting of seeder birds that were not vaccinated but housed with vaccinated penmates, exhibited significantly lower S. Infantis levels in both caeca (P = 0.0014) and spleen (P < 0.0001) compared to the non-vaccinated group. These findings underscore the potential of a live-attenuated S. Typhimurium vaccine administered to 2-day-old chicks in conferring protection against S. Infantis in broilers up to slaughter age.

KEYWORDS:

• Salmonella infantis
• broiler
• vaccination
• cross-protection
• poultry
• seeder-bird model

Acknowledgements

The authors would like to express their appreciation to many PhD students of the group of Prof. Van Immerseel for their assistance during the euthanasia and bacteriological analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by a grant received from Elanco Animal Health.