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

Poultry products are an important source of foodborne infections in humans. Amongst these, the prevalence of Infantis is rising. In this study, the protection efficacy of an authorized live-attenuated Typhimurium vaccine against Infantis, was examined using a seeder-bird model in broilers. Vaccinated birds displayed a significantly lower colonization of Infantis bacteria in the caeca compared to the non-vaccinated counterparts ( = 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 Infantis concentration between all-vaccinated and non-vaccinated birds was significant in both caeca ( = 0.0003) and spleen ( = 0.0002). Interestingly, a third group, consisting of seeder birds that were not vaccinated but housed with vaccinated penmates, exhibited significantly lower . Infantis levels in both caeca ( = 0.0014) and spleen ( < 0.0001) compared to the non-vaccinated group. These findings underscore the potential of a live-attenuated Typhimurium vaccine administered to 2-day-old chicks in conferring protection against Infantis in broilers up to slaughter age.