Protection of gnotobiotic pigs against Salmonella enterica serotype Typhimurium by rough mutant of the same serotype is accompanied by the change of local and systemic cytokine response

We have demonstrated that severe systemic disease caused by virulent LT2 strain Salmonella enterica serotype Typhimurium in gnotobiotic piglets can be alleviated by oral inoculation with an avirulent rough (R) mutant of the same serotype 24 h before challenge with the virulent strain. Protected piglets had no signs of enteritis. The concentrations of TNF-α, IL-1β, IL-8 and IL-10 were measured by ELISA in ileal washings and plasma of uninfected and infected pigs. The cytokines were not detected in plasma of germ-free piglets, and low concentrations of IL-1β and IL-8 were found in their ileal washings. The pre-inoculation of the rough mutant induced an increase in IL-8 and decrease in IL-1β and IL-10 in plasma. The virulent LT2 strain induced very high TNF-α concentrations in the ileum which were reduced in the pigs pre-inoculated with the R mutant.