Figure 1. Comparison of M15 fitness in immunocompromised and wild-type C57BL/6 mice. Groups of various immunocompromised mice (iNos^−/−, IL10^−/−, and CD40L^−/− in C57BL/6 background along with wild-type mice as control group) were infected with 5 × 10⁷ cfu of Salmonella Typhimurium (wild-type, SB300; ssaV mutant, MT12; ssaV and hha double mutant, MT15) by oral gavage. Mice were sacrificed at 4 d p.i. and bacterial colonization was assessed. Graph represents colonization of S. Typhimurium strains at different host sites: (A) cecum, (B) mesenteric lymph nodes, (C) spleen, and (D) liver. Broken lines in the graphs shows minimum detection limit. n.s., not significant; *statistically significant (P < 0.05, t test).