SscA and SseC are required for fitness during infection. (A) RAW 264.7 cells were infected with wild type, ∆sscA or ∆sseC mutant S. Typhimurium and the change in intracellular bacteria numbers between 2 h and 20 h post-infection was determined in gentamicin protection experiments. Data are expressed as the mean with standard error of three separate experiments. The competitive index of the ∆sscA mutant (B) and ∆sseC mutant (C) was determined in the spleen, liver and cecum 72 h after infection of C57BL/6 mice. Each data point represents an individual animal and data is from two separate experiments. *, p<0.05.