Fig. 4.

ΔydiV Salmonella overexpress fliC in systemic tissues. C57BL/6 mice were orally infected with 10⁶ ΔydiV or WT Salmonella harboring the PfliC::gfp reporter construct. Splenocytes were harvested from infected animals, and fliC expression by intracellular bacteria was quantified by flow cytometry as described in Materials and Methods. (Left) On average, 10 times more ΔydiV than WT transcribed fliC in the spleen. (Right) To facilitate direct comparison of gene expression from ΔydiV and WT bacteria, the two groups of mice were colonized to similar levels (Materials and Methods). Data from two independent experiments are combined.