FIG 4.

Effect of LldR on S. Typhimurium (S. Tm) lldPRD transcription and fitness in vivo. (A to C) Groups of wild-type C57BL/6 mice were treated with streptomycin by oral gavage. One day later, animals were intragastrically infected with the S. Typhimurium wild-type strain (IR715), a ΔlldD mutant (CG6), or a ΔlldR mutant (CG200). Cecal content was collected for RNA extraction 5 days after infection. S. Typhimurium RNA levels were assessed for lldP (A), lldR (B), and lldD (C). Transcription was normalized to that of S. Typhimurium 16S rRNA. (D) Swiss Webster mice were inoculated with a 1:1 ratio of an S. Typhimurium wild-type (WT) strain (AJB715) and a ΔlldD mutant (CG6) or the wild-type strain (AJB715) and a ΔlldR mutant (CG200). Colonic and cecal contents were collected 8 days after infection. Wild-type and mutant populations were enumerated on selective agar, and the competitive index was calculated. The number of mice per group (N) is indicated for each bar. To determine differences between groups, a two-tailed, unpaired Student's t test was applied to the ln-transformed data. Bars are the geometric mean ± standard error. *, P < 0.05; **, P < 0.01; nd, not detected; ns, not significant.