FIG 7.

The ΔCD1492 mutant has decreased expression of toxin, motility, and sporulation regulators. (A) qRT-PCR analysis of the motility and toxin-associated sigma factor sigD, the sigD-dependent gene fliC, and the sporulation and sigD regulator rstA in the ΔCD1492 mutant relative to those in parent strain 630Δerm. Cultures were grown on 70:30 agar medium for 12 h, RNA was harvested, cDNA was prepared, and qPCR was performed with gene-specific primers as outlined in Materials and Methods. (B) Motility of 630Δerm, ΔCD1492 (MC674), and sigD (RT1075, negative control) mutant strains in one-half-concentration BHI medium with 0.3% agar. Swimming diameters were measured every 24 h for a total of 168 h. (C) qRT-PCR analysis of fliC transcript levels in the cecal contents of hamsters infected with 630Δerm (n = 5) or MC674 (ΔCD1492; n = 5). The mean values and the standard errors of the means are shown (*, P ≤ 0.05 by two-tailed Student t test).