FIG 7.

Effect of efp mutation on virulence gene expression. (A) mRNA levels of virF, virB, and ipaC were reduced in the efp mutant, as determined by quantitative real-time PCR analysis. Values were normalized to the amount of dksA mRNA in each sample, and results shown are relative to the wild-type level, which was set to 1. Values shown are averages of results from three independent experiments. Error bars depict 1 standard deviation. mRNA levels of virF, virB, and ipaC were compared to those of the wild type by using the Student t test. *, P < 0.01; **, P < 0.001. (B) VirF levels were reduced in the S. flexneri efp mutant. VirF was detected by Western blotting using antisera to VirF. Whole-cell lysates of equivalent numbers of cells of wild-type 2457T, 2457T cured of the virulence plasmid (CFS100), and the Δefp, Δefp/pEfp, and Δefp CpxR D51E mutants were used. The lower band is a protein detected in all samples, which served as a loading control.