FIG. 2.

CsrA and Cra influence S. flexneri attachment to epithelial cells. (A) Equivalent numbers of each strain were added to subconfluent monolayers and allowed to attach for 15 min prior to washing and staining. The total number of bacteria attached to 100 Henle cells was determined for each strain. Strains tested were 2457T (WT), AGS110 (uvrY), AGS120 (csrA), and AGS190 (cra). Values were normalized to the wild-type attachment level for each experiment. Wild-type adherence was 60 to 90 bacteria/100 cells (average, 0.8 bacteria/cell). Data presented are the mean values with standard deviations for three independent experiments. *, P < 0.05, and **, P < 0.01, compared to WT (by Student's t test). (B) Representative images from bacterial invasion of Henle cells by 2457T (WT), AGS110 (uvrY), or AGS190 (cra). Intracellular bacteria were visualized by Giemsa staining and microscopy.