Figure 6.

Strain C227-11 adherence promotes translocation of Shiga toxin type 2a (Stx2a) across T84 monolayers. Supernatants from the basolateral compartment of polarized monolayer dishes were collected 24 hours after infection, and the cytotoxicity (CD₅₀) per milliliter was determined on Vero cells. Bars show the mean CD₅₀ from at least 3 separate experiments, with each done in triplicate. A, The CD₅₀ values were normalized such that the sample from C227-11 was set to 100. *P < .05, **P < .001, and ***P < .0001, by analysis of variance with the Tukey post hoc test, for comparison between C227-11, mutants, and complements. B, DH5α(pBADaggDCBA) and DH5α were incubated with 500 ng/mL of Stx2a during the 3-hour period of T84-cell infection. *P < .0396, by a 1-tailed unpaired t test, for comparison between DH5α(pBADaggDCBA) and DH5α(pBAD). Bars show mean CD₅₀ levels, as determined on Vero cells in a representative experiment, with each experiment done in triplicate. Error bars represent 1 SD. Abbreviation: SD, standard deviation.