FIG. 8.

Hispidin pretreatment inhibited escape of the wild type and the PI-PLC mutant from the phagosome. Bacteria that escape from the phagosome and enter the cytosol become decorated with polymerized actin and can be stained with fluorescent phalloidin. After removal of uninternalized bacteria with gentamicin at 30 min, the percentage of cells that escaped at 1.5 h after infection was calculated as described in Materials and Methods. (A) Cells were either not pretreated (control) or pretreated with hispidin (5 μM) for 30 min and infected with the wild type. The data are the averages ± standard errors of the means for three experiments, and the difference is highly significant (P < 0.001). The data for cells pretreated with SK&F 96365 are taken from a previous study, in which the control gave an identical value (35). (B) Cells were pretreated with hispidin (5 μM) for 30 min and infected with the PI-PLC mutant. The data are averages ± standard errors of the means for three experiments, and the difference is highly significant (P < 0.01).