FIG. 5.

Association and entry of wild-type or mutant L. monocytogenes cells into J774 cells. Association and entry of the wild type (▴), the plcB (broad-range PLC) mutant (⧫), the plcA (PI-PLC) mutant (●), or the hly (LLO) mutant (■) were measured by the entry assay as described in the text. (a) Total number of bacteria (extracellular plus intracellular) associated with the cells. (b) Percentage of intracellular bacteria calculated as described in the text. These data represent the mean ± standard error for three to five cell preparations. ∧∧, P < 0.01 by Student’s t test for the percentage of intracellular bacteria (wild-type) compared to the percentage of intracellular bacteria (LLO mutant) at 1 and 5 min. , ∗∗, P < 0.01 by Student’s t test for the percentage of intracellular bacteria (wild type) compared to the percentage of intracellular bacteria (broad-range PLC mutant) at 10 and 20 min.