FIG. 1.

Intracellular multiplication of S. dysenteriae mutants. The number of intracellular bacteria was determined at each time point by lysing the infected Henle cells and plating the contents to selective media. Henle cells were counted and the percentage of infected cells was determined. Error bars represent the standard deviations for the means of three independent experiments. Differences between the mutants and wild type were not statistically significant (P > 0.05) except for SDU380 compared to the wild type at 120 min (P < 0.01).