Figure 6. The ppx mutants display defect in invasion and intracellular survival in INT 407 human intestinal epithelial cells. (A) Invasion assay and (B) Intracellular survival assay. The dotted line across the bar graph indicates the limit of detection (10 CFU/mL). Each bar represents the mean ± SE from 2 independent experiments with duplicate samples in each experiment. *P ≤ 0.05 **P ≤ 0.001.