FIG. 5.

CF collected from the prtTΔ mutant shows decreased killing of A549 alveolar cells in culture and reduced hemolytic activity. (A) Confluent A549 cells were incubated in the presence of WT (left) and prtTΔ (center) CF for 12 h at 37°C with 5% CO₂. Cells were subsequently stained with Hemacolor, washed, and visualized by microscopy. Control, untreated cells are shown in the right panel. Bar, 100 μm. (B) CF-induced loss of A549 cell viability (cytotoxicity), as measured by XTT assay. (C) CF-induced hemolysis of SRBCs, as measured by hemoglobin release. The results are representative of three independent experiments performed in triplicate and are expressed as the means ± standard deviations for three replicates.