FIG 2.

Effect of S. maltophilia wild-type and virB10 mutant strains on A549 cell monolayers that had been treated with apoptosis-inducing staurosporine. (A) A549 cells were either uninfected (UI) or infected with parental strain K279a (WT), virB10 mutant NUS15 (virB10), or complemented mutant NUS15(pvirB10) (virB10/virB10+), and at 6 h postinoculation, the amounts of viable host cells were enumerated. As indicated, one set of cells that had been infected with the virB10 mutant was also treated with the pan-caspase inhibitor Z-VAD-FMK. UI cells and UI cells treated with the lysing agent Triton X-100 provided controls for cell death induced by staurosporine alone. (B) Staurosporine-treated A549 cells were infected with WT strains K279a, UPSm1, UPSm2, UPSm3, and UPSm5, and then the numbers of viable host cells were determined, as indicated for panel A. In panels A and B, raw data appear in the left panels, and data are normalized to the value for UI cells in the right panels. Asterisks indicate significant differences in death following infection with the strains or treatments (*, P < 0.05; **, P < 0.01). Data are presented as the means and standard deviations of results from three independent experiments (n = 3 each).