Mtb H37Rv infection induces apoptosis and caspase activation.

<p>(A) Raw264.7 cells were screened for induction of apoptosis using Annexin-V/PI staining after 48 h infection with Mtb H37Rv at a MOI of 1. Staurosporine (500 nM) was used for making positive control for apoptosis. After washing and Annexin V-/PI staining, cells were analyzed by flow cytometry. Data are respresentative of at least three independent experiments with similar results. (B) Quantitative analysis of the percentage of Annexin V-positive cells as described in B. ***, <i>P</i><0.001 (C) Cellular levels of caspase-3, caspase-9, and caspase-12 during Mtb-infection in Raw264.7 cells. (D) The effect of caspase inhibitor z-VAD-fmk on the CHOP expression in Mtb-infected Raw264.7 cells. Raw264.7 cells were infected with Mtb at a MOI of 1 for 3 h, and then incubated for 0–48 h. The statistical significance (***<i>P</i><0.001) of observed differences between z-VAD-fmk treated and untreated groups following infection with Mtb H37Rv were verified by two-tailed t-test. Immunoblot analysis was performed as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0028531#s4" target="_blank">Materials and Methods</a>.