Fig 7.

M. leprae survives inside epithelial cells. Intra- and extracellular M. leprae viability in RPMI 2650 and A549 cells was determined by the use of a Live/Dead kit. (A) RPMI 2650 cells at 33°C. (B) A549 cells at 33°C. (C) A549 cells at 37°C. Intracellular M. leprae bacilli (black bars) were recovered by lysing buffer, while extracellular bacteria (gray bars) were recovered after washing steps. In parallel, M. leprae bacilli were incubated in cell-free medium (white bar). Bacteria were stained by the use of a Live/Dead BacLight Bacterial Viability kit and enumerated by direct counting via fluorescence microscopy at a magnification of ×1,000. The data represent the mean values ± SD of the results of five experiments with duplicate samples from each one. *, P < 0.05; **, P < 0.01; ***, P < 0.001.