Figure 4.

Nuclear DNA fragmentation of L. pneumophila-infected A549 cells detected by the TUNEL method. MOI dose-response relationship of nuclear DNA fragmentations 2 days after infection with the virulent AA100jm strain (A-D) and the avirulent dotO mutant strain (E-H). Nuclear DNA fragmentation of cells 2 days after exposure to 30 μM mitomycin C (I) and with no treatment (control) (J). Cells were observed with a confocal laser scanning microscopy (all 200 ×). The nuclear DNA fragmentation is shown in green (FITC staining), and A549 cell nuclei in red (PI staining).