Fig. 2.

SidF is important in apoptosis resistance exhibited in L. pneumophila-infected macrophages. Uninfected U937 or cells infected with Lp02(dot/icm intact), Lp03(dotA⁻), Lp02(ΔsidF), or Lp02(ΔsidF/pSidF) at an MOI of 1 for 8 h were treated with 2 μM staurosporine for an additional 4 h. After fixation, bacterial vacuoles were labeled by immunostaining, and the morphology of cell nuclei was labeled with Hoechst staining. The apoptotic status of infected cells was scored by counting infected cells displaying fragmented nuclei. Data shown are averages of three independent experiments, with standard deviations.