Figure 3. Importance of Mtb nuoG for Inhibition of Macrophage Apoptosis.
(A) The in vitro growth of wild-type (squares), mutant (full triangles), and complemented bacteria (empty triangles) was analyzed at the indicated time points in triplicate cultures (error bars showing ±SD are smaller than symbols).
(B and C) Induction of apoptosis by infection of differentiated human THP-1 cells (B) or cultured primary mouse macrophages (C) with wild-type (Mtb), the ΔnuoG deletion mutant (MtbΔ), or complemented mutant (MtbΔC). Cells were harvested either at day 3 (B) or day 1 (C) after infection, stained by TUNEL assay, and analyzed using flow cytometry.
(D) The percentage of infected macrophages in (C) was determined by acid-fast staining.
(E) M. kansasii was transfected with empty cosmid (pY), empty plasmid (pMV), cosmid J21 (J21), and Mtb nuoG behind the constitutive promoter of pMV261 (pMV+nuoG), and induction of apoptosis in THP-1 cells was determined by TUNEL staining and flow cytometry. All results shown are means ±SD of triplicate cultures and are representative of three independent experiments.
Asterisks indicate statistical significance as in Figure 1. ns, not significant.