FIG. 1.

X4 but not R5 HIV-1 induces massive apoptosis among CD4 T cells. Human lymphoid cultures ex vivo were infected for 12 days with the R5 viral strain 49-5 (B and E) or the X4 viral strain NL4-3 (C and F) or kept uninfected (A and D). Apoptosis of CD4 T cells was determined independently by annexin V staining (A to F), caspase-3 activity (A to C), and depolarization of the mitochondrial membrane (D to F). Presented are flow cytometry dot plots from a typical experiment from among three independent experiments using different donor tissues.