Abl kinase inhibitors arrest HIV-1 Env-mediated fusion at the hemifusion step.

CHO-K1 cells that do not express GM1 were transfected with a GFP expressing plasmid (green), and 24 h later infected with WT vaccinia virus or vaccinia virus expressing HIVADA Env. After another 24 h, CHO-K1 cells were overlaid for 3 h with U87.CD4.CCR5 cells pre-treated for 1 h with DMSO, TAK-779, or IMB. Cells were fixed and stained with CTX-555 (red), and counterstained with TO-PRO 3 (blue). Images were collected using an oil objective (magnification X63). Images were cropped but relative cell size was maintained. The percentage of hemifused cells is listed.