Capture of HIV-1 infectious virions by α4β7 expressed on 293T cells. Serial dilutions of the HIV-1 infectious molecular clones R2184c4.IMC.LucR (A) and WEAU3-3.IMC.LucR (B) were incubated with either α4β7-expressing 293T cells or mock-transfected 293T cells for 1 h at 37°C. Cells were washed and overlaid with TZM-bl cells. Activation of the Luc reporter gene in the TZM-bl cells was measured 48 h later using a Britelite luminescence reaction kit. Circles, virus grown in PBMCs and incubated with mock-transfected 293T cells; squares, virus grown in 293T cells and incubated with mock-transfected 293T cells; triangles, virus grown in PBMCs and incubated with α4β7-expressing 293T cells; inverted triangles, virus grown in 293T cells and incubated with α4β7-expressing 293T cells. RLU, relative light units.