HAP2 can fuse the VSVΔG pseudovirus to target cells. (A) Cartoon illustrates the generation of VSVΔG-HAP2 pseudoviruses. Transfected BHK cells express HAP2 protein on the surface and were infected with VSVΔG-G. The viral genome encodes GFP, replacing VSVG. Infection results in viral-induced expression of GFP by target cells (green cytoplasm). VSVΔG-HAP2 pseudoviruses were collected from the supernatant. (B) The activity of VSVΔG-HAP2 was tested on BHK (untransfected, naive), BHK-HAP2, and BHK-EFF-1 cells. Figure adapted with permission from Avinoam et al. (2011). (C) Titers of VSVΔG pseudoviruses. The type of protein on the viral membrane (EFF-1 or HAP2) and on the BHK target cells (naive, EFF-1, or HAP2) is indicated. Titers in infectious units (IU) represent the number of cells expressing GFP per microliter 24 h after virus inoculation. Data are mean ± SEM (n = 3 experiments). We found no significant difference between infection with VSVΔG-HAP2 and VSVΔG–EFF-1 of the different BHK target cells (two-tailed paired t test).