FIG. 4.

Complementation of SG3^IN2 virus with homologous trans-IN protein. pSG3^IN2 and pSG3^wt were transfected alone and separately cotransfected into 293T cells with pLR2P-vprIN. The culture supernatants were collected 48 h later, filtered through 0.45-μm-pore-size filters, and analyzed for HIV-1 p24 antigen by enzyme-linked immunosorbent assay (Coulter Inc.). Next, 25, 5, and 1 ng of each virus (p24 antigen equivalents) was used to infect monolayer cultures of P4 indicator cells. Two days later, the cells were stained and infection-positive cells were counted. The virus infectivity results represent infectious units per 25-ng equivalent of p24 antigen. The data shown are the means from three independent experiments.