FIG. 4.
Analysis of HIV-1SF2 and HIV-1NL4-3 fusion to target cells. (A) Top: fusion differences between HIV-1SF2 and HIV-1NL4-3 were determined using a BlaM-Vpr fusion assay essentially as described by Cavrois et al. (6). HeLa-CD4+ cells were incubated with HIV-1SF2BlaM-Vpr and HIV-1NL4-3BlaM-Vpr, and the infected blue cells were counted from acquired images. Shown are averages of triplicate determinations of one experiment representative of three independent experiments. Bottom: Western blot analysis indicates similar levels of BlaM-Vpr fusion protein incorporated into the virions. (B) Effects of BFLA-1 on fusion activities of HIV-1SF2BlaM-Vpr and HIV-1NL4-3BlaM-Vpr. The fusion activity of the control sample for each virus was set as 1 for comparison purposes. Data shown represent one of two experiments. (C) Differential sensitivities of HIV-1SF2 and HIV-1NL4-3 to inhibition by T-20 measured using a single-round infectivity assay with P4-R5 Magi cells. Results are averages from at least three determinations. The experiment was repeated three times.