FIG. 1.
HIV-1 Env-mediated fusion with PBL and HOSCD4X4R5 cells. Fusion activity was monitored as described in Materials and Methods by using HeLa cells infected with vaccinia virus vectors which express gp120-gp41 from a CXCR4-utilizing isolate (IIIB, vPE16) and a CCR5-utilizing isolate (Ba-L, vCB43). (A) Gray bars, untreated PBL; black bars, PBL treated with 10 mM MβCD for 30 min at 37°C; white bars, MβCD-treated PBL loaded with 75 μg of cholesterol/ml complexed with MβCD. (B) HIV-1IIIB (gray bars) and HIV-1Ba-L (black bars) were expressed in HeLa cells, and fusion with HOSCD4X4R5 cells treated with different amounts of cyclodextrin (at 37°C and for 30 min) was monitored as described in Materials and Methods.