Time of intervention in HIV-1 life cycle. HeLa/CD4-LTR-β-gal cells were infected with HIV-1IIIB cell-free virus before A) bDLE (2 IU), B) T-20 (100 μM), C) UC781 (70 nM), D) 118-D-24 (120 μM) and E) Amprenavir (0.1 mM), were added upon HIV-1 inoculation (time zero) or at various time points post-infection. β-gal activity was measured following 24 hr of incubation. Percentage values are relative to the positive control (infected cells without drug pretreatment). The data represent the means ± standard deviations from three separate experiments, each of which was carried out in duplicate.