FIG 2.

Time-of-addition assay. The target of the antiviral compound 16l was identified by comparing its activity in the time scale to those of reference drugs. In the assay, a panel of reference drugs sequentially targeting distinct replication steps of HIV-1 from entry to the integration into cell chromosome was used (shown as bars at the bottom): IgGb12 (an anti-gp120 antibody that binds the CD4-binding site), maraviroc (a CCR5 coreceptor inhibitor), enfuvirtide (T20, a fusion inhibitor), azidothymidine (AZT) (a reverse transcriptase inhibitor), and dolutegravir (DTG) (an integrase inhibitor). For compound 16l, the efficacy was at its maximum only when the virus was pretreated as for IgGb12, and it was ineffective once the virus attached the CD4 cell surface receptor.