Robust Antiretroviral Activity of Peptide 2 Requires Expression of Both Vif and A3G. HEK293T cells were co-transfected with either VSV-G pseudotyped, + Vif (left panel) or ΔVif provirus (right panel), with or without A3G (as indicated below each histogram). During the incubation period, Peptide 2 was dosed into the specified samples (50 μM final concentration). The viral particles collected from the cell culture media over 48 h were normalized for their p24 content and incubated with JC53-bl cells for analysis of infectivity corresponding to luminescence as described in Methods. Infectivity of +Vif virions is shown as percent of the infectivity measured for +Vif/-hA3G/-peptide condition (14,498 red units). The (-) A3G/ΔVif virus control virions lacked Vif and the cells did not express A3G. Infectivity of the ΔVif virions is shown as percent of the infectivity measured with ΔVif/-hA3G/-peptide conditions (5,827 red units). The error bars represent the standard deviation with n = 3.