Some Gag- and Nef-specific CTLs cells do not require de novo viral protein synthesis for early killing of HIV-1–infected cells. 1CC4.14 cells were infected with 600 fg of Gag p24/cell of VSV-G Env-pseudotyped NL4-3-ΔEnv-HSA and assessed for killing by CTLs (⁵¹Cr release) in the presence and absence of ART. (A) Uninfected or infected cells with or without ART were examined by flow cytometry for cell-surface expression of HLA A*02 and HSA reporter at 48 hours after infection, confirming that ART blocked the de novo viral protein expression seen in untreated cells (HSA expression and A*02 down-regulation by Nef). (B) Specific lysis of uninfected or infected target cells (with or without ART) was assessed by ⁵¹Cr-release assay over time. The data shown are representative of 2 independent experiments.