Impact of Nef on HIV-1–specific CTL antiviral activity is not influenced by CTL functional avidity or Rev dependence of the epitope source protein. Nef-effect ratios for the tested CTL clones were compared according to functional avidity and Rev-dependence status. (A) Nef-effect ratio plotted against functional avidity (SD₅₀) for each tested CTL clone; there was no significant correlation by the Pearson test. (B) Functional avidities of CTLs targeting Gag-derived epitopes compared with those directed against epitopes located in non-Gag proteins; the horizontal bars represent the means. There was no significant difference between groups by the Kruskal-Wallis test for multiple comparisons. (C) Nef-effect ratios plotted for CTLs recognizing epitopes from “early” (Rev-independent, Nef and Rev) versus “late” (Rev-dependent, Gag, Pol, Vpr, and Env) proteins. There was no significant difference between groups by a 2-tailed Student t test.