Gag-specific CTLs overall are less susceptible to Nef. The effect of Nef on CTL antiviral activity was compared according to the epitope source protein. Gag epitopes in general had higher Nef-effect ratios than epitopes located in Pol and Nef. (A) The data plotted according to proteins. Each dot represents the Nef-effect ratio of an epitope; the horizontal bar represents the mean. Statistical significance was assessed using the Kruskal-Wallis test followed by the Dunn post test for multiple comparisons. (B) Gag epitopes compared with all other epitopes from non-Gag proteins. A 2-tailed Student t test was used to compare the 2 groups.