SIV infection of CD4⁺ T-cell subsets in peripheral blood of RMs and SMs. Naive (CD28^dullCCR7⁺CD95⁻), T_CM (CCR7⁺CD95⁺), and T_EM (CCR7⁻CD95⁺) CD4⁺ T cells were flow cytometrically sorted from peripheral blood of SIVsmmE543-infected RMs (■), SIVmac239-infected RMs (□), and SIVsmm-infected SMs (●), and infection levels of individual subsets were determined by quantitative PCR. Infection frequencies of individual subsets are compared between RMs and SMs (A). Infection frequencies of different subsets are compared within RMs (B) and SMs (C). Horizontal lines represent the median. P values are based on the Mann-Whitney test (A) or the Wilcoxon matched pairs test (B-C). Correlation between plasma viral loads and infection frequencies of T_CM (D-E) and T_EM (F-G) in peripheral blood of SIV-infected RM (D,F) and SIV-infected SM (E,G). Lines are based on linear regression and r and P values are based on Spearman rank correlation coefficient.