CCR5 expression on T cells derived from MALT in natural and nonnatural hosts. (A) Representative contour plots showing CD4 and CCR5 staining of T cells isolated from the gastrointestinal tract of healthy uninfected RMs, baboons, SMs, and AGMs (top) and the lung (through bronchial alveolar lavage) of healthy uninfected RMs and SMs (bottom). (B) Summary of CCR5 expression on CD4⁺ T cells isolated from the gastrointestinal tract of the species listed in panel A. Statistically significant differences in CCR5 expression on CD4⁺ T cells from natural and nonnatural hosts of SIV were observed with the use of one-way nonparametric ANOVA (Kruskal-Wallis) followed by the Dunn multiple comparison test and the Mann-Whitney U test. For nonnatural RM hosts of SIV versus natural SM hosts of SIV, P < .001; and versus natural SGM hosts of SIV, P < .01. For nonnatural BAB hosts versus natural SM and AGM hosts, P < .05. (C) Representative contour plots showing CD8 and CCR5 staining of T cells isolated from the gastrointestinal tract of healthy uninfected RMs, baboons, SMs, and AGMs (top) and the lung (through bronchial alveolar lavage) of healthy uninfected RMs and SMs (bottom).