Tropism for CD45RA⁺ and CD45RO⁺ CD4⁺ T cells during NSI to SI HIV-1 conversion. Patient PBMCs were FACS sorted in CD45RA⁺ CD45RO^– CD4⁺ and CD45RA^– CD45RO⁺ CD4⁺ T cells, and clonal virus isolation was performed on these T-cell subsets. (a) The frequency of infected cells with either NSI or SI HIV-1 variants (NSI or SI load) in total (top), CD45RO⁺ (middle), and CD45RA⁺ (bottom) CD4⁺ T cells relative to SI conversion in patient ACH171 (left panels) and 490 (right panels). Filled symbols indicate SI clones, and open symbols indicate NSI clones. In the top panel, serum RNA load is indicated by triangles. (b) Ratio of NSI load in CD45RO⁺ to NSI load in CD45RA⁺ CD4⁺ T cells (left) and ratio of SI load in CD45RA⁺ to SI load in CD45RO⁺ CD4⁺ T cells (right) of patient ACH171 (filled circles) and ACH490 (open circles). (c) Prevalence of SI phenotype among HIV-1 clones isolated from CD45RA⁺ (circles) or CD45RO⁺ (squares) CD4⁺ T-cell subset in ACH171 and ACH490.