Memory B-cell subsets frequency in HIV-2 infection.(a) Relative proportions of total memory cells (CD27⁺, top graph), switched memory cells (CD27⁺IgD^neg, middle graph) and unswitched memory cells (CD27⁺IgD⁺, bottom graph), within total B-cells, in the HIV-2 cohort, as well as seronegative (Seroneg) and HIV-1-infected individuals. (b) HIV-2-infected patients were further subdivided according to disease stage (early: >350 CD4⁺ T-cells/μl; late: <350 CD4⁺ T-cells/μl) and levels of plasma viral load (aviremic: undetectable plasma viral load; viremic: detectable). The frequencies of the B-cell subsets described in (a) were compared between seronegatives and all subgroups of HIV-2-infected individuals. Each dot represents one individual and bars indicate median. Filled circles refer to ART-treated individuals. Statistical analysis was performed using the Mann–Whitney test and the significant P values are shown. ART, antiretroviral therapy.