Abstract
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Abstract; Background: World over, there are antiretroviral therapy naïve individuals infected with HIV who maintain their CD4+T cell count above 500 cells/µl over 7-10 years and viral loads well controlled below undetectable levels (termed elite controllers, ECs) or at least 2,000 copies/mL (termed viremic controllers, VCs) for at least 12 months. Mechanisms responsible for HIV control in these individuals have not been fully elucidated. We hypothesized that CD4+T cells from elite and viremic controllers are naturally resistant to HIV-1 infection by blocking R5-tropic viral entry. We conducted a case-controlled study in which archived peripheral blood from 31 ECs/VCs and 15 progressors were investigated using in vitro HIV-1 infectivity assays. Results: Briefly, we purified CD4+T cells from peripheral blood using EasySep CD4+ positive selection kit followed by CD4+T cell activation using IL-2, anti-CD28 and anti-CD3. Three days post-activation, CD4+T cells were spinoculated and co-cultured with vesicular stomatitis virus G (VSV-G)-pseudotyped HIV, R5 (ADA-enveloped)- and X4 (NL4.3-enveloped v)-tropic HIV-1. Three days post infection, we quantified and compared the percentage infection of CD4+T cells in cases and controls. We demonstrate that a subgroup of Ugandan elite and viremic controllers possess CD4+T cells that are specifically resistant to R5-tropic virus, remaining fully susceptible to X4-tropic virus. Conclusion: Our study suggests that a subgroup of Ugandan elite and viremic controllers naturally control HIV-1 infection by blocking R5-tropic viral entry. Further research is needed to explore mechanisms of HIV control in the African population.