HIV-1 outcompetes HIV-2 in dually infected Senegalese subjects with low CD4 counts

Abstract

Dual infection with HIV-1 and HIV-2, which is not uncommon in West Africa, has important implications for transmission, progression, and antiretroviral therapy. Few studies have examined HIV viral dynamics in this setting. We compared HIV-1 and HIV-2 viral loads from 65 dually infected, antiretroviral therapy-naïve Senegalese subjects. Participants provided demographic information and blood, oral fluid, and cervicovaginal lavage (CVL) or semen samples for virologic and immunologic testing. Associations between HIV-1 and HIV-2 levels in plasma, PBMC, oral and genital samples were assessed using linear regression models with generalized estimating equations to account for subjects with multiple samples over time. In analyses adjusting for CD4 count, age, sex, and commercial sex work, HIV-1 RNA levels were significantly higher than HIV-2 levels in semen, CVL, and oral fluids. HIV-1 and HIV-2 PBMC viral DNA loads were similar in those with CD4 counts above 500 cells/μl. However, compared to those with high CD4 counts, subjects with CD4 counts below 500 cells/μl had higher HIV-1 and lower HIV-2 DNA levels. In plasma, subjects with CD4 counts above 500 cells/&mul had mean HIV-1 plasma RNA viral loads approximately one log₁₀ copies/ml higher than HIV-2, with HIV-1 levels significantly higher and HIV 2 levels showing a trend toward lower mean viral loads among subjects with CD4 counts below 500 cells/μl. Our data are consistent with the hypothesis that with decreasing CD4 counts and HIV disease progression, HIV-1 outcompetes HIV-2 in dually-infected individuals. This finding may help explain the differences in epidemiology between HIV-1, HIV-2, and HIV-dual infection.