Persistence of distinct HIV-1 populations in blood monocytes and naive and memory CD4 T cells during prolonged suppressive HAART

OBJECTIVE: Reservoirs of HIV-1 are a major obstacle to virus eradication. There is therefore a need to clearly understand the molecular nature of the virus populations that persist in patients with sustained suppression of plasma viraemia on highly active antiretroviral therapy (HAART). DESIGN: We performed a detailed analysis of the genotypes of HIV-1 quasispecies isolated from highly purified blood cell types taken from three selected patients with sustained undetectable viral loads on HAART for 7 years. METHODS: We used polychromatic flow cytometry to sort naive and memory CD4 T cells, CD14 monocytes, and CD56+CD3- natural killer (NK) cells from the total peripheral blood mononuclear cells after 7 years of HAART. Clonal analysis was used to determine coreceptor use and drug-resistance genotypes of HIV-1 quasispecies in the sorted blood cell types. RESULTS: We detected HIV-1 DNA in memory and naive CD4 T cells and in CD14 monocytes, but not in the CD56+CD3- NK cells. Phylogenetic analysis demonstrated that the various blood cells types of two of the three patients harboured genetically distinct HIV-1 quasispecies. Drug-resistance mutations were also distributed differently from one cell type to another. This compartmentalization suggests a minimal virus trafficking between blood cell types during suppressive HAART. CONCLUSIONS: We observed a cell-specific compartmentalization of the residual virus populations during prolonged suppressive HAART. The coexistence of numerous HIV-1 quasispecies with different resistance genotypes and coreceptor use in cellular reservoirs may be relevant for future antiretroviral treatment strategies.