Cell type-specific heterogeneity of the HIV-1 V3 loop in infected individuals: selection of virus in macrophages and plasma.

The primary targets for infection of HIV-1 are CD4+ T cells and monocyte/macrophage cells. We investigated the genotype heterogeneity of HIV-1 in distinct blood compartments, CD4+ T cells, monocytes, and plasma. Nucleotide sequences of proviral DNA from CD4+ T cells, monocyte cells, and cell-free virion RNA from plasma were determined in three HIV-1 infected individuals. We found that the heterogeneity in proviral DNA from CD4+ T cells was much higher than that found in monocyte cells or in virion RNA from plasma. These data showed that different swarms of HIV-1 exist in individually infected cells and plasma. Furthermore, predicted V3 amino acid sequences in the infected monocytes were very similar to the reported sequence of prototypic macrophage-tropic HIV-1 isolates. Our results show that macrophage-tropic virus is quite homogeneous in monocytes/macrophages and has a common V3 structure in contrast to T-cell-tropic virus in vivo.