Distinct quasi-species in the blood and the brain of an HIV-2-infected individual.

Sequences of the HIV-2 envelope C2-C3 region were obtained after direct PCR amplification of proviral DNA from the brain and peripheral blood mononuclear cells of an HIV-2-infected AIDS patient. Tissue-specific sequences confirmed previous observations that HIV-2 is indeed present in the central nervous system of infected individuals. Distinct but related quasi-species were present in these two different tissues of the same individual. Residues at position 18 and 19 of the V3 loop and overall charge of the loop suggest that the brain virus was NSI/macrophage tropic; whereas the sequences from the two blood samples were indicative of a SI/T-cell tropic virus. This is the first description of these two genotypes in the same HIV-2-infected individual. Analysis of more samples from different compartments would help to better understand tissue-specific factors in quasi-species evolution in vivo.