Divergence of HIV-1 quasispecies in an epidemiologic cluster

Background: During treatment with blood components prepared from an HIV-infected donation, two recipients became infected in 1985. One recipient infected her sexual partner. Objective: To evaluate the evolution of the originally-shared HIV-1 quasispecies in different human hosts over lime, sequence data were obtained from serum from the actual donation sample of blood, and from plasma samples collected from the four members of the epidemiologic cluster over a period extending from 1986 to 1993. Methods: The V3 hypervariable region of env and the gag p17 gene were analysed. CD4 and CD8 counts, as well as HIV RNA burden data, were collected. Results: One patient died from AIDS during the study. This patient showed a greater degree of diversity in the V3 region, with a higher positive charge over time, than the other individuals. Phylogenetic analysis revealed that the V3 sequences from each of the four individuals occupied separate branches of a phylogenetic reconstruction (tree). Two distinct subgroups evolved in the donor, one with GPGR and the other with GSGR/GSGK at the tip of the V3 loop. This latter group was not detected in the other individuals. The sequences in the sexual partner were no more related to those in the infecting transfusion recipient than to sequences from the other members of the cluster, consistent with sexual transmission having occurred at a time shortly after the recipient was infected. Conclusion: The shared HIV-1 quasispecies in this epidemiologic cluster diverged in an individual-specific manner.