Gross defects in the vpr and vpu genes of HIV type 1 cannot explain the differences in RNA copy number between long-term asymptomatics and progressors.

Disease progression in HIV-1-infected individuals is strongly associated with persistent and high numbers of HIV-1 RNA copies. We previously reported a markedly lower viral RNA load in eight long-term asymptomatics (LTAs) compared to seven matched progressors (at 1 year after seroconversion or entry in the study, p < 0.001) (Hogervorst E, et al.: J Infect Dis 1995;171:811-821). Here we extend our study to examine whether a difference in viral load can be attributed to infection by viruses having distinct vpr and vpu genes. Sequencing of vpr and vpu genes from serum samples collected at seroconversion from both long-term asymptomatics and progressors showed full-length and intact open reading frames of both genes in all subjects. At the protein level, no difference was discerned in domains of putative functional importance within Vpr and Vpu between the two groups. Phylogenetic analysis showed no clustering of LTA sequences, which interdigitated with sequences from progressors. We therefore concluded that nonprogression is not likely to be explained by deletion of vpr and vpu, or by gross sequence abnormality in these genes.