PHYLOGENETIC AND SEROLOGICAL CHARACTERIZATION OF 2 UGANDAN HIV-1 ISOLATES

HIV-1 isolates Ug06 and Ug23 were established in culture from peripher al blood mononuclear cells (PBMCs) of Ugandan subjects. The isolates w ere studied for phylogenetic and serological relationships with each o ther and with the laboratory strains, HTLV-III(B) and HIV-1MN. The res ults suggest that the Ugandan isolates are related to different subgro ups of African viruses with 17.3% of genetic distance between UG06 and the U455 provirus (Uganda); and 12.6% of genetic distance between UG2 3 and the JY1 provirus (Zaire). Analysis of the predicted amino acid s equences for Ug06 and Ug23 showed marked sequence heterogeneity in the V3 region and CD4-binding site. A conserved amino acid sequence was i dentified in the C-terminal immunodominant region of the envelope glyc oprotein gp120. The isolates were compared in virus-neutralization exp eriments with HTLV-III(B) and HIV-1MN Stocks, using panels of Western blot-positive North American and Ugandan sera. The North American seru m samples showed broad neutralizing activity against both of the Ugand an isolates. However, the Ugandan serum panel demonstrated strain-spec ific activity against either Ug06 or Ug23. Furthermore, the African se rum specimens showed higher prevalence and titers of neutralizing acti vity against the HIV-1MN stock as compared with HTLV-III(B).