GREATER DIVERSITY OF THE HIV-1 V3 NEUTRALIZATION DOMAIN IN TANZANIA COMPARED WITH THE NETHERLANDS - SEROLOGICAL AND GENETIC-ANALYSIS

Objective: To compare variation in the HIV-1 V3 neutralization domain in Tanzania and The Netherlands. Methods: For serologic analysis, the specificity of anti-V3 antibodies (immunoglobulin G) for a panel of V3 peptides was determined in sera from 55 symptomatic HIV-1-infected Ta nzanians and 51 Dutch AIDS patients. For genetic analysis, viral RNA w as isolated from 15 of the Tanzanian sera and six of the Dutch sera. T he V3 encoding region was reverse-transcribed, polymerase chain reacti on-amplified and bacterially cloned, and sequences were determined ove r a stretch of at least 207 nucleotides. Results: Thirty-five per cent of the Tanzanian sera, versus 2% of the Dutch sera, showed the highes t reactivity to a V3 sequence of Zairian origin (RKSIHVGPGQAFYATG). Tw enty-nine per cent of the Tanzanian sera, versus 82% of the Dutch sera , showed the highest reactivity to V3 sequences of US/European origin (RKSIXIGPGRAFYTTG; X = H, P or N). The Tanzanian RNA sequences showed greater diversity (mean distance, 19%) than the Dutch RNA sequences (1 0%). The measured anti-V3 specificities of the Tanzanian sera did not match accurately with the V3 sequences recovered from these sera. Howe ver, reactivity to the Zairian V3 peptide was associated with the sequ ence GPGQ, found in the centre of the V3 in 50% of the Tanzanian seque nces. Sera from both countries that showed similar reactivities to the peptide panel contained RNA sequences that were relatively distant. C onclusions: The diversity of the HIV-1 population in Tanzania is much greater than that in The Netherlands. An indication of the HIV-1 V3 va riation in a particular geographic region can be obtained by serologic al methods, but sequence analysis should not be omitted.