Abstract
During the period 1996โ1997, three highly homogeneous variants of HIVโ1 were identified, circulating among injecting drug users (IDUs) in the former Soviet Union republics. One of these belonged to HIVโ1 genetic subtype A (IDUโA), another belonged to HIVโ1 genetic subtype B (IDUโB) and the third was a recombinant between the first two variants (CRF03_AB). However, since 1997, the HIVโ1 epidemic has affected an increasing number of geographic regions in Russia. This study was undertaken to survey the prevailing genetic variants and to estimate the current proportions of these three HIVโ1 genetic subtypes in Russia. Blood samples were taken in 1999โ2003 from 1090 HIVโinfected individuals and analysed by gag/env HMA. The IDUโA variant was found to be the majority variant (89.7โ100%) in 44 of 45 regions of the Russian Federation studied. The IDUโA variant was also found to spreading rapidly through heterosexual transmission in 1999โ2003 (30/34, 88%). CRF03_AB predominates in the Kaliningrad region only (28/29, 96.6%). The IDUโB variant is currently of minor importance in the IDU epidemic but other European subtype B variants predominate among men having sex with men (18/18, 100%). Sequence analysis of the env V3 encoding regions derived from HIVโ1 infected individuals in Yekaterinburg (the main centre of the HIVโ1 epidemic in Russia in 2002โ2003) showed that the IDUโA variant is still highly homogeneous. The mean pairwise nucleotide distance (nโ=โ9) was 2.89โยฑโ1.14 (range 1.36โ6.14). However, the mean genetic distance between each sequence within the samples collected from the Yekaterinburg IDUโA variant subset and the IDUโA consensus is 2.51โยฑโ1.06 (range 1.36โ4.66) and considerably higher than in South Russia in 1996 (0.79โยฑโ0.51, range 0.38โ1.90). The current HIVโ1 epidemic in Russia is almost entirely caused by a highly homogeneous Aโsubtype strain, which will influence vaccine development strategies and must be taken into account in the quality control of molecular tests for the diagnosis of HIVโ1. J. Med. Virol. 74:191โ196, 2004. ยฉ 2004 WileyโLiss, Inc.