RESUMO
Countries of the former Soviet Union are experiencing an emerging HIV-1 epidemic due to a rapid expansion of HIV-1 among injecting drug users (IDUs). To study the molecular epidemiology of HIV-1 among IDUs in St. Petersburg, Russia, virus sequences were obtained from 22 individuals. Phylogenetic analysis of the env and gag regions revealed circulation of two major HIV-1 populations, one belonging to HIV-1 subtype A, and another being a recombinant of subtype A and B viruses (gagA/envB). Both virus populations were highly homogeneous, with a mean pairwise genetic distance of <2%, and similar to viruses obtained earlier from IDUs in other regions of the former Soviet Union. Distribution of the two major HIV-1 genotypes in St. Petersburg correlated with geographical origin of infections. In one individual, a virus type previously unseen among IDUs was found, which demonstrates the possibility that new viruses are entering this risk group.