Serological approaches to subtyping of HIV-1 in injecting drug users in Russia: evidence of subtype homogeneity at the main sites of the epidemic

The aim of this study was to develop and evaluate a simple V3 peptide-based enzyme immunoassay (PEIA) for large-scale serotyping of HIV-1 specimens de rived from injecting drug users (IDUs) in the Russian Federation. Two synth etic peptides were evaluated, named P1 (RKSIHIGPGRAFYATGD) and P2 (RTSVRIGP GQVFYKTGD), in an PEIA on 63 HIV-1 IDUs sera for which genotypes had been d etermined by heteroduplex mobility assay (HMA) and sequencing. The sensitiv ities of P1 (subtype B) and P2 (subtype A) were 87% and 75% respectively. S pecificity of the assay was 100% for both peptides, with 100% predictive va lues of a monoreactive positive test for both peptides. Using the PEIA with peptides P1 and P2, we have serotyped 375 of 477 serum samples derived fro m IDUs in 4 main sites of the HIV-1 epidemic in Russia. The results demonst rated a high level of subtype homogeneity in all regions studied. In 3 of 4 territories, Tver' (n=345), and Rostov-on-Don (n=61) regions, and Krasnoda r Kray (n=27), 100% of typable sera were found to belong to env subtype A. On the other hand, all specimens serotyped in the Kaliningrad region (n=38) belonged to env subtype B, and there is strong evidence that the recombina nt gagAenvB virus which has caused the largest outbreak of HIV-1 in Russia is located in this region. At the present time another parental strain with gagBenvB genotype is of minor importance in the IDUs HIV-1 epidemic in Rus sia.