Using phylogenetic analysis to trace HIV-1 migration among western European injecting drug users seroconverting from 1984 to 1997

Objective: To reconstruct the epidemiological relationships of the HIV epid emics among injecting drug users (IDU) in western Europe. Methods: HIV env V3 sequences of and epidemiological data were obtained fro m 145 IDU who seroconverted in three sequential periods: 1984-1988, 1989-19 92 and 1993-1997. The sequences were phylogenetically analysed and examined for signature patterns characteristic of northern European IDU, including the conserved CCC codon in the V3 loop. Results: Subpopulations of genetically related HIV strains were observed in Italy, France, Scotland and Spain, in contrast to the Netherlands, Austria and Switzerland. This difference between the two groups of countries sugge sts that the HIV epidemics amongst IDU in the latter group was caused by mu ltiple virus introductions. In Edinburgh and the surrounding area, most IDU were infected with the same GGC strain over the 12-year study period. The epidemic among IDU in north-western Europe started with GGC viruses, wherea s in south-western Europe non-GGC viruses predominated. This geographical s eparation has faded during the course of the epidemic, most likely because of virus exchange among IDU populations. (C) 2001 Lippincott Williams & Wil kins.