Molecular evidence of homosexual transmission of HIV type 2 in Spain

Eight HIV-2-infected Caucasian men living in the same geographical area in Gipuzkoa (northern Spain) have been identified in the last 5 years. HIV-2 i nfection in this area is uncommon, and no other cases of HIV-2 infection ha ve been found after extensive testing for HIV-1/2 antibodies. Epidemiologic al data suggested a possible link among the identified subjects, with homos exual contact being the most likely way of transmission. A genetic analysis of four of the subjects, from whom specimens were available, was conducted . Phylogenetic and signature pattern studies of the reverse transcriptase ( RT) and env genes supported a single source of infection. Interindividual n ucleotide variability ranged from 2.4 to 4.8% in the RT region and from 5.2 to 6.1% in the env gene, whereas the mean divergence between patient and c ontrol strains was 9.8 and 18.3%, respectively. The nucleotide and amino ac id signature patterns were closely related in viruses from the four examine d individuals. This is the first report of a cluster of HIV-2 infections wi th genetic sequence data support. The singularity of this cluster should al ert clinicians on the possibility of HIV-2 outside endemic areas.