Multiple introductions of HIV-1 subtype E into the western hemisphere.

The genetic analysis of viruses from 11 HIV-infected Uruguayan military personnel, 6 of whom are thought to have acquired their infection while deployed as part of the UN Transitional Authority in Cambodia, is reported. They were screened for antibodies to HIV-1 before deployment, on return, and one month after return. 10 (.8%) of 1300 individuals acquired HIV-1 infection during overseas deployment. 6 of these 10 and 5 military personnel with domestically acquired infections volunteered for this study. The five had been diagnosed when tested as part of sentinel screening or at blood donation. Medical histories indicated that for all but 1 of the 11 subjects (who did not deploy to Cambodia), transmission most likely occurred through heterosexual exposures. The virus was successfully isolated by coculture in six individuals (four nondeployed, two deployed), and the genetic analyses were carried out on DNA prepared from cocultured peripheral blood mononuclear cells (PBMC) from these subjects. Genetic analyses of viruses from the other five subjects were done on DNA from primary PBMC. Phylogenetic analysis of the DNA sequences from the gp 120 fragment obtained from the five subjects who did not deploy and had not traveled outside South America revealed that all clustered within the B subtype of HIV-1. Of the six subjects who were infected while deployed to Cambodia, five harbored HIV-1 subtype E, while the sixth isolate (UR5) was subtype B. Cross-sectional surveys in several populations in Uruguay have revealed a low overall seroprevalence of HIV-1, with the highest prevalence (1.26% of 868 patients tested) found in a population from a sexually transmitted diseases clinic in Montevideo. The biological consequences of the introduction of subtype E HIV-1 into the western hemisphere are not known, but data from Thailand suggest that subtype E may be associated with a higher risk of heterosexual transmission than B.