Introduction of HIV Type 1 into an Isolated Population: Molecular Epidemiologic Study from Greenland

Introduction of HIV-1 into a population may not always give rise to a subsequent epidemic. Greenland is an isolated and sparsely populated island in The Danish Kingdom. We aimed to estimate the number of introductions of HIV-1 into Greenland, the number of subsequent epidemics, and the countries from which the virus was introduced. Phylogenetic analyses were performed on three regions of HIV-1 (gag, pol, and env) in samples from 70 Greenlandic patients. Furthermore, we included gene sequences from contemporary Danish HIV-1-infected patients and sequences from the Los Alamos HIV Sequence Database. All Greenlandic sequences were subtype B except one sequence found to be a recombinant (probably CRF13). Sequence clusters in the phylogenetic trees indicated that there had been at least nine introductions of HIV-1 into Greenland. One cluster, supported by bootstrap values of 81, 76, and 96% for gag, pol, and env, corresponding to one introduction, contained 53 (76%) of the Greenland patients. The patients in th...