PHYLOGENETIC ANALYSIS OF THE NEF GENE REVEALS A DISTINCTIVE MONOPHYLETIC CLADE IN KOREAN HIV-1 CASES

To study the genetic variation of the HIV-1 strains prevalent in South Korea, we analyzed the nef sequences derived from 46 HIV-l-positive i ndividuals living in various geographic regions in Korea. Phylogenetic analysis revealed four subtypes of HIV-1: A (3 patients), B (41 patie nts), D (I patient), and a type that could not be clearly classified t o any known subtype (1 patient). Thirty-five of the 41 Korean subtype B isolates formed a distinct monophyletic clade that is not related to any of the international sequences from the Los Alamos Database or Ge nBank as of June 1997. Indeed, the presence of unique conserved sequen ces was identified among the Korean isolates in this Korean subtype B group. The variations in the nucleotide sequences of a majority (32 of 35) subtype B samples within the Korean clade were 1.9% to 8.8%, and amino acid sequences varied from 3.9% to 15.5%. These results suggest that HN-I strains currently present in South Korea might have originat ed from a few sources or might be developing through a certain selecti ve pressure. This is the first report on the molecular nature of the H IV-I infection present in South Korea.