Introduction of human immunodeficiency virus 2 infection into South Korea

Although human immunodeficiency viruses 1 and 2 (HIV-1 and HIV-2) share mode of transmission, their epidemiologic characteristics differ and international spread of HIV-2 has been limited. To investigate the extent of HIV-2 infection in South Korea and to clarify the characteristic of HIV-2 isolates, we describe epidemiological, serological and genetic analyses of five HIV-2 isolates from South Korea. Five of 964 HIV antibody-positive serum specimens showed positive reactivity by HIV1/2 enzyme immunoassay (EIA), HIV-2 Western blot analysis, HIV-2 particle agglutination (PA) test and line immunoassay (LIA) but negative or indeterminate one by HIV-1 PA test and HIV-1 Western blot analysis. To confirm HIV-2 infection by genetic analysis, reverse transcription-polymerase chain reaction (RT-PCR) was performed on five HIV-2 seropositive samples. PCR products from gag (197 bp) and env gene regions (137 bp) were obtained with three of the five samples with HIV-2 specific gag primers and with all the five samples with env primers. To obtain larger sequences for a more comprehensive phylogenetic analysis, we performed PCR for a 1191 bp env region of HIV-2 but only two such products were obtained. For the phylogenetic analysis, three 197 bp gag and two 1191 bp env PCR products were cloned and sequenced. Based on the gag and env sequences alignments, three isolates (KR4063, KR7051 and KR8091) were clustered phylogenetically within HIV-2 subtype A. In conclusion, HIV-2 virus is present in South Korea and was detected in five subjects. Furthermore, the prevalence of HIV-2 infection should be monitored continuously in South Korea to assess the spread of this virus and to assist in the diagnosis of HIV infection.