HIV-2 infection in Thailand.

Neither the seroprevalence of HIV-2 nor the sensitivity of enzyme immunoassays for the detection of antibodies to this retrovirus have been defined in Thailand. We, therefore, Investigated these enigmas using banked sera previously screened for HIV-1 by a test that did not distinguish between HIV-1 and HIV-2. All 1,013 HIV-seroreactive specimens were positive to HIV-1 on retesting, and 740 (73%) were reactive to both HIV-1 and HIV-2. The thirty-six samples that reacted with HIV-2 at a titer of > or = 1:4,096 were further tested to discriminate between HIV-1 and HIV-2 by immunoblot assays incorporating HIV-2 recombinant proteins. One specimen was untypeable, but all others were determined to be HIV-1. Seventy-three percent of sera from Thai HIV-1 infected subjects cross-reacted with HIV-2, but not a single case of HIV-2 infection could be confirmed. The finding suggests low prevalence of HIV-2 infection in Thailand and that current testing for HIV-2 antibody is not necessary in Thai population.