A newly developed immunofluorescence assay for simultaneous detection of antibodies to human immunodeficiency virus type 1 and type 2.

Immunofluorescence assays (IFA) that simultaneously distinguish between antibodies against closely related human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) infections have not been readily available. Serum specimens from 95 HIV-1-infected, 26 HIV-2-infected and 3 HIV-1/HIV-2 dually infected individuals and 106 seronegative blood donors were evaluated for the ability to serologically discriminate HIV-1 and HIV-2 infections by means of IFA employing three types of cells whose morphology varied within one field of microscopy. Mixtures of HIV-1-infected, HIV-2-infected and uninfected cells were used in the present study. In consequence, all serum specimens from individuals infected with HIV were confirmed to contain antibodies to HIV-1 and/or HIV-2. None of the sera from the blood donors were positive. Serum specimens from HIV-1-infected or HIV-2-infected individuals were diagnosed as single infection with HIV-1 (85/95) and HIV-2 (22/26), respectively, by this new assay. Although another 14 (10/95 and 4/26) were shown to be seropositive for both HIV-1-infected and HIV-2-infected cells, these results suggest that this assay is potentially simple and useful for screening and confirming both HIV-1 and HIV-2 infections simultaneously.