HIV-1 and HIV-2 are the two main types of HIV. HIV-1 is the most widespread type worldwide. HIV-2, a less prevalent and less pathogenic (disease-causing) type, is found principally in western Africa. Large genetic differences between HIV-1 and HIV-2 mean that tests keyed to one will not reliably detect the other.
Confirmation and differentiation of HIV-1 and HIV-2 antibodies in serum specimens that show reactive results with third- (HIV-1/-2 antibody only) and fourth- (HIV antigen and antibody) generation HIV serologic assays.
Negative results for both HIV-1 and HIV-2 antibodies usually indicate the absence of HIV-1 and HIV-2 infection. Positive HIV-1 antibody, but negative HIV-2 antibody results, indicates the presence of HIV-1 infection.
