Clinical Significance

The etiological agent of acquired immunodeficiency syndrome (AIDS) has been identified as two types of retrovirus, collectively designated as human immunodeficiency virus (HIV). HIV is transmitted by sexual contact between HIV-infected individuals, exposure to contaminated blood or blood products, and prenatal infection of a fetus or perinatal infection of a newborn from an infected mother. Antibodies to HIV are detected in AIDS patients and in HIV-infected asymptomatic individuals; HIV infection is always detected in AIDS patients and seropositive individuals by cell culture or after amplification of viral RNA and/or proviral DNA.

Serological cross-reactivity between HIV-1 and HIV-2 has been shown to be highly variable from sample to sample. This variability requires the inclusion of antigens to both HIV-1 and HIV-2 for the screening of antibodies to HIV-1 and HIV-2. The presence of HIV-1 and/or HIV-2 antibodies and/or p24 antigen in the blood indicates potential infection with HIV-1 and/or HIV-2. Early after infection with HIV, but prior to seroconversion, HIV antigens may be detected in serum or plasma specimens. The HIV structural protein most often used as the marker of antigenemia is the core protein p24.  This assay utilizes HIV p24 monoclonal antibodies to detect HIV p24 antigen prior to seroconversion, thereby decreasing the seroconversion window and improving early detection of HIV infection.