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For Consumers

Approval of 2nd Fourth Generation HIV Diagnostic Test for earlier detection of infection

On July 22, 2011, FDA approved a second "Fourth Generation" HIV diagnostic assay, the GS HIV Combo Ag/Ab EIA, made by Bio-Rad Laboratories of Redmond, WA.  The GS HIV Combo Ag/Ab EIA is an enzyme immunoassay kit for the simultaneous qualitative detection of Human Immunodeficiency Virus (HIV) p24 antigen (the substance found on the virus that triggers the production of antibodies) and antibodies (a specialized immune protein that helps fight infection produced because of the introduction of an antigen) to HIV Type 1 (HIV-1 groups M and O) and HIV Type 2 (HIV-2) in human serum or plasma.

The test is intended as an aid in the diagnosis of HIV-1 and/or HIV-2 infection, including acute or primary HIV-1 infection, and can be used as an aid in the diagnosis of HIV-1 and/or HIV-2 infection in pediatric subjects (i.e., children as young as 2 years of age). The GS HIV Combo Ag/Ab EIA is intended for manual use and for use with the Bio-Rad EVOLIS™ Automated Microplate System.

Levels of p24 antigen increase early after initial infection, before HIV antibody is produced. Because it detects HIV-1 p24 antigen, in addition to antibodies, the assay can be useful in diagnosis of earlier, acute phase (recent) infection with HIV, prior to the emergence of antibodies produced by the infected patient, effectively reducing the window period - that period after initial infection and before the detection of infection based on formation of detectable antibodies.

Results from the GS HIV Combo Ag/Ab EIA cannot be used to distinguish between the presence of HIV-1 p24 antigen, HIV-1 antibody, or HIV-2 antibody in a sample.

The GS HIV Combo Ag/Ab EIA is not intended for routine use in screening blood or plasma donors, as the effectiveness of this test for use in the screening of these donors has not been established. However, in urgent situations where traditional licensed blood donor screening tests are unavailable or their use is impractical, this assay can be used as a blood donor screening assay.

The product label is available on the FDA web site.

Richard Klein
Office of Special Health Issues
Food and Drug Administration


Page Last Updated: 08/21/2014
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