Fourth Generation HIV Diagnostic Test Approved, permitting earlier detection of infection

On June 18, 2010, FDA approved a new, "4th generation" HIV diagnostic assay. The ARCHITECT HIV Ag/Ab Combo Assay is the first HIV diagnostic assay that simultaneously detects both antigen and antibodies for the Human Immunodeficiency Virus (HIV). The new test is also the first diagnostic test approved by FDA indicated for use in children as young as 2 years of age, and pregnant women.

This single, automated test, known as the ARCHITECT HIV Ag/Ab Combo Assay, is a highly sensitive chemiluminescent microparticle immunoassay intended to be used as an aid in the diagnosis of HIV-1/HIV-2 infection, including acute or primary HIV-1 infection. It is specific for the detection of the HIV-1 p24 antigen (the substance found on the virus that triggers the production of antibodies), as well as antibodies to HIV-1 groups M and O, as well as antibodies to HIV-2.

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 ARCHITECT HIV Ag/Ab Combo Assay can be useful in extending diagnosis in 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. The median detection time was demonstrated to be 7 days earlier (range 0 to 20 days) compared to 3rd generation enzyme immunoassay antibody tests to which they were compared.

Currently, most tests used in the diagnostic setting detect HIV antibodies only.

While the assay is not intended to be used for routine screening of blood donors, it is approved as a donor screening assay for HIV-1/HIV-2 infection in urgent situations where licensed blood donor screening tests are unavailable or their use is impractical.

Approximately 18 million persons in the United States are tested for HIV each year, and an estimated one million people are living with HIV. In 2008, CDC estimates that approximately 56,000 people are newly infected with HIV each year. This new test can help diagnose on-going and more recent infection, helping make people aware of their HIV status, get treatment and help to reduce the spread of HIV by people unaware of their serostatus.

The ARCHITECT HIV Ag/Ab Combo Assay is manufactured by Abbott Laboratories, Abbott Park, Illinois.

Richard Klein
Office of Special Health Issues
Food and Drug Administration

Kimberly Struble
Division of Antiviral Drug Products
Food and Drug Administration