HEALTH - AIDS

FDA Approves Test to Help Diagnose Main Virus that Causes AIDS

by Dan Perkins

Source: FDA Release dated October 5, 2006 (P06-157)

The U.S. Food and Drug Administration (FDA) has approved a test that significantly enhances the health community's ability to detect the main virus that causes of AIDS in the Western hemisphere.

The test, which is called the APTIMA HIV-1 RNA Qualitative Assay, or more simply the APTIMA Test, is manufactured by Gen-Probe Incorporated, a company located in San Diego, California.  

An assay is an examination or trial of something.  It is a term often used in medical and scientific circles to refer to a test, or more specifically, the analysis of a substance in order to determine its components.

The APTIMA Test, developed by Gen-Probe, is significant because it is able to detect the RNA (the nucleic acid or genetic material) of the HIV-1 virus, the main virus that causes AIDS.  The FDA has approved the test for the detection of HIV-1 RNA to help researchers diagnose HIV-1 infection.  It is the first test of its kind approved by the agency.

"This product offers medical diagnostic laboratories the ability to perform a gene-based test for HIV-1 that, until now, was only available as part of a larger kit used to screen blood and plasma donors," said Jay Epstein, M.D., director, Office of Blood Research and Review, Center for Biologics Evaluation and Research (CBER), FDA. "This test also can detect infection with HIV-1 earlier than HIV antibody tests when used to detect primary HIV-1 infection."

CBER, which is one of six centers within the FDA, is responsible for the regulation of biologically-derived products, including blood intended for transfusion, blood components and derivatives, vaccines and allergenic extracts, and cell, tissue and gene therapy products. CBER also regulates AIDS-related diagnostic tests.

The APTIMA Test has important implications for medical diagnostic use because it could be a potential alternative to the traditional Western blot test now used for confirmation of HIV-1 infection.  This is especially true when screening tests for HIV-1 antibodies are positive. In addition, the Western blot can, in some instances, be difficult to interpret and may not always provide a conclusive result. In such cases, the APTIMA Test may be helpful in HIV-1 diagnosis. The APTIMA Test can also be used in clinical laboratories and public health facilities to detect early HIV-1 infection, before the appearance of antibodies to HIV-1.

The FDA found that the sensitivity of the APTIMA Test is comparable to that of FDA approved viral load tests that measure the amount of HIV-1 virus circulating in the blood of patients with established HIV-1 infection.  These viral load tests are used to monitor the treatment and progression of AIDS in patients.

The APTIMA Test, which has been approved for the diagnosis of primary HIV-1 infection, as well as for confirming HIV-1 infection when tests for antibodies to HIV-1 are positive, holds great promise for healthcare workers in the United States and other developed countries, but not necessarily for their counterparts in Africa, where the primary virus that causes AIDS is HIV-2.

According to the Centers for Disease Control and Prevention (CDC), evidence of a second strand of HIV first appeared in 1986, 2 years after researchers discovered the primary causative viral agent of AIDS, the human immunodeficiency virus type 1 (HIV-1). The second type of HIV, called HIV-2, was isolated from AIDS patients in West Africa, where researchers believe the virus might have been present decades earlier.

Studies of the natural history of HIV-2 are limited, but to date comparisons with HIV-1 show some similarities while suggesting differences, according to the CDC.

The CDC web site provides the following clarification: "Both HIV-1 and HIV-2 have the same modes of transmission and are associated with similar opportunistic infections and AIDS. In persons infected with HIV-2, immunodeficiency seems to develop more slowly and to be milder. Compared with persons infected with HIV-1, those with HIV-2 are less infectious early in the course of infection. As the disease advances, HIV-2 infectiousness seems to increase; however, compared with HIV-1, the duration of this increased infectiousness is shorter. HIV-1 and HIV-2 also differ in geographic patterns of infection; the United States has few reported cases (of HIV-2)."

Although the APTIMA Test might not have immediate application to the majority of AIDS cases in Africa, the FDA's approval of the test has great significance for the African American community, where AIDS has become the leading cause of death. 

In 2002, (the most recent year for which data are available), HIV/AIDS was the second leading cause of death for all African Americans aged 35–44. In the same year, HIV/AIDS was the number one cause of death for African American women aged 25–34.

The agency notes that of all of the diseases that disproportionately affect African Americans, HIV/AIDS is having a particularly devastating effect.  African Americans make up approximately 13 percent of the U.S. population, but the CDC reports that one half of the estimated new cases of HIV/AIDS diagnosed in the U.S. in 2004 were for African Americans.  Making matters worse is the fact that African Americans do not live as long as people in other racial or ethnic groups that have AIDS.

The CDC website putsthese findings into perspective with this simple, but alarming declaration: "It is not an exaggeration to say that HIV/AIDS is an epidemic in the African American community."

The End