Researchers have confirmed for the first time the benefit of an innate defense system present in the few patients who remain healthy after years of infection with HIV despite receiving no treatment, according to an article published in the September edition of the Journal of Virology. The study found that the subset of HIV-infected patients referred to as long-term survivors or nonprogressors have higher amounts of a key enzyme in their white blood cells. At the same time, a related biotech company is poised to begin preclinical testing on a drug designed to confer similar protection on most HIV patients. Approximately five percent of patients with HIV, or human immunodeficiency virus, do not develop AIDS, or do so very slowly. Researchers have been trying for years to understand what sets long-term nonprogressors apart. Past research suggested that such patients maintain higher levels of an enzyme in white blood cells called APOBEC-3G (A3G), and the new study confirmed it in the first experiments on human cells. Researchers at the University of Rochester Medical Center believe that A3G “edits,” or introduces changes in, the HIV genetic code every time the virus copies itself. By doing so, A3G corrupts the HIV gene code and prevents the virus from reproducing. Unfortunately, HIV has evolved to counter A3G with viral infectivity factor (Vif), a protein that “grabs” A3G and tricks the body into destroying it. With the “editing enzyme” gone, HIV is free to overwhelm the immune system, leaving patients vulnerable to AIDS infections that take three million lives per year.
