There could be a new weapon on the horizon in the battle against HIV.
Researchers have long observed that among HIV-infected patients, some remain healthy and apparently suffer no damage to their immune system for 10 to 15 years or more. Last week, researchers claimed to find the missing factors that help this group of patients fight HIV, although others have been quick to voice doubt.
Dr. David Ho, director of the Aaron Diamond AIDS Research Center in New York City, announced last week on the Science magazine Web site his group has discovered this long-sought substance, fueling a wake of controversy.
The substance in question is known as \CAF,"" short for CD8 antiviral factor, named by Dr. David Levy. In 1986, Levy, of the University of California at San Francisco, noticed these HIV-defeating substances. Although he could not identify them, he knew they were produced by CD8 T-cells, a major player in the battle against HIV, and thus named this HIV-defeating substance CD8 antiviral factor, or ""CAF.""
The searching for CAF remained unsuccessful until 1995 when Dr. Robert C. Gallo, director of the Institute of Human Virology at the University of Maryland, identified a group of compounds, called beta-chemokines. These compounds can suppress some types of the HIV, but not all, leaving further work to be done.
The molecules identified by the Aaron Diamond group belong to the family of alpha-defensins, small proteins usually produced by white blood cells to attack bacteria by breaking its membrane. They discovered such alpha-defensins in HIV-infected, healthy patients but not in those who become sick from HIV.
Experiments further showed alpha-defensins can block the reproduction of HIV. The researchers concluded that ""alpha-defensins account for the anti-HIV activity of CAF (CD8 antiviral factor) that is not attributable to beta-chemokines.""
Other researchers, including Levy, believe that conclusion is too far from its ground.
""This is definitely not it,"" said Levy in an interview this week with The New York Times. ""Along the way we've ruled out a lot of factors, including the defensins.""
""Alpha-defensin is nothing novel,"" said Dr. Miroslav Malkovsky, professor of Medical Microbiology and Immunology at UW-Madison, who specializes in the pathogenesis and treatment of HIV-induced disorders.
""A Japanese group showed [alpha-defensin's] ability to inhibit virus replication in 1993'we have known this for a long time."" When asked if alpha-defensin serves as a good candidate for CAF, namely one that can suppress HIV for some 10 or more years,"" Malkovsky said, ""I really don't think they meet the criteria for CAF.""
Suspicion of experimental flaws has also been raised by the co-discoverer of defensin, Dr. Michael E. Selsted of the UC-Irvine.
In an earlier interview, Selsted pointed out that ""[The Aaron Diamond scientists] grew their CD8 cells along with other white blood cells that are known to produce defensins; so their defensins might not be coming from the CD8 cells.""
Even if alpha-defensins are the long-hidden members of CAF, one Aaron Diamond researcher admitted they might have little use for medical application because they are difficult to manufacture.
Most researchers do agree that much work needs to be done before any type of victory can be claimed. Dr. David Watkins of the Department of Pathology and Laboratory Medicine at UW-Madison said this study represents merely ""a small step toward explaining why some people stay healthy"" after becoming infected by HIV.
