Scientists Considering Risks of Using Hepatitis C-Related Virus To Treat HIV
The "harmless and fairly common" virus GBV-C, which is closely related to hepatitis C, could help prevent HIV-positive individuals from developing AIDS by stopping HIV from entering cells, but scientists are concerned that injecting HIV patients with GBV-C could result in less protection against HIV if an individual's immune system clears the virus, the Milwaukee Journal Sentinel reports. Carolyn Williams, an epidemiologist at the National Institute of Allergy and Infectious Diseases, and Jack Stapleton, director of the AIDS program at the University of Iowa, examined the effects of GBV-C in 271 gay men who participated in the Multicenter AIDS Cohort Study, which has periodically tested and examined HIV-positive gay men over the past 20 years (Marchione, Milwaukee Journal Sentinel, 3/2). All participants had recently been infected with HIV, and 40% had GBV-C present in their samples, while 50% had antibodies for GBV-C, meaning that they had once been infected but had cleared the infection. Researchers found that 79% of the men carrying GBV-C were still alive after 10 years, compared with 36% of the men who tested negative for GBV-C, and only 16% of men who had cleared the virus survived at least 10 years. So far, eight clinical studies have found a "beneficial association" between GBV-C and HIV (Kaiser Daily HIV/AIDS Report, 2/14). "This is the strongest analysis to date supporting the protecting role" of GBV-C in delaying HIV disease progression, the researchers said. According to Stapleton, GBV-C increases the production of chemokines, chemicals that occupy the same docking sites on blood cells that HIV uses to enter cells. In addition, GBV-C decreases the amount of CCR5, another receptor on the surface of blood cells, decreasing the opportunity for HIV to locate an opening. "[T]here is not a way for HIV to get in the cells -- the doors are gone," Williams said.
Weighing Risks, Benefits
Despite the evidence that GBV-C has a protective value against HIV, scientists are hesitant to inject patients with the virus because of the negative effects that could result if the virus is cleared. "It makes me nervous to infect someone with something that may give them a benefit" but that could be harmful if they clear the virus, Williams said, adding, "A lot more work will be done" on GBV-C in the next few years. Stapleton said that it might be ethical to treat HIV patients with GBV-C if all other treatment options have failed. Richard Olds, chair of medicine at the Medical College of Wisconsin, said that he did not know of another example of a virus being used as a treatment for a completely unrelated virus. "There's no exact parallel. This is a unique thing to try," he said, adding, "Obviously, we need to do the study" (Milwaukee Journal Sentinel, 3/2).