Scientists Link Harmless Virus to Slowing of HIV's Effects

Infection with a common harmless virus, GBV-C, seems to slow the progress of HIV and prolong survival of AIDS patients, according to evidence reported by American scientists at the 10th Conference on Retroviruses and Opportunistic Infections in Boston yesterday. Swedish scientists at the conference reported a study supporting the link between the harmless virus and HIV, but the Swedish and American authors disagreed about whether GBV-C could cause the apparent benefit or whether it was an indicator of another, as yet undetected, factor that might account for the variability of HIV infection.

The Swedish and American researchers and other conference participants agreed that much more research is needed to determine the importance of the link before it could have any impact on AIDS care. They also agreed that more testing is needed to determine how often GBV-C infects people, how frequently people recover from infection, and the age at which most people become infected.

Discovered in 1995, the virus was first called hepatitis G. Subsequent research has shown that the virus does not cause hepatitis or any other known disease in humans or animals, and therefore neither Swedish nor American blood banks screen donors for it. Limited testing has shown that up to 2 percent of US blood donors and up to 3 percent of Swedish blood donors are infected with GBV-C. In the Swedish and American studies presented at the conference, the GBV-C prevalence in the HIV-infected groups observed was 57 and 86 percent, respectively.

Beginning in 1998, at least nine small studies by American and European scientists reported hints of a link between GBV-C and HIV, although other studies have failed to confirm the findings.

Dr. Jack Stapleton and colleagues of the University of Iowa reported evidence suggesting how GBV-C could slow HIV. By adding GBV-C to human blood cells, the researchers discovered that GBV-C blocked the docking sites on the CD-4 blood cell HIV needs for entry. They also found that adding GBV-C led to the production of chemokines, natural substances that inhibit HIV.

Dr. Per Bjorkman's team from the University of Lund-Sweden, reported a study of HIV-positive men and women who were tested for GBV- C at diagnosis and later in their illness. With his colleague Dr. Leo Flamholc, Bjorkman found that the initial test for GBV-C did not predict whether the patients would survive longer. Both studies found that the overall death rate for patients who had had GBV-C, then cleared it from their bloodstreams, worsened severely.

Experts noted that if further studies show GBV-C significantly slows the progression of HIV, scientists might attempt to identify a protein that could be used to mimic GBV-C infection for HIV patients.

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