Home > News

FRIDAY, June 18 (HealthDayNews) -- American researchers think they've figured out why a seemingly harmless viral infection helps extend the lives of people with HIV, the virus that causes AIDS.

The viral infection appears to prime the immune system, helping to prevent HIV from successfully attacking white-blood cells, the scientists report in the June 19 issue of The Lancet.

"The next thing we have to do is determine a way to mimic the effect of this virus and learn how to make it persist, so it can continue to induce these changes in the cell that help HIV," said co-author Dr. Jack Stapleton, director of the University of Iowa HIV Program, in a written statement.

The virus in question, known as GBV-C or virus G, first came to the attention of scientists in the mid-1990s, although it apparently has been attacking humans for thousands of years. The virus is a cousin of the hepatitis family of viruses, but unlike those pathogens, it doesn't seem to cause any symptoms.

Like hepatitis B and the AIDS virus, virus G is spread through exposure to blood and sexual contact. Research among healthy blood donors suggests about 1.5 percent to 2 percent of the population carry the active virus, while about 13 percent have acquired it at some point in the past.

In March, Stapleton and colleagues reported in the New England Journal of Medicine that 85 percent of 271 HIV-positive men studied showed signs of infection with the virus. Those who weren't infected were 2.78 times more likely to die after five to six years than those who were persistently infected with the virus.

The study is limited because it only looks at men who were examined before powerful drugs revolutionized the treatment of AIDS in the mid-1990s. Now, many AIDS patients are enjoying fairly good health.

In the new study, Stapleton and colleagues infected white-blood cells -- key players in the immune-system -- with both virus G and HIV. They then compared them to cells infected with HIV alone.

Double infection boosted immune-system proteins called chemokines that bind to "docking sites" on white-blood cells, potentially preventing HIV from gaining entry.

Stapleton said the next steps are to figure out how to make the effects of virus G last for a long time and to test the virus as a treatment for HIV.

"The fact that GBV-C is such a common infection, and that it's been so extensively studied and not shown to cause any diseases, distinguishes it from other live viruses and makes it a more realistic option," said Stapleton in a statement.

Convincing patients to accept treatment with virus G may be a challenge, said Dr. David Thomas, professor of medicine at Johns Hopkins University School of Medicine.

"There's not a lot of enthusiasm for going around and infecting people with things, even though the studies appear to look positive. There's not too many people who would sign up for such studies," he said.

And while virus G appears to be harmless, Thomas said it might not be.

"It's very difficult to prove that something doesn't cause harm, especially when it's an infection that continues on for years and years," he said.

More information

(SOURCES: David Thomas, M.D., professor of medicine, Johns Hopkins University School of Medicine, Baltimore; prepared statement by Jack Stapleton, M.D., director, University of Iowa HIV Program, Iowa City; June 19, 2004, The Lancet

Copyright © 2004 ScoutNews LLC. All rights reserved.