Outlook improving for AIDS vaccine

Progress to be discussed at Baltimore conference

August 29, 1999|By Diana K. Sugg | Diana K. Sugg,SUN STAFF

Scientific advances, increased federal money for research, and Third World countries finally waking up to the fact that AIDS has ravaged their populations is creating optimism for a milestone that could save millions: a vaccine for the deadly AIDS virus.

Just two years ago, when President Clinton pledged to Morgan State University graduates that scientists would find a vaccine for AIDS within a decade, there was plenty of cynicism. Today, there is much less.

"It is possible that the components for a reasonably successful vaccine are almost there, in our hands, but we don't know it yet," said Dr. Robert C. Gallo, co-discoverer of the AIDS virus. "I'm much more positively inclined than a year or two ago."

Today, more than 1,000 physicians, scientists and others from 20 countries will discuss progress on the AIDS vaccine at a weeklong conference held annually in Baltimore, with Gallo and the University of Maryland's Institute of Human Virology, which he directs, as the hosts.

The meeting, which began years ago as an informal gathering of Gallo and his colleagues, has grown into one of the largest AIDS conferences in the world.

No one thinks a vaccine to stop the human immunodeficiency virus is as close as a few years away, and no one wants to raise false expectations about stopping a virus that infects 16,000 people a day worldwide. The subject is fraught with political, ethical and financial issues. And in the lab, scientists are facing one of their most elusive and toughest targets.

Unlike polio or other viruses, no infected person has ever been shown to clear HIV from his body, so scientists have no clues as to what might work. They say they don't even know if a natural protective state against HIV can exist in humans. Also, the virus mutates quickly within individuals and populations -- changing its genetic makeup, which makes it harder to fight. And the major target of HIV is the very thing the body needs to defend itself: the immune system.

"The barriers are almost all scientific constraints," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

More than 90 percent of new infections occur in developing countries, where few people have access to the complex and expensive medication regimen that can keep the virus in check. Among those who take the "cocktail" drugs, resistant HIV strains are emerging. More than 33 million people are infected with HIV around the globe. About 13.9 million have died.

Experts say the only long-term answer is a vaccine that prevents HIV.

"It's the silver bullet," said Steven Fisher, a spokesman for AIDS Action, the nation's leading advocacy group.

At this week's conference, Gallo expects one of the more significant discussions to deal with Tat, or transactivating protein, which is made by HIV. Over the years, researchers have found that Tat plays a key role in HIV spreading and wreaking damage.

"You can regard it as one of the missiles from HIV infection that leads to the problems in the immune system and facilitates the virus' spread," said Gallo, who has done some of the work. Researchers have shown that vaccinating monkeys against Tat lowers the amount of the virus and lessens the immune system's impairment.

Gallo and his collaborators have tested Tat in humans for safety, both as a preventive vaccine and as a therapeutic one -- meaning it would help control the virus in someone already infected. He said his group's strategy will be to create a sort of vaccine cocktail, by combining an inactivated Tat protein with another vaccine approach.

The difficulties with the AIDS vaccine have led some scientists to conclude that a therapeutic vaccine is more realistic than one that can prevent infection. By keeping HIV from multiplying in the body, the therapeutic vaccine would stop the virus from progressing to the disease stage. Lower levels of HIV in a person's body also make it more difficult to transmit the virus.

"This would be a major achievement," Gallo said. "But my personal belief is we haven't tried hard enough yet to accept that notion completely."

Others involved in the AIDS fight say they are heartened by what is going on outside the labs.

Federal efforts that appeared uncoordinated and bogged down in bureaucracy for a few years now seem to be coming together, Fisher said. For two years, the position of director of the new federal Vaccine Research Center was unfilled before Dr. Gary Nabel of the University of Michigan was hired in April.

"That was like having a Manhattan Project without having a Robert Oppenheimer," Fisher said.

Funding for AIDS vaccine research at the National Institutes of Health has doubled since fiscal year 1995, according to NIH figures. Now, of the $1.8 billion in NIH money for AIDS, 11 percent is devoted to vaccine efforts, according to Fauci.

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