Hopes for an AIDS Cure Remain Alive

The cell cultures in the Aaron Diamond lab are engineered to switch on a fluorescent biochemical tag, if and when a candidate molecule flips the virus from latency to replication.

Bieniasz said a cure for AIDS isn't around the corner, but these experiments are a vital first step. "What we are looking for here is essentially proof-of-principal that you can do this without having wide-ranging effects on cells," he said.

Other research is also yielding valuable clues to latency.

Dr. Stephen Deeks is an associate professor of medicine at the University of California, San Francisco's General Clinical Research Center. His work, also funded by amfAR, focuses on that tiny minority of HIV-infected individuals -- less than 1 percent -- who have remained healthy for more than 20 years without the need for drug therapy.

These so-called "elite controllers" typically carry virus that stays at low or undetectable levels. "So, the question remains, what makes these individuals different?" said Deeks.

"One model is that they have an immune system that allows them to control the virus very effectively," he said. In fact, some -- but not all -- of these people have immune cells that are especially rich in HLA receptors. "These receptors allow immune cells to recognize very specific parts of an infection, such as a virus," he said.

That could be part of the story. Or, these individuals might have been lucky enough to contract what researchers call a "replication-impaired" form of HIV -- a kind of weakling strain that is easy to keep at bay.

"That remains a theory," Deeks said, "mainly because the virus is actually very hard to find in these individuals. But we are aggressively trying to find that out."

The answers his team comes up with could help the 99 percent of infected patients with no such defenses against HIV.

"If it's the immune response that's key, and if we can figure out what those responses are, then we can develop vaccines that focus in those areas," Deeks said. Vaccine research could also receive a boost if it's a particular strain of virus that causes long-term control, he said.

Cutting-edge drug therapies have already beaten HIV down to infinitesimally low levels. In 2005, a team led by Dr. David Margolis of the University of North Carolina made a big splash by announcing in theThe Lancetthat it had significantly depleted levels of latent virus in four patients.

In the study, Margolis' team added a common epilepsy drug, valproic acid, to the patients' standard mix of antiretroviral drugs. All of the patients had already exhibited very low viral loads for years.