Feb. 9 (Bloomberg) -- The U.S. government and the richest charity are offering bounties to a new wave of scientists to wipe out HIV, the virus that causes AIDS and is one of the world’s biggest killers.

Frustrated by one failure after another, the U.S. is asking scientists to outline a major program to find a cure for HIV, while the Bill & Melinda Gates Foundation in Seattle is offering grants of $100,000 for researchers working on ways to drive the virus from patients’ bodies for good. Scientists are responding with new methods to stamp HIV from human cells and tissues where traces of it can hide for years, evading treatment.

Experimental vaccines and sexual gels called microbicides have failed to prevent the spread of the disease, which strikes 2.7 million new patients each year. The challenge is all the more urgent since Merck & Co.’s Ad5 vaccine, the most promising effort to date, flopped in 2007.

“If the vaccine had worked, I don’t think any of this would be happening,” said David Margolis, a doctor at the University of North Carolina in Chapel Hill, who has been working for years to cure HIV. “Getting so close to an effective vaccine and then having to start from scratch again has made people wisely step back and re-evaluate the whole playing field of options.”

New Funding

The National Institutes of Health asked scientists last year to describe how they would eliminate HIV from its hideouts in body cells, where it can evade detection and lie dormant for years before springing back to growth. The effort, which may involve scientists at Harvard University, the University of California at San Diego and other institutions, will be a major topic at the annual Conference on Retroviruses and Opportunistic Infections, beginning on Feb. 8 in Montreal.

Margolis, along with researchers at Merck & Co., Johnson & Johnson, Harvard, Johns Hopkins University and other institutions, proposed a government-funded effort to discover how HIV persists in the body even after powerful drugs drive the virus below levels detectable by conventional means. The Seattle-based Gates Foundation, the world’s biggest private charity, is asking for proposals aimed at the same goal.

To cure HIV, scientists must devise a way to expunge the virus from the human body. The most-effective HIV drugs so far aren’t powerful enough to accomplish that goal.

For about 12 years, doctors have known that HIV can lie dormant in cells, where they evade detection by the body and are safe from drugs floating through the bloodstream and penetrating tissues. HIV hijacks genetic machinery to make copies of itself that are released into the body as the infected cell dies.

‘Reservoir of Virus’

“It’s very easy to get the number of viruses circulating in the system down to an undetectable level,” said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, in a telephone interview. “However, to knock it out, we’ll either have to get true eradication, or get the reservoir of virus that’s inside cells so low that it can’t come back.”

Decreasing the amount of virus hiding inside cells might allow the body’s protective immune system to handle the infection on its own, without drugs. That would be equivalent to a “functional cure,” similar to a remission that cancer patients achieve when they don’t have to take drugs, Fauci said.

Lifelong Drugs

Latent HIV acts like a smoldering fire that can burst into flame at any time. What that means, said Myron Cohen, director of the University of North Carolina’s Center for Global Health and Infectious Diseases, is that without a cure, once a patient is diagnosed with HIV and begins taking drugs, the need for taking medicine never ends.

Pressure to find a cure has increased in the two years since Merck’s Ad5 vaccine flopped in 2007. Another approach to treatment, gels to prevent HIV transmission during sexual intercourse, also proved futile.

For now, that leaves only the option of giving lifelong drugs to sustain people already infected. The lifetime cost of treatment for U.S. HIV patients is more than $600,000. The U.S. has committed $50 billion over the next five years to combat HIV in Africa, where cheap generic drugs are staples of treatment, Cohen said.

“Can we sustain this spending for 50 years?” Cohen said Jan. 23 on the infectious-disease ward of the University of North Carolina Hospital in Chapel Hill. “We can’t treat our way out of the epidemic. Cure of HIV is an idea whose time has come.”

Search for Patients

Margolis would like to start testing a drug, Merck’s Zolinza, that shows potential to flush out latent HIV. He is hoping that the medicine will turn on the growth of HIV in the cells where it is latent, so that the virus will kill them and its hiding place will be gone.

To test Zolinza and other drugs, scientists are searching for patients in the earliest stages of HIV infection. Their cases may show how to limit the number of cells with latent infections, and might be the first candidates for curative treatment, researchers said.

“People are starting to take this idea seriously again,” Cohen said in an interview at his office. “The cancer field is always talking about cure: Walk for the cure, run for the cure, ride for the cure.”

He added, “It’s a good thing, it’s inspirational, and now it’s time for us in the HIV field to do the same.”

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: February 9, 2009 00:00 EST