Progress, no big breakthrough, in hunt for HIV cure

Scientists, stymied for decades by the complexity of the human immunodeficiency virus, are making progress on several fronts in the search for a cure for HIV infections, a leading medical research conference was told this week in Seattle.

Promising tactics range from flushing hidden HIV from cells to changing out a person's own immune system cells, making them resistant to HIV and then putting them back into the patient's body.

A major stumbling block is the fact that HIV lies low in pools or reservoirs of latent infection that even powerful drugs cannot reach, scientists told the Conference on Retroviruses and Opportunistic Infections, one of the world's largest scientific meetings on HIV/AIDS.

"We need to get the virus to come out of the latent state, then rely on the immune system or some other treatment to kill the virus," said Dr. Kevin De Cock, director of the Center for Global Health at the U.S. Centers for Disease Control and Prevention.

HIV, which surfaced more than 30 years ago, infects more than 33 million people worldwide. Thanks to prevention measures, tests that detect HIV early and new antiretroviral drugs that can control the virus for decades, infection with the virus that causes AIDS is no longer a death sentence.

Still, questions of cost, side effects, drug resistance and ultimate lifespan, make lifelong use of antiviral drugs a less-than-ideal solution.

The International AIDS Society last year formally added the aim of finding a cure to its HIV strategy of prevention, treatment and care.

Early human trials of vaccines designed to prevent or treat infection with the difficult to target virus have proved disappointing. HIV is a "provirus" that is integrated into the DNA of a host cell, where it can remain latent or eventually reactivate.

"It has proven to be an incredibly formidable challenge to develop a vaccine," said John Coffin, professor of molecular biology at Tufts University in Boston. "In recent years the pendulum is swinging back."

Scientific advances in molecular engineering are allowing researchers to delve more deeply into the mechanism of HIV.

"Vaccines work by recognizing the surface of the virus and eliminating it," said Dr. Dennis Burton, professor of immunology and microbial science at the Scripps Research Institute in La Jolla, California. "HIV is a highly evolved virus that has developed a surface incorporating features to avoid antibody responses," including instability.

He presented research showing that "broadly neutralizing antibodies" can be designed to recognize and penetrate HIV, giving researchers new vaccine targets.

Merck & Co presented data showing for the first time that its cancer drug Zolinza, also known as vorinostat, can disrupt latent HIV infection.