Human trials of HIV vaccine beginning

CHICAGO, May 13 (UPI) -- Dozens of medical centers across the United States are gearing up to begin human studies of a new vaccine to fight the Human Immunodeficiency Virus, or HIV, researchers announced Monday.

Rush-Presbyterian St. Luke's Medical Center, as well as Emory University in Atlanta and Ohio State University will be among the centers involved in the study, in which healthy people will receive the vaccine under development by the pharmaceutical giant, Merck & Company of Whitehouse Station, N.J.

Other studies of the vaccine already underway involve inoculating people already infected with HIV, the virus that causes AIDS.

"Ideally, we hope to get a preventative vaccine," Beverly Sha, an infectious disease specialist at Rush, told United Press International.

"Many of us think that the only way out of this epidemic is getting a preventable vaccine," Sha said, noting many developing countries, such as those in Africa, cannot afford lifelong medications to treat HIV infection or monitor the side effects of treatments.

Because the vaccine seems to boost the immune system in those already infected, it may also be possible to use it as a treatment for HIV infection, she said.

The trials are slated as safety trials, testing the safety of the vaccine and not whether it prevents HIV infection, which will continue into 2003, Merck spokeswoman Janet Skidmore told UPI.

Skidmore said the vaccine is being tested at 70 medical centers across the country under various protocols.

Other vaccines against HIV also are in clinical trials. Furthest along is AIDSVAX, owned by VaxGen, of Brisbane, Calif. AIDSVAX currently is in the last phase of human trials, which should be completed this year, VaxGen spokesman Jim Key told UPI. The results will be announced in early 2003 and if the vaccine looks effective, the company will file for FDA approval at that time, Key added.

The Merck vaccine uses a gene from HIV called gag to stimulate an immune response by the body to fight the virus. There are actually two vaccines. Each uses a different vector or delivery mechanism but the principle behind each is the same -- to deliver the gag gene inside cells for the purpose of eliciting production of so-called killer cells that will specifically target HIV-infected cells.

This process is known as cellular immune response, Sha noted, adding research suggests this may be very important for long-term immunity against HIV.

One advantage of this vaccine over others is that the gag gene is common to all strains of HIV. Hence this vaccine could be used all over the world, Sha said.

Other vaccines, such as AIDSVAX, use gp120, a protein on the surface of HIV that mutates and varies from strain to strain. Therefore a vaccine effective in Africa may not work in the United States or other areas of the world, Sha said.

The two strategies may not be mutually exclusive, however. Jorge Flores, chief of vaccine clinical research branch in the division of AIDS at the National Institute of Allergy and Infectious Diseases, told UPI some experts believe "a combination of approaches" may yield better results.

It could be difficult to put into practice, Flores said, because it would require companies to collaborate on their different vaccines. However, at least two companies, VaxGen and Aventis Pharmaceuticals, of Bridgewater, N.J., plan to collaborate with their two vaccines on a combined study in Thailand.

That study has not yet begun, Key told UPI.

Merck released preliminary results of its vaccine trials in February at the 9th Conference on Retroviruses and Opportunistic Infections in Seattle. The company indicated the medication was well tolerated and induced a favorable immune response.

"It's important to stress that these human studies are really critically important to getting us to effective vaccines," Sha said. "It's doubtful that these vaccines will be the ultimate strategy (in preventing HIV infection), but these will lead us along to getting to that point."

(Reported by Steve Mitchell, UPI Medical and Health Correspondent, in Washington)