The Hutch part of big study of HIV vaccine in S. Africa

A major, large-scale test of the most promising HIV vaccine to date has begun in South Africa, under the co-direction of scientists from Seattle's Fred Hutchinson Cancer Research Center.

The trial involves 3,000 participants and is the first large test of the effectiveness of an HIV vaccine in Africa, the birthplace of AIDS where 25 million people now live with the virus.

The test will determine whether the vaccine can prevent HIV infection in some people, and whether it can decrease viral levels in those who become infected after being vaccinated.

Most vaccine studies have been much smaller and simply were testing for vaccine safety or how well a vaccine stimulates the immune system.

The new trial also will assess for the first time whether a vaccine can work against several HIV strains, which vary worldwide. And it will be tested mainly in heterosexuals, while earlier tests of the new vaccine have been mainly in gay men.

"We've not seen the levels of immune response in any other vaccines preceding this," said Dr. James Kublin of "The Hutch," who is helping to lead the project along with Dr. Glenda Gray, a researcher in Soweto, South Africa. "That's why we're so enthusiastic."

Scientists have been praising this latest experimental vaccine for more than two years, calling it the most promising yet. More than 100 preparations have been tested in animals and humans, but the virus mutates and is a difficult target.

The South Africa study is part of the international HIV Vaccine Trials Network, headquartered at The Hutch. It is financed by the National Institute of Allergy and Infectious Diseases and the South African AIDS Vaccine Initiative.

If the trial goes well, another one will involve 10,000 or more volunteers. That could begin in three to five years, Kublin said.

Further development of the vaccine or its use in combination with another, booster vaccine also could be necessary to increase the percentage of people it protects.

The new vaccine, made by Merck, uses a common cold virus to carry three HIV genes into the body by injection. Part of each gene is common to the six major HIV strains found in various parts of the world. That's why scientists hope the preparation will trick the immune system into making "killer cells" against most strains. The preparation cannot cause infection, because it contains only part of the virus.

The tests also will determine whether using the cold virus, called an adenovirus, is practical to use as part of the vaccine. If a person already has been exposed to that particular adenovirus, his immune response to the HIV genes inside could be somewhat suppressed, scientists said.

The trial will be conducted at five locations throughout South Africa. Half the volunteers will be injected with the vaccine; half will receive placebo, or harmless dummy vaccine. No one will know which group was given which until after four years. Infection rates of the two groups then will be compared.

During the trial, all volunteers will be counseled to keep using condoms and otherwise protect themselves against HIV infection.

Kublin said South Africa was selected for the trial because it has some of Africa's best scientists and facilities. It also has one of the highest rates of new HIV infections in the world. More than 5 million South Africans now carry the virus.

An earlier test of the safety and efficacy of the new vaccine is under way. It involves nearly 3,000 people in six countries, including 100 gay men in Seattle. About half the volunteers have shown high levels of immune response to the vaccine, with the only significant side effects being fever and aches.

About four years ago, what was then the largest trial of an HIV vaccine ended in disappointment when the vaccine stimulated antibodies against the virus, but not enough to kill it. The three-year trial, involving 5,400 people in North America and Europe, showed no difference in infection rates between those who receive the vaccine and those who received a placebo.

Warren King: 206-464-2247 or wking@seattletimes.com