First human tests of AIDS vaccine to begin within weeks

Studies of prostitutes basis for new research

July 11, 2000
Web posted at: 5:01 p.m. EDT (2101 GMT)

From staff and wire reports

DURBAN, South Africa (CNN) -- The first vaccine designed specifically to fight the HIV strain in Africa has been cleared for testing in humans, the International AIDS Vaccine Initiative said Tuesday at the 13th World AIDS Conference here. Based on genetic material taken from the virus, the vaccine targets HIV's "A" strain, the dominant form found in Kenya and many other parts of the continent.

Developed in partnership between researchers at England’s Oxford University and the University of Nairobi, the vaccine is one of several being studied with funding from the nonprofit initiative.

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The genesis of the vaccine is a curious phenomenon observed among some people active in Nairobi's sex trade, according to Dr. Omu Anzale, director of a clinic that studies HIV and other sexually transmitted diseases. Of some 2,000 prostitutes studied, about 5 percent were found to have developed a natural resistance to the disease.

"The very first exposure wasn't able to cause infection, but was able to prime their immune system," said Anzale, explaining that the women's T-cell production increased significantly.

T cells are key cells that coordinate immune system response. HIV focuses its attack on these cells, disarming the body’s ability to fight disease. Usually, the body doesn't recognize the virus quickly enough to produce enough of the T cells needed for an effective defense.

"Our hope is that once somebody has been given the vaccine, they will respond vigorously by producing T cells," Anzale said.

An Italian lab has developed a patch form of a vaccine that combines a mutation of HIV with another virus that the immune system already knows how to fight. The goal is to modify the immune system to hunt down HIV and kill it before it can cause damage.

The first vaccine trial is scheduled to begin within six to eight weeks in the United Kingdom. It will move to Africa by year's end.

"After you vaccinate the patient, we are hoping they develop this immune response and stop anti-retroviral drugs and control HIV in the absence of therapy," said Julianna Lisziewicz of the Research Institute for Human and Genetic Therapy.

Such a breakthrough could still be years away, however.

Some Nairobi prostitutes who had initial resistance to HIV later developed infection, Anzale said, explaining that as long as the women continued to have frequent partners, this resistance appeared to stay intact. Several took time off and were infected when they returned to work.

What this means, said Anzale, is that constant exposure is a key component of HIV resistance. In terms of a vaccine, this may mean repeated booster treatment.

The South African government has said it will use a vaccine even if it is found to be just 40 percent effective. Considering those currently in trials, that could mean development of a usable immunization within five to seven years, officials said.

Women could benefit greatly

Any treatment to aid resistance to HIV would be welcome for many South African women, whose infection rate now surpasses that of men.

Many experts at the World AIDS Conference say women are victimized because they don’t have the power in male-dominated African society to insist that their partners wear condoms. Women in the country echo the sentiment. Female condoms are available but expensive -- about $5 U.S. for a pack of three. This cost is beyond the reach of most women in South Africa.

Condoms for men are freely distributed in clinics, at concerts and in other public places, but the female condom is not. Other possibilities being studied include the development of microbicides, which women would apply internally to prevent disease, much like modern spermicidal preparations.

But such anti-microbial treatments are still in the preliminary research stage and confined to the pharmaceutical laboratory.

CNN Correspondents Eileen O'Connor and Charlayne Hunter-Gault, and Reuters contributed to this report.

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