AIDS Vaccine Hopes Rise from Africa

Though the road to an effective HIV vaccine has been "littered with the wreckage of promising but ultimately failed candidates," the author wrote, scientists are now encouraged by some African prostitutes' ability to resist infection despite years of exposure. Investigations of the blood of more than 100 prostitutes in Nairobi have demonstrated a natural resistance to HIV infection. From studying that blood, scientists in England and Kenya have concocted the first experimental vaccine expressly intended for Africa. The first, most tentative phase of clinical trials now underway in Kenya shows promise. In Nairobi residents who are considered at low risk of contracting the virus, the vaccine appears to stimulate the same immunological response recorded in the sex workers: elevated levels of a component of the human immune system known as cytotoxic T-lymphocyte cells, the "killer T-cells" that fight the virus most effectively.

The debate over how best to fight AIDS globally continues to pit treatment against prevention. Frank Plummer, the Canadian researcher who first detected the immunity among Nairobi's sex workers, said, "They've found the problem but have focused on the wrong answer. I'm all for treatment, but focusing on treatment as the solution is not going to solve this [crisis]."

Studies of blood taken from the 18 Kenyans who were injected with the vaccine show "an 80 to 90 percent indication that it actually presents an immune response," said Andrew McMichael, a researcher at Oxford University in England and a leader in investigating killer T-cells. "I think the chances are better than even-probably a lot better than even-that this is going to be something useful," he said.

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