Dear Log,
«McMichael and his team have taken an entirely different road, inspired by the discovery of prostitutes in Kenya who remained HIV-negative in spite of frequent sex with infected men. The Kenyan women were remarkable not for their antibodies but for the high levels of what are known as killer T-cells - those white blood cells that divide and attack other cells that have been invaded by a virus. The Oxford vaccine, now in trials there, in London and in Nairobi, uses DNA to trigger a strong killer cell response. The results in mice have been good. Now the vaccine is being tested in healthy people with no likelihood of exposure to HIV. In two to three years, it could face the crunch test in people at risk. "It will be about five to six years before we know if it works," says McMichael.»
The gist of the story is that the epidemic began to fade once a mutant strain of the virus developed in a prostitute; it was both more virulent (killing other strains of the virus) and didn't cause any symptoms whatsoever in the host.
