A theory about the origin of HIV -- which, if conclusively determined, could aid vaccine researchers -- claims that a '50s oral polio vaccine known as CHAT was cultured in kidneys of chimpanzees infected with SIV, the primate counterpart to HIV.

On one side of the debate is Edward Hooper, the British medical researcher and former BBC correspondent who penned last year's The River: A Journey to the Source of HIV and AIDS (see "The River Runs Through It," POZ, March 2000). His 1,070-page opus' main contention is that HIV was a gigantic scientific goof begun 40 years ago during a polio-eradication campaign in the then-Belgian Congo.

On the other side are researchers -- including CHAT-maker Hilary Koprowski -- who say that chimps, the only primates known to carry SIV, were never used at all. They contend that HIV began as the result of a "natural transfer" -- that hunters came in contact with SIV-contaminated blood through cuts on the hand or by eating uncooked chimp meat.

Hooper's theory fingers Koprowski for one of history's worst plagues, but last fall, New York University School of Medicine researchers seemed to confirm the natural transfer theory when tests of seven frozen samples of the oral vaccine administered found neither HIV nor SIV.

Stanley Plotkin, MD, of the Wistar Institute, the Philadelphia-based medical research center that helped develop the '50s vaccine, wrote to POZ after the SIV-free results were announced. He detailed 11 points on which he questioned Hooper's methods and findings, chief among them the claim that 16 observers of the vaccine-making process denied the use of chimps. "Although science can never prove a negative," he said in closing, "I conclude that the hypothesis of The River is wrong." For his part, Hooper -- the dissenter who holds most of the burden of proof -- says he located a woman whom he believes received an original, weakly contaminated CHAT vaccine, but has yet to contract AIDS. She has agreed to undergo blood testing, but the results will not be known for some time.