Analysis of stored vaccine samples by four independent research groups shows conclusively that they were not contaminated with the AIDS virus, thereby refuting the widely disseminated theory proposed by British author Edward Hooper in his 1999 book, "The River."
"Some beautiful facts have destroyed an ugly theory," said immunologist Robin A. Weiss of University College, London. Weiss, who did not participate in any of the studies, wrote an editorial in Nature, one of two journals that published the findings this week.
"The new data may not convince the hardened conspiracy theorist who thinks that contamination of [the vaccine] was subsequently and deliberately covered up," he said. "But those of us who were formerly willing to give some credence to the . . . hypothesis will now consider that the matter has been laid to rest."
Dr. Hilary Koprowski, who conducted the tests on behalf of the Wistar Institute in Philadelphia, said he was very happy with the findings.
"I never believed one word of the accusations because there were no facts," he said. "What bothered me was that somehow this may have created a difficulty in eradicating polio" because some people would refuse to be immunized for fear of contracting AIDS.
"With these articles putting an end to any possibility that vaccination had anything to do with AIDS, I hope that the [polio] eradication campaign will be [successfully completed] in two to three years."
A 1992 article in Rolling Stone magazine first made the argument linking the vaccine to AIDS. Hooper, who could not be reached for comment Wednesday, later incorporated the thesis into his 1,000-page book.
It is generally accepted that HIV, the virus that causes AIDS, originated in chimpanzees before spreading to humans.
Most researchers believe that the virus was transmitted to humans when people captured and ate chimpanzees or were bitten by them. Hooper, however, charged that the transfer was an inadvertent result of polio vaccine tests.
Koprowski led a team of researchers that tested a newly developed live-virus polio vaccine called CHAT during the late 1950s in the region of Africa that is now Rwanda, Burundi and Congo. That is the same area where the first large outbreaks of AIDS occurred, about the same time that the vaccine was tested. Hooper thought that was too big a coincidence.
He charged that the Wistar team prepared some batches of the vaccine using cells from chimpanzee kidneys. Those cells, he said, carried SIVcpz, the chimpanzee immunodeficiency virus that ultimately leaped to humans and became HIV.
Koprowski and others have said all along that the vaccines were prepared using only the cells of monkeys, which do not carry HIV, and that chimpanzee cells were not used. The new findings, appearing in today's Nature and Friday's Science, confirm their claim.
The new studies show that "all the viruses were grown on monkey cells, which is what was claimed initially," said Clayton Buck, chief executive and acting director of Wistar. "As far as I am concerned, the issue is really put to rest for all practical purposes."
Four separate groups in England, France, Germany and Sweden have now examined vaccine samples removed from freezers at Wistar, looking at the DNA of the viruses and the cells in which they were grown. In all cases, the cells were found to be only from rhesus or macaque monkeys and the only virus present was the polio virus.
Wistar no longer had samples of one vaccine preparation, called CHAT 10A-11 that Hooper thought to be the most suspect. But an original vial of the batch was found at Britain's National Institute for Biological Standards and Control. It too was found to contain only monkey cells and polio virus.