'No evidence' that polio vaccine led to Aids epidemic

Three independent laboratories have failed to find evidence that an experimental polio vaccine used in the Belgian Congo in the Fifties sparked the Aids epidemic.

Three independent laboratories have failed to find evidence that an experimental polio vaccine used in the Belgian Congo in the Fifties sparked the Aids epidemic.

The Wistar Institute, the private biomedical research laboratory in America that ran the vaccine trials, yesterday released the results of tests it commissioned on remnants of the vaccine stored for 40 years at its headquarters in Philadelphia.

Claudio Basilico, head of Wistar's independent scientific committee investigating the trials, told the Royal Society in London that the tests failed to find evidence of either SIV, a chimpanzee virus closely related to HIV, or chimpanzee tissue, which some critics have suggested was used to make the oral polio vaccine used in the Congo.

"The different tests performed by the three independent laboratories did not find any evidence of SIV or HIV in the samples, nor did they find chimpanzee DNA," said Dr Basilico, also chairman of microbiology at New York University Medical Center. "In fact, the laboratories were able to determine that all of the Wistar samples were grown in monkey cell cultures rather than chimpanzee cell cultures."

Clayton Buck, acting director of the Wistar, repeated the institute's position that the polio vaccine was made using Asian monkeys, which are not naturally infected with SIV. "We trust these results will put to rest any remaining concerns of a link between a Wistar-produced oral polio vaccine and Aids. The findings should also serve to restore public confidence in the production and administration of vaccines and in the response of science to public inquiry."

But Edward Hooper, the author of a book claiming Wistar's polio vaccine was made with contaminated chimpanzee tissue, denounced the latest findings as irrelevant. "This means nothing at all for the polio vaccine theory," he said.

And the reason why key witnesses of Mr Hooper's hypothesis retracted statements about the production of polio vaccine using chimp tissue, he said, was because representatives of the Wistar extracted the retractions under duress.

"They were given printed statements to sign with their name written in pencil at the bottom," he said.

Aids scientists accept SIV must have crossed from chimpanzees into humans to cause the HIV epidemic but are divided on when this occurred and how. Most believe it happened in the Thirties from close blood-to-blood contact, probably resulting from hunting chimps for food, a common practice in central Africa. Leading virologists, notably Beatrice Hahn of the University of Alabama in Birmingham, say the "cut-hunter" theory is the only plausible explanation of how HIV entered the human population.