Polio vaccine cleared of Aids link

By STEVE CONNOR

LONDON - Three independent laboratories have failed to find any evidence that an experimental polio vaccine used in the Belgian Congo in the 1950s sparked the Aids epidemic, but the findings are unlikely to end the controversy.

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

Dr Claudio Basilico, chairman of microbiology at New York University Medical Centre and head of Wistar's independent scientific committee investigating the polio trials, told the Royal Society in London that the tests failed to find any 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.

"There is nothing in the results from these tests to support the theory that HIV entered the human population during the late 1950s polio-virus clinical trials in Africa," Basilico said.

"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.

"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, the acting director of Wistar, repeated its position that the polio vaccine was made using Asian monkeys, which are not naturally infected with SIV.

"We trust that 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," he said.

But Edward Hooper, the author of a book claiming that Wistar's polio vaccine was made with contaminated chimpanzee tissue, denounced the latest findings as irrelevant.

In response to claims that key witnesses of his hypothesis have retracted statements about the production of polio vaccine using chimp tissue, Hooper said representatives of Wistar had extracted the retractions under duress.

"They were given pre-printed statements to sign with their name written in pencil at the bottom."

Aids scientists accept that 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 1930s and was the result of close blood-to-blood contact, probably resulting from hunting chimps for food, a common practice in central Africa.

Hooper's alternative hypothesis has been difficult to prove but equally difficult to disprove. Nevertheless, leading virologists who have studied HIV evolution are convinced that the "cut hunter" theory is the only plausible explanation of how HIV entered the human population.

- INDEPENDENT