Polio vaccine to be tested for possible link to AIDS

Some hold theory that contaminated tissue from chimpanzee was used


Scientists in three laboratories in the United States and Europe are preparing to test samples of an experimental polio vaccine stored for more than 40 years to determine whether it might have inadvertently been the spark that ignited the worldwide AIDS epidemic.

The scientists will be testing a highly controversial and seemingly far-fetched theory that holds that an oral polio vaccine, used in vaccine trials in what was then the Belgian Congo in the 1950s, might have been made with chimpanzee tissue that might have been contaminated with an ancestor of the AIDS virus.

The Wistar Institute, a research center in Philadelphia, made the vaccine and has kept a few drops of material used in its preparation frozen since 1957. After the AIDS and polio vaccine theory was raised in 1992, Wistar appointed an independent committee of scientists to look into the questions. The committee recommended testing the vaccine. But Wistar never carried out the tests, it said, because of a lack of scientific interest.

Now, responding to a book, "The River," by Edward Hooper, an English journalist, published last fall by Little Brown, the institute has reactivated the panel and is having the tests performed. Findings are not expected before June.

This time, many laboratories want an opportunity to test the material. Medical journals have asked for rights to publish the findings even before samples are shipped to participating laboratories.

"Labs are drooling over doing this, because it's a sure publication in a high-profile journal," said Dr. David Ho, who directs the Aaron Diamond AIDS Research Center in Manhattan and is a panel member.

Chances are slim that the new tests will conclusively prove or disprove the theory, partly because no one can be sure that what is to be tested actually represents the vaccine that was used in what is now Congo. If there was contamination, it might have affected only part of the vaccine, all of which was used in the trials.

The experimental vaccine was never marketed and is not the one that has been used to nearly eradicate polio.

On Feb. 29, the Wistar Institute transferred the remaining polio vaccine to an independent laboratory that will prepare and divide the material for distribution to three laboratories and a fourth if there is enough material, Dr. Clayton A. Buck, the institute's chief administrative officer, said in an interview.

By early next month, the material will be carried by hand to the participating laboratories. There, scientists will begin a number of tests aimed at detecting any AIDS-related virus and determining which kind of animal tissue was used to make the vaccine. The focus is on tissue from chimpanzees because they carry a simian virus that is believed to be the ancestor of HIV-1, the virus responsible for the overwhelming majority of AIDS cases in the world.

All samples will be coded so that the scientists doing the tests will not know whether the samples represent the vaccine or something else being used as a quality control. The code, known only to the independent laboratory and the committee, will be broken after the scientists complete the testing.

The AIDS virus has infected 30 million people, making it one of the worst epidemics in history. The contaminated vaccine theory is based entirely on circumstantial evidence. But if it is correct, AIDS would also be the worst medically caused epidemic in history. With so little evidence but so much at stake, scientists are arguing passionately about the theory's plausibility. Learning how the AIDS epidemic arose could prevent similar epidemics.

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