Scientists from the Wistar Institute conducted polio-vaccine tests in the Congo region in the late 1950s. That, a British journalist believes, is when the chimpanzee virus was introduced in humans. The scientists say that's not true.
Philadelphia Inquirer, Monday 8 November 1999
This article is part of a
collection of material on
Polio vaccines and the origin of AIDS
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After years of speculation, scientists now agree that the AIDS pandemic began when an AIDS-like virus from a chimpanzee, probably in west-central Africa, jumped species and infected a human being sometime around the middle of this century.
What's still a mystery, however, is exactly how that cross-species jump occurred.
The most popular theory in scientific circles is that the chimp virus entered the human race when an African hunter in a remote area butchered a chimpanzee for food and accidentally cut himself, exposing his own blood to infected chimpanzee blood.
But there's a competing hypothesis: The chimp virus may have been unwittingly introduced into humans when scientists from Philadelphia's Wistar Institute conducted mass human trials of an experimental polio vaccine in the former Belgian Congo and nearby countries during the late 1950s.
That hypothesis, which has been kicking around on the edges of mainstream science for more than a decade, is the subject of a new book, The River: A Journey to the Source of HIV and AIDS, by British journalist Edward Hooper.
The 1,070-page work has received mixed reviews in academic medical journals and has drawn the interest of AIDS activists.
Hooper has asked activists not to politicize the issue. He worries that demonstrations might jeopardize the book's chances of prompting a thorough investigation into the possible connection between the polio-vaccine trials and today's AIDS epidemic.
"We can't roll back the years and make AIDS go away," Hooper, 48, said in a recent interview. "But if, as I propose, a dreadful, tragic mistake has been made, we can at least learn from that mistake."
Both Hilary Koprowski, former director of Wistar, and his former deputy, Stanley Plotkin, describe the book as the stuff of science fiction. "If this book were written 400 years ago, he [Hooper] would invoke alchemy and magic," Koprowski said.
Most AIDS experts regard Hooper's hypothesis as theoretically possible but highly improbable.
Max Essex, a professor of virology and chairman of the Harvard AIDS Institute, called the theory interesting but unsupported by available scientific evidence. He added that the book could have "quite unfortunate" consequences.
"African people of influence could use this as a possible scapegoat explanation for the origin of the epidemic, making cooperative efforts [with the West] less possible," he said.
For example, collaborative efforts are under way between researchers in the United States, Uganda, Kenya and South Africa to develop an AIDS vaccine that might stem the mounting human and economic toll that AIDS is taking in Africa. Hooper's book, Essex fears, could thwart such efforts.
Drawing on a mound of circumstantial evidence that he gathered in hundreds of interviews and thousands of medical papers, Hooper posits that some batches of Wistar's polio vaccine were accidentally tainted with the chimp form of the AIDS virus, known as SIVcpz, picked up in the manufacturing process.
Monkey kidney cells - not chimp cells - were routinely used to grow the polio virus during the race to develop polio vaccines in the 1950s.
But Hooper points out that Wistar and its Belgian colleagues established a chimpanzee colony - the Lindi Camp - just outside the present-day Kisangani in central Congo, headquarters of the polio campaign.
The camp, Hooper alleges, not only provided chimps on which to test the vaccine, but also supplied the scientists with chimp kidneys to grow the vaccine virus back in Philadelphia and possibly in Belgium and Congo as well.
Between 1957 and 1960, a million people, mostly children, in what is now Congo, Rwanda and Burundi, got the polio vaccine developed by Koprowski, Hooper says.
A few children, Hooper suggests, likely became infected with the chimp form of AIDS when contaminated polio vaccine was squirted into their mouths. The AIDS-like virus might have been taken up by cells on the tonsils and gotten into the bloodstream.
As these infected children grew up, Hooper speculates, they could have passed the virus on to others through sexual contact, possibly triggering the AIDS pandemic that has stricken more than 33 million people worldwide.
Of the 39 confirmed cases of HIV-positive blood collected in Africa before 1981, 87 percent came from towns where Koprowski's polio vaccine was administered, Hooper says. One hundred percent, he says, came from places within 100 miles of the vaccination sites.
While acknowledging that he has found no smoking gun, Hooper believes that the geographic correlations are more than coincidental.
"Nobody is accusing Wistar of deliberate wrongdoing," he said. "They were involved in trying to develop a vaccine to save millions of lives. But the anecdotal and circumstantial evidence is now highly persuasive."
Both Koprowski, now a professor at Thomas Jefferson University, and Plotkin, a vaccine consultant to Pasteur Merrieux Connaught, vehemently deny that any chimp kidney tissues were used to make the polio vaccine.
The vaccine was made in the kidneys of rhesus macaque monkeys, supplied by a dealer in New York or New Jersey, and shipped to Wistar from India and the Philippines, Koprowski said in an interview last week.
Asian macaques are not naturally infected with SIV and the kidney cells of these monkeys do not support the growth of either SIV or HIV, scientists agree.
Koprowski said the chimps at Lindi were used to study the safety and effectiveness of the experimental vaccine.
He said the laboratory notebooks, documenting exactly how the African version of his vaccine was grown in monkey kidney tissue, were kept by his former associate, Thomas Norton, who is deceased.
Koprowski and Plotkin said that searches of Wistar files, Plotkin's garage and Koprowski's personal papers had failed to turn up the notebooks or other documents that could prove that monkey kidneys - not chimp kidneys - went into making the vaccine.
Widely regarded as eminent scientists, both Koprowski and Plotkin say they have been stung by Hooper's allegations, which they contend have damaged their professional reputations.
To help settle the controversy, Plotkin, the former chief of infectious disease at Children's Hospital of Philadelphia and inventor of the rubella vaccine, is seeking two independent laboratories to test what is believed to be the one remaining sample from which the vaccine used in Africa was made.
That sample, now under lock and key at Wistar's research facility at 36th and Spruce Streets, could be tested for any traces of SIV, HIV or the genetic material of the primate species used to culture the virus.
Clayton A. Buck, a cell biologist and chief administrative officer of Wistar, said he would cooperate in having the sample tested. "I feel confident that it's going to turn up negative" for AIDS-related viruses, he said. "But it would be good to get the results out there just so the public could have the information."
In 1995, Swedish scientists tested some actual vaccine left over from the African trials - and came up with no evidence of either SIV or HIV.
For Wistar, Hooper's book reopens a controversy brought to light by a 1992 Rolling Stone magazine article.
That article prompted Wistar to appoint an expert panel of outside scientists to examine the polio vaccine-AIDS theory.
The panel's 1992 report concluded "with almost complete certainty" that the polio-vaccine trials were not the origin of AIDS.
Its certainty was based on one key fact: That the earliest documented case of HIV-1, the type of HIV that set off the global pandemic, was a 25-year-old merchant marine from Manchester, England, who died of AIDS in 1959.
The sailor, according to the medical journal the Lancet, had traveled to Africa in 1955 but had returned to England before the Wistar polio trials had begun in Congo in 1957. Therefore, the panel reasoned, the vaccine trials could not be blamed for his HIV infection.
But in 1995, David Ho, head of the Aaron Diamond AIDS Research Center in New York, discovered that tests of the sailor's blood had been tainted and that he had never been infected with HIV. Moreover, he had never traveled to Africa.
With the sailor's case thrown out, the polio-vaccine hypothesis was at least possible.
But there is mounting scientific evidence that those polio-vaccine trials were not responsible for the transfer of an AIDS-like virus from monkey to man.
Last year, Ho's lab confirmed the existence of HIV in a 1959 blood sample from Kinshasa, the former Leopoldville, whose authenticity previously had been in doubt. That sample is now the earliest known case of AIDS.
By comparing the genetic sequences of that sample with the sequences in HIV subtypes from around the world, Ho was able to construct the family tree for HIV.
Ho placed the virus from the Leopoldville man close to the base of the tree, near to the time when the virus jumped from chimp to man. By Ho's calculations that occurred around 1950 or so, well before the Wistar polio-vaccine trials began.
Early next year, that date of origin is expected to be pushed back even further when Bette Korber, a molecular immunologist at the Los Alamos National Laboratory, publishes yet more refined calculations of when AIDS got started.
In an interview, she declined to reveal her findings, but said they would show there is "no way" the African polio trials of the 1950s could have triggered the AIDS pandemic.
In the meantime, research by Beatrice Hahn, a virologist at the University of Alabama at Birmingham, is showing that AIDS stemmed from a chimpanzee subspecies found in west-central Africa, but not in Congo. She bases her conclusion on genetic testing of the four samples of SIV isolated from chimps.
It's quite possible, Hahn theorized, that the chimp virus, once it entered a hunter in west-central Africa, was passed on through sex or blood to other people who eventually traveled about 150 miles south to the bustling city of Kinshasa.
From there, she said, the virus could easily move up the Congo River to the interior, spreading among the thousands of people who traveled those waters, especially in the 1950s, after the Belgians eased travel restrictions on the river.
However, she concedes that her findings are based on small numbers of chimpanzees kept at sanctuaries because of the difficulty of getting blood samples from chimps in the wild.
Hahn now plans to collect urine and fecal samples from wild chimps for genetic analysis and, hopefully, more clues about the rise of HIV.
Hahn said some adherents of Hooper's theory recently consulted her about tracking wild chimps near the old Lindi Camp. They hope, of course, to find an SIV sample that would poke a gaping hole in the theory that Hahn has constructed.
"I'm fully cooperating," Hahn said. "I'd just love them to prove me right."