Chimpanzees, HIV and polio vaccines

 

(September 2000)

 

While medical scientists have no problems identifying and explaining the origins of HIV in the Simian Immunodeficiency Virus (or SIV), there has been a long-standing theory, almost in the conspiracy theory category, to the effect that the introduction of the virus into humans came from contaminated polio vaccine used in Africa in the 1950s. This theory has been pushed hardest in a recent book by Edward Hooper, called The River, but which he first put forward in an article in Rolling Stone in 1992.

 

According to Hooper, an oral polio vaccine prepared at The Wistar Institute and administered to people in the then Belgian Congo in the late 1950s provided the route of transmission for HIV or HIV-related viruses from chimpanzees to humans. While this is a feasible pathway for transmission, so is contact with chimpanzee meat by hunters, so the real test comes down to any evidence of contamination in surviving samples of the vaccines. In fact, in The River, Hooper called for tests to be carried out on samples of the vaccines.

 

Tests have now been carried out at three independent laboratories on 1950s-era polio vaccine samples from The Wistar Institute, and they have not found any traces of SIV, HIV-1, or DNA indicating that chimpanzee cells were used to prepare the vaccine. The finding was announced at a Royal Society meeting in London entitled 'Origins of HIV and the AIDS Epidemic.'

 

The key to Hooper's case was that chimpanzee cells had been used in the preparation of the vaccine. In fact, the tests identified DNA from only one species of primate, the Asian macaque monkey, not the chimpanzee, in the Wistar vaccine samples. This bears out the repeated assertions by the two former Wistar scientists who developed the vaccines, Dr. Hilary Koprowski and Dr. Stanley Plotkin, that no chimpanzee cells were used in the preparation of the vaccines.

 

For the tests, the Wistar vaccine samples were subdivided and coded by Dr. Vincent Racaniello, Columbia University College of Physicians and Surgeons, New York. Sets of the samples were then delivered to the three independent laboratories that had agreed to perform the tests, so that the laboratories had no idea which samples were which.

 

The Wistar Institute covered costs of about $20,000 associated with the testing, with the participating laboratories contributing additional materials and services estimated to approach $100,000 in total. Hooper, who did not contribute to the costs, was reported in Nature to be unmoved, claiming that he had found a 'smoking gun,' individuals who had confirmed that chimpanzee kidneys were being sent to the United States and Belgium in the 1950s, and claiming also that different batches of the vaccine were made in different laboratories, so that the wrong batches may have been tested.

 

Plotkin was quoted by Science as saying, "I'm sure Mr. Hooper will be disappointed by the results of this meeting. There is no gun. There is no bullet. There is no shooter. There is no motive. There is only smoke created by Mr. Hooper." Plotkin was referring here to his efforts in the past year in tracking down former colleagues, and gathering 16 written statements testifying that these people had never worked with chimpanzee cells.

 

One result of his campaign, as reported in Nature, is that the Catholic church in Kenya is now advising parents against polio immunization on the grounds that there are risks of contamination. This is unfortunate, as even Hooper does not claim that the contamination continues to this day. So, while Hooper stubbornly urges that, "We should be trying to find the truth and learn from the truth," the lesson he is trying to force on scientists is one they have already learned.

 

The odd point here is that the scientists could not have been blamed even if they had inadvertently set loose the virus in humans, as they had no way of knowing about this in advance. So, while Hooper claims not to be seeking a scapegoat for AIDS, this claim does not really stand up under scrutiny. And it is not surprising that some of the scientists became rather heated and engaged in personal attacks on Hooper as a man that several of them accused of misrepresenting them.

 

There was a return to science after the chair threatened to close the meeting, and Bette Korber, a geneticist at Los Alamos National Laboratory expanded on her model for the spread of HIV, which sees it infecting humans somewhere between 1915 and 1941, and spreading slowly until there were thousands of people infected. Two other studies, one from Belgium and one from Britain, gave similar timelines. (For a discussion of why the disease may have spread slowly at first, see Logging and the spread of new diseases, this month.)

 

All Hooper's campaign can achieve, apart from increased sales of his book, is a squandering of research money to defend scientists against unsubstantiated claims and the possible deaths of children who have not been vaccinated because of fears sparked by his claims.