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.