Report on a landmark conference on the origin of AIDS

Did polio vaccines cultured in chimpanzee tissues trigger the aids epidemic in Africa?

The Royal Society played host to an extraordinary meeting in September 2000, convened to examine the hotly disputed theory that the AIDS epidemic was sparked by trials of oral polio vaccine (OPV) in Africa in the 1950s. The theory claims that SIV (simian immunodeficiency virus), a virus naturally carried by chimpanzees without ill effect, was unwittingly passed to humans in contaminated polio vaccines which were cultured in ground-up chimpanzee kidneys. Once in its new host, the virus mutated into HIV (human immunodeficiency virus) with devastating effect: 50 million people are now infected, most of them in Africa. The evidence which first pointed to such an explanation was the striking correlation between the earliest AIDS cases in Africa and the sites of OPV trials in the former Belgian Congo between 1957 and 1960.

Most scientists now believe that HIV in man was acquired from SIV in chimpanzees; what is disputed is the manner of that acquisition: accidental or iatrogenic (doctor-induced). It is argued that OPV could only have been the source of the infection if the vaccine was prepared using chimpanzee tissues – and the scientists who made the vaccine vociferously deny this crucial point. Professor Hilary Koprowski and Dr. Stanley Plotkin were scathing about such an accusation and brandished sworn statements from former collaborators categorically denying that chimpanzee kidneys were ever used in the manufacture of their vaccine. Investigative journalist and self-taught scientist Edward Hooper is the main proponent of the theory which he has researched for the past ten years and which he describes in his book ‘The River: A Journey to the Source of HIV and AIDS’. He claims chimpanzee tissues were used and that he has eye-witness evidence to prove it. He too produced signed statements from former health workers involved in the project, even including one from the same Belgian vet quoted by Plotkin, saying that ‘untoward approaches’ had been made to former colleagues, urging them to ‘sign letters which would change the content or emphasis of their previous testimony’. This acrimonious impasse may never be resolved.

Smoking gun

Many scientists present at the meeting felt that the evidence against the OPV theory is now sufficient to lay it to rest, including genetic dating techniques which suggest that HIV emerged before the OPV trials, which could not then be held responsible. Hooper does not accept this conclusion, maintaining that this data could also be interpreted in support of his theory. He has also recently obtained what he describes as a ‘smoking gun’: testimonies that chimpanzee kidneys were indeed used by Koprowski and that their use was to be kept secret. These new revelations ensure the case is not yet closed and that further investigations are warranted. They are warranted because the implications, if the theory is correct, are enormous: that medical science may have unwittingly ignited the global pandemic of AIDS: not an accusation to be made or taken lightly.

If we did indeed acquire AIDS from chimpanzees, it was unquestionably through our exploitation of them; either for food, pets or laboratory tools, or even through trapping, or killing them for raiding crops. There was consensus at the meeting that the term ‘cut hunter’ should be replaced by ‘natural transfer’ to reflect the broader scenarios by which transmission may have occured in the mainstream theory to which most scientists subscribe. In fact, the plentiful opportunities for natural transfer to occur are currently giving cause for alarm because chimpanzees and gorillas have recently been found to harbour previously unknown herpes viruses closely related to the human virus which causes Kaposi’s sarcoma, a type of skin tumour, in man. As the timber trade expands into new parts of the West African forest, the loggers, roadbuilders and others start consuming local ‘bushmeat’, including primates. The potential for this to cause another new ‘zoonosis’ (disease from another animal) is a very serious threat.

A distinctive trigger?

There was one other theory presented at the meeting which seems extremely plausible and worthy of further attention and research. The idea is that the massive use of unsterilised needles in African medicine in the twentieth century was responsible for transmitting the virus from an infected person to many other people, prompting the virus to become more virulent: a process known to happen with many other pathogens, for example hepatitis C, which was spread via unsterilised needles in Egypt in the 1950s. The many inoculation campaigns in Africa are a distinctive enough twentieth century phenomenon to explain why the epidemic took off when it did and not before, given that people have had contact with infected chimpanzees for centuries. A distinctive trigger mechanism is rather lacking in the natural transfer theory, which postulates that increased travel in the twentieth century was responsible for spreading the virus to epidemic proportions. This is rather unsatisfactory, however, in view of the slave trade, various wars and colonial upheavals in Africa over the centuries, which involved large movements of people but were not sufficient to ignite an epidemic: we do need an explanation which identifies some peculiarly twentieth century phenomenon as the culprit. If the virus was more easily transmissible – i.e. through airborne droplets, like a cold or flu virus – an epidemic could be spontaneous and we would not need to invoke a trigger. BSE, on the other hand, is not contagious enough to trigger an epidemic without assistance. That assistance was identified as the cannibalistic recycling of infected animal material to naturally herbivorous cattle.

One of the prominent scientists at the meeting, Professor Albert Osterhaus, gave a chilling presentation on newly-emerging viral diseases in man and other animals; asserting that they all became virulent after crossing the species barrier from another animal. He noted that the greatest causes of death over the past century have been AIDS and the three major flu epidemics, all of which, he affirmed, were acquired from animals.

Admitting mistakes

Whether they are right or wrong, proponents of iatrogenic theories of the origin of AIDS, particularly the OPV theory, have an important point to make about the conduct of science and its unwillingness to admit the possibility of mistakes, even though entirely unintentional. Establishing the cause of the AIDS epidemic is no mere academic exercise: it could have implications for the treatment or containment of the disease and it could certainly help us avoid similar catastrophes in the future. We have had plenty of them in the past, including the contamination of yellow fever vaccines with hepatitis B and the infection of millions of people, through polio vaccines, with SV40; a monkey virus which, the evidence suggests, has carcinogenic effects in man.

It is therefore disturbing that scientists and journalists, including Andrew Tyler (he was a Fleet Street journalist for many years before becoming Director of Animal Aid), who have written about the theory over the past decade have been subject to censorship and ridicule.

The fact that this meeting went ahead, despite attempts to scupper it, is a positive sign that some scientists are willing to face potentially unpalatable truths, although others still are not.

Koprowski has been honoured and lauded for what the scientific community regard as his role in the eradication of polio and clearly does not wish to add the accolade ‘father of AIDS’ to his CV. His attitude of contempt for non-scientists and their ‘irresponsible fantasies’ is not helpful to his case, however. Science must demonstrate its integrity or, according to the late Professor Bill Hamilton, co-organiser of the conference, ‘the public will be justified in its disillusionment with science.’

A close call

Whatever the truth of this controversy, the Royal Society meeting was able to conclude, categorically, that injecting any animal material into humans is ‘incredibly dangerous’; that we should exercise much more caution in such practices; and that even if we did not bring the AIDS epidemic upon ourselves then it was a ‘close call’.

The message we should take from this is clear: all vaccines and other biological products for human use should be cultured in human, rather than animal, cells or tissues; that we should not be using animals as ‘living reactors’; and that the potential risks of xenotransplantation are so enormous that it must never be allowed to happen.

My own conclusion is that as long as we have intimate contacts with animals, we will continue to catch deadly diseases from them; whether from farming them, eating them, hunting them, using them as laboratory specimens, or even trading and keeping them as pets. All of these relationships constitute exploitation and therefore ‘homogenic’ may be a more appropriate term than ‘iatrogenic’, ie. human-induced; meaning that through our exploitation of other species we often bring disease upon ourselves.

Kathy Archibald, Animal Aid scientific researcher.