Professor Robin Weiss, one of the organisers of the Royal Society conference on the origins of HIV and AIDS, recently declared the oral polio vaccine (OPV) theory of origin dead. "Some beautiful facts have destroyed an ugly theory", he wrote.
He is wrong. Not one relevant fact (beautiful or otherwise) has been produced to refute the OPV theory. The conference proceedings contain a wide range of alternative hypotheses and arguments, but each has its own flaws or limitations. The debate is still far from settled.
This is only underlined by Dr Plotkin's two papers, which contain numerous allegations that I have misquoted or misrepresented witnesses. However, in every such instance, I stand by what I have written. The persons concerned were quoted accurately, fairly and in context - and I have the tape recordings to prove it. It is for others to decide why some interviewees modified their statements when approached by Dr Plotkin and his team.
There has been a disturbing tendency on the part of many of the scientists involved in the "origins of HIV and AIDS" debate, including Professor Robin Weiss, one of the surviving organisers of the Royal Society meeting on this topic, to prematurely pronounce the oral polio vaccine (OPV) theory of origin disproved or deceased.
This tendency, which first became apparent during the meeting itself, became rather more apparent during the recent burst of publicity orchestrated by those twin pillars of the scientific establishment, Nature and Science.
In late April, 2001, Professor Weiss announced in Nature that "some beautiful facts have destroyed an ugly theory". In Science meanwhile, journalist and AIDS specialist Jon Cohen paraphrased the Munchkin coroner in "The Wizard of Oz", concluding "the theory is not only merely dead, it's really most sincerely dead".
These claims, quite simply, are incorrect. Not one single relevant fact (beautiful or otherwise) has been produced to refute the OPV theory. And wishing someone (or, in this case, something) dead does not make it so.
Let us look a little more closely at the "facts" on which Weiss and Cohen base their arguments. A number of selected samples of American-made CHAT oral polio vaccine from the 50s and 60s have been released for testing, and found not to contain HIV, SIV or chimpanzee DNA. However, as I pointed out repeatedly at the Royal Society conference, many of the one million doses of CHAT which were fed in the Belgian territories of central Africa during the 1957-1960 period were made in Belgium, not the USA. Even more importantly, there is growing historical evidence that other batches of CHAT were produced locally in Africa itself.
It now becomes apparent that the CHAT pool numbers (such as 13 and 10A-11) are irrelevant, because different batches of each pool were made in different laboratories. (Unfortunately, Professor Weiss confuses the terms "pool" and "batch" in his Nature commentary.) It is the questions about where these batches of CHAT were made, and where they were fed, that are crucial. So far only samples of American-made vaccine have been tested - and, despite claims to the contrary, there is no evidence to suggest that any of the recently tested samples were prepared for use in Africa.
The vaccine-makers claim that the CHAT pool 13 fed in the Congolese capital, Leopoldville, was made in the USA. However, these claims are undermined by the memory of Professor Henry Gelfand, who hand-delivered the vaccine from Brussels to Leopoldville, and who told me he was "99.9% certain" that it was made in Belgium. And they are further, crucially, undermined by the testimony of the late Dr Gaston Ninane, who was based at the medical laboratory in Stanleyville in the late 1950s, and who helped conduct many of the CHAT vaccinations in Africa. In the course of several interviews, Dr Ninane repeatedly told me that because of the difficulty of keeping live polio vaccine sufficiently cool during the long journey from the US to the Congo, only the very earliest CHAT vaccine batches fed in Africa came from the United States.
Much as I welcome the fact that any CHAT samples have been released (even after seven years of delay), the tests conducted to date do not prove, or even suggest, that the CHAT vaccine fed in Africa was HIV-free. The tests, quite simply, have been conducted on the wrong samples. The extravagant claims now being made for the testing suggest that the main purpose of the exercise was to convince the world that CHAT vaccine has been "exonerated". The testing, in short, was essentially a public relations exercise.
Secondly, contributors like doctors Sharp, Korber and Holmes propose that the Most Recent Common Ancestor of the AIDS pandemic (HIV-1 Group M) viruses seen today existed in or around 1931 (nearly 30 years before the polio vaccine trials), and that the various Group M subtypes existed first in humans, not chimps. This, they claim, "disproves" the OPV theory, or renders it "untenable". The data produced by these geneticists are useful, but I am surprised by the extrapolations they make from them. It is important to bear in mind that their work is theoretical, not empirical. In reality, the dating work is supported by just two partial sequences from before 1980, one of which (the small fragment of ZR59, allegedly originating from 1959) comes from a serum sample of uncertain provenance. Furthermore, phylogenetic analysis such as this does not make proper allowance for the possibility of recombination, one of the two ways in which lentiviruses like HIV evolve. A growing number of geneticists believe that if recombination occurred at or near the beginning of HIV-1 Group M (as might have happened, for instance, in a polio vaccine tissue culture), then it would both be impossible to detect by modern methods, and would invalidate attempts to date the Group M family tree. The phylogenetic work by Sharp, Korber and Holmes can be used to advance a hypothesis about the age of HIV-1 Group M, but it cannot prove a hypothesis like "cut hunter/natural transfer", or disprove a hypothesis like "OPV/AIDS".
The other alleged disproofs of the OPV theory, such as Professor Hahn's insistence that the ancestor of Group M comes only from chimpanzees from west central Africa (not those from the former Belgian Congo), or Professor Beale's assertion that a simian immunodeficiency virus from an infected chimpanzee could not survive through to a polio vaccine made from that animal's kidneys, are also unproven hypotheses. In the first case, the available data is inadequate to make such a claim; in the second, nobody has yet done the proper experiments.
Similarly, the contributions by doctors Plotkin and Koprowski (including the additional article which Plotkin has been allowed to include in the published proceedings, entitled "Postscript relating to new allegations made by Edward Hooper ...") are based largely on assertion, and contain many provable inaccuracies. Indeed, Dr Plotkin in particular gives the unfortunate impression that he is trying to discredit the proponent of the OPV theory as much as the theory itself. Of special note are his several claims that persons quoted in The River, or in my presentation to the Royal Society, either did not say what I claim they said, or were misrepresented. However, in every instance I stand by what I have written. The persons in question were quoted accurately, and in context - and I have the tape recordings to prove it. It is for others to decide why some interviewees modified their testimonies when approached by Dr Plotkin and his colleagues.
Against these various alleged disproofs must be set the evidence for the OPV theory. Central to this evidence is the finding that over 84% of the earliest examples of HIV-1 Group M in the whole of Africa (and therefore the world), and 70% of the earliest African instances of Group M-related AIDS, come from the same towns and villages where CHAT vaccine was fed in 1957-60. Despite the various claims that have been made, supporters of the "cut hunter/natural transfer" theory have not yet managed to propose a persuasive alternative explanation for the striking distribution of these first recorded examples of virus and disease.
In addition, there is a growing body of historical and scientific evidence to support the OPV theory of origin, most especially new evidence about the vast numbers of chimps which were sacrificed (and had their organs removed) by the scientists who were developing and testing CHAT, and about CHAT vaccine being made locally in the then Belgian colonial territories of central Africa.
To me, the most striking thing about this debate thus far is the number of scientists who claim to have disproved OPV, but whose evidence, when examined, is found to rely heavily on conjecture and "plain personal prejudice". This is regrettable, even if it perhaps partly derives from an understandable desire to protect the good name of vaccination.
An experimental OPV may have sparked the AIDS pandemic, or it may not have, but nobody is yet in a position to pronounce. What we have seen, however, is an unsettling eagerness by many scientists to persuade people - at all costs - that the debate is over. This suggests that any alleged "disproofs" which may emerge in future should be viewed with a healthy degree of scepticism - unless the evidence presented is absolutely watertight.
Professor Weiss and Mr Cohen like to paraphrase famous lines, so let me also try my hand, using Shakespeare and Mark Twain as models. The gentlemen do protest too much, methinks. Reports of the theory's death have been greatly exaggerated.
The above quotation about "plain personal prejudice" came from Professor Robin Weiss, in the "Concluding Remarks" which he delivered to the Royal Society meeting last September. This welcome admission that his views might be prejudiced came at the end of a speech which had contained some vitriolic assertions about the OPV theory.
In marked contrast to his comments that day, and to his claims in Nature in April this year that the OPV theory had been "destroyed", is the far more balanced and conciliatory summing-up which he has now contributed to the published proceedings of the Royal Society meeting. I welcome Robin Weiss's reassessment of his position, in particular his acknowledgement that the OPV theory has not been refuted - and that this is still an ongoing debate, to which further salient contributions are likely to be made in the future.
EH 14 June 2001