Following our recent report on findings regarding the origins of HIV, aidsmap received the following letter from Edward Hooper, the author of a recently published investigation into the orgins of the HIV epidemic in an oral polio vaccination campaign in the late 1950s.
We reproduce the letter in full in the interests of scientific scrutiny of the statements made last week at the Seventh Retroviruses Conference.
"I am increasingly concerned by some of the statements made, and articles written, about Dr Bette Korber's presentation on the origin of AIDS made at the Seventh Conference on Retroviruses and Opportunistic Infections.
Some reports of Korber's hypothesis, and the alternative hypothesis of iatrogenic (physician-caused) introduction via an experimental oral polio vaccine (OPV), have been accurate and commendably balanced; others less so.
In several articles, Dr Korber is quoted as saying that her results render the OPV theory, as expounded in my book The River, "highly unlikely". I would dispute that statement.
Dr Korber has apparently used "the world's fastest super-computer" to calculate a date of 1930, plus or minus twenty years, for the introduction to humans of the virus which spawned AIDS.
However, Korber's research is theoretical, and based on certain assumptions.
One key assumption is that the transfer of chimpanzee SIV to humans involved a single event, perhaps a hunter becoming infected via the blood of a chimp.
Dr Korber also subscribes to the hypothesis proposed by Dr Beatrice Hahn's group, that the chimp in question was a "central chimpanzee", or Pan troglodytes troglodytes, from west central Africa (Cameroon, Gabon, Equatorial Guinea and Congo Brazzaville). This, too, is unproven.
The troglodytes SIVs are genetically very close, and represent a convincing ancestor, to a minor HIV-1 variant (Group N), which is known to have infected just three persons worldwide. They are also, currently, closer than any other known viruses to the major HIV-1 variant (Group M), which has infected 50 million persons and caused the AIDS pandemic. However - and this is vital - they are not convincingly close."
Hooper also reveals that an expedition is underway to look for other samples of SIV from the region where chimps used in polio vaacine research were first entrapped.
"Many virologists believe that we have not yet sampled from the primate group which is infected with the immediate ancestor to HIV-1 Group M. In particular, there is an almost complete dearth of information from the huge rain forest in the Democratic Republic of Congo (DRC, the former Belgian Congo). To this end, an expedition has recently gone out to Kisangani, in the "rebel"-held area of DRC, to collect faeces for SIV analysis from the eastern chimpanzee (Pan troglodytes schweinfurthii) and the pygmy chimpanzee or bonobo (Pan paniscus).
Between June 1956 and February 1958, nearly 400 eastern chimps and bonobos were used for polio research at Lindi Camp, near Kisangani. About 100 died from natural causes. As research on the remaining 300 animals was completed, they were sacrificed in groups, and such materials as kidneys and blood were recovered from them. It is these materials which, I believe, were later used to produce certain batches of CHAT, an experimental OPV that was administered to over a million Africans in present-day DRC, Rwanda and Burundi between 1957 and 1960.
CHAT was "fed" at 28 different venues, and 64% of the first cases of AIDS in Africa through 1980 came from the vaccinated towns and villages. So did 82% of the earliest samples of HIV-1-positive blood in Africa, again through 1980. None of these early instances of AIDS or HIV-1(M) infection came from troglodytes territory in west central Africa.
Hooper also challenges assertions by scientists such as Professor Robin Weiss that the same oral polio vaccine was tested in Europe and America.
"CHAT was also fed in Europe and America (including to over seven million Polish children), but these campaigns employed different batches and pools of vaccine from those used in Africa."
Not having had a chance to study Dr Korber's methodology (as yet
unpublished), it is difficult to comment on her dating, other than to point out that she herself has acknowledged that her methods do not allow for recombination between viruses, which is now known to play a major role in lentiviral evolution. Allowing for this might well bring her introduction date nearer the present.
However, even if one accepts her "start date" of 1910-1950, this in no way falsifies the OPV theory. It simply requires that the last common ancestor, the virus which gave birth to the Group M pandemic, would be a virus which infected a specific chimpanzee (schweinfurthii or paniscus), rather than one which had just crossed from a troglodytes chimp to a hunter.
The OPV hypothesis is no more, and no less, "unlikely" than the hypothesis of Korber and Hahn, which requires the SIV-infected chimp hunter from Cameroon or Gabon to infect nobody locally, but to emigrate to the Belgian Congo where, directly or indirectly, he would infect others, who would themselves need to be located in geographically diverse parts of the Congo, Burundi or Rwanda, in order to create the "starburst" of Group M subtypes. This would require a rapid spread of the virus (and probably the disease) in
the Belgian Congo between the thirties and fifties. We see no evidence of either.
Dr Stanley Plotkin, formerly of the Wistar Institute in Philadelphia, where CHAT vaccine was originally made, claimed at a news conference after Korber's presentation that "no chimpanzee tissue was used to make the oral polio vaccine". I would question whether he is in a position to give such an assurance. During an interview in 1994, Dr Plotkin told me that CHAT had already been developed by the time he arrived at the Wistar in August 1957.
He also said that, although he had been involved with small-scale American trials of CHAT, he did not recall having been involved with the Congo trials of 1957-8, or with the Ruzizi trial (in Congo and Burundi) that ended in April 1958. The 750,000 doses of CHAT fed in Africa after Ruzizi appear not to have been manufactured at the Wistar, but at the Rega Institute and RIT vaccine house in Belgium. Remarkably, it seems that no records about the methods used to produce CHAT - either in the US or Belgium - still exist.
The jury is still out about how AIDS began. We need a lot more information, including further isolates of chimp SIV, before anyone can confidently claim that their hypothesis of origin has won the day.