Press Conference Statement by Stanley Plotkin MD

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Embargoed until 9/11/00 15:45 BST

Mr. Hooper has presented the hypothesis that CHAT, a type 1 polio vaccine developed in the US by Dr. Koprowski, and tested there, in Europe and in the former Belgian Congo in the late 50s, was contaminated with HIV. He is not the first to present that hypothesis, and many scientists, including myself, (as I was involved in those tests) have spent a great deal of time researching the origin of the HIV viruses. During the last year, I have studied Mr. Hooper's book and have done an extensive reconstruction of what actually happened 40 years ago, based on documents and testimony. I also did everything possible to facilitate the PCR tests on the vaccine samples conducted by Wistar.

We now know conclusively that the events postulated by Mr. Hooper did not happen for three reasons:

First, chimpanzee tissues were not used to make CHAT. Sixteen scientists with first hand knowledge say no, supported by documents of the time. In particular, the three key people in the three laboratories where it is said that vaccine was made in chimpanzee cells are at this meeting to testify. In fact, the vaccine was made in macaque monkey cells and there is absolutely no concrete evidence that chimp tissues were used. The logistical problems of getting chimp tissues from the Congo to the US or Europe means that many people would have been involved, and it is inconceivable that no one would remember it.

Second, even if chimp tissue had been used, the work of three laboratories tells us that HIV started spreading in about 1930, long before the CHAT vaccination in the Congo. Moreover, as Dr. Beale will show later today, even if SIV contaminated cells had been used, they would not have survived the preparation of polio vaccine.

Third, even if the vaccine had been contaminated with SIV, the first cases of AIDS are not associated with CHAT vaccination. Mr. Hooper made significant mistakes in

reporting where vaccination was done, and in general, the epidemiology of AIDS is consistent with sexual transmission but does not agree with the polio hypothesis.

I'm sure Mr. Hooper will be disappointed by the results of this meeting, but it is now time for all of the scientists present to reassure the public about the safety of vaccination in general and to move on to the important issues of how to prevent AIDS through vaccine development.

Stanley A. Plotkin, MD


Backgrounder For Press From Stanley Plotkin MD

Embargoed until 9/11/00 15:45 BST

Edward Hooper has hypothesized that a type 1 oral polio vaccine called CHAT, developed by Dr. Hilary Koprowski at the Wistar Institute in Philadelphia, was contaminated with a simian relative of HIV(SIV) that infected vaccinees and transformed itself into the HIV we know today. An essential part of his hypothesis is that cells from chimpanzee kidney were used to make the vaccine, as only the chimpanzee SIV is close enough to have mutated to the human virus.

The contamination of the vaccine, so the theory goes, happened in Philadelphia, Belgium or Kisangani in the then Belgian Congo, and the transfer to humans occurred supposedly during vaccination campaigns conducted in the Congo between 1957 and early 1959.

His evidence for this is the existence of a chimpanzee colony near Kisangani in the Congo, which was the centre for experimental work on a variety of viruses, and the alleged recollection of certain individuals with only peripheral knowledge of the colony that chimp tissues may have been sent elsewhere. Hooper also contends that early cases of AIDS in the Congo all occurred within 175 miles of CHAT vaccination sites.

As I was a Fellow in the Koprowski laboratory at the time, and a participant in the Congo trials, I have thoroughly investigated Mr. Hooper's claims.

First, 16 persons with first- hand knowledge of the situation at the Wistar Institute, at the RIT Labs in Belgium, and at the Provincial Laboratory in Kisangani, deny categorically that chimpanzee cells were ever used to make vaccine.

Second, contrary to his statements, contemporaneous documents show that macaque monkey, and not chimpanzee cells were used to make the vaccine.

Third, the transport of chimp kidneys to the US or to Europe would have been expensive, logistically difficult and unnecessary in view of the easy availability of monkey tissues.

Moreover, several people quoted by Mr. Hooper regarding transport of chimp kidneys deny they ever said what was attributed to them.

Fourth, the virology laboratory at Kisangani was primitive at the time and incapable of producing vaccine in any cell culture, let alone from chimpanzee.

Fifth, even if the chimps had been used, those housed in the Kisangani colony were almost all young and unlikely to carry SIV since they weren't yet sexually active. Also, to date evidence from the laboratory of Beatrice Hahn shows that the SIV strains most closely related to HIV- 1 have been recovered to the West of the Congo.

Sixth, actual experiments carried out in several laboratories showed that even if kidney cells had been contaminated with SIV, the virus would not have survived vaccine preparation.

Seventh, early eases of AIDS in the Congo were detected in cities, where sexual transmission was more likely and where medical surveillance was better.

Eighth, key coincidences cited by Hooper of cases occurring in proximity to vaccination sites are based on mistakes concerning where vaccination was done. Other coincidences linking the two by 175 miles are specious.

Ninth, vaccination trials conducted in the United States and in Europe with the same lots of vaccine did not result in cases of AIDS.

Tenth, phylogenetic data from three other laboratories place the origin of HIV- 1 spread in the 1930s, well before CHAT vaccination.

Although science can never prove a negative, I conclude from the above that the hypothesis of The River is highly improbable, and does not require further investigation.

Much more important issues such as developing vaccines for the prevention of AIDS deserve our attention.

Stanley A. Plotkin, M.D.
Emeritus Professor, University of Pennsylvania, Philadelphia,
Emeritus Professor, Wistar Institute, Philadelphia, Pennsylvania
4650 Wismer Road
Doylestown, PA 18901
Tel: (215) 297- 9321
Fax: (215) 297- 9323
Stanley.Plotkin@Aventis.com