THE claim that doctors in Central Africa ignited the AIDS pandemic in the
late 1950s by testing polio vaccine contaminated with the chimpanzee version of
HIV came under heavy fire from scientists this week.
At a charged meeting at the Royal Society in London, Claudio Basilico of the
New York University School of Medicine announced the results of independent
tests on surviving samples of the vaccine. He said researchers found no trace of
HIV, SIV (the primate version) or chimp DNA. The tests, he said, revealed no
evidence that medical treatments gave rise to AIDS.
The CHAT vaccine was developed in the late 1950s in what is now the
Democratic Republic of Congo, by doctors including Hilary Koprowski and Stanley
Plotkin from the Wistar Institute in Philadelphia. The researchers insist that
they used only monkey tissue to grow the vaccine. But in his controversial book
The River, Edward Hooper last year claimed that the use of chimp kidney
tissue in the preparation of the vaccine allowed SIV to cross from apes to
people鈥攁nd created AIDS.
Advertisement
Hooper鈥檚 theory caused such an uproar that the Wistar Institute asked three
independent laboratories to test samples of the 40-year-old vaccine. But at the
Royal Society meeting, Hooper immediately dismissed Basilico鈥檚 tests as
irrelevant because, he said, the key batches of vaccine, which he claims were
produced with chimp kidney tissue, no longer exist.
There followed a heated exchange with Plotkin over whether chimpanzees had
actually been used in preparing the vaccine. Hooper produced witness accounts.
Plotkin said he had retractions from the same people.
Kevin De Cock of the Centers for Disease Control and Prevention in Atlanta, a
specialist in the epidemiology of HIV, dismissed Hooper鈥檚 claim that there is a
geographical link between the first AIDS cases and the sites of the vaccine
tests. 鈥淚t is impossible to conclude when or where HIV emerged,鈥� De Cock said.
The established view is that humans became infected with SIV early in the 20th
century, after coming into contact with infected blood while butchering
chimps.
A new mathematical model also casts doubt on vaccine as the source. Bette
Korber of Los Alamos National Laboratory in New Mexico told the meeting that
mutation rates suggested that a key subtype of HIV-1, which accounts for most
AIDS cases in Africa, probably crossed from animals to humans around 1930.
AIDS researcher Preston Marx of the Tulane Regional Primate Research Center
in Louisiana, who does not agree with Hooper鈥檚 theory, nevertheless dismissed
the use of models such as Korber鈥檚. 鈥淭hese assume there is no natural selection
in the virus. I think they鈥檙e untenable.鈥�
Marx also presented a new explanation for how the two biologically and
geographically distinct types of HIV arose: HIV-1 in Central Africa and HIV-2 in
West Africa. He says that millions of people were injected to treat syphilis and
malaria鈥攐ften with reused and unsterilised needles. Hence the two strains
of HIV, which are thought to have evolved from versions of SIV in different
primates, would have been able to mutate and spread quickly as the virus passed
from patient to patient.