Kate Wong Scientific American
Researchers
have long puzzled over the origin of AIDS. Most hold that it arose
when a simian version of HIV jumped to a human, probably in West
Africa in the early- to mid-20th century, and a number of theories
have emerged to explain just how it made that jump. None have
been proved, but the list of ideas may be getting shorter. New
reports published this week in Nature and Science may finally
refute one particularly controversial proposal.
The theory
in question emerged in 1999, when journalist Edward Hooper published
The River: A Journey to the Source of HIV and AIDS. In this book,
he asserted that scientists testing a new oral polio vaccine (OPV)
in Africa in the late 1950s inadvertently sparked the AIDS pandemic.
He argued that the polio researchers grew the vaccine in cells
taken from chimpanzees infected with the simian immunodeficiency
virus (SIV) variant most closely related to HIV, which, when introduced
into humans, was able to establish a lethal foothold in the new
host.
Since then,
four independent teams have combed the remaining stocks of the
original vaccine, searching for chimpanzee tissue, HIV and SIV.
But none of the stocks—including the one used to make the
OPV tested in the Congo vaccine trial that Hooper specifically
blamed for touching off the spread of HIV—have yielded any
such signs. The investigators did, however, find evidence of macaque
monkey tissue, thus backing the OPV researchers' claims that they
grew the vaccine in macaque cells. Other results fail to support
arguments made by Hooper on the basis of the evolutionary tree
formed by various HIV strains.
"The
new data may not convince the hardened conspiracy theorist who
thinks that contamination of OPV by chimpanzee virus was subsequently
and deliberately covered up," Robin A. Weiss writes in a
commentary accompanying the reports in Nature. "But those
of us who were formerly willing to give some credence to the OPV
hypothesis will now consider that the matter has been laid to
rest."
|
