快猫短视频

THE AIDS pandemic was not caused by polio vaccines tested in Africa in the
1950s, say several teams of researchers. Their work should settle the issue once
and for all.

In 1999, writer Edward Hooper put forward this controversial theory in his
book The River. He claimed that tissue from chimpanzees was used to
prepare the CHAT vaccine given to around a million people in what is now the
Democratic Republic of Congo. According to Hooper some batches of the vaccine
became contaminated with SIV, the chimp version of HIV, allowing the virus to
jump to humans. However, the Wistar Institute in Philadelphia, which made the
vaccine, insists only macaques were used.

Now two teams, led by Simon Wain-Hobson of the Pasteur Institute in
Paris, and Neil Berry of Britain鈥檚 National Institute for Biological Standards
and Control (NIBSC) in Hertfordshire, have analysed old stocks of the vaccine.
They found no trace of HIV, SIV or chimp DNA. But they did find macaque DNA,
confirming that the vaccine was prepared in macaque cells. 鈥淚f chimp sequences
were present, we would have picked them up,鈥� says Berry.

Hooper dismissed similar results presented at a meeting of the Royal Society
in London last year, saying that the key batches of the vaccine no longer exist.
But Berry鈥檚 team managed to find a vial of vaccine 10A-11 at the NIBSC that
originally came from the Wistar Institute in 1958. Hooper specifically
implicated batch 10A-11, so the finding that this too was free from SIV is a
significant blow to his theory.

Another team, led by Edward Holmes of Oxford University, has created the
fullest evolutionary tree so far for HIV by comparing the DNA of 197 strains
from the Congo. The tree suggests that the virus jumped from chimps to humans
just once, years before the vaccination campaign started. 鈥淲e鈥檝e removed one
more piece of evidence from the theory,鈥� says Holmes.

But Wain-Hobson says there鈥檚 no room for complacency. 鈥淲e were lucky,鈥� he
says. 鈥淲hen you are using animal tissues, you have got to be careful. How can
you test for a virus you don鈥檛 know?鈥�