FW: New Scientist: US develops lethal new viruses
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- Date
- 2003-10-30 08:58
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- email · email
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Tony:
Do you happen to know if this is independent research or if it's USG sponsored? RAF
US develops lethal new viruses
19:00 29 October 03 Exclusive from New Scientist Print Edition.
Ascientist funded by the US government has deliberately created an extremely deadly form of mousepox, a relative of the
smallpox virus, through genetic engineering.
The new virus kills all mice even if they have been given antiviral drugs as well as a vaccine that would normally protect
them.
The work has not stopped there. The cowpox virus, which infects a range of animals including humans, has been genetically
altered in a similar way.
The new virus, which is about to be tested on animals, should be lethal only to mice, Mark Buller of the University of St Louis
told New Scientist. He says his work is necessary to explore what bioterrorists might do.
But the research brings closer the prospect of pox viruses that cause only mild infections in humans being turned into
diseases lethal even to people who have been vaccinated.
And vaccines are currently our main defence against smallpox and its relatives, such as the monkeypox that reached the US
this year. Some researchers think the latest research is risky and unnecessary.
"I have great concer about doing this in a pox virus that can cross species," said lan Ramshaw of the Australian National
University in Canberra on being told of Buller's work.
Ramshaw was a member of the team that accidentally discovered how to make mousepox more deadly (New Scientist, 13
January 2001). But the modified mousepox his team created was not as deadly as Buller's.
No rebound
Since then, Ramshaw told New Scientist, his team has also created more deadly forms of mousepox, and has used the
same method to engineer a more deadly rabbitpox virus.
But this research revealed that the modified pox viruses are not contagious, he says. That is good news in the sense that
these viruses could not cause ecological havoc by wiping out mouse or rabbit populations around the world if they escaped
from a lab.
However, this discovery also means some bioterrorists might be more tempted to use the same trick to modify a pox virus
that infects humans. Such a disease, like anthrax, would infect only those directly exposed to it. It would not spread around
the world and rebound on the attackers. But there is no guarantee that other pox viruses modified in a similar way would
also be non-contagious.
Ramshaw's team made its initial discovery while developing contraceptive vaccines for sterilising mice and rabbits without
killing them. The researchers modified the mousepox virus by adding a gene for a natural immunosuppressant called IL-4,
expecting this would boost antibody production.
Instead, the modified mousepox virus was far more lethal, killing 60 per cent of vaccinated mice. The addition of IL-4 seems
to switch off a key part of the immune system called the cell-mediated response.
Maximised production
Now Buller has engineered a mousepox strain that kills 100 per cent of vaccinated mice, even when they were also treated
with the antiviral drug cidofovir. A monoclonal antibody that mops up IL-4 did save some, however.
His team "optimised" the virus by placing the IL-4 gene in a different part of the viral genome and adding a promoter
sequence to maximise production of the IL-4 protein, he told a biosecurity conference in Geneva last week.
Buller has also constructed a cowpox virus containing the mouse IL-4 gene, which is about to be tested on mice at the US
Army Medical Research Institute of Infectious Diseases at Fort Detrick, Maryland.
Cowpox infects people, but Buller says the IL-4 protein is species-specific and would not affect the human immune system.
The experiments are being done at the second-highest level of biological containment.
Ramshaw says there is no reason to do the cowpox experiments, as his group's work on rabbits has already shown the
method works for other pox viruses. While viruses containing mouse IL-4 should not be lethal to humans, recombinant
viruses can have unexpected effects, he says. "You'd hope the combination remains mouse-specific."
Why his group's engineered viruses are not contagious is a mystery, he says. It is not, for instance, because the host dies
faster than usual, taking the virus with it. But his findings could explain why pox viruses containing IL-4 have never evolved
naturally, even though the viruses frequently pick up genes that affect their host's immunity.
Despite the concerns, work on lethal new pox viruses seems likely to continue in the US. When members of the audience in
Geneva questioned the need for such experiments, an American voice in the back boomed out: "Nine-eleven". There were
murmurs of agreement.
Debora MacKenzie, Geneva