DEADLY VIRUS: US develops lethal new viruses

[Guest guest]

> US develops lethal new viruses

> Public release date: 29-Oct-2003

>

> Contact: Claire Bowles

> claire.bowles

> 44-207-331- 2751

> New Scientist

>

> US develops lethal new viruses

> http://www.eurekalert.org/pub_releases/2003-10/ns-udl102903.php

>

> A SCIENTIST 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 concern about doing this in a pox virus that

can

> cross species, " said Ian 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, p 4). But the

modified

> mousepox his team created was not as deadly as Buller's.

> 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.

> 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.

> ###

> Written by Debora MacKenzie, Geneva

> New Scientist issue: 1 November 2003

> PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS STORY AND, IF

PUBLISHING

> ONLINE, PLEASE CARRY A HYPERLINK TO: http://www.newscientist.com.

> " These articles are posted on this site to give advance access to other

> authorised media who may wish to quote extracts as part of fair dealing

with

> this copyrighted material. Full attribution is required, and if publishing

> online a link to http://www.newscientist.com is also required. Advance

> permission is required before any and every reproduction of each article

in

> full - please contact celia.. Please note that all

material

> is copyright of Reed Business Information Limited and we reserve the right

> to take such action as we consider appropriate to protect such copyright. "

> UK CONTACT - Claire Bowles, New Scientist Press Office, London: Tel:

> 44-0-20-7331-2751 or email claire.bowles.

> US CONTACT - Michelle Soucy, New Scientist Boston Office: Tel:

617-558-4939

> or email michelle.soucy.

>

>

>

>

>

>