Text 8009, 78 rader
Skriven 2005-10-30 08:34:54 av Rich Gauszka (1:379/45)
Ärende: Bird Flu - Modify the chickens
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From: "Rich Gauszka" <gauszka@hotmail.com>


http://www.timesonline.co.uk/article/0,,25149-1847760,00.html

            Scientists aim to beat flu with genetically modified chickens
            By Mark Henderson, Science Correspondent



            THE long-term threat of an avian flu pandemic could be greatly
reduced by a project to produce genetically modified chickens that can resist
lethal strains of the virus.
            British scientists are genetically engineering chickens to
protect them against the H5N1 virus that has devastated poultry farms in the
Far East, with a view to replacing stocks with birds that are not susceptible
to influenza.



            The technique should also offer protection against many other
strains of flu with the potential to start a human pandemic, such as the H7
subgroup that was responsible for an outbreak in Dutch poultry in 2003.

            If chicken populations were to be replaced with transgenic birds
that were resistant to flu, it would remove a reservoir of the virus and make
it much harder for it to spread to humans and trigger a pandemic.

            The team, led by Laurence Tiley, Professor of Molecular Virology
at Cambridge University, and Helen Sang, of the Roslin Institute, near
Edinburgh, has already shown that chicken cells can be protected against flu by
inserting small pieces of genetic material.

            The researchers are now ready to begin a similar procedure with
eggs and the first experiments are expected within weeks. Any breakthrough,
however, will come too late to have an impact on the present outbreak of H5N1.

            Even if the technique works, it will be several years before it
can be used to stock farms and it also faces important regulatory hurdles and a
battle to win over public opinion. If these obstacles are overcome and farmers
are willing to adopt GM chickens, the entire world stock could be replaced
fairly quickly.

            "Once we have regulatory approval, we believe it will only take
between four and five years to breed enough chickens to replace the entire
world population," Professor Tiley said. "Developing flu-resistant chickens has
clear benefits for human health and animal welfare, as we wouldn't have to
slaughter chickens around the world. Chickens provide a link between the wild
bird population, where avian influenza thrives, and humans, where new pandemic
strains can emerge. Removing that bridge will dramatically reduce the risk
posed by avian viruses."

            The research team is following three parallel approaches. One
involves inserting a working copy of a gene that makes an antiviral protein
called Mx, which is defective in many chicken breeds, and should improve their
ability to fight off H5N1 and other strains.

            The second approach is to harness a technique called RNA
interference, in which small fragments of the genetic signalling chemical RNA
are used to disrupt the workings of the flu virus.

            By engineering chicken cells to make small RNA molecules that
confuse the flu virus, the scientists hope to confer resistance to a wide
variety of strains. The third strategy is similar to the second, but involves
using RNA molecules as decoys, which trick the flu virus into copying them
rather than itself. All three could potentially be incorporated




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