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 British scientists say they have genetically modified chickens in a
bid to block bird flu and that early experiments show promise for
fighting off the disease that has devastated the U.S. poultry and
egg industries.
Their research, which has been backed by the UK government and top
chicken companies, could potentially prevent repeats of this year's
wipeout: 48 million chickens and turkeys killed because of the
disease since December in the United States alone.
But these promising chickens - injected with a fluorescent protein
to distinguish them from normal birds in experiments - won't likely
gatecrash their way into poultry production any time soon. Health
regulators around the world have yet to approve any animals bred as
genetically modified organisms (GMOs) for use in food because of
long-standing safety and environmental concerns.
Bird flu has become a global concern among researchers over the past
decade because of its threat to poultry and human health, and UK
researchers have been toiling in genetic engineering for years to
control its spread.
People who are in close contact with infected poultry are most at
risk for flu infections, and scientists are concerned about the risk
for a human pandemic if the virus infects someone and then mutates.
No humans have been infected in the latest U.S. outbreak, but there
have been cases in Asia in recent years.
"The public is obviously aware of these outbreaks when they're
reported and wondering why there's not more done to control it,"
said Laurence Tiley, a senior lecturer in molecular virology at the
University of Cambridge, who is involved in the experiments.
Scientists argue that GMO livestock could help control diseases and
feed the world's growing population. But if salmon's arduous swim to
approval is anything to go by, their breakthroughs will be slow to
come to market.
The U.S. Food and Drug Administration (FDA) has been reviewing a
type of GMO salmon for the past 20 years, even though the agency
deemed it safe for humans in 2010. Developed by AquaBounty
Technologies Inc, it was engineered to grow faster than normal.
Consumer activists have pushed back hard against GMO animals for
food, arguing that GMO crops, already widely used and marketed,
contribute to health and environmental problems.
FOOLING THE VIRUS
At Cambridge and the University of Edinburgh's Roslin Institute,
scientists are using genetic engineering to try to control bird flu
in two ways: by blocking initial infections in egg-laying chickens
and preventing birds from transmitting the virus if they become
infected.
Two of the world's biggest chicken breeders, Germany's EW Group and
Arkansas-based Cobb-Vantress, have funded parts of the research,
though they too harbor significant reservations about GMO breeding.
EW Group is interested in research to learn more about how chickens
respond to flu, said Jim McKay, group director for science and
technology. However, the company has a policy against breeding GMO
animals and feels consumers are not ready to accept them in the food
chain.
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Cobb-Vantress, owned by top U.S. chicken company Tyson Foods Inc,
has stopped supporting research into GMO chickens "at this time"
because there is no approved commercial use, said Mitch Abrahamsen,
vice president of research and development.
To genetically engineer chickens, the UK researchers inject a
"decoy" gene into a cluster of cells on the yolk of a newly laid
egg. The egg will hatch into a chick containing the decoy gene,
which it will be able to pass on to its offspring.
The decoy gene is injected into the chicken chromosome alongside the
fluorescent protein that makes the birds glow under ultraviolet
light, similar to glow-in-the-dark posters in college dorm rooms.
The birds would not be bred to glow if they are commercialized.
When the modified birds come into contact with the flu, their
genetic code is designed to trick the virus into copying the decoy
and to inhibit the virus' ability to reproduce itself.
In one study with a form of decoy, scientists put 16 infected
conventional chickens in contact with a mixture of 16 normal and 16
GMO chickens that contained a decoy. The GMO birds were found to be
less susceptible and succumbed to infection more slowly than the
conventional birds, said Tiley.
FARMER PROTECTIONS
A more flu-resistant bird could be a notable advance from the basic
steps that farmers now rely on to avoid infections in barns,
including banning visitors and disinfecting vehicle wheels.
Wild ducks, which can carry the virus, are thought to have spread
the disease in the United States by dropping contaminated feces and
feathers on farms. Humans can then transport the disease on their
boots and trucks.
The first GMO animal, a mouse, was produced in the 1980s for
research purposes, according to the U.S. FDA. In 2009, the agency
approved an anticoagulant derived from a GMO goat.
The FDA said "there are many reasons for producing" GMO animals and
that it could not provide a timeline for a decision on the GMO
salmon. The British researchers have not asked the agency to review
the GMO chickens.
"We've got enough positive results to make us think it's worth
taking it further," said Helen Sang, who took part in the flu
experiments and is the Roslin Institute's personal chair in
vertebrate molecular development.
"The benefit could be enormous."
(Editing by Jo Winterbottom and Mary Milliken)
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