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Genetically modified (GM) chickens could help stop transmission of bird flu, which first emerged in 1996 in China and has since killed or caused the culling of millions of chickens worldwide.

Since making a jump to humans in 1997, bird flu has also killed over 300 people. It remains one of the diseases with a potential to cause a pandemic and is a major drawback for the poultry industry, especially in Asia.

Now, researchers have developed GM chickens that, although not resistant to the virus, do not transmit it to other birds in the flock. Their proof-of-principle study was published today in Science (14 January).

UK researchers modified chickens to produce 'decoy' RNA molecules in their cells that attach to a molecule inside the virus, called replicase, which replicates virus's genetic information (DNA).

They think this may be fooling the virus into replicating the decoy molecule instead of its own DNA.

According to the study, the same technique could be applied to other animals such as pigs, in which another potentially pandemic flu strain, swine flu, originated. But it might be years until the GM chickens are ready for commercial use.

So far, developing countries have been using vaccines to protect chickens from flu.

"As avian flu evolves, vaccines need to change and [they] can also drive the mutation of the virus, so vaccines are not the full answer to avian flu," Helen Sang, a researcher with the University of Edinburgh team, told SciDev.Net.

Sang added they now want to engineer chickens that are fully resistant to flu.

John Marshall, an epidemiological biologist at Imperial College London, told SciDev.Net: "It's the first time a chicken has been modified to reduce transfer of the avian flu infection to other chickens. But a lot is still unknown."

Sang agreed that more research is needed to ensure GM chickens do not suffer side effects and are safe for consumption.

Ricarda Steinbrecher, a geneticist and co-director of EcoNexus, a non-profit organisation researching emerging technologies, said that if the chickens are eventually released, there might be biosafety issues related to their movement between countries.

The internationally agreed Cartegena Protocol on Biosafety's risk assessments, which are the basis for countries' decisions on importing GM stock, do not include impacts of GM animals on neighbouring counties, and some have called for the updating of the Protocol to include emerging GM animals, such as GM mosquitoes tested in the wild.

To date, no GM animals have been approved for commercial use. Closest to commercial release is GM salmon, developed by US-based company AquaBounty to grow twice as fast as normal, which is waiting for US Food and Drug Administration's approval.

Link to full paper in Science

References

Science 331, 223 (2011)

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