Scientists have genetically modified chickens to prevent the transmission of avian influenza, an innovation that could cut the risk of a lethal strain crossing to the human population and boost the poultry industry.
The chickens created at Cambridge and Edinburgh universities produce a genetic “decoy” molecule that mimics part of the replication machinery of the flu virus. This diverts the enzyme required for the virus to pass between cells – and stops the infection.
Although GM birds could still succumb when injected with the lethal H5N1 strain, they never passed the infection on to healthy cagemates, even those without genetic modification.
The research appears in the journal Science.
Apart from their flu protection, the GM birds are indistinguishable from non- GM chickens of the same breed. Laurence Tilney of Cambridge university said they would be safe to eat.
“The nature of the genetic modification and the decoy molecule makes it extremely unlikely that it could have any negative effects on people consuming the chickens or their eggs,” said Dr Tilney.
However the scientists emphasise that the research chickens are not intended for human consumption. Their safety would have to be assessed by agencies such as the European Food Safety Authority and the US Food and Drug Administration.
Unlike GM plants, no GM animal has been approved for commercial use. Closest to authorisation is probably the fast-growing GM salmon developed by US-based AquaBounty – and it has faced strong opposition.
The researchers hope that consumers suspicious of their GM chickens would be persuaded by the purpose for which they are bred. “Disease resistance is perhaps a special case for GM because it is clearly a beneficial characteristic for animal welfare and human health,” said Dr Tilney.
Unlike vaccination, which only works against some strains of flu and needs to updated frequently as the virus evolves, GM could give a permanent built-in resistance passed down many generations of birds.
Once approved, it would take several years for GM strains to become established in the world’s chicken flocks. The industry loses millions of birds a year to avian flu, but protection is needed most in east Asia, where the disease is most prevalent.
The same GM decoy technique could be used to make chickens resistant to the other viral infections that devastate commercial flocks such as Newcastle and Marek’s diseases. It could also be applied to other animals susceptible to flu, notably pigs.
By Clive Cookson
The Financial Times