Poultry International

of Veterinary Medicine, said: "Avian influenza has had a devastating effect on poultry farmers in many parts of Asia and the Middle East. Experience has shown that the virus regularly jumps species from wild birds into chickens, and represents an ongoing problem despite the best efforts to prevent and contain these outbreaks. Replacing vulnerable chickens in such areas with birds that do not pass on the virus would have positive consequences for animal welfare, farmers' livelihoods and consumer safety."

Since bird flu can jump the gap between species, this development could not only protect the health of domestic poultry but could also reduce the risk of bird flu epidemics leading to new flu virus epidemics in the human population.

Countering any potential concerns over the possibility of the GM birds entering the food chain, Dr Tiley pointed out that the GM chickens are research birds, not intended for human consumption. He added that: "Chickens are potential bridging hosts that can enable new strains of flu to be transmitted to humans. Preventing virus transmission in chickens should reduce the economic impact of the disease and reduce the risk posed to people exposed to the infected birds."

all strains of Influenza A, because they all have the same replication process. "We expect the decoy to work against all strains of avian influenza and that the virus will find it difficult to evolve to escape the effects of the decoy.

“This is quite different from conventional flu vaccines, which need to be updated in the face of virus evolution as they tend only to protect against closely matching strains of virus and do not always prevent spread within a flock."

Decoy

The researchers modified the chickens to manufacture a small "decoy" molecule that mimics an important control element of the bird flu virus. The virus cannot reproduce itself because it tries to use the decoy molecule instead of its own viral genetic material in its replication process. When the transgenic chickens were infected with avian flu, they became sick but did not transmit the infection to other chickens kept in the same pen with them. This was the case even if the other chickens were normal (non-transgenic) birds.

Dr Tiley pointed out that the resistance mechanism will work against

Avian influenza viruses bursting from infected cells. FATIQLESS™

Courtesy of Emily Bruce and Dr Paul Digard.

Multiple benefits

Professor Helen Sang, from The Roslin Institute at the University of Edinburgh, described the results as very encouraging. She added that: "Using genetic modification to introduce genetic changes that cannot be achieved by animal breeding demonstrates the potential of GM to improve animal welfare in the poultry industry. This work could also form the basis for improving economic and food security in many regions of the world where bird flu is a significant problem."

Professor Douglas Kell, BBSRC chief executive, said: "The present approach provides a very exciting example of novel approaches to producing disease-resistant poultry." □