Cambridge researchers have made a breakthrough in the study of transgenic animals, which could be of immense importance in preventing the spread of avian flu.

In a study published in the academic journal Science, researchers report the creation of a strain of genetically modified chickens that is incapable of transmitting bird flu. The study was led by Dr Laurence Tiley, of the Department of Veterinary Medicine, in collaboration with the Roslin Institute in Scotland, the animal sciences laboratory famous for breeding Dolly the Sheep.

The researchers developed transgenic chickens which become ill when infected with influenza, but do not pass the virus on to other chickens, even ones that have not been genetically modified. They achieved this by a modification of the animals’ DNA. A gene injected into the chickens leads to the manufacture of a ‘decoy’ molecule. The decoy is highly similar to a crucial viral molecule which is needed to control the virus’s replication cycle. When the decoy is present, the virus is tricked into recognising it instead of the native molecule, and the virus fails to replicate and spread to other birds.

The research has the potential to be of great importance globally in preventing the spread of so-called Bird Flu, a group of potentially lethal avian influenzas. Of particular concern is the notorious H5N1 subtype, which, since it emerged as a mild disease in Hong Kong in 1997, has mutated to become highly virulent and transmissible to humans. Epidemiologists are concerned that this virus could mutate to a form which is transmissible between humans, opening the possibility of a global pandemic in which millions could die.

Professor Douglas Kell, Chief Executive of the body that funded the research, said, "The potential of pathogens, such as bird flu, to jump to humans and become pandemic has been identified by the Government as a top level national security risk."

If transgenic chickens were used commercially, it would keep Bird Flu from being able to decimate entire chicken stocks rapidly. Furthermore, by preventing transmission to humans, there would be a vastly reduced risk of a human pandemic developing. Currently, H5N1 is being held in check by vaccination, but new vaccines must be constantly developed as the virus mutates. In contrast, the transgenic chickens provide a future-proof solution that will continue to be effective.

The transgenic chickens are currently not suitable for human consumption. The next step for researchers will be modifying them to produce a strain suitable for commercial use. Researchers also hope to create chickens which are fully resistant to avian flu.