Scientists at the Roslin Institute (part of the University of Edinburgh) and Cambridge University have developed genetically modified (GM) chickens could stop bird flu outbreaks spreading within poultry flocks.

The development would protect the health of domestic poultry and could also reduce the risk of new flu virus epidemics in the human population.

The study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), is published in the journal, Science.

Preventing flu epidemics

Dr Laurence Tiley, Senior Lecturer in Molecular Virology from the University of Cambridge, explained that chickens are potential bridging hosts that can enable new strains of flu to be transmitted to humans.

He said: "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.

"The genetic modification we describe is a significant first step along the path to developing chickens that are completely resistant to avian flu. These particular birds are only intended for research purposes, not for consumption."

Genetic modification

The Cambridge and Roslin scientists introduced a new gene to chickens that produced a small 'decoy' molecule to mimic an important control element of the bird flu virus.

This decoy molecule tricks the virus' replication system so that it replicates the decoy rather than the viral genome.

When the transgenic chickens were infected with avian flu, they became sick but did not transmit the infection on to other chickens.

This was the case even if the other chickens were normal (non-transgenic) birds.

Dr Tiley continued: "The decoy mimics an essential part of the flu virus genome that is identical for all strains of influenza A.

"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."

Food security risk

Professor Douglas Kell, BBSRC Chief Executive, said: "Infectious diseases of livestock represent a significant threat to global food security.

"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.

"The BBSRC funds world-class research to help to protect the UK from such eventualities and the present approach provides a very exciting example of novel approaches to producing disease-resistant poultry."

Published paper

In the abstract of the paper, Lyall and co-authors explain that the infection of chickens with avian influenza virus poses a global threat to both poultry production and human health that is not adequately controlled by vaccination or by biosecurity measures. A novel alternative strategy is to develop chickens that are genetically resistant to infection.

The researchers generated transgenic chickens expressing a short-hairpin RNA designed to function as a decoy that inhibits and blocks influenza virus polymerase and hence interferes with virus propagation. Susceptibility to primary challenge with highly pathogenic avian influenza virus and onward transmission dynamics were determined.

Although the transgenic birds succumbed to the initial experimental challenge, onward transmission to both transgenic and non-transgenic birds was prevented, concluded Lyall and co-authors.

Reference:
Lyall J., R.M. Irvine, A. Sherman, T.J. McKinley, A. Núñez, A. Purdie, L. Outtrim, I.H. Brown, G. Rolleston-Smith, H. Sang and L. Tiley. 2011. Suppression of Avian Influenza Transmission in Genetically Modified Chickens. Science, 14 January 2011: 331 (6014): 223-226. DOI: 10.1126/science.1198020

Further Reading

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You can view the full paper in Science (fee payable) by clicking here.