More Sick Science - GMO Chickens To Avoid H5N1

Genetically modified chickens could stop bird flu epidemic

01/16/2011 23:18:00

Transgenic chickens that will not transmit avian influenza virus to other chickens have been grown by researchers at the Universities of Cambridge and Edinburgh, according to the journal Science published last week.

This finding may help to stop bird flu outbreaks spreading within poultry flocks and would not only protect the health of domestic poultry but also reduce the risk of bird flu epidemics leading to new flu virus epidemics in humans.

"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. 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," said Dr. Laurence Tiley, Senior Lecture from the University of Cambridge.

To produce these transgenic chickens, the scientists introduced a new gene that manufactures a small "decoy" molecule that mimics an important control element of the bird flu virus. The replication machinery of the virus is tricked into identifying the decoy molecule instead of the viral genome and this interferes with the replication cycle of the virus.

If the chickens were infected with avian flu, they became sick but did not transmit the virus.

"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," Dr. Tiley added.

The avian flu is an infection caused by avian (bird) influenza (flu) A viruses. These influenza A viruses occur naturally among birds. Wild birds worldwide get flu A infections in their intestines, but usually do not get sick from flu infections. However, avian influenza is very contagious among birds and some of these viruses can make certain domesticated bird species, including chickens, ducks, and turkeys, very sick and kill them.

According to the Centers for Disease Control and Prevention, of the human cases associated with the ongoing HPAI H5N1 outbreaks in poultry and wild birds in Asia and parts of Europe, the Near East and Africa, about 60 percent of those people reported infected with the virus have died. Most cases have occurred in previously healthy children and young adults and have resulted from direct or close contact with H5N1-infected poultry or H5N1-contaminated surfaces. In general, HPAI H5N1 remains a very rare disease in people.

The HPAI H5N1 virus is resistant to amantadine and rimantadine, two antiviral medications licensed by the US Food and Drug Administration (FDA) for influenza A. Two other antiviral medications, oseltamivir and zanamivir, can be used for the treatment of HPAI H5N1 aaccording to the World Health Organization.

Stephen Lau and editing by Aimee Keenan-Greene

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