Scientists create GM chicken that does not spread bird flu to other chickens

"Scientists have developed genetically modified [GM] chickens that don't transmit bird flu [H5N1] to other chickens," HealthDay News/Bloomberg Businessweek reports. "This achievement could stop bird flu outbreaks from spreading within poultry flocks and possibly reduce the risk of bird flu epidemics that could lead to flu virus epidemics in humans, according to the researchers at the Universities of Cambridge and Edinburgh in the United Kingdom," whose findings appear in the Jan. 14 issue of the journal Science, according to the news service (Preidt, 1/13).

"H5N1 bird flu has been circulating in Asia and the Middle East, with occasional outbreaks in Europe, since 2003 and has killed or forced the destruction of hundreds of millions of birds, according to the world animal health organization OIE," Reuters writes. The virus "rarely infects people but when it does it is deadly: the World Health Organization has documented 516 cases in people since 2003 and the virus has killed 306 of them." Health officials also worry about the potential for the virus to "evolve into a form that people can easily catch and pass to one another, causing the transmission rate to soar and producing a pandemic in which millions of people could die," according to the news service (Kelland, 1/13).

"In developed countries, H5N1 outbreaks are controlled by swiftly culling the animals. In poor countries, however, there are lots of small farms, few health regulations and long-held cultural practices involving birds," Nature News writes. "Instead, developing countries try to control H5N1 by vaccinating birds. This doesn't prevent them from silently acquiring mild forms of the disease and, if not monitored well, transmitting it to healthy birds. What's more, flu viruses mutate quickly and are famous for evading vaccines" (Hughes, 1/13).

"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," the Financial Times writes. "Once approved, it would take several years for GM strains to become established in the world's chicken flocks," the news service adds (Cookson, 1/13).

As the researchers described in Science, the GM chickens they created "carry a genetic tweak that diverts an enzyme crucial for transmitting the H5N1 strain," according to Nature News (1/13). "When the GM chickens were exposed to the avian flu, they were still infected, getting sick and eventually dying, but they didn't pass on that virus to other chickens in close proximity, both transgenic birds and normal ones," TIME writes. "Normally, once a few chickens have been infected with H5N1, the virus burns like wildfire through a flock, often with near 100% mortality. But the transgenic chickens effectively acted as firewalls for avian flu, stopping the spread cold" (Walsh, 1/13). Nature News adds: "The researchers say that although large-scale distribution of the genetically modified (GM) birds will one day be feasible, their study is meant only to show proof-of-concept of the technique" (Hughes, 1/13).

"Many farmers have gone to great lengths to prevent a poultry-based pandemic, but the newest results are 'a significant first step along the path to developing chickens that are completely resistant to avian flu,'" the University of Cambridge's Lawrence Tiley, who was the lead author of the study, said in a prepared statement, according to Scientific American's "Observations" blog. The blog adds additional details on how scientists created the GM chickens and notes while GM crops "can boost yield, increase nutritional value and stave off disease, …they have been met with opposition from numerous corners. … How this technology and its regulation will play out on the animal side of agriculture remains to be seen" (Harmon, 1/13).

Nature News also examines the cost associated with creating the GM chickens, as described by Helen Sang, a geneticist at the Roslin Institute of the University of Edinburgh who led the team who developed the chickens. "Sang says that using their methods, it costs approximately £50,000 (US$79,000) to produce 'a small number of stable transgenic birds you can characterize and breed from'," the news service writes.

Reuters notes that Sang "told a joint briefing the GM chickens could offer a way to improve economic and food security in parts of the world where bird flu is a major threat, but said using them would probably add slightly to farming costs."

"Countries like China are interested in the possibility of genetic modification to protect their poultry stocks and people," Sang said. "It will inevitably be more expensive because you'd have to use the products of breeding companies to stock the producers," she added. Reuters notes, "At the same time, the need for vaccination and losses from whole flocks being infected should be reduced … The researchers said they now plan to work on trying to make chickens that are fully resistant to bird flu rather than just blocking bird-to-bird transmission" (1/13).