The idea of tweaking genes for healthier, tastier or more abundant food makes some people uneasy. But what if genetically modified food could help prevent the spread of a deadly disease, saving human and animal lives as well as money?
"The chickens can be infected, but they don't pass the virus on to other chickens in the flock," said study co-author Professor Helen Sang from The Roslin Institute at the University of Edinburgh.
Bird flu outbreaks in the U.S. are rare and involve viral strains that generally affect birds. But over 400 human cases of H5N1 have been reported in more than a dozen countries across Europe, Asia, Africa and the Pacific, according to the Centers for Disease Control and Prevention. Roughly 60 percent of these have been fatal.
Although there's no sign of H5N1 in the U.S., the country still feels the fury of bird flu. The virus is transmitted to chickens by wild birds, forcing farmers to slaughter entire flocks. So while it hasn't threatened public health, bird flu continues to fuel significant animal welfare worries and economic woes.
But given the logistical challenges of replacing current flocks with the flu-fighting variety -- not to mention mixed feelings about genetically modified food – the GM approach to beating bird flu may be hard to get off the ground.
"Replacing the world's chicken population with genetically modified chickens wouldn't be cheap. It looks good on a drawing board, but it might not fly," said William Schaffner, chair of preventative medicine at Vanderbilt University Medical Center. "There are lots of great ideas out there, but the filter of realty whittles them down pretty quickly."
But as poultry farming becomes more centralized, farmers are beginning to get their stock from a few, large suppliers, according to Sang.
"I think it would be very hard to get to the backyard chickens in many of the affected countries," Sang said. "But the majority of the poultry raised are coming from a small number of breading companies and producers who could choose to incorporate the genetic modification into their breeding program."
To stop the virus from spreading between chickens, Sang and colleagues inserted a gene that manufactures a "decoy" molecule into the chicken genome. The decoy tricks the virus' replication machinery into using the wrong materials. So unlike vaccines that prompt a strain-specific immunological attack, the genetic modification can thwart multiple strains.
"It's reassuring to know that some people are thinking about influenza in terms other than vaccination," said Philip Alcabes, professor of public health at Hunter College. Genetically modified chickens might not be the answer, but new approaches are much needed, Alcabes said.
In Sept. 2010, the FDA declared salmon genetically modified to grow twice as quickly safe to eat -- a decision that garnered opposition from public interest groups, who called the salmon "FrankenFish."
But study co-author Dr. Laurence Tiley from the University of Cambridge hopes the chickens -- and their potential to save flocks and even human lives -- will make people think twice about genetically modified foods.