As bird flu
continues to haunt people and poultry around the planet, a coop of genetically modified chickens in Australia is stirring hope that science might soon outfox the H5N1 virus. If so, it could spell doom not just for avian flu, but for a slew of infectious diseases.
Researchers at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) are borrowing a technique from plant science, in which individual genes are "switched off" via RNA interference to produce changes like larger fruit, stronger stems or drought resistance. According to the Geelong Observer newspaper
, this process has let CSIRO create genetically modified chickens that seem resistant to H5N1.
"Right now is the first time we have ever produced a resistant animal to a major disease like this," recently retired CSIRO executive Martyn Jeggo tells the Observer. "If we can do it for one, why the hell can't we do it for every other disease? This is a proof-of-concept project which is massive, massive, massive."
This genetic strategy was first revealed several years ago, but Jeggo says it's now reaching a critical stage in development. As scientists from the U.K. reported in 2011
, the flu virus still infected their transgenic chickens, but it didn't go on to attack more birds. That's because the genetically modified organisms, or GMOs, had a gene that produced a "decoy" molecule in their cells, mimicking part of the virus's molecular-control mechanism. The virus then unwittingly used this decoy in place of its own genetic material, rendering it incapable of replicating itself within the chicken's cells.
"Although the transgenic birds succumbed to the initial experimental challenge," the study's authors wrote
, "onward transmission to both transgenic and nontransgenic birds was prevented." CSIRO's work seems to up the ante, hinting at the birth of truly flu-proof birds. "If this avian influenza stuff works," Jeggo says, "you'll want to be in Geelong."
The U.S. agricultural industry has been awash in gentically modified crops since the 1990s, using technology that can boost food yields but that still has many critics, especially in Europe. GMO opponents fear unintended consequences if GMOs breed with wild relatives, as well as potentially undiscovered health effects for people who eat them. There is little scientific support for such concerns, and the U.S. Food and Drug Administration may soon approve genetically modified salmon
, a move some worry will open the floodgates for a menagerie of transgenic animals. But Jeggo says such controversies shouldn't apply to flu-proof chickens, since CSIRO is adjusting natural genes, not adding new ones.
"Most of the furor and uproar ... has been about introducing new genes and not knowing what the effect of that is," he tells the Observer. "This is a gene which is already there. A gene we can turn off so virus can't get in and so the chickens can be healthy."
RNA interference (RNAi) occurs naturally in animals as a way of adapting to viral threats, and according to CSIRO researcher John Lowenthal, the genetically modified chickens simply accelerate this process. It's too early to know for sure if they're actually resistant to bird flu, he adds, but they have been shown to express RNAi molecules. And the hope is their flu-fighting genes will take flight in future generations.
"The next generation of chickens will inherit higher levels of RNAi, which is why they are called GMOs, because it's an inheritable trait," Lowenthal tells the Observer. "[T]he capability is passed on."
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