Silencing the bird flu gene: scientists prep live hen trials

Bird flu has devastated poultry stocks and killed hundreds in Asia. http://www.flickr.com/photos/joegatling/

Researchers hoping to produce modified chickens hatched with in-built resistance to bird flu will conduct trials on live hens later this year, an Australian scientist said on Tuesday.

CSIRO research scientist, Dr Tim Doran, has been using a technique called gene silencing to “switch off” virus genes that make chickens susceptible to H5N1, the bird flu that has devastated livestock and killed 359 people worldwide since 2003.

H5N1 can be transmitted from bird to human; however, health authorities fear a pandemic could break out if the disease mutates and develops the ability to jump more readily from person to person.

Dr Doran said his team has shown, in mice and in fertilised chicken eggs, that gene silencing techniques can stop bird flu by interrupting the virus’ reproduction processes. They have now produced transgenic chickens, which should be resistant to H5N1 and be able to pass that resistance onto their chicks.

“We are getting geared up to do what we call a challenge experiment, where we test our transgenic chickens for resistance to bird flu virus. We expect the first lot of those experiments to be conducted late this year or early next year,” Dr Doran said on Tuesday, speaking from the CSIRO’s Emerging Infectious Diseases Symposium in Geelong.

Dr Doran’s research involves creating chickens which carry in every cell special molecules called RNA interference molecules.

“These RNA interference molecules are always being made within the chicken cell and they do nothing in that chicken cell until the virus infects that cell,” said Dr Doran.

“Once that happens, our RNA interference molecules can recognise the viral genes and say ‘I am now targeting you and I can switch you off.’ The virus is stopped in its tracks.”

“We are hopeful that our results will be positive. Once we have chickens that are resistant to bird flu, the aim would be to commercialise these birds in regions of the world where highly pathogenic bird flu continues to be a serious problem for the poultry industry.”

Dr Doran said no flu-resistant chicken breeds developed as a result of the research could enter the food chain without approval from Australia’s regulatory bodies, such as the Office of the Gene Technology Regulator and Food Standards Australia and New Zealand or without appropriate assessment by international health and science communities.

David Tribe, Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at the University of Melbourne said Dr Doran’s research was important to shore up food supplies for a growing global population and reduce the risk of a bird flu pandemic.

“This is a big story, it’s a really big advance,” said Dr Tribe, who is not involved in the CSIRO research.

“There is an important health benefit and an economic benefit. It’s a demonstration of a completely new approach to protecting animals against a virus.”

Dr Tribe said it was important to weigh the risks of genetic modification against the potential benefits.

“There are questions as to how it would influence virus evolution and it’s an area where you would want some extensive thought about what the implications are but it is not doing much different than the immune system does in terms of developing resistance to infection anyway,” he said.

“But if we were not to do anything new ever, then we wouldn’t have antibiotics or vaccines. Doing nothing is very dangerous. Doing nothing about food security is going to do more harm.”

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