GM Chicken Could Put Flu to Flight

By IAN JOHNSTON

GENETICALLY modified chickens, able to resist all strains of influenza, including the current H5N1 bird-flu virus, could be produced within two years – if the public is prepared to eat the birds’ meat.

Scientists at the Roslin Institute, near Edinburgh, and Cambridge University are working on three ways to make birds resistant to flu by changing their genetic make-up.

One technique involves activating a gene called Mx, which is found in many animals but which is often “switched off” in domestic chickens. Two artificial molecules have also been invented which interfere with the way the virus works.

All the techniques have been shown to work in cells cultured in the laboratory and the team at Roslin will shortly start a breeding programme.

Dr Helen Sang, of Roslin, who is working with Professor Laurence Tiley of Cambridge and others on the project, said: “It is something we are just starting to do.

“What we’re thinking is if we can make our birds resistant and if it’s accepted by the poultry breeding companies – which would mean acceptance by the public – we would make commercial poultry flocks resistant to influenza.

“We have three different ways to make birds resistant to Avian influenza. Those methods have been tested to some extent by testing chicken cells in culture.

“The thing about the process is you can model it in chicken cells in culture, but nothing is the same as the whole animal.”

Some believe the best way to fight the threat of bird flu causing a pandemic in humans would be to contain outbreaks of the disease in birds. Current strategies include culling and vaccination.

However, the world’s entire chicken population – some 35 billion birds – could be replaced by flu-resistant birds in seven years – dramatically reducing the chance of a pandemic flu.

“The world pool of avian influenza would be much smaller so it would cut the risk quite a lot. All the three different approaches that Laurence has identified would be effective against all strains of influenza,” Dr Sang said.

The researchers should know in one to two years if the GM chickens really are flu-resistant.

“Certainly in a couple of years, but it’s a new thing. Nobody has made a GM bird resistant to any virus and the specific details are all very new,” Dr Sang said.

“The good thing is we don’t expect most of it would have any effect on the birds themselves. But it’s like all these things: we always find something we have not thought of.

“One of the issues we would investigate, if we show they are resistant, would be how easy it would be for influenza to develop resistance to our resistance which is why we want to try different tracks.”

Dr Sang admitted there was a “big question” whether people would eat a GM chicken.

Europeans have proved particularly reluctant to eat GM crops. But she said: “I think it’s very important to talk about this sort of thing now. It gives a chance for people to think about it. Our intention is to try it out, see if it works and if it does work, put that information out to the public to see what the response is.

“It [the GM gene] just behaves like any other gene in the chicken. When you eat a chicken, you eat all its DNA and chromosomes and you wouldn’t expect it to have any effect.”

The Mx gene, which is found in humans, produces an anti-viral to fight flu, but the virus has developed ways of fighting back. The gene is triggered by a protein called interferon and flu is able to block its production.

The first of the three flu-fighting techniques involves triggering Mx, not by interferon but by the presence of the virus itself.

The second and third techniques both use RNA interference, with one blocking the viral protein that blocks interferon and the other producing harmless flu decoys which the virus then replicates.

The genetic information for all three can be introduced into chicken embryos using a hollowed-out virus.

It still has the virus’ ability to get inside a cell, but instead of taking over the cell and producing more virus, it instead conveys the genetic information developed by the scientists.

Professor Tiley, a molecular virologist, said human flu pandemics happened about three times every 100 years and that was what scientists meant when they said another one was inevitable. The H5N1 strain is the most likely current candidate, because it has shown it can infect humans and has killed at least 64 people since 2003.

As flu – named because it was previously thought to be caused by supernatural “influences” – originates from birds, creating a world- wide chicken flock that was resistant to the disease would decrease the likelihood of a human pandemic.

Professor Tiley believes that despite the sceptical reaction to GM produce, a chicken better able to defeat flu would be acceptable to most.

“This is one example of GM where you can make a strong case for it on health, animal welfare and economic grounds,” he said.

“With something like Avian flu, people can see the benefits. I think most people in the UK would consider eating a GM chicken that had been engineered to be resistant to flu.”

However, Jack Winkler, director of Food and Health Research, said the pro- and anti-GM camps were “so distrustful of each other that they will not accept rational arguments”.

Public acceptance of a GM chicken would depend on one thing: “How big the flu epidemic is,” he said.

“If we get hundreds and thousands of people coming down with flu or hundreds and thousands of people dying, then people might well say ‘I’m scared’ and be willing to do anything.”