Could gene-editing chickens prevent future pandemics? | Gene modification

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Diseases such as bird flu cause millions of birds to be slaughtered every year. But that doesn’t have to be the case for much longer.

Vaccines are a preventative strategy used in some countries, but they do not prevent birds from becoming infected, contracting mild versions of the disease and passing it on to healthy chickens. In fact, this imperfect shield can make matters worse, causing the virus to mutate in order to escape the vaccine.

And an even more sinister possibility is that the viruses that plague domestic birds could spread to humans with lethal effect.

Scientists are therefore working on a more permanent solution: gene editing, which is designed to alter specific genes in an organism to improve certain characteristics or inhibit others. It is sometimes grouped in the same category as genetic modification, which involves the transfer of a gene from one organism to another.

Genetically modified organisms are tightly regulated in the EU, due to long-standing fears of unintended effects on the environment and public health. Some campaign groups say gene editing carries similar risks.

The use of gene editing techniques “could not only exacerbate the negative effects of industrial agriculture on nature, animals and humans, but it could effectively transform both nature and ourselves (by food we eat) into a gigantic genetic engineering experiment with unknown effects, potentially irrevocable results ”, Greenpeace said in a press release earlier this year.

Proponents, meanwhile, say gene editing technology is just a more precise version of traditional selective breeding of animals.

At the heart of the gene editing solution is the Crispr tool, designed to work like a pair of genetic scissors. This tool could be used, for example, to remove a section of chicken DNA in order to prevent the bird flu virus from settling in cells and replicating itself.

Professor Helen Sang, a geneticist at the Roslin Institute at the University of Edinburgh, is part of a team of scientists working on the early stages of such a project. The Crispr technology is effective because it allows the evaluation of the modification in cells grown in the laboratory – if these results seem encouraging, it can then be tested in birds, she says.

Almost everything we eat has been selectively raised – from crops to poultry. But in many places, genetically modified crops are common. In the United States, for example, most soybeans and corn are designed to maximize production. In 2015, US regulators also granted the first approval of an animal (an Atlantic salmon) whose DNA had been scientifically altered for human consumption. Disease resistant pigs should be next on the list.

Selective breeding fundamentally alters the genetics of an organism but is seen as natural, while the use of gene editing technology for the same purpose is seen as unnatural, noted Dr Laurence Tiley, molecular virologist in the department. of Veterinary Medicine from the University of Cambridge.

Tiley and Sang’s research a decade ago quickly succeeded in genetically modifying chickens to prevent the spread of bird flu. But they didn’t proceed with the project after realizing the technology wasn’t robust enough to completely prevent birds from catching the flu in the first place.

In the years that followed, Crispr technology grew from relative obscurity to a revolution in biomedical research, clinical medicine and agriculture.

Obviously, these gene editing tools do not match the intended nature, but are very precise, explains Tiley. “You can make exactly the change you want in exactly the right place. And you can check it … and confirm that there is nothing else that you have made further changes to.

Earlier this year, a UK government consultation opened the door to genetic modification of crops and livestock in England. Changes to the current strict rules – which originate in the EU and make editing of genes for crops and livestock nearly impossible – aim to bring widespread benefits to consumers and farmers, including healthier nutrition, use less antibiotics and better animal welfare.

But campaigners say the easing of the rules could be worse for animal welfare, for example, if the technology was used to promote growth rather than animal health, or to allow livestock to be kept in shelters. overcrowded conditions.

It’s not a situation either / or, says Tiley, adding, “I think there’s a clear case to improve animal production… to reduce the transmission of infectious diseases. But there are some things that no matter how hard you try, you’re going to have a disease problem, and if you can genetically modify those problems, then it’s a good thing to do.

In rich countries, chicken consumption has increased by 70% since 1990 and continues to grow, with 65 billion chickens consumed in the world every year. Until an alternative protein becomes the default solution, the traditional way of consuming protein must be improved, says Yehuda Elram, director of Israeli startup EggXYt, which is working on gene editing tools to modify genes. DNA fragments in chickens to attack. viruses that cause bird flu.

“With Covid, the world is becoming more and more familiar with what science can do to solve very difficult problems. We are trying to do our part to improve the way chickens are produced, to improve animal welfare, ”says Elram.

It is not so easy to confer disease resistance in pigs via gene editing, mainly due to the very different physiology of the avian egg compared to mammals. The technology also needs to be refined to be made less laborious, says Jiři Hejnar of the Czech Academy of Sciences.

Hejnar’s lab has published encouraging publications proof of concept data early 2020 describing the use of Crispr to make chickens resistant to avian leukosis virus (ALV), which can lead to symptoms such as weakness, diarrhea and tumor formation in poultry. But the project was scrapped due to a lack of commercial interest, he said.

Even as science advances, the business case for such advancements is hampered by the lack of global regulatory consensus and consumer acceptance, the scientists said.

We have the tools to develop disease resistant chickens, but it’s important to bring the public with the trip, says Tiley. “If someone jumps into a room and yells fire, people tend to react. And so if someone says GM food is dangerous, people tend to take it at face value, ”he says.

But, the Covid experience may have impressed people that pandemics can be very bad, he says: “If you choose your species carefully and your goals, in an easily justifiable way, let’s say bird flu in chickens, arguments you can make that are persuasive enough.

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