Are chickens resistant to avian influenza?Dolly the Sheep Labs announces a new genetic modification

British scientists use gene editing technology to identify and modify parts of chicken DNA to limit the spread of avian influenza viruses in animals (Freepik)

On July 5, 1996, Dolly the sheep was born. It was the first mammal to be cloned from adult cells.The experiment is in roslin instituteIn Edinburgh, Scotland, they have now achieved another success on the road to breeding genetically modified poultry.

A team of scientists at Roslyn, working with colleagues from other institutions, have developed the world’s first chickens that are resistant to bird flu. This innovation comes at a time when avian influenza has become “All human zoonotic diseases“.

The infection has killed hundreds of millions of birds around the world over the past two years, but it has also spread to mammal populations such as seals, sea lions and mink, killing several people.

doctor Mike McGrewPrincipal Investigator, Roslin Institute University of EdinburghStressing that avian influenza “is causing unprecedented deaths in wild birds and having a devastating impact on farmed poultry, there are growing concerns that avian influenza could jump to humans and trigger another pandemic.”

Bird flu has killed millions of poultry and wild birds over the past three years. It also affects mammals such as sea lions (Matthias Kulka/Getty)

There is a vaccine against bird flu. But “due to the rapid evolution of influenza viruses, vaccinating birds is expensive and has limited effectiveness. Stricter biosecurity measures, such as keeping chickens indoors, can impact animal welfare,” he points out, thus justifying the use of gene editing rationality.

“this gene editing “It offers a promising route to permanently combating the disease, which can be passed on from generation to generation, protecting poultry and reducing risks to humans and wild birds,” he explained.

The team created birds with a tiny change in one gene and were highly resistant to bird flu, with nine out of 10 showing no signs of infection when exposed to typical doses of the virus.they published study in magazine nature communications.

However, the infection was not completely prevented, which scientists say must be achieved before genetically modified chickens can be introduced to farms. They say this because of the risk of the virus evolving and becoming more dangerous to humans.

Scientists say the birds showed no signs of DNA changes affecting their health or well-being after using gene editing (Getty)

“At natural doses, our genetically modified chickens seem to really Resistantbut when we take very high doses, we observe Infect. “This proves to us that we can make chickens resistant to this virus, but we’re not there yet,” said Professor Wendy Barclay from the university. Imperial College Londonco-author of the study.

Preliminary results indicate Editing three genes, instead of just one, prevents infection. This study focused on one gene, ANP32which produces a protein that is hijacked by the flu virus to replicate.

Team uses gene editing technology to raise chickens Crisp Introducing small changes in genes ANP32A. When gene-edited chickens were inoculated with 1,000 infectious units of the virus (equivalent to real-world exposure), only one in 10 chickens became infected and shed very small amounts of the virus over several days. All control birds were infected.

When exposed to the extremely high dose of 1 million infectious units, 5 out of 10 chickens became infected, although the viral load was much lower than in control chickens.

The chickens were produced using gene-editing technology to alter the part of the DNA responsible for producing the ANP32A protein. During infection, influenza viruses hijack this molecule to help replicate (Freepik)

Because the virus has the potential to evolve, any progression of infection poses risks. Moreover, analysis showed that the virus from the gene-edited chicken had acquired mutations that helped it replicate using two related proteins (ANP32B and ANP32E). Some of these mutations also allow the virus to use the human version of ANP32.

“The fact that we are taking a step toward making the virus more capable of infecting other species is not what we want to do at all,” Barclay said. “We are not shocked by the mutations we see, But the progress we’ve made means we’ll need more rigorous editing in the future,” he added.

When the genes for all three proteins were targeted, viral replication was completely blocked in laboratory-grown chicken cells, which the team plans to test in live chickens.

teacher James WoodDirector of Veterinary Medicine Teaching and Research Office Cambridge UniversityHe, who was not involved in the study, expressed his views to the Science Media Center: “This study provides an important proof of principle for the genetic control of avian influenza and its spread among chickens. Show a Significant but not absolute resistanceFrom chickens to low-virulence avian influenza viruses following the introduction of genetic mutations in breeding lines. “

Viral loads in infected gene-edited chickens are much lower than virus loads/files typically observed during infection of non-gene-edited chickens

“The use of disease-resistant gene-edited chickens in livestock farming would be an exciting development, and the pyramidal structure of the global poultry industry could enable the rapid introduction of these flu-resistant chickens into many countries and continents.”

Research shows there are no apparent harmful effects on the health and welfare of the chickens produced, but these results must first be demonstrated on a larger scale before being introduced into commercial farming.

There are already precedents for gene editing in other species around the world. In 2021, the government Japan Approved for sale were red snapper lacking the gene for myostatin, which inhibits muscle growth, and tiger puffer fish that had a gene that controls appetite removed. Both gene-edited fish grow faster and are more productive than conventional fish.

Gene-edited salmon have already appeared in North America. They grow much faster than animals of the same species that do not carry the genetic modification (AquaBounty Technologies, Inc.)

And salmon Advantages here It was genetically modified to grow faster and in 2015 became the first genetically modified animal approved for human consumption in the United States and Canada.

pigs gal security They were approved for human consumption in the United States in 2020. They are genetically modified so they do not produce alpha-galactose. It is intended for use by people with alpha-galactose syndrome, which can cause mild to severe allergic reactions.

In 2020, the United States also approved ““smooth-haired cow” (PRLR-Smooth) I eat food. They are genetically modified to have a coat of fur that increases the animal’s resistance to high temperatures.

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