Scientists in the UK have used gene-editing technology to breed chickens that are partially resistant to avian influenza — one of the world’s most costly animal diseases.
By altering a small section of chickens’ DNA, researchers were able to restrict the virus from infecting birds, with 90% of birds showing no signs of infection when exposed to a typical dose.
However while the scientists described the results as an “encouraging step forward”, more gene edits would be needed to produce poultry that couldn’t be infected by bird flu — meaning the developments are some way from being introduced into commercial poultry production.
Scientists from the Roslin Institute in Edinburgh, Imperial College London and the Pirbright Institute used Crispr gene editing techniques to alter a small section of DNA responsible for a protein called ANP32A — a molecule that flu viruses hijack during infection to replicate themselves.
When gene-edited chickens were exposed to a normal strain of avian flu virus only one in 10 birds were infected, with no spread to other chickens.
When exposed to an extremely high dose of the virus, five out of 10 birds had breakthrough infections. However, the gene edit did offer some protection, with the amount of virus in the infected chickens proving to be much lower than in the control birds.
The edit also helped to limit the spread of the virus to non-edited birds in the same incubator, the researchers said in their paper, published in the journal Nature Communications.
Blocking breakthrough infections
While the initial research showed promising signs, breakthrough infections can pose a risk because of the virus’ potential to evolve — which could make the virus more dangerous to humans.
To address the challenge, the next stage of their research saw the scientists edit three proteins rather than one. Preliminary lab results showed virus replication was completely blocked, and the team plan to test this in live chickens in future.
Scientists hope that using gene editing, which is deemed less controversial than genetic modification because the small changes made to DNA could occur naturally over time, could be a safe and effective way of controlling bird flu in future.
Principle investigator Dr Mike McGrew of the Roslin Institute said vaccinating birds against bird flu — which has cost the UK poultry industry more than £100m — is expensive and can have limited success.
“Gene-editing offers a promising route towards permanent disease resistance, which could be passed down through generations, protecting poultry and reducing the risks to humans and wild birds,” he added.
“Our work shows that stopping the spread of avian influenza in chickens will need several simultaneous genetic changes.”
Professor Wendy Barclay from Imperial College London added: “Although we haven’t yet got the perfect combination of gene edits to take this approach into the field, the results have told us a lot about how influenza virus functions inside the infected cell and how to slow its replication.”
