Scientists alter chickens’ DNA to reduce spread of bird flu

Researchers have altered parts of chickens’ DNA to significantly impede the transmission of bird flu without damaging their health, an intervention that could prove a simple and cost-effective way of protecting animals and humans from the disease.

In a peer-reviewed study published in Nature on Tuesday, researchers from Edinburgh university, Imperial College London and the Pirbright Institute used gene editing techniques to alter the section of chicken DNA responsible for producing ANP32A, a protein that the flu virus takes over to replicate itself.

In the study, chickens whose ANP32A molecule had been gene-edited were exposed to a normal dose of the H9N2-ULD strain of avian flu and nine out of 10 remained uninfected, with no transmission to other chickens.

The spread of bird flu is an increasing concern for health authorities, animal welfare groups and food producers. More than 100mn animals were culled last winter, and the spread to humans in a few isolated cases stoked fears of a new pandemic.

James Wood, head of veterinary medicine at the University of Cambridge who was not involved in the study, called the research a “breakthrough” that “provides important proof of principle of the utility of gene editing in introducing genetic resistance to disease caused by influenza in farmed animals”.

The researchers exposed the birds to an “artificially high dose” of avian flu to further test their resilience. In that case, half the birds became infected. But the intervention still provided some protection, with the viral load in the gene-edited group “much lower” than is typically seen in birds with avian flu.

The gene editing process also curbed transmission to just one of the four non-gene edited chickens in the same incubator. Among the gene-edited chickens, no transmission was recorded.

The birds showed “no signs” that the change in their DNA affected their health or wellbeing.

There were limitations in the study, however. In the chickens whose ANP32A molecule was edited, the virus had utilised two related proteins to replicate. In lab tests, scientists found that the virus could mutate utilising human cell cultures but it still remained at “low” levels, with more changes needed to spread efficiently in humans.

The researchers found that the individual edit of ANP32A was “not robust enough for application in the production of chickens”, but they then modified an additional section of DNA in lab-grown chicken cells. The virus was “successfully” blocked after three gene edits.

“The study highlights the importance of responsible gene editing and the need to be alert to the risks of driving viral evolution in unwanted directions if complete resistance is not achieved,” the researchers concluded.

“The use of gene edited, disease resistant chickens in farming would be an exciting advance,” Wood said, adding that a much larger sample would be needed to successfully demonstrate that the intervention has no impact on animals’ health.

Wood cited a potential benefit for the global poultry industry, which could rapidly introduce “influenza-resistant chickens across many countries and continents”.