Scientists have bred gene-edited chickens to fight bird flu

When ANP32A gene-edited chickens were exposed to a normal dose of the H9N2-UDL strain of avian influenza virus, commonly known as avian influenza , 9 out of 10 birds remained uninfected and no other chickens were infected.

The research team then exposed the gene-edited birds to an artificially high dose of avian influenza virus to further test their resistance.

When exposed to the high dose, half the group became infected—5 of the 10 birds. However, gene editing did provide some protection: the amount of virus in infected gene-edited chickens was much lower than the level typically seen during infection in chickens without gene editing.

Gene editing has also helped limit the further spread of the virus. There was no transmission of the virus to birds with edited genes.

The scientists found that in birds with the ANP32A gene edited, the virus had adapted to recruit two related proteins—ANP32B and ANP32E—to replicate.

After laboratory testing , the scientists found that some mutations allowed the virus to use the human version of ANP32, but its replication remained low in human airway cell cultures.

Experts say additional genetic changes will be required for the virus to become infected and spread effectively among people.

However, the results show that the team believes editing the ANP32A gene alone is not robust enough for use in chicken production.

To prevent the emergence of escape viruses—viruses that adapt to evade gene editing and cause infection—the research team then targeted additional sections of DNA responsible for producing all three proteins—ANP32A, ANP32B and ANP32E—within lab-grown chicken cells.

In laboratory cell cultures, virus growth was successfully blocked by three gene changes.

The next step is to try to breed chickens with changes in all three genes. 

The study highlights the importance of responsible gene editing and the need to be attentive to the risks of viral evolution in undesirable directions unless full resistance is achieved, experts say.

Avian influenza is a serious global threat with devastating impacts on both farmed and wild bird populations. In the UK alone , the current outbreak of H5N1 bird flu has decimated seabird populations and cost the poultry industry more than £100 million in losses.