They’re attacking bird flu with gene editing: It’s revolutionary technology – New York Times International Weekly – International

A new study finds that scientists have used CRISPR gene-editing technology to create chickens that are somewhat resistant to avian influenza.

The study suggests that genetic engineering could help reduce mortality from avian influenza, a group of viruses that pose a danger to animals and humans. But it also highlights the limitations of the approach.

Some breakthrough infections still occur, especially when transgenic chickens are exposed to very high doses of virus. When scientists edited just one gene in a chicken, the virus quickly adapted. The findings suggest that creating flu-resistant chickens requires editing multiple genes, and that scientists need to proceed with caution to avoid pushing the virus further.

The study “demonstrates that we can make progress in making chickens resistant to viruses,” said Wendy Barclay, a virologist at Imperial College London and one of the study’s authors. “But we’re not there yet.”

Some scientists not involved in the study reached different conclusions.

Carol Cardona, an expert on influenza and avian health at the University of Minnesota, said the results show how difficult it is to breed a chicken that can stay one step ahead of influenza viruses, which are known to evolve rapidly. In recent years, the highly lethal avian influenza virus H5N1 has spread around the world, killing countless wild and farmed birds. It also infects wild mammals and has been detected in a small number of humans. Scientists fear the virus could mutate and spread more easily among humans, potentially triggering a pandemic.

Many countries have attempted to eradicate the virus by tightening farm biosecurity, isolating infected facilities and culling infected flocks. But the virus spread so widely among wild birds that it proved uncontrollable, and some countries have begun vaccinating poultry.

Mike McGrew, an embryologist at the University of Edinburgh’s Roslin Institute and one of the authors of the new study, said gene editing “has the potential to provide a new way to permanently alter an animal’s ability to resist disease.”

The gene-editing technology used in the study, CRISPR, is a molecular tool that allows scientists to make specific edits to DNA, changing the genetic code at precise points in the genome. The researchers used it to modify a chicken gene that codes for the ANP32A protein, which the influenza virus hijacks to replicate itself.

These modifications did not appear to have a negative impact on the health of the hens.

The researchers studied viral samples from infected gene-edited birds. These samples had significant mutations that appeared to enable the virus to use the edited ANP32A protein to replicate.

Even in the absence of the ANP32A protein, the mutated influenza virus was able to replicate using two other proteins from the same family. When the team created chicken cells lacking these three proteins, the virus was unable to replicate.

Researchers are now trying to breed chickens with edits to all three genes.

Author: Emily Ansis