Building Blocks: CRISPR helps make chickens more resistant to bird flu

Emily Anthes

NEW YORK: Scientists have used the gene-editing technology known as CRISPR to create chickens that have some resistance to avian influenza, according to a new study that was published in the journal Nature Communications on Tuesday.

The study suggests that genetic engineering could potentially be one tool for reducing the toll of bird flu, a group of viruses that pose grave dangers to both animals and humans. But the study also highlights the limitations and potential risks of the approach, scientists said.

Some breakthrough infections still occurred, especially when gene-edited chickens were exposed to very high doses of the virus, the researchers found. And when the scientists edited just one chicken gene, the virus quickly adapted.

The findings suggest that creating flu-resistant chickens will require editing multiple genes and that scientists will need to proceed carefully to avoid driving further evolution of the virus, the study’s authors said.

The research is “proof of concept that we can move toward making chickens resistant to the virus,” Wendy Barclay, a virologist at Imperial College London and an author of the study, said at a news briefing. “But we’re not there yet.”

Some scientists who were not involved in the research had a different takeaway. “It’s an excellent study,” said Dr. Carol Cardona, an expert on bird flu and avian health at the University of Minnesota.

But to Dr. Cardona, the results illustrate how difficult it will be to engineer a chicken that can stay a step ahead of the flu, a virus known for its ability to evolve swiftly.

“There’s no such thing as an easy button for influenza,” Dr. Cardona said. “It replicates quickly, and it adapts quickly.”

Avian influenza refers to a group of flu viruses that are adapted to spread in birds. Over the last several years, a highly lethal version of a bird flu virus known as H5N1 has spread rapidly around the globe, killing countless farmed and wild birds.

It has also repeatedly infected wild mammals and been detected in a small number of people. Although the virus remains adapted to birds, scientists worry that it could acquire mutations that help it spread more easily among humans, potentially setting off a pandemic.

Many nations have tried to stamp out the virus by increasing biosecurity on farms, quarantining infected premises and culling infected flocks.

But the virus has become so widespread in wild birds that it has proved impossible to contain, and some nations have begun vaccinating poultry, although that endeavour presents some logistic and economic challenges.

If scientists could engineer resistance into chickens, farmers would not need to routinely vaccinate new batches of birds. Gene editing “promises a new way to make permanent changes in the disease resistance of an animal,”

Mike McGrew, an embryologist at the University of Edinburgh’s Roslin Institute and an author of the new study, said at the briefing. “This can be passed down through all the gene-edited animals, to all the offspring.”

CRISPR, the gene-editing technology used in the study, is a molecular tool that allows scientists to make targeted edits in DNA, changing the genetic code at a precise point in the genome.