Gene-edited pigs show signs of resistance to major viral disease

Scientists at the University of Edinburgh�s Roslin Institute have produced pigs that may be protecte

Scientists at the University of Edinburgh�s Roslin Institute have produced pigs that may be protected from an infection, Porcine Reproductive and Respiratory Syndrome (PRRS), that costs the swine industry billions each year. - Credit: Archant

Scientists believe they may have come up with a solution to a virus described as “one of the greatest challenges facing pig producers today” which is endemic in most pig-producing countries.

Porcine Reproductive and Respiratory Syndrome (PRRS) causes severe breathing problems in young pigs and breeding failures in pregnant females, but vaccines have failed to stop its spread, causing the pig sector estimated losses of 1.5bn euros a year in Europe alone.

Now a research team from the University of Edinburgh’s Roslin Institute, in collaboration with breeding firm Genus, have used gene editing to produce pigs that appear to be able to combat it successfully.

Early tests have shown cells from the pigs are completely resistant to infection with both major subtypes of the virus that causes the disease.

The animals are otherwise healthy and the change should not affect their ability to fight off other infections, researchers say.

The team used a gene-editing tool to cut out a small section of the CD163 gene, which plays a key role in enabling the virus to establish an infection, in the pigs’ DNA code. Laboratory tests of cells from the pigs with the modified CD163 gene have confirmed that the change to the pig’s DNA blocks the virus from being able to cause infection.

The next stage of the research will be to test whether the pigs are resistant to infection when exposed to the virus.

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Previous studies by another team have produced pigs that lack the entire CD163 molecule, and which do not become ill when exposed to the PRRS virus.

In the latest study, only the section of CD163 that interacts with the PRRS virus is removed and the molecule appears to retain its other functions.

Lead researcher Professor Alan Archibald said: “Genome-editing offers opportunities to boost food security by reducing waste and losses from infectious diseases, as well as improving animal welfare by reducing the burden of disease. Our results take us closer to realising these benefits and specifically address the most important infectious disease problem for the pig industry worldwide.”

Jonathan Lightner, chief scientific officer for Genus, said this, and other gene edits, would be evaluated. The study is published in the journal Plos Pathogen.