Early laboratory tests have revealed that cells from the pigs are resistant to infection from both major subtypes of the virus that causes the PRRS disease.

PRRS causes severe breathing problems in young pigs as well as breeding failures in pregnant sows. The viral disease is endemic in most pig-producing countries worldwide and is estimated to cost the pig industry in Europe more than €1.5bn each year.

Scientists at the University of Edinburgh, working in conjunction with genetics firm Genus, have used a gene-editing tool to cut out a small section of the CD163 gene in the pig’s DNA code.

The CD163 gene is understood to play a key role in enabling the PRRS virus to establish an infection.

The researchers state that the gene editing should not affect their ability to fight off other infections.

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

Specific editing

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.

Laboratory tests of cells from the pigs with the modified CD163 gene have confirmed that this change in the pig’s DNA blocks the virus from being able to cause infection.

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

“Our results take us closer to realising these benefits and specifically address the most important infectious disease problem for the pig industry worldwide,” Professor Alan Archibald from the Roslin Institute at the University of Edinburgh said.

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