Pigs that may be protected from Porcine Reproductive and Respiratory Syndrome (PRRS) have been produced following a collaborative project between genetics company Genus, PIC’s parent company, and the Roslin Institute.
The development of pigs that appear to be resistant to a disease that costs the global pig industry billions of dollars each year could have profound benefits to animal welfare and society, the researchers said.
The team, based at The Roslin Institute, used gene editing techniques to produce pigs that are potentially resistant to the PRRS virus (PRRSv). Early tests have revealed that cells from the pigs are completely resistant to infection with both major subtypes of the virus that cause the disease. The animals are otherwise healthy and the change, which should not affect their ability to fight off other infections, the researchers say.
PRRS, which causes severe breathing problems in young pigs and breeding failures in pregnant females, is endemic in most pig producing countries worldwide. Vaccines have mostly failed to stop the spread of the virus, which continues to evolve rapidly. Consequently, it is one of the greatest challenges facing pig producers today. In Europe alone, the disease is estimated to cost the pig industry more than €1.5 billion each year.
In the latest study, only the section of CD163 that interacts with PRRSv was removed and the molecule appeared to retain its other functions. Studies have shown that PRRSv targets immune cells called macrophages. A molecule on the surface of these cells called CD163 plays a key role in enabling PRRSv to establish an infection.
The research team at the University of Edinburgh’s Roslin Institute, in collaboration with Genus, used a gene-editing tool called CRISPR/Cas9 to cut out a small section of the CD163 gene in the pigs’ DNA code.
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.
Lead researcher Professor Alan Archibald, of The Roslin Institute, 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.”