Pig gene editing development possible PRRS ‘game changer’

Scientists have been able to edit pigs’ genes to make them resistant to porcine reproductive and respiratory syndrome, which is endemic in most pig-producing countries.
Scientists are one step closer to tackling porcine reproductive and respiratory syndrome (PRRS) with the creation of gene-edited resistance to the virus.
In what has been described as a game-changing development, scientists have been able to edit pigs’ genes to make them resistant to the deadly disease, which is endemic in most pig-producing countries and costs the industry around £1.75 billion a year in lost revenue across Europe and the US.
The disease, which can cause breathing problems and death in young animals – and result in sows losing their litters – infects pigs using a receptor on their cell’s surface called CD163. To date, vaccines have, for the most part, failed to stop the spread of the virus.
Therefore, researchers at The University of Edinburgh’s Roslin Institute – the birthplace of Dolly the sheep – decided to apply gene editing techniques to remove a small section of the CD163 gene; resulting in the receptor being able to retain its ordinary function in the body and reduced side effects.
While other groups have successfully created PRRS-resistant pigs, they only did so by removing the whole receptor.
Post-procedure blood tests showed no signs of infection and no pigs became ill following exposure to the virus.
Lead researcher Christine Tait-Burkard, of the Roslin Institute, said: “This could truly be a game changer in terms of PRRS because every veterinarian in the field knows there are problems with treating it.
“Firstly, the vaccinations are sometimes problematic and can generate – rather than solve – problems in the herd. Secondly, PRRS is a moving target and a fast-evolving virus, which seems to escape a lot of our combating mechanisms.”
Producing pigs completely resistant to the virus would remove the need for veterinary intervention – because there would not be anything to treat – and enhance animal welfare, Dr Tait-Burkard explained.
It is hoped the general principle could also potentially be used in the fight against a host of infections in other animals.