Scientists genetically engineer pigs immune to costly disease

Scientists have genetically engineered pigs to be immune to one of the world’s most costly animal diseases, in an advance that could propel gene-editing technology into commercial farms within five years. The trial, led by the University of Edinburgh’s Roslin Institute, showed that the pigs were completely immune to porcine reproductive and respiratory syndrome (PRRS), a disease that is endemic across the globe and costs the European pig industry nearly £1.5bn in pig deaths and decreased productivity each year. Pigs infected with PRRS are safe to eat but the virus causes the animals breathing problems, causes deaths in piglets and can cause pregnant sows to lose their litter. There is no effective cure or vaccine, and despite extensive biosecurity measures about 30% of pigs in England are thought to be infected at any given time. After deleting a small section of DNA that leaves pigs vulnerable to the disease, the animals showed no symptoms or trace of infection when intentionally exposed to the virus and when housed for an extended period with infected siblings.