Pigs that are resistant to a deadly viral disease have been created by scientists at Edinburgh’s Roslin Institute.
The gene-edited animals remained healthy when exposed to classical swine fever (CSF), a highly contagious and often fatal disease. The virus was eradicated in the UK in 1966, but there have been several outbreaks since and it continues to pose a major threat to pig farming worldwide.
“Classical swine fever is a devastating disease for livestock and farmers as we saw with the outbreak in the UK, 25 years ago,” said Helen Crooke, mammalian virology deputy leader at the Animal and Plant Health Agency (APHA), where the pig trial was performed. “Hopefully this breakthrough can help bolster the resilience of the livestock sector to the disease.”
Classical swine fever, also known as hog cholera or pig plague, causes fever, skin lesions, convulsions, diarrhoea – and often death within 15 days.
In the UK, periodic outbreaks since the 1960s, have led to the culling of 75,000 pigs. And in countries such as China, Russia and Brazil, where the disease is endemic, CSF is controlled through costly and labour-intensive vaccination programmes and international trade restrictions.
Dr Christine Tait-Burkard, a group leader at the Roslin Institute, said: “This virus has a severe effect on animal welfare and productivity.”
The latest study, the first to demonstrate resistance through gene editing, targeted a gene responsible for producing a protein called DNAJC14. This protein had been shown to play a critical role in the replication of pestiviruses (the virus family that includes CSF) once they enter the cell. Previous studies in cells had found that altering just a few letters of the DNA code blocked viral replication.
In the latest study, scientists at the Roslin Institute created a line of pigs with the same precise edits to their DNA. Four of the pigs were then exposed to CSF, along with four control pigs, at APHA’s biosecure facility.
A week after inoculation, the control animals were showing symptoms of the disease and had high levels of the virus in their blood. By contrast, the gene-edited pigs were completely healthy and showed no signs of infection. Several generations of gene-edited pigs were monitored and no adverse effects on health or fertility were observed.
The same gene is involved in the replication of pestiviruses that infect cattle and sheep – less severe diseases, but ones that continue to circulate in the UK – and the team is now investigating whether the same edit confers resistance for these species.
The advance comes as many countries are relaxing rules around gene editing in agriculture, with the UK’s Precision Breeding Act paving the way for gene-edited crops. Countries including the US, Japan and Brazil have already approved gene-edited livestock. Based on previous work at Roslin, Genus, a company based in Basingstoke, has generated pigs that are resistant to a virus that causes porcine reproductive and respiratory syndrome, which have been approved for sale in the US and are expected to go on the market there in 2026.
Dr Simon Lillico, research scientist at the Roslin Institute and a co-author, said: “In my mind there is a moral imperative that if we can make animals that are disease resistant then we probably should do.”
Dr Emily Clark, of EMBL’s European Bioinformatics Institute, who was not involved in the research, said: “Decades of genomic research have made it possible to pinpoint and precisely edit the genes involved in disease resistance. Research like this is helping to create healthier animals, reduce losses for farmers in areas affected by swine fever, and marks a major step forward in using genomics-enabled innovation to build resilience to disease in livestock populations.”
The findings are published in the journal Trends in Biotechnology.
