Gene-edited pigs are resistant to classical swine fever
Simon Lillico
A little genetic tweaking can make pigs completely resistant to classical swine fever, a major problem for farmers around the world. The same gene change should also make cattle and sheep resistant to related viruses that infect livestock.
Widespread use of gene-edited pigs resistant to classical swine fever will improve animal welfare and increase productivitywhich should will lead to a reduction in greenhouse gas emissions and below prices in stores. “This will help ensure sustainable livestock production and beautiful, healthy and happy pigs,” says Helen Crook at the UK Animal and Plant Health Agency.
Classical swine fever is a highly contagious viral disease that causes illnesses ranging from fever to diarrhea to miscarriages and can kill large numbers of pigs.
Although the disease has been eradicated in many regions, it reappears from time to time. Six million pigs were slaughtered to stop outbreak in the Netherlands in 1997For example, while Japan has been fighting to re-eradicate the disease since 2018.
When the disease is present, vaccines containing live, attenuated strains of the virus are used to protect livestock, but this is labor-intensive and expensive. “Vaccination requires careful coordination and monitoring,” says Christine Tate-Burkard at the University of Edinburgh, UK.
Countries that vaccinate cannot export the vaccine to disease-free regions. And any failure in vaccinations can lead to outbreaks — something that recently happened in the Philippines, Tate-Burkard says.
But the classical swine fever virus has an Achilles heel. The group of viral proteins consists of one long chain of amino acids that must be cut into pieces to become functional, and it uses pork protein to do the cutting.
A change in one amino acid in this pork protein, called DNAJC14, can block cutting. Therefore, Tate-Burkard and her colleagues used CRISPR gene editing to create pigs with this tiny change.
The team then sent some of the pigs to a secure facility, where Crook and her colleagues sprayed live pig viruses into their noses. None showed any signs of infection – no symptoms, antibodies or detectable virus – while all the normal pigs became sick.
“These animals were completely resistant to viral replication and remained happy and healthy throughout the study,” says Crook.
The work was partly funded by the large international breeding company Genus, which is now considering commercializing the pigs.
The family has already been created gene-edited pigs are resistant to another serious disease called porcine reproductive and respiratory syndrome.. These pigs are currently approved in the US, Brazil and other countries. Genus is awaiting approval in Mexico, Canada and Japan—key U.S. export markets—before it begins selling sperm to farmers.
Where gene editing is used to make tiny changes that might occur naturally, it is less strictly regulated in many countries than traditional genetic engineering. Japan already approved three gene-edited fish.
England due to the imminent start of approval of gene-edited plantsbut has not yet completed the rules for the livestock. These rules will almost certainly require that gene changes do not affect welfare.
According to scientists, no side effects were observed in pigs resistant to classical swine fever. Simon Lillicomember of the University of Edinburgh team, but further research will be needed to confirm this.
He also notes that in conventional breeding such welfare requirements do not exist. “A level playing field would be great,” he says. “Of course there are conventionally bred animals with lower welfare.”
Viruses very closely related to classical swine fever cause viral diarrhea in cattle and borderline disease in sheep. Diseases in cattle and sheep are less lethal but still affect welfare and productivity. The Edinburgh team is now studying whether changes made to pigs will work in cattle and sheep.
Topics:
