Scientist with pigs The Roslin Institute

U.K. researchers approach gene editing for PRRS resistance, differently

Scientists create gene-edited pigs resistant to PRRS by using techniques to remove a small section of the CD163 gene.

Source: The Roslin Institute 

Scientists at The Roslin Institute have produced pigs that can resist one of the world's most costly animal diseases, by changing their genetic code, according to the Roslin Institute at the University of Edinburgh in the United Kingdom.

Tests with the porcine reproductive and respiratory syndrome virus found the pigs do not become infected at all. The animals show no signs that the change in their DNA has had any other impact on their health or well-being.

PRRS is endemic in most pig-producing countries worldwide, costing the pig industry around $2.5 billion each year in lost revenue in the United States and Europe alone.

The virus infects pigs using a receptor on their cells’ surface called CD163. Scientists used gene-editing techniques to remove a small section of the CD163 gene. They focused on the section of the receptor that the virus attaches to, leaving the rest of the molecule intact.

The team collaborated with Genus PLC to produce pigs with the specific DNA change. Previous studies had shown that cells from these animals were resistant to the virus in lab tests, but this is the first time researchers have exposed these pigs to the virus to see if they become infected.

Researchers found that none of the animals became ill when exposed to the virus, as blood tests found no trace of the infection.

Other groups have used gene editing to create PRRS-resistant pigs by removing the whole CD163 receptor. However, removing only a section of CD163 allows the receptor to retain its ordinary function in the body and reduces the risk of side effects, the researchers say.

Genetically modified animals are banned from the food chain in Europe. It is not clear what regulations would apply to gene-edited animals, however, as the approach is different.

“These results are exciting but it will still likely be several years before we’re eating bacon sandwiches from PRRS-resistant pigs. First and foremost we need broader public discussion on the acceptability of gene-edited meat entering our food chain, to help inform political leaders on how these techniques should be regulated. We also need to carry out longer-term studies to confirm that these genetic changes do not have any unforeseen adverse effects on the animals. If these studies are successful and the public are accepting of this technology, we would then be looking to work with pig breeding companies to integrate these gene edits into commercial breeding stocks,” states Christine Tait-Burkard, Ph.D., the Roslin Institute.

This research was made possible by interdisciplinary research over many years, supported by long-term strategic funding by the UK’s Biotechnology and Biological Sciences Research Council. It was also funded by Genus PLC and is published in the Journal of Virology.

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