Source: Julie Larson Bricher, MEATINGPLACE, 7/3/18


Researchers at the University of Edinburgh's Roslin Institute have used gene editing techniques to produce pigs that resist the virus that causes Porcine Reproductive and Respiratory Syndrome (PRRS).

PRRS costs the pig industry around $2.5 billion each year in lost revenue in the United States and Europe alone. The disease causes breathing problems and deaths in young animals and if pregnant sows become infected, it can cause them to lose their litter.

The research team, in collaboration with global animal genetics company Genus PLC, focused on the cell surface of a receptor (CD163) where the virus attaches and removed the section, leaving the rest of the gene molecule intact. Testing of the gene-edited pigs found that they do not become infected at all with PRRS, and the animals showed no signs that the change in their DNA has had any other impact on their health or wellbeing.

PRRS is endemic in most pig-producing countries worldwide, noted the researchers in a press release. Vaccines have mostly failed to stop the spread of the virus, which continues to evolve rapidly.

Other groups have used gene editing to create PRRS-resistant pigs by removing the whole CD163 receptor. 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 said.

"These results are exciting but it will still likely be several years before we're eating bacon sandwiches from PRRS-resistant pigs," said Christine Tait-Burkard of the University of Edinburgh's Roslin Institute and lead author of the study.

"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," she said. "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 such studies are successful, noted Tait-Burkhard, and the public accepts the technology, researchers would work with pig breeding companies to integrate these gene edits into commercial breeding stocks.

Genetically modified (GM) 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.

GM techniques have been controversial because they can involve introducing genes of other species into an animal. In contrast, gene editing speeds up processes that could occur naturally through breeding over many generations, without introducing genes from other species.

The research was co-funded by the Biotechnology and Biological Sciences Research Council and Genus PLC, is published in the Journal of Virology.

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