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Gene-edited pigs are resistant to billion dollar virus, study finds
Scientists have produced pigs that can resist one of the world’ s most costly animal diseases, by changing their genetic code.
T ests with the virus – called Porcine Reproductive and Respiratory Syndrome, or PRRS – 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 wellbeing.
PRRS costs the pig industry around $ 2.5 billion(£ 1.75bn) each year in lost revenue in the US 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 virus infects pigs using a receptor on their cells’ surface called CD163. Researchers at the University of Edinburgh’ s Roslin Institute used gene editing techniques to remove a
08 | Farming Monthly | July 2018 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, a leading global animal genetics company, 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.
This is the first time researchers have exposed these pigs to the virus to see if they become infected.
They found that none of the animals became ill when exposed to the virus. Blood tests found no trace of the infection.
This research, co-funded by the Biotechnology and Biological Sciences Research Council and Genus PLC, is published in the Journal of Virology.
PRRS is endemic in most pig producing countries worldwide. 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 say.
Dr Christine Tait-Burkard, of the University of Edinburgh’ s Roslin Institute, said:“ 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
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