Gene editing based on CRISPR technology has already been successfully applied to sickle cell disease, and other companies are also working on developing similar forms of therapeutics. As this technology progresses, gene editing would only seem natural to reach animals.
Precision Porcine Gene Editing
Pigs immune to disease could become the first genetically modified animals available for commercial launch. International breeding company Genus has created hundreds of gene-edited pigs for large-scale meat production.
Using CRISPR-Cas9 technology, the company hopes to tackle porcine reproductive and respiratory syndrome (PRRS) by creating gene-edited pigs immune to the virus infection. The details of the experiment used in editing these pigs are detailed in the report "Generation of a commercial-scale founder population of porcine reproductive and respiratory syndrome virus-resistant pigs using CRISPR-Cas."
Using CRISPR technology, experts can snip out the part of the DNA that codes for a protein called CD163, the preferred binding point of the virus. As a result, pigs are immune to PRRS but otherwise function normally.
The team believes that this is a groundbreaking accomplishment in agriculture toward improving animal health, reducing antibiotic use on the farm, lowering production costs, and reducing waste. They also claim that applying this technology to eliminate other livestock diseases that are harmful to both animals and humans would be a vital step that would benefit consumers, society, and the environment.
The firm hopes that by the end of the year, the U.S. Food and Drug Administration (FDA) will formally approve their gene-edited pigs for widespread human consumption. The PRRS-resistant pig from Genus is the first gene-edited food animal production that has been publicly announced to be going through a full FDA investigational new animal drug (INAD) regulatory review.
FDA has approved two genetically modified food animals, but neither is consumed widely. One is salmon, which contains a gene from another fish species and grows faster, although consumer concerns limit its sales. The other one is the GalSafe pig, made by Revivicor, which has DNA inserted to cripple a gene for a sugar molecule on the surface of its cells.
What is PRRS?
PRRS is a disease caused by arterivirus, which causes pneumonia, abortion, and loss of vigor in pigs. It is transmitted among swine within a herd through contact and exchange of bodily fluids like saliva.
Also known as "blue-ear pig disease", it is a viral infection which causes minimal symptoms in some animals while killing others. Its major symptoms include respiratory distress, reproductive failure, and a high mortality rate for piglets.
Since the 1980s, it has been a global issue that has affected pig farms, costing farmers $2.4 billion a year. According to the Iowa State University College of Veterinary Medicine, PRRS is the most economically significant disease that has affected swine production in the U.S. since classical swine fever was eradicated.
Vaccine programs have already been rolled out, but they only reduce symptoms and do not eradicate the disease. This is why scientists considered exploring gene editing technology as an alternative.
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