Pigs worldwide are plagued by a series of viral diseases that slow growth, cause illness and drastically restrict reproduction. One of the most pervasive is known as Porcine Respiratory and Reproductive Syndrome, or PRRS. As Iowa State University’s College of Veterinary Medicine notes, the disease wreaks havoc on pigs:
Primary clinical signs among young pigs are fever, depression, lethargy, stunting due to systemic disease, and pneumonia. Sneezing, fever and lethargy are followed by expiratory dyspnea and stunting …. Postweaning mortality often is markedly increased, especially with more virulent strains and the occurrence of ever-present concurrent and secondary infections.
PRRS increases pork production costs approximately $580 million annually, according to a 2017 estimate, as breeders attempt to manage the disease or prevent it with vaccination and other measures.While these practices help keep PRRS in check, Christine Burkard, assistant professor of infection and immunity at the Roslin Institute in Scotland, says her team has devised a solution to this pressing animal welfare concern.
Using CRISPR-Cas9 gene editing, the researchers have successfully deleted part of a gene from the pig genome, changing the structure of a corresponding protein called CD163 so the virus can’t attach to it. The gene-edited animals are PRRS resistant, showing “no signs of infection and no viremia or antibody response indicative of a productive infection,” Burkard and her colleagues reported in a 2018 study.
The disease-resistant pigs are beginning to enter breeding programs for further study. Following approval by the Food and Drug Administration, they could begin to enter the US food supply.
The Talking Biotech podcast, produced by Kevin Folta, is available for listening or subscription: