University of Missouri Scientists Breed PRRS Resistant Pigs using CRISPR

The porcine reproductive and respiratory syndrome virus (PRRSV) affects pigs worldwide and is considered the most economically significant disease of swine. Vaccinations have mostly failed to prevent the syndrome's spread, but a new approach by biologists at the University of Missouri may mark a turning point. They developed a commercial agricultural application for the revolutionary CRISPR/Cas9 gene-editing method—to breed pigs resistant to infection.

CRISPR/Cas9 is a gene-manipulation tool that allows scientists to make changes in DNA with razor-sharp accuracy. For porcine reproductive and respiratory syndrome, Missouri's Randall Prather, Kristen Whitworth and Kevin Wells used the technique to breed three piglets that lacked a protein in cells that acts as a doorway for the virus.

The edited piglets were grouped together in a pen with seven normal piglets, and were inoculated with PRRSV. After five days, the normal pigs grew feverish and ill, but the genetically edited pigs remained in top health throughout the study despite sharing close quarters with their sick pen mates.

Blood testing also revealed that the edited animals did not produce antibodies against the virus, proving that they evaded infection entirely. This work and other recent experiments demonstrate the promise of CRISPR/Cas9 for the care of domestic animals.

For more on the study, read the article on Scientific American.