Pigs That Are Resistant to Incurable Disease Developed at University of Missouri
Discovery about PRRS virus could save swine industry hundreds of millions of dollars; Exclusive deal signed with global leader in animal genetics
Dec. 08, 2015
Christian Basi, BasiC@missouri.edu, 573-882-4430
COLUMBIA, Mo. — Porcine Reproductive and Respiratory Syndrome (PRRS) virus was first detected in the U.S. in 1987. Pigs that contract the disease have extreme difficulty reproducing, don’t gain weight and have a high mortality rate. To date, no vaccine has been effective, and the disease costs North American farmers more than $660 million annually. Now, a team of researchers from the University of Missouri, Kansas State University, and Genus plc have bred pigs that are not harmed by the disease.
“Once inside the pigs, PRRS needs some help to spread; it gets that help from a protein called CD163,” said Randall Prather, distinguished professor of animal sciences in the College of Agriculture, Food and Natural Resources. “We were able to breed a litter of pigs that do not produce this protein, and as a result, the virus doesn’t spread. When we exposed the pigs to PRRS, they did not get sick and continued to gain weight normally.”
For years, scientists have been trying to determine how the virus infected pigs and how to stop it. Previously, researchers believed that the virus entered pigs by being inhaled into the lungs, where it attached to a protein known as sialoadhesin on the surface of white blood cells in the lungs. However, two years ago Prather’s group showed that elimination of sialoadhesin had no effect on susceptibility to PRRS. A second protein, called CD163, was thought to “uncoat” the virus and allow it to infect the pigs. In their current study, Prather’s team worked to stop the pigs from producing CD163.
“We edited the gene that makes the CD163 protein so the pigs could no longer produce it,” said Kristin Whitworth, co-author on the study and a research scientist in MU’s Division of Animal Sciences. “We then infected these pigs and control pigs; the pigs without CD163 never got sick. This discovery could have enormous implications for pig producers and the food industry throughout the world.”