Is the future of bacon bright?

Thursday, January 7, 2016

University of Missouri, Kansas State University

and Genus team up to put an end to the PRRS virus

Imagine living in a world where swine producers could rest easy knowing that a highly contagious swine disease would never hit their barns. What was once a dream has now become a reality. Researchers at the University of Missouri in collaboration with Genus plc and Kansas State University have discovered a viable option to protecting swine herds from the deadly Porcine Reproductive and Respiratory Syndrome Virus. Reproduction failure, reduced growth and premature death are all results of PRRSv, but can now be a thing of the past.

New technology
Gene editing technology has the potential to save North American producers over $664 million dollars every year. Vaccines have proven to be ineffective in controlling the spread of PRRSv or administering a cure in the last 25 years according to a press release issued by Genus. Small changes were made to inactivate a single gene that produces a protein known as CD163.

The PRRS virus requires CD163 to "uncoat" the virus, therefore, allowing the infection to occur in the pigs. Researchers took the edited DNA sequence and injected it into a zygote cell using the CRISPR/Cas9 method and a micropipette. Gene editing allows precise changes to be made in the genome of the animal without introducing genetic material from another organism as stated by Genus.

Tiger and Wildcat collaboration
Dr. Randall Prather, a professor of animal sciences at the University of Missouri along with Kristin Whitworth, co-author on the study and a research scientist in MU's Division of Animal Sciences, and Associate Professor Kevin Wells collaborated with professor of diagnostic medicine and pathobiology Raymond Rowland at the College of Veterinary Medicine at Kansas State University. Rowland was in charge of challenging the pigs with the PRRS virus. The pigs consisted of unedited, or wild-type and edited, or PRRSv resistant. These piglets were randomly assigned ear tags before being shipped to Kansas State University.

The reason for assigning ear tags before changing facilities was to hide the genotypes and litter from which the piglets originated from the KSU researchers.

Results
After challenging the the set of piglets with the PRRSv, the wild-type pigs showed symptoms consistent with the PRRS infection.

The knockout pigs, or gene-edited pigs, showed no clinical signs of illness regardless of being constantly exposed to their infected pen mates.

Not only did they not become ill, but researchers found no other changes in their development compared to pigs that produce the CD163 protein, as stated in the University of Missouri's news release.

This means, by editing-out the CD163 protein, the pigs continued to grow and mature normally.

Producer's perspective
Brent Sandidge is a third-generation owner and operator of Ham Hill Farms, located in Marshall.

"There's not too many people in the US that have not been affected by PRRS at some point or another," he said. "It's a very devastating disease."

Sandidge has unfortunately become familiar with three mutated strains of the PRRS virus.

"The thing about PRRS, is the way it mutates," Sandidge reflected. "The stuff that used to be 25 years ago was pretty mild and then they've gotten progressively worse. In this area, we're PRRS negative. You know, we just really worked our tails off to keep it that way."

Biosecurity on farms can assist in the prevention of spreading PRRS virus before the commercialized PRRS-free pigs are available for purchase.

He commented that 20-30 years ago, producers were not as concerned with biosecurity because there were less imported goods and fewer people traveling.

"There's just a lot more concerns for people involved in agriculture today," Sandidge admitted.

As far as the new gene-edited pigs are concerned, Sandidge wants to see more research done before he decides to ship these swine to his farm.

"I think they've only tried it on one strain," Sandidge said. "One challenge on one strain, so you know it'll be interesting to see, to move forward with it and you know, see what happens."

Conclusion
As the gene-editing technology continues to develop, swine producers can expect to wait five years until PRRS-resistant animals are available. Genus has stated they intend to commercialize the technology through PIC, their porcine division.

"This discovery could have enormous implications for pig producers and the food industry throughout the world," said Whitworth.

Contact Michaela Leimkuehler at mleimkuehler@marshallnews.com