Kansas State University researcher Raymond "Bob" Rowland said his latest work is helping eradicate a devastating swine disease. The disease is caused by porcine reproductive and respiratory syndrome (PRRS) virus, which costs the U.S. pork industry more than $600 million in losses every year.

In his latest study, Rowland, professor of diagnostic medicine and pathobiology in the Kansas State College of Veterinary Medicine, has created a way to protect offspring from the PRRS virus during the sow's pregnancy. He has found that mothers without the CD163 protein are resistant to the PRRS virus and give birth to healthy, normal piglets. The work appears in Nature's Scientific Reports.

"We have created a protective shell against the PRRS virus during the reproductive phase of production," Rowland said. "The offspring does not become infected during pregnancy and is born a healthy piglet. During this critical phase of production, we have essentially ended a disease."

The PRRS virus causes two forms of disease: a respiratory form that weakens young pigs' ability to breathe, and a more severe reproductive form that causes mass deaths in pigs during late pregnancy.

"The reproductive form not only has a tremendous economic impact but also a psychological impact on people who work with pigs," said Rowland, who has spent more than 20 years studying PRRS. "When we look at ways to control this disease, it really begins with reproduction. We want to keep this disease out of the reproductive process, and we have found a way to do that."

To address the devastating reproductive form of the virus, Rowland collaborated with University of Missouri professor Randall Prather and a team to develop PRRS-resistant pigs. Using CRISPR/Cas9 technology, the researchers found that pigs without the CD163 protein showed no signs or evidence of being infected with the PRRS virus. CD163 is the receptor for the virus.

The research can save swine producers millions of dollars by protecting pigs from the PRRS virus during the critical reproductive process, Rowland said. However, he conceded that because offspring are born normal, they may still be susceptible to the disease later in life.

"This is one tool that we can use," Rowland said. "It doesn't mean that we can give up on vaccines or diagnostics, but it does create more opportunities for other tools to become more effective. Because this pig is born healthy, it will respond better to a vaccine or a diagnostic test. We are enhancing other aspects of disease control as well."

Rowland will present the research at the 2017 North American PRRS Symposium being held Dec. 1-3 in Chicago, Ill. 

Other Kansas State University researchers involved in the project include laboratory research manager Maureen Kerrigan and doctoral student and research assistant Luca Popescu.