New research from the US is helping to eradicate a devastating swine disease—one which is caused by the porcine reproductive and respiratory syndrome (PRRS) virus, and costs the US pork industry more than $600 million in losses every year.
In a study published recently in Nature’s Scientific Reports, Professor Raymond Rowland from the College of Veterinary Medicine at Kansas State University, describes how he created a way to protect offspring from the PRRS virus during pregnancy. He found that mothers without the CD163 protein are resistant to the PRRS virus and give birth to healthy, normal piglets.
“We have created a protective shell against the PRRS virus during the reproductive phase of production,” Professor 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 disease in two forms: 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 Professor Rowland, who has spent more than 20 years studying the PRRS virus. “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, Professor Rowland and others developed PRRS-resistant pigs. Using CRISPR/Cas9 technology, the group 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.
Professor Rowland is hopeful the research will save swine producers millions of dollars because pigs are protected from the PRRS virus during the critical reproductive process. But because offspring are born normal, they may still be susceptible to the disease later in life.
“This is one tool that we can use,” he 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.”