For decades, veterinarians and producers have struggled to contain porcine reproductive and respiratory syndrome virus (PRRSV).

The highly pathogenic swine virus mutates rapidly, making control a moving target. Pigs infected with PRRSV suffer from high morbidity and mortality rates. Even those who live endure difficulty breathing, fever, and loss of appetite. Today, the disease affects as many as half of all swine breeding farms in the United States. It’s the most costly issue the swine industry faces.

In a recent study published in the journal Preventive Veterinary Medicine, researchers used data collected by the Morrison Swine Health Monitoring Program (MSHMP) at the University of Minnesota (UMN) to estimate that PPRS costs pork producers in the United States $1.2 billion in losses annually between 2016 and 2020—$380 million in the breeding phase and about $820 million in the growing phase.

“The progressive mentality and collaborative nature of U.S. producers, and veterinarians from different companies and clinics throughout the country, enabled us to build a highly representative database, which has allowed us to understand the epidemiology of PRRSV in this country and collaborate with researchers from other institutions to better understand the impact of this disease,” says Cesar A Corzo, director of the MSHMP.

Researchers at the UMN College of Veterinary Medicine (CVM) are producing cutting-edge research to enhance understanding of how producers can more effectively prevent PRRS from ravaging their herds, and offer them optimized treatments when an outbreak does occur. Their research is funded by grants through the United States Department of Agriculture (USDA), the National Science Foundation (NSF), the National Institutes of Health (NIH), and the Swine Health Information Center (SHIC).

Below are some examples of advancements in PRRS prevention and tracking that have been enabled by UMN researchers and partnerships.

AI brings 30 years of data to the real world

An AI-driven initiative started by CVM researchers is harnessing huge amounts of data on PRRSV variants to help farmers better understand how the rapidly evolving virus moves within and between herds—and the best course of action for getting pigs healthy again.

The CVM’s Morrison Swine Health Monitoring Project Database houses nearly 40,000 sequences of PRRSV RNA, representing more than half of the U.S. swine breeding herd. But the full potential of the data to teach us about the virus has yet to be realized, awaiting advances in machine learning that could take full advantage of the information it stores. Kim VanderWaal, an associate professor in the Department of Veterinary Population Medicine, is among the CVM researchers spearheading a new AI-based platform that can finally make full use of the data. 

Read more here.

Tracking the rapidly changing virus

Armed with an incredible amount of data, CVM researchers with the UMN Swine Group and Morrison Swine Health Monitoring Project are tracking how PRRSV evolves and detecting new variants as they emerge. They’re also tracking what variants are circulating at any given time, investigating recombination—when two variants infect a pig at the same time, those two variants can create a new variant—and how much cross-immunity pigs have against different newly emerging variants.

Another study recently published in Virus Evolution provides the first experimental evidence showing that the virus evolves more rapidly in immunized pigs than in pigs that were not vaccinated. This study not only answers long-standing questions about how pig management may influence viral evolution for PRRS but also showcases the innovative and interdisciplinary strengths of the Swine Group.

“Having so much data allows us to take a 30,000-foot look at what has been going on with the virus’s evolution over the past 20 years,” VanderWaal says. “Part of the question is how different two PRRS viruses must be before infection by one genetic variant is not enough to protect against the other. Keeping up with the current variants really is a moving target, but utilizing data to look at the virus in an aggregate way allows us to start to see things differently.”

Read more here.

Working with colleagues across the pond

In 2019, swine researchers at CVM were awarded a $3 million Ecology and Evolution of Infectious Diseases grant by the National Institute of Food and Agriculture, National Science Foundation, National Institutes of Health, and the United Kingdom Government’s Biotechnology and Biological Sciences Research Council. With that funding, researchers in Minnesota partnered with their colleagues in the U.K. to track how the PRRS evolves.

Declan Schroeder, a professor in the Department of Veterinary Population Medicine, made a huge breakthrough thanks to the grant. The Schroeder Lab was able to establish the first-ever evidence that the full genome of the PRRS virus is detectable within 24 hours of sampling. The research is an example of a success story fueled by collaboration and the expertise that the CVM brings to PRRSV research.

Now complete, this research can give veterinarians a better tool to rapidly diagnose the infection in animals.

“People have tried one or two components of this project on their own, but we’ve put together a truly interdisciplinary team,” Schroeder says. “The whole project can’t function without each member's expertise.”