PhD-candidate Guilherme Milanez Preis, working with Drs. Cesar Corzo and Fabio Vannucci on the epidemiology of Senecavirus A. In an article for the National Hog Farmer, Preis shares the latest results of his work on Senecavirus A prevalence in the USA.Continue reading “Shedding light on the epidemiology of Senecavirus A”
University of Minnesota scientists are collaborating to look at how PRRS virus evolves to understand disease spread, and advance mitigation and control efforts
ST. PAUL, MINNESOTA —- A new grant of nearly $3 million will help University of Minnesota College of Veterinary Medicine (CVM) researchers and collaborators at the University of Edinburgh’s Roslin Institute investigate how porcine reproductive and respiratory syndrome (PRRS) virus evolves and spreads. The research will help scientists and producers anticipate a herd’s susceptibility to different strains of PRRS virus, and customize mitigation efforts accordingly. The data generated could be used to inform future vaccine designs. The grant is funded jointly 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. It will cover the next four years of research.
PRRS virus costs the US swine industry more than $560 million each year. First described in Indiana, North Carolina, Iowa, and Minnesota in the late 1980s, the virus rapidly spreads within barns and between farms. It has since remained one of the industry’s biggest game changers. Since its emergence in the United States, scientists have worked to reduce its impact.
But while a host may build immunity to a certain strain of PRRS virus after infection, that strain—as with any RNA virus—can counter-evolve to survive in that host and spread. And viruses often compete for hosts—some are better than others at evading the host’s immunity, depending on what that host is used to. This process is called “multistrain dynamics,” and has been investigated extensively in human medicine, but has rarely been explored in animals—until now. This project aims to help farmers understand how PRRS virus evolves, changes, moves, and persists. It also helps producers explore ways of out-maneuvering PRRS virus.
As with many RNA viruses, PRRS virus rapidly evolves and acquires genetic changes over time. However, scientists can study and potentially predict the genetic diversity of PRRS virus in pigs better than they can study other viruses in humans or wildlife because of the rich availability of data—they know where farms are, so they know what the distribution of hosts looks like. They also know how animals are moving between farms, and there is already a lot of ongoing sequencing, so scientists know where and when strains of the virus occur. Researchers don’t have this information readily available for studying the same questions in a human virus.
Kim VanderWaal, PhD, assistant professor in the Department of Veterinary Population Medicine (VPM) at the CVM, is the principal investigator on the project. She says, “Studying PRRS virus’s evolution will help us better understand and hopefully control PRRS virus, but it will also help us understand the evolution and drivers of genetic diversity in viruses in humans and other animals.”
The U of M Veterinary Diagnostic Laboratory has been collecting samples of the PRRS virus for nearly three decades. As part of the grant’s research team, Albert Rovira, DVM, PhD, an associate professor in the VPM, and his team will continue to sequence small parts of RNA from the lab’s collection to determine which samples are new variations of the virus. “We also have hundreds of virus isolates saved in the lab’s freezer,” says Rovira, who notes that these isolates could be used to infect pigs during the research.
The project is partially built on data collected by the Morrison Swine Health Monitoring Project (MSHMP) at the University of Minnesota, which tracks the occurrence of PRRS virus in roughly 50% of the United States’ breeding swine population. MSHMP is coordinated by Cesar Corzo, DVM, MS, PhD, associate professor in the VPM, who is also on the research team for this grant. “One of the reasons Minnesota is so ideally situated for this research is that this dataset is one-of-a-kind,” says VanderWaal.
Another specific asset to this team’s approach is the contributions of Declan Schroeder, PhD, virologist and associate professor in the VPM. Schroeder’s lab was able to develop a new technique that can describe the full genomic strain profile of PRRS virus within 24 hours of sampling. Schroeder says this research can give veterinarians a better tool to rapidly diagnose the infection in animals.
This work is also extremely timely. Another part of this project aims to track the spread of different strains of PRRS virus, including newly evolved ones. “An emergence of a new strain was last seen in 2014,” says VanderWaal. “and we see a general pattern where a significant new type or strain appears every three to five years.”
Last week, Drs. John Deen and Jerry Torrison were interviewed about African Swine Fever, the virus decimating the Chinese hog industry. They shared why it is a concern for our swine farmers in the Midwest, and how the University of Minnesota is participating in the effort to prepare for it.
Watch the full video on the KTTC website.
The University of Minnesota Swine Group and the Center for Animal Health and Food Safety (CAHFS) have partnered with the Swine Health Information Center (SHIC) to develop and implement a system for near real time global surveillance of swine diseases. The output of the system is the identification of hazards that are subsequently scored using a step-wise procedure of screening, to identify increments in hazards that, potentially, may represent a risk for the US.
The first version of the system is now live, with the first three reports available, including data from November 5, 2017 to January 14, 2018.
Beginning in early March the tool will be available for spontaneous reporting by stakeholders, such as producers and practitioners both overseas and in the United States. During the first year of the project, the system will be developed and beta-tested for USDA-classified tier 1 reportable foreign animal swine diseases (ASF, CSF, FMD), but in the future more diseases will be tracked.
“As we have learned in recent years, we need to pay attention to external health threats as part of our overall risk management. Keeping tabs on global trends is a prudent investment,” said Dr. Jerry Torrison, Director of the University of Minnesota Veterinary Diagnostic Laboratory.
The current concern continues to focus on African swine fever in Poland and surrounding countries. Infected wild boars continue to be identified in the vicinity surrounding Warsaw, and the possibility of spread of the disease to the pig intensive area of eastern Poland continues to be a concern. Countries in the region are using a combination of increased hunting of wild boar along with boar proof fencing along borders to attempt to control the spread of the disease.
Visit z.umn.edu/SwineGlobalSurveillance to access the reports, and coming soon, to use the tool to provide spontaneous reporting.
In this month column of the National Hog Farmer, Dr. Albert Rovira from the University of Minnesota is reviewing the cases of intoxication due to ionophores, these antibiotics given through the feed to control bacterial and coccidial infections in swine.Clinical signs are non-specific. Indeed, pigs become weak and stop eating but do not have a fever. In more severe cases, neurological signs can be noted. However, histological lesions are striking with a dramatic change of the muscle structure as is shown in Figure 1 below.
There are three main causes of ionophore intoxication in swine:
- Dosage error in the diet: the optimal concentration is very small, between 15 and 30 parts per milliom.
- Mixing ionophore and tiamulin: Tiamulin prevents the ionophore from being excreted by the body, leading to toxic blood levels.
- Inclusion of ionophores designed for another species. Usually, the levels are incorporated at a concentration higher than the toxic level.
In conclusion although cases of ionophore intoxication are rare in swine, it may become more prevalent starting in 2017, with the approval of the only swine ionophore as a growth promotant.