As one of only a select few facilities in the U.S. to have access to the highly contagious African swine fever (ASF) virus, University of Minnesota researchers have reached a major breakthrough in the efforts to develop effective mitigation strategies to control ASF and keep it from entering North America.
The U of M research team, led by Gerald Shurson, a professor in the College of Food, Agricultural and Natural Resource Sciences, and Declan Schroeder, an associate professor from the College of Veterinary Medicine, have been working directly with the ASF virus, and have also developed a surrogate virus, Emiliania huxleyi virus (EhV), which is similar in structure and stability to ASF.
Developed in the Schroeder Lab, EhV can be safely used in field studies to help scientists understand more about how the virus is transmitted in real-world conditions, and what strategies are effective to prevent its spread, the U of M release explains. EhV is also low-risk, as it only infects one specific species of marine algae and poses no harm to humans, plants or animals.
Through novel testing, researchers work to measure and compare the two viruses and their ability to survive and potentially become infectious under various environmental conditions.
In a transport study, the EhV virus was tested through inoculation into conventional and organic soybean meals and a swine complete feed, then transported in the trailer of a commercial transport vehicle for 23 days covering 29 states in various regions of the U.S. At the conclusion of the study, the EhV virus was detected in all feed samples with no degradation. These results demonstrate for the first time that an ASF-like virus can retain viability in swine feed during long-term transport across the continental U.S.
In the release, Schroeder explains, “Given the possible routes of entry of a foreign animal disease into the U.S., imports of feed and feed ingredients from ASF-positive countries pose a risk. If a potentially ASF-contaminated feed ingredient were to enter the U.S., results from our recent 23-day feed transport study that used EhV as a surrogate for ASF show it continues to be remarkably stable.”
Meanwhile, ASF has been found to survive in blood at temperatures of 4 degrees Celsius for 735 days and surviving in various cured and frozen meat across the world, U of M researchers turned up the heat to see how much the virus could withstand.
The study results found that both viruses were able to survive temperatures reaching 100 degrees Celsius—the temperature at which water boils—confirming that ASF is much harder to destroy than previously thought. Additionally, these findings suggest that current biosecurity protocols in the U.S. may be insufficient.
“This is a major breakthrough to reach our goal of accelerating research for understanding the survival of ASF in various feed ingredients and complete feeds, as well as evaluating the effectiveness of various mitigation strategies to inactivate ASF in feed and decontamination strategies for feed mills if they were to become contaminated with ASF,” says Shurson.
With the EhV surrogate virus, researchers can now begin to determine exactly how U.S. biosecurity protocols should be adjusted to better keep pigs and feed sources safe.
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