Survival of ASFV and other viral pathogens in feed

Researchers have found that African swine fever virus (ASFV) could survive in a simulated Trans-Atlantic feed shipment.

The study, published in PLOS ONE, evaluated the survival of ASFV and other important viral pathogens of livestock in animal feed ingredients imported into the United States under simulated transboundary conditions. The viruses were selected based on global significance and impact to the livestock industry, including Foot and Mouth Disease Virus (FMDV), Classical Swine Fever Virus (CSFV), Influenza A Virus of Swine (IAV-S), Pseudorabies virus (PRV), Nipah Virus (NiV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Swine Vesicular Disease Virus (SVDV), Vesicular Stomatitis Virus (VSV), Porcine Circovirus Type 2 (PCV2) and Vesicular Exanthema of Swine Virus (VESV). Surrogate viruses with similar genetic and physical properties were used for 6 of the viruses.

One of the researchers, Megan Niederwerder, Kansas State University assistant professor of diagnostic medicine and pathobiology, commented, “The ultimate goal of our research is to understand what mitigation tools may be utilized to reduce the risk of African swine fever virus being introduced, whether in the country of origin or once feed arrives in the U.S.”

Niederwerder is collaborating with Kansas State University’s Biosecurity Research Institute to continue studying the risk of ASFV in feed and feed ingredients. She is studying the whole feed transport cycle — from the shipment of feed as it is imported to the U.S. to when pigs consume their feed on the farm.

Niederwerder and her team are performing the research in a biosafety level-3 laboratory. They have been studying 5-gram amounts of complete feed and feed ingredients, some of which include soyabean meal, lysine, dried distillers grains, choline and vitamin D.

Researchers place the ingredients in 50-millilitre tubes in an environmental chamber and use meteorological data to programme the chamber’s temperature and humidity, to mimic a Trans-Pacific or Trans-Atlantic journey. The trans-Atlantic model that simulates travel from Eastern Europe takes 30 days.

The researchers then study if the virus is still present at a dose infectious to pigs after the simulated shipment and if there are any additives that may stop the virus from spreading through feed.

It was found that Senecavirus A (representing FMDV), Feline Calicivirus (representing VESV), Bovine Herpesvirus Type 1 (representing PRV), PRRSV, Porcine Sapelovirus (representing SVDV), ASFV and PCV2 maintained infectivity during transport, while Bovine Viral Diarrhea Virus (representing CSFV), VSV, Canine Distemper Virus (representing NiV) and IAV-S did not. Notably, more viruses survived in conventional soyabean meal, lysine hydrochloride, choline chloride, vitamin D and pork sausage casings.

The researchers say their results demonstrate the survival of several viral pathogens in multiple feed ingredients or feed products and support the hypothesis that contaminated feed ingredients could serve as vehicles for the transport of viral pathogens between regions, countries or even across continents.

Article: Survival of viral pathogens in animal feed ingredients under transboundary shipping models by Scott A. Dee, Fernando V. Bauermann, Megan C. Niederwerder, Aaron Singrey, Travis Clement, Marcelo de Lima, Craig Long, Gilbert Patterson, Maureen A. Sheahan, Ana M. M. Stoian, Vlad Petrovan, Cassandra K. Jones, Jon De Jong, Ju Ji, Gordon D. Spronk, Luke Minion, Jane Christopher-Hennings, Jeff J. Zimmerman, Raymond R. R. Rowland, Eric Nelson, Paul Sundberg and Diego G. Diel, published in PLoS ONE (2018) 13(3): e0194509, doi: 10.1371/journal.pone.0194509

[SOURCE: Kansas State University, PLOS ONE]