Livestock: New PEDv Strain in Minnesota Not a Concern, Say Scientists- DTN

    A new strain of the porcine epidemic diarrhea virus, or PED, was recently identified in a Minnesota herd, but the news shouldn’t alarm pork producers, scientists told DTN. That’s because the new strain is nearly identical to the existing strain that caused the deaths of millions of piglets in the past 18 months.

    Douglas Marthaler, assistant professor of veterinary population medicine at the University of Minnesota, and one of the scientists that discovered the new strain, said the latest mutation likely will not cause any harm to the pork industry in the short term.

    “Again, all viruses change over time, and the concern associated with this mutation is very minimal,” he said. “The industry has done an excellent job of increasing biosecurity and implementing prevention and control measures. As long as the industry continues with their excellent prevention and control measures, there is no additional threat to the industry.”

    Many changes to viruses, he said, often result in non-function viruses. That means the viruses are unable to infect a host. “If the changes are function, the offspring virus is different from the parental virus,” Marthaler said. “Normally, these changes are small. We have observed multiple small changes within PED.”

    Paul Sundberg, vice president of science and technology for the National Pork Board, said the new strain was found to be 99.9% identical to the original virus that broke out in the U.S. in the spring of 2013.

    “While there’s no good way to be absolutely certain, there’s no reason to believe that this is anything other than a natural shift of the viral genetic material,” he said.

    PED is what is referred to as an RNA virus, Sundberg said, which is known for making genetic ‘mistakes’ as it infects and reproduces. “It’s not at all surprising that a PED virus with some genetic changes has been found,” he said.

    Ongoing efforts to develop vaccines, Sundberg said, shouldn’t need to be derailed or altered in any way to help the industry fight PED.

    “There’s so little change in this virus that it is quite likely that that is the case, but that’s a question that will have to be confirmed with more testing,” he said. “Vaccines are made with either the whole cell or, if it can be identified, a portion of the cell that is ‘conserved’ and common from strain to strain.”

    The likelihood is because this virus is so similar to the original virus — 99.9% the same — if a vaccine is going to be effective against the original strain, it will also be effective against the new strain, Sundberg said.

    “But that’s playing the odds,” he said. “To be absolutely certain, it needs to be tested to find out.”

    The findings of a genetic test conducted on the virus in a herd on a Minnesota farm were published in a letter from the Centers for Disease Control and Prevention in December. The testing was done at the request of the farm’s veterinarian, Sundberg said, not because the clinical portrait of the animals had changed, but rather to know for sure which strain was involved.

    “Finding a change like this in the virus isn’t a surprise,” he said. “Although there is no predicting a timeframe, we should expect to find more. We won’t know if the change is significant to the clinical picture, the diagnostic capability or the immunity developed unless we continue to sequence them as they come into the lab, test them and analyze the data.”

    Sundberg said the industry as a whole is working hard to stay ahead of the PED virus by implementing good biosecurity measures — something that won’t change regardless of how the virus changes.

    Harry Snelson, a veterinarian who represents the American Association of Swine Veterinarians, said since this strain has just been identified, it may be awhile before the potential implications to the U.S. swine herd are fully understood.

    “It’s unclear whether or not it will become a significant variant and what impact that may have on vaccine development or clinical disease in the swine herd,” he said.

    Last summer a new study found that swine can contract the deadly virus by eating contaminated feed. As of Jan. 1, PED has been identified in 32 states, and has killed an estimated 8 million pigs.




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