Veterinary research identifies third strain of PEDv

By Georgi Gyton

- Last updated on GMT

There is no evidence to say the new strain would spread among the North American swine population
There is no evidence to say the new strain would spread among the North American swine population

Related tags Infectious disease Livestock Pork

A third naturally occurring strain of porcine epidemic diarrhoea virus (PEDv) has been identified by researchers in the US state of Minnesota.

The findings were published in a letter in the Emerging Infectious Diseases Journal​ of the Centers for Disease Control and Prevention, authored by Douglas Marthaler, James Collins and Kurt Rossow from the University of Minnesota’s Veterinary Diagnostic Laboratory, and Laura Bruner from the state’s Swine Vet Center, who detailed the evolution of the virus.

PEDv was first reported in the US in April 2013, spreading throughout the country, and was later found in Mexico and Canada. It caused severe illness and death in piglets, and had a 99.5% nucleotide (organic molecules, and subunits of DNA) identity with the virulent strain blighting China’s hog population in 2010.

Two North American PEDv variant-INDEL strains have been identified in the US over the past two years, which the researchers said suggested that either the original strain had mutated, or that two strains were presently concurrently in the US.

After the PEDv variant-INDEL strains were identified and analysed in February 2014, the lab decided to sequence the complete PEDv genome in order to try and clarify the relationship between the different strains found in the US.

The researchers have identified three naturally occurring US PEDv strains: the original PEDv, the PEDv with changes in the spike gene (INDEL), and the newly identified PEDv strain S2aa-del (identified from samples of Minnesota herds). The clinical presentation of diarrhoea with S2aa-del was reported to be as severe as – and more than – cases caused by the prototype PEDv Colorado/2013.

The authors of the letter​ said that documenting PEDv variation was vital to understanding the natural evolution of the virus, and to possibly identifying portions of the genome associated with different clinical disease features.

"A consistent model to properly evaluate these differences is required to control PEDv infection,"​ read the letter. "The most compelling need is to understand how exposure by sows to different PEDv strains correlates with protection of piglets from clinical disease. Whether the PEDv S2aa-del strain will circulate in the North American swine population is not known."

According to Reuters, Marthaler said the original strain may have mutated in response to increased immunity in herds, but he added that it was unknown whether the third strain even existed outside the Minnesota herd in which it was found.

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