title: Emergence of Porcine epidemic diarrhea virus in the United States: clinical signs, lesions, and viral genomic sequences.
abstract: During the 10 days commencing April 29, 2013, the Iowa State University Veterinary Diagnostic Laboratory received the first 4 of many submissions from swine farms experiencing explosive epidemics of diarrhea and vomiting affecting all ages, with 90-95% mortality in suckling pigs. Histology revealed severe atrophy of villi in all segments of the small intestines with occasional villus-epithelial syncytial cells, but testing for rotaviruses and Transmissible gastroenteritis virus (Alphacoronavirus 1) were negative. Negative-staining electron microscopy of feces revealed coronavirus-like particles and a pan-coronavirus polymerase chain reaction (PCR) designed to amplify a conserved region of the polymerase gene for all members in the family Coronaviridae produced expected 251-bp amplicons. Subsequent sequencing and analysis revealed 99.6-100% identity among the PCR amplicons from the 4 farms and 97-99% identity to the corresponding portion of the polymerase gene of Porcine epidemic diarrhea virus (PEDV) strains, with the highest identity (99%) to strains from China in 2012. Findings were corroborated at National Veterinary Services Laboratories using 2 nested S-gene and 1 nested N-gene PCR tests where the sequenced amplicons also had the highest identity with 2012 China strains. Whole genome sequence for the virus from 2 farms in 2 different states using next-generation sequencing technique was compared to PEDV sequences available in GenBank. The 2013 U.S. PEDV had 96.6-99.5% identity with all known PEDV strains and the highest identity (>99.0%) to some of the 2011-2012 Chinese strains. The nearly simultaneous outbreaks of disease, and high degree of homology (99.6-100%) between the PEDV strains from the 4 unrelated farms, suggests a common source of virus.
authors: 1Gregory W. Stevenson and Kyoungjin J. Yoon, Veterinary Diagnostic Laboratory, Iowa State University, 1600 South 16th Street, Ames, IA 50011. stevengw@iastate.edu; kyoon@iastate.edu.
authors: Gregory W
authors: GW
authors: Stevenson
authors: Hai
authors: H
authors: Hoang
authors: Kent J
authors: KJ
authors: Schwartz
authors: Eric R
authors: ER
authors: Burrough
authors: Dong
authors: D
authors: Sun
authors: Darin
authors: D
authors: Madson
authors: Vickie L
authors: VL
authors: Cooper
authors: Angela
authors: A
authors: Pillatzki
authors: Philip
authors: P
authors: Gauger
authors: Beverly J
authors: BJ
authors: Schmitt
authors: Leo G
authors: LG
authors: Koster
authors: Mary L
authors: ML
authors: Killian
authors: Kyoungjin J
authors: KJ
authors: Yoon
mesh_terms: D000818:Animals; D018352:Coronavirus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D003967:Diarrhea / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004196:Disease Outbreaks / Q000662:veterinary*; D005243:Feces; D007150:Immunohistochemistry / Q000662:veterinary; D008854:Microscopy, Electron / Q000662:veterinary; D010802:Phylogeny; D053485:Porcine epidemic diarrhea virus / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000821:virology*; D014481:United States
chemical_list: D004279:DNA, Viral
keywords: Diarrhea; Porcine epidemic diarrhea virus; enteric disease; porcine