title: Emergence of a virulent porcine reproductive and respiratory syndrome virus in vaccinated herds in the United States.
abstract: In early 2014, a Minnesota sow farm with a solid vaccination history suffered a severe porcine reproductive and respiratory syndrome (PRRS) outbreak with unusually high morbidity and mortality in piglets and sows, as well as anorexia and secondary bacterial infections in nursery pigs. Due to the unusual clinical severity in a PRRS-immune herd, genetic characteristics of the virus were examined to determine if a new PRRSV genotype had emerged. Phylogenetic analysis indicated that the virulent strain (PRRSV2/USA/Minnesota414/2014) was related to virulent strains circulating in the mid-western United States in recent years, and that the nonstructural protein 2 (nsp2) gene of MN414 contained an insertion-deletion pattern typical of existing type 2 virulent strains. We conclude that the MN414 isolate is a recently evolved member of the virulent lineage 1 family of type 2 PRRSV.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA.
authors.forename: Xiong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Veterinary Diagnostic Laboratory, University of Minnesota, 1333 Gortner Avenue, St. Paul, MN 55108, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Marthaler
authors.affiliation: Veterinary Diagnostic Laboratory, University of Minnesota, 1333 Gortner Avenue, St. Paul, MN 55108, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Rovira
authors.affiliation: Veterinary Diagnostic Laboratory, University of Minnesota, 1333 Gortner Avenue, St. Paul, MN 55108, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Rossow
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA. Electronic address: murta001@umn.edu.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Murtaugh
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D004196:Disease Outbreaks; D019143:Evolution, Molecular; D016679:Genome, Viral; D008910:Minnesota / Q000453:epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology* / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000145:classification* / Q000302:isolation & purification* / Q000472:pathogenicity; D012367:RNA, Viral / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013552:Swine; D014774:Virulence
chemical_list: D012367:RNA, Viral
keywords: Full genome; Phylogeny; Type 2 PRRSV; Virulent strain