title: Emergence of a virulent porcine reproductive and respiratory syndrome virus (PRRSV) 1 strain in Lower Austria.
abstract: BACKGROUND
  In spring 2015, an outbreak of porcine reproductive and respiratory syndrome (PRRS) struck Lower Austria caused by a PRRS virus (PRRSV) strain spreading rapidly among both previously PRRSV negative and vaccinated pig herds. This case report describes the first well-documented emergence of the PRRSV strain responsible for this outbreak.
  
  
  METHODS
  A PRRSV seronegative piglet-producing farm in Lower Austria encountered losses in foetuses and suckling piglets of up to 90 %; clinical signs in sows and nursery piglets included fever and reduced feed intake. Additionally, high percentages of repeat breeders and losses of up to 40 % in nursery piglets occurred. An infection with PRRSV was suggested by the detection of antibodies by enzyme linked immunosorbent assay and confirmed by quantitative real time PCR. The underlying PRRSV strain, termed AUT15-33, was isolated by passage on porcine alveolar macrophages, partially sequenced (ORF2-7) and grouped as PRRSV-1, subtype 1. In phylogenetic analysis of the genome region coding for the structural proteins, ORF2-7, AUT15-33 clustered with Belgian strains but identities were as low as 88 %. In contrast, analysis of ORF7 sequences revealed a close relationship to Croatian strains from 2012 with an identity of 94 - 95 %.
  
  
  CONCLUSIONS
  In the year following the outbreak, the same PRRSV strain was identified repeatedly in different regions of Austria. It can be speculated that the new strain has novel advantageous properties.
authors.affiliation: Institute of Virology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Leonie J
authors.initials: LJ
authors.lastname: Sinn
authors.affiliation: Vetpraxis Hegerberg, 3072 Kasten 25, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Klingler
authors.affiliation: Institute of Virology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lamp
authors.affiliation: Institute of Pathology and Forensic Veterinary Medicine, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Rene
authors.initials: R
authors.lastname: Brunthaler
authors.affiliation: Institute of Pathology and Forensic Veterinary Medicine, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Weissenböck
authors.affiliation: Institute of Virology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Till
authors.initials: T
authors.lastname: Rümenapf
authors.affiliation: Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
authors.forename: Andrea
authors.identifier: 0000-0001-5037-7269
authors.initials: A
authors.lastname: Ladinig
keywords: Acute outbreak; Austria; Field isolate; Porcine reproductive and respiratory syndrome virus (PRRSV)