title: Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012.
abstract: BACKGROUND
  In 2012, equine influenza (EI) virus was confirmed as the cause of outbreaks of respiratory disease in horses throughout South America. In Uruguay and Argentina, hundreds of vaccinated thoroughbred horses in training and racing facilities were clinically affected.
  
  
  OBJECTIVE
  To characterise the EI viruses detected during the outbreak in Uruguay and Argentina.
  
  
  METHODS
  Virus was detected in nasopharyngeal swabs by a pan-reactive influenza type A real-time RT-PCR. The nucleotide sequence of the HA1 gene was determined and analysed phylogenetically using mega 5 software. Amino acid sequences alignments were constructed and virus was antigenically characterised with specific ferret antisera. Paired serum samples were tested by haemagglutination inhibition and single radial haemolysis.
  
  
  RESULTS
  The diagnosis of EIV was confirmed by real-time RT-PCR, virus isolation and serological testing. The phylogenetic analysis of HA1 gene sequences of 18 EI viruses indicated that all of them belong to clade 1 of the Florida sublineage of the American lineage and are closely related to viruses isolated in the United States in 2012. The HA1 of viruses identified in horses in racing facilities in Maroñas, Uruguay, and in Palermo, Argentina, displayed 100% amino acid sequence identity and were identical to that of a virus isolated in Dubai in 2012, from vaccinated endurance horses recently imported from Uruguay.
  
  
  CONCLUSIONS
  The surveillance data reported illustrate the international spread of EI viruses and support the recommendations of the OIE expert surveillance panel to include viruses of the Florida sublineage in vaccines.
authors.affiliation: CICVyA, INTA, Instituto de Virología, Buenos Aires, Hurlingham, Argentina.
authors.forename: Cecilia Olguin
authors.initials: CO
authors.lastname: Perglione
authors.affiliation: Virology Unit, The Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gildea
authors.affiliation: CICVyA, INTA, Instituto de Virología, Buenos Aires, Hurlingham, Argentina.
authors.forename: Agustina
authors.initials: A
authors.lastname: Rimondi
authors.affiliation: CICVyA, INTA, Instituto de Virología, Buenos Aires, Hurlingham, Argentina.
authors.forename: Samuel
authors.initials: S
authors.lastname: Miño
authors.affiliation: CICVyA, INTA, Instituto de Virología, Buenos Aires, Hurlingham, Argentina.
authors.forename: Aldana
authors.initials: A
authors.lastname: Vissani
authors.affiliation: Cátedra de Enfermedades Infecciosas, Escuela de Veterinaria, Universidad del Salvador, Buenos Aires, Argentina.|Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
authors.forename: Mariano
authors.initials: M
authors.lastname: Carossino
authors.affiliation: Virology Unit, The Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland.
authors.forename: Ann
authors.initials: A
authors.lastname: Cullinane
authors.affiliation: CICVyA, INTA, Instituto de Virología, Buenos Aires, Hurlingham, Argentina.|Cátedra de Enfermedades Infecciosas, Escuela de Veterinaria, Universidad del Salvador, Buenos Aires, Argentina.
authors.forename: Maria
authors.initials: M
authors.lastname: Barrandeguy
mesh_terms: D000818:Animals; D001118:Argentina / Q000453:epidemiology; D004196:Disease Outbreaks; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology*; D006736:Horses; D053123:Influenza A Virus, H3N8 Subtype / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D009305:Nasopharynx / Q000821:virology; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D014583:Uruguay / Q000453:epidemiology
keywords: Argentina; Florida clade 1; equine influenza