title: The first reported Florida clade 1 virus in the Nordic countries, isolated from a Swedish outbreak of equine influenza in 2011.
abstract: Equine Influenza Virus (EIV) is a major cause of respiratory disease in horses and the virus constantly undergoes antigenic drift. Here we characterize and describe the HA1 and the NA genes of H3N8 within samples obtained from outbreaks in Sweden during November-December 2011. Both clade 1 and clade 2 viruses of the Florida sublineage were identified. The index case of clade 2 was transported to Sweden from Spain through the Netherlands, whereas the clade 1 had its origin from a Swedish stud farm. The clade 1 virus was efficiently spread between training yards by unvaccinated young horses, but vaccinated horses were also presented with clinical signs of respiratory disease. No virus of the Eurasian lineage was isolated during this outbreak. Clade 1 has previously been described in outbreaks in numerous of other countries, but this is the first time it has been detected in Sweden. The results from this study shows the importance of including both clade 1 and clade 2 of the Florida sublineage in equine influenza vaccines, supporting the ESP and OIE recommendations.
authors: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden. Electronic address: helena.back@mpa.se.
authors: Helena
authors: H
authors: Back
authors: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden.
authors: Louise Treiberg
authors: LT
authors: Berndtsson
authors: Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Uppsala, Sweden.
authors: Gittan
authors: G
authors: Gröndahl
authors: Department of Disease Control and Epidemiology, National Veterinary Institute, Uppsala, Sweden.
authors: Karl
authors: K
authors: Ståhl
authors: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors: John
authors: J
authors: Pringle
authors: Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden.
authors: Siamak
authors: S
authors: Zohari
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000235:genetics*; D004196:Disease Outbreaks / Q000662:veterinary*; D004285:Dogs; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology*; D006736:Horses; D053123:Influenza A Virus, H3N8 Subtype / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D007252:Influenza Vaccines / Q000592:standards; D061985:Madin Darby Canine Kidney Cells; D009439:Neuraminidase / Q000235:genetics; D010802:Phylogeny; D013548:Sweden; D014195:Travel; D014611:Vaccination / Q000592:standards / Q000662:veterinary
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D009439:Neuraminidase
keywords: Clade 1; Clade 2; Horse; Phylogenetic characterization; influenza