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Genetic evolution of equine influenza strains isolated in France from 2005 to 2010

Abstract : REASON FOR PERFORMING THIS STUDY: Equine influenza virus (EIV) is considered the most economically important equine respiratory pathogen worldwide. The H3N8 subtype, responsible for all outbreaks of equine influenza globally, evolves perpetually. Mutations in the genome of these viruses have the potential to modify their antigenic properties and recognition by pre-existing antibodies. Objectives: The aim of this study was to determine the genetic evolution of EIV strains in France and to compare it with the evolution of strains isolated globally. Analysis of the sequence data was performed to investigate any possible links between the outbreaks. Study design: Retrospective genetic analysis study of archived material. Methods: Analyses were performed on the HA1 domain of haemagglutinin H3 of EIV isolated in a previous study carried out from November 2005 to October 2010. The nucleic acid sequence of 41 strains was analysed and translated. The French viruses were compared with 59 Clade 1 strains and 83 Clade 2 strains. Strains were aligned chronologically and on the basis of their geographical origin. Results: The 16 Clade 1 strains are all derived from the outbreak that started in the Grosbois training yard in 2009. The virus genome appears to have been stable during the outbreak. The 25 Clade 2 strains were isolated over the 5-year period during which several mutations had emerged. Some strains incorporate a sporadic mutation, and others a mutation that may occur several times but does not persist. However, all strains are gradually moving towards definitive mutations. Conclusion: This study demonstrated that EIVs have evolved in France during this period in a similar manner to EIVs globally. The data lend support to the current World Animal Health Organisation recommendation that the vaccines contain a representative of both Clade 1 and Clade 2 of the Florida sublineage.
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Submitted on : Wednesday, September 23, 2020 - 1:41:17 PM
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Loïc Legrand, Pierre-Hugues Pitel, Ann Cullinane, Guillaume Fortier, Stéphane Pronost. Genetic evolution of equine influenza strains isolated in France from 2005 to 2010. Equine Veterinary Journal, Wiley-Blackwell, 2015, 47 (2), pp.207-211. ⟨10.1111/evj.12244⟩. ⟨hal-02946740⟩



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