Genetic evolution of equine influenza virus strains (H3N8) isolated in France from 1967 to 2015 and the implications of several potential pathogenic factors

Stéphanie Fougerolle (1, 2, 3) , Loïc Legrand (1, 2, 3) , Fanny Lecouturier (4, 2) , Corinne Sailleau (5) , Romain Paillot (6, 3, 2) , Aymeric Hans (4, 2) , Stéphane Pronost (1, 3, 2)

1 LABÉO - LABÉO, Pôle d’analyses et de recherche de Normandie
2 Fondation Hippolia
3 U2RM - Unité de Recherche Risques Microbiens
4 Laboratoire de pathologie équine de Dozulé
5 VIRO - Virologie UMR1161
6 AHT - Animal Health Trust

Equine influenza virus (EIV) is a major respiratory pathogen of horses despite the availability of equine influenza vaccines. This study aimed to determine genetic evolution of EIV strains in France between 1967 to present. A whole genome comparative analysis was also conducted on recent French strains in order to identify potential factors of pathogenicity. Comparison of French EIV sequences with vaccine and worldwide epidemic strains revealed amino acid substitutions in both haemagglutinin (HA) and neuraminidase, especially within the antigenic sites and/or close to receptor binding sites (HA). Amino acid substitutions were also identified in other genes, mainly the polymerase complex proteins and PB1-F2. Viruses belonging to Eurasian and American lineages have circulated until 2003 and Florida sub-lineage Clade 2 strains predominates since 2005. The last French strain (2015) displayed several specificities in HA suggesting the occurrence of antigenic drift with presence of pathogenic markers in the PA and PB1-F2 genes.

Domaines: Biologie animale; Médecine vétérinaire et santé animale

Stéphanie Fougerolle, Loïc Legrand, Fanny Lecouturier, Corinne Sailleau, Romain Paillot, et al.. Genetic evolution of equine influenza virus strains (H3N8) isolated in France from 1967 to 2015 and the implications of several potential pathogenic factors. Virology, 2017, 505, pp.210-217. ⟨10.1016/j.virol.2017.02.003⟩. ⟨hal-02168198⟩