Legrand L J, Pitel P-H Y, Cullinane A A, Fortier G D, Pronost S L
Equine Vet J. 2015 Mar;47(2):207-11. doi: 10.1111/evj.12244.
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.
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.
Retrospective genetic analysis study of archived material.
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.
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.
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.
进行本研究的原因：马流感病毒（EIV）被认为是全球经济上最重要的马呼吸道病原体。负责全球所有马流感疫情爆发的H3N8亚型不断进化。这些病毒基因组中的突变有可能改变其抗原特性以及被现有抗体识别的能力。
本研究的目的是确定法国EIV毒株的遗传进化，并将其与全球分离毒株的进化进行比较。对序列数据进行分析以调查疫情之间的任何可能联系。
对存档材料进行回顾性遗传分析研究。
对在2005年11月至2010年10月进行的一项先前研究中分离出的EIV血凝素H3的HA1结构域进行分析。分析并翻译了41个毒株的核酸序列。将法国病毒与59个1类毒株和83个2类毒株进行比较。毒株按时间顺序并根据其地理来源进行比对。
16个1类毒株均源自2009年在格罗斯布瓦训练场爆发的疫情。在疫情期间病毒基因组似乎一直稳定。25个2类毒株是在5年期间分离出来的，在此期间出现了一些突变。一些毒株含有零星突变，另一些毒株含有可能出现几次但不会持续的突变。然而，所有毒株都在逐渐朝着确定的突变发展。
本研究表明，在此期间法国的EIVs进化方式与全球的EIVs相似。这些数据支持了世界动物卫生组织目前的建议，即疫苗应包含佛罗里达亚系1类和2类的代表毒株。
