H3N8 equine influenza virus (EIV) is an important and significant respiratory pathogen of horses. EIV is enzootic in Europe and North America, mainly due to the suboptimal efficacy of current vaccines. We describe, for the first time, the generation of a temperature sensitive (ts) H3N8 EIV live-attenuated influenza vaccine (LAIV) using reverse-genetics approaches. Our EIV LAIV was attenuated (att) in vivo and able to induce, upon a single intranasal administration, protection against H3N8 EIV wild-type (WT) challenge in both a mouse model and the natural host, the horse. Notably, since our EIV LAIV was generated using reverse genetics, the vaccine can be easily updated against drifting or emerging strains of EIV using the safety backbone of our EIV LAIV as master donor virus (MDV). These results demonstrate the feasibility of implementing a novel EIV LAIV approach for the prevention and control of currently circulating H3N8 EIVs in horse populations.

H3N8马流感病毒（EIV）是马的重要重要呼吸道病原体。EIV在欧洲和北美是动物共患病的，主要是由于目前疫苗的效果欠佳。我们首次描述了使用反向遗传学方法生成温度敏感（ts）H3N8 EIV减毒流感疫苗（LAIV）的过程。我们的EIV LAIV在体内衰减（att）并能够在单次鼻内给药后在小鼠模型和天然宿主马中诱导出针对H3N8 EIV野生型（WT）攻击的保护作用。值得注意的是，由于我们的EIV LAIV是使用反向遗传学产生的，因此可以使用我们的EIV LAIV的安全主链作为主供体病毒（MDV）轻松针对漂移或新兴EIV株更新疫苗。这些结果证明了实施一种新的EIV LAIV方法来预防和控制马群中当前正在传播的H3N8 EIV的可行性。