Equine Influenza Virus in Asia: Phylogeographic Pattern and Molecular Features Reveal Circulation of an Autochthonous Lineage
Equine Influenza Virus in Asia: Phylogeographic Pattern and Molecular Features Reveal Circulation of an Autochthonous Lineage
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DOI：
10.1128/jvi.00116-19
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发表时间：
2019-07-01
影响因子：
5.4
通讯作者：
Wang, Xiaojun
中科院分区：
文献类型：
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作者：
Mino, Samuel;Mojsiejczuk, Laura;Wang, Xiaojun
马流感病毒（EIV）会导致马匹出现严重的急性呼吸道疾病。目前，属于H3N8亚型的毒株分为两个分支，佛罗里达空地1号（FC1）和佛罗里达空地2号（FC2），于2002年出现。FC1和FC2分支在过去十年中在亚洲和中东国家均有报道。在这项研究中，我们描述了 EIV 谱系的进化、流行病学和分子特征，重点关注 2007 年至 2017 年在亚洲检测到的谱系。全基因组系统发育表明 FC1 和 FC2 构成独立且不同的谱系，没有证据表明进化枝之间存在重配。 FC1 作为单一谱系进化，而 FC2 在 2004 年左右出现了分歧事件，产生了两个得到良好支持且共存的亚谱系：欧洲亚谱系和亚洲亚谱系。此外，还确定了 EIV 在亚洲国家的两种不同传播模式。 FC1 疫情是由美洲独立引入 EIV 引起的，亚洲分离株在基因上与当代美国谱系相似。另一方面，在亚洲大陆国家检测到的FC2菌株符合2006年具有共同祖先的本土单系群，并显示出在当地宿主中流行的证据。在亚洲 FC1 和 FC2 群体的所有病毒蛋白中均检测到了特征性氨基酸特征模式。几个变化位于 HA1 蛋白的顶部、抗原位点内部或附近。需要进一步的研究来评估这些抗原变化对疫苗接种计划的潜在影响。 重要性 马流感病毒 (EIV) 复杂且持续的抗原进化仍然是疫苗开发和有效免疫计划设计的主要障碍。本研究提供了全面的分析，显示了 EIV 的进化动态，包括亚洲大陆内的传播和循环及其与全球 EIV 种群在 10 年间的关系。此外，我们还可以更好地了解亚洲国家的 EIV 分子进化及其对抗原性的影响。该研究强调了全球马匹运动与该地区 EIV 流通之间的关联。为了减轻影响马业的疫情爆发风险并帮助选择未来疫苗配方中包含的病毒株，了解 EIV 的进化势在必行。
Equine influenza virus (EIV) causes severe acute respiratory disease in horses. Currently, the strains belonging to the H3N8 subtype are divided into two clades, Florida Glade 1 (FC1) and Florida Glade 2 (FC2), which emerged in 2002. Both FC1 and FC2 clades were reported in Asian and Middle East countries in the last decade. In this study, we described the evolution, epidemiology, and molecular characteristic of the EIV lineages, with focus on those detected in Asia from 2007 to 2017. The full genome phylogeny showed that FC1 and FC2 constituted separate and divergent lineages, without evidence of reassortment between the clades. While FC1 evolved as a single lineage, FC2 showed a divergent event around 2004 giving rise to two well-supported and coexisting sublineages, European and Asian. Furthermore, two different spread patterns of EIV in Asian countries were identified. The FC1 outbreaks were caused by independent introductions of EIV from the Americas, with the Asian isolates genetically similar to the contemporary American lineages. On the other hand, the FC2 strains detected in Asian mainland countries conformed to an autochthonous monophyletic group with a common ancestor dated in 2006 and showed evidence of an endemic circulation in a local host. Characteristic aminoacidic signature patterns were detected in all viral proteins in both Asian-FC1 and FC2 populations. Several changes were located at the top of the HA1 protein, inside or near antigenic sites. Further studies are needed to assess the potential impact of these antigenic changes in vaccination programs.IMPORTANCE The complex and continuous antigenic evolution of equine influenza viruses (EIVs) remains a major hurdle for vaccine development and the design of effective immunization programs. The present study provides a comprehensive analysis showing the EIV evolutionary dynamics, including the spread and circulation within the Asian continent and its relationship to global EIV populations over a 10-year period. Moreover, we provide a better understanding of EIV molecular evolution in Asian countries and its consequences on the antigenicity. The study underscores the association between the global horse movement and the circulation of EIV in this region. Understanding EIV evolution is imperative in order to mitigate the risk of outbreaks affecting the horse industry and to help with the selection of the viral strains to be included in the formulation of future vaccines.