野鸟源H5N8禽流感病毒遗传变异分析与致病性评估

Genetic evolution analysis and pathogenicity evaluation of wild birds-origin H5N8 avian influenza virus

本试验在野鸟禽流感病毒紧急疫情检测过程中鉴定并分离到1株H5N8高致病性禽流感病毒,利用病毒全基因组测序、系统发育及关键氨基酸位点分析解析了该野鸟源H5N8禽流感病毒分离株遗传进化情况,通过体外复制动力学试验及小鼠感染试验,评价了该野鸟源H5N8禽流感病毒分离株对哺乳动物致病性。进化分析显示,该病毒株属于Clade 2.3.4.4,可以不经适应直接感染小鼠并在呼吸系统内复制,表现出有限的组织嗜性,对小鼠呈低致病性。其在体内外复制能力较低。结果表明,本试验加深了对野生鸟携带H5N8禽流感病毒的认识和理解、对野鸟源H5N8禽流感病毒生物学特性的评价,为预测野鸟源H5N8禽流感病毒遗传进化趋势及其生物安全风险评估提供借鉴和参考。

In recent years, the outbreak of the H5N8 HPAIVs has brought serious threats to the poultry industry and human health. Furthermore, the H5N8 influenza virus has rapidly evolved. Constant appearance of new subtypes through mutations and reassortments bring new challenges to the prevention and control of influenza. Wild animals play an important role in the evolution, spread and transmission of the H5N8 influenza virus.In this study, we conducted emergency outbreak detection and identified one H5N8 avian influenza virus isolate in wild birds.Phylogenetic analysis of wild-animals origin H5N8 influenza viruses was performed by genome sequencing and multiple sequence aligning.Amino acid mutation site analysis were conducted to reveal the genetic evolution. We carried out replication kinetics tests in vitro and in vivo to evaluate the pathogenicity and infectivity of H5N8 avian influenza in mammals.Phylogenetic analysis revealed that the H5N8 isolate was clustered in to Clade 2.3.4.4.The H5N8 isolate can directly infected and replicated inthe respiratory system without previous adaptation in mice but exhibited low pathogenicity to mice.The H5N8 avian influenza virus were equipped with low replication ability both in vitro and in vzvo.In summary,our research has deepened the understanding of the H5N8 influenza virus in wild birds.The evaluation of the biological characteristics and analysis of genetic evolution of the wild animal-derived H5N8 flu virus provided reference to biosafety risk assessment of HPAIV H5N8 influenza virus.