Abstract Since 2013, influenza H7N9 virus has caused five epidemic waves of human infection. The virus evolved from low pathogenic to highly pathogenic in wave 5, 2017, while the prevalence of host receptor-binding tropism in human-infecting viruses maintained dual-receptor-binding property with preference for avian receptor. A human-infecting H7N9 virus was isolated after the fifth epidemic wave and possessed an avian and human dual-receptor specificity, with a moderately higher affinity for human receptor binding. A V186I (H3 numbering) substitution in the receptor-binding site of the hemagglutinin (HA) molecule is responsible for the alteration of the dual-receptor-binding tropism. Viral strains which contain I186 amino acid of avian- and human-infecting H7N9 viruses were all isolated during or after wave 5, and their HA genes clustered in a same phylogenetic clade together with 2018–9 H7N9 isolates, highlights a new evolutionary path for human adaption of natural H7N9 viruses.

中文翻译：

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第五波流行后分离的人类感染甲型流感 (H7N9) 病毒的新血凝素双受体结合模式

摘要 自 2013 年以来，H7N9 流感病毒已造成五次人类感染流行波。该病毒在 2017 年第 5 波中从低致病性进化为高致病性，而人类感染病毒中宿主受体结合趋向性的流行保持了双受体结合特性，优先选择禽类受体。在第五波流行后分离出一种感染人类的​​ H7N9 病毒，该病毒具有禽类和人类双重受体特异性，对人类受体结合的亲和力略高。血凝素 (HA) 分子受体结合位点中的 V186I（H3 编号）取代是改变双受体结合趋向性的原因。在第 5 波期间或之后，所有感染禽类和人类的 H7N9 病毒都分离出含有 I186 氨基酸的病毒株，