Guo Lei, Li Nan, Li Wenlong, Zhou Jienan, Ning Ruotong, Hou Min, Liu Longding
Institute of Medical Biology, Chinese Academy of Medical Science, 935# Jiaoling Road, Kunming, Yunnan 650118, China.
Kunming City Center for Disease Control and Prevention, 4# Ziyun Road, Kunming, Yunnan 650228, China.
Virus Evol. 2020 Apr 20;6(1):veaa021. doi: 10.1093/ve/veaa021. eCollection 2020 Jan.
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.
自2013年以来，H7N9流感病毒已引发了五波人类感染疫情。该病毒在2017年的第五波疫情中从低致病性演变为高致病性，而感染人类的病毒中宿主受体结合嗜性的流行情况保持了对禽类受体有偏好的双受体结合特性。在第五波疫情之后分离出了一种感染人类的H7N9病毒，它具有禽类和人类双受体特异性，对人类受体结合具有适度更高的亲和力。血凝素（HA）分子受体结合位点中的V186I（H3编号）取代导致了双受体结合嗜性的改变。含有感染禽类和人类的H7N9病毒I186氨基酸的病毒株均在第五波疫情期间或之后分离得到，并且它们的HA基因与2018 - 9 H7N9分离株一起聚集在同一个系统发育分支中，这突出了自然H7N9病毒适应人类的一条新进化路径。
