Reassortment with Dominant Chicken H9N2 Influenza Virus Contributed to the Fifth H7N9 Virus Human Epidemic
Juan Pu, Yanbo Yin, Jiyu Liu, Jiyu Liu, Xinyu Wang, Yong Zhou, Zejiang Wang, Yipeng Sun, Honglei Sun, Fangtao Li, Jingwei Song, Runkang Qu, Weihua Gao, Dongdong Wang, Zhen Wang, Shijie Yan, Mingyue Chen, Jinfeng Zeng, Zhimin Jiang, Haoran Sun, Yanan Zong, Chenxi Wang, Qi Tong, Yuhai Bi, Yinhua Huang, Xiangjun Du, Kin‐Chow Chang, Jinhua Liu, Jinhua Liu
Abstract
Avian H9N2 influenza virus, although primarily restricted to chicken populations, is a major threat to human public health by acting as a donor of variant viral genes through reassortment to co-circulating influenza viruses. We established that the high prevalence of evolving H9N2 virus in vaccinated flocks played a key role, as donor of new sub-clade PB2 and PA genes in the generation of a dominant H7N9 virus genotype (G72) with enhanced infectivity in humans during the 2016-2017 N7N9 virus epidemic. Our findings emphasize that the ongoing evolution of prevalent H9N2 virus in chickens is an important source, via reassortment, of mammalian adaptive genes for other influenza virus subtypes. Thus, close monitoring of prevalence and variants of H9N2 virus in chicken flocks is necessary in the detection of zoonotic mutations.