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H7N9 virulent mutants detected in chickens in China pose an increased threat to humans

2017; Springer Nature; Volume: 27; Issue: 12 Linguagem: Inglês

10.1038/cr.2017.129

1748-7838

Jianzhong Shi, Guohua Deng, Huihui Kong, Chunyang Gu, Shujie Ma, Xin Yin, Xianying Zeng, Pengfei Cui, Yan Chen, Huanliang Yang, Xiaopeng Wan, Xiurong Wang, Liling Liu, Pucheng Chen, Yongping Jiang, Jinxiong Liu, Yuntao Guan, Yasuo Suzuki, Mei Li, Zhiyuan Qu, Lizheng Guan, Jinkai Zang, Wenli Gu, Han Shuyu, Yangming Song, Yuzhen Hu, Zeng Wang, Linlin Gu, Wenyu Yang, Libin Liang, Hongmei Bao, Guobin Tian, Yanbing Li, Chuanling Qiao, Li Jiang, Chengjun Li, Zhigao Bu, Hualan Chen,

Respiratory viral infections research

Certain low pathogenic avian influenza viruses can mutate to highly pathogenic viruses when they circulate in domestic poultry, at which point they can cause devastating poultry diseases and severe economic damage. The H7N9 influenza viruses that emerged in 2013 in China had caused severe human infections and deaths. However, these viruses were nonlethal in poultry. It is unknown whether the H7N9 viruses can acquire additional mutations during their circulation in nature and become lethal to poultry and more dangerous for humans. Here, we evaluated the evolution of H7N9 viruses isolated from avian species between 2013 and 2017 in China and found 23 different genotypes, 7 of which were detected only in ducks and were genetically distinct from the other 16 genotypes that evolved from the 2013 H7N9 viruses. Importantly, some H7N9 viruses obtained an insertion of four amino acids in their hemagglutinin (HA) cleavage site and were lethal in chickens. The index strain was not lethal in mice or ferrets, but readily obtained the 627K or 701N mutation in its PB2 segment upon replication in ferrets, causing it to become highly lethal in mice and ferrets and to be transmitted efficiently in ferrets by respiratory droplet. H7N9 viruses bearing the HA insertion and PB2 627K mutation have been detected in humans in China. Our study indicates that the new H7N9 mutants are lethal to chickens and pose an increased threat to human health, and thus highlights the need to control and eradicate the H7N9 viruses to prevent a possible pandemic.