title: Newly Emergent Highly Pathogenic H5N9 Subtype Avian Influenza A Virus.
abstract: The novel H7N9 avian influenza virus (AIV) was demonstrated to cause severe human respiratory infections in China. Here, we examined poultry specimens from live bird markets linked to human H7N9 infection in Hangzhou, China. Metagenomic sequencing revealed mixed subtypes (H5, H7, H9, N1, N2, and N9). Subsequently, AIV subtypes H5N9, H7N9, and H9N2 were isolated. Evolutionary analysis showed that the hemagglutinin gene of the novel H5N9 virus originated from A/Muscovy duck/Vietnam/LBM227/2012 (H5N1), which belongs to clade 2.3.2.1. The neuraminidase gene of the novel H5N9 virus originated from human-infective A/Hangzhou/1/2013 (H7N9). The six internal genes were similar to those of other H5N1, H7N9, and H9N2 virus strains. The virus harbored the PQRERRRKR/GL motif characteristic of highly pathogenic AIVs at the HA cleavage site. Receptor-binding experiments demonstrated that the virus binds α-2,3 sialic acid but not α-2,6 sialic acid. Identically, pathogenicity experiments also showed that the virus caused low mortality rates in mice. This newly isolated H5N9 virus is a highly pathogenic reassortant virus originating from H5N1, H7N9, and H9N2 subtypes. Live bird markets represent a potential transmission risk to public health and the poultry industry.
  
  
  OBJECTIVE
  This investigation confirms that the novel H5N9 subtype avian influenza A virus is a reassortant strain originating from H5N1, H7N9, and H9N2 subtypes and is totally different from the H5N9 viruses reported before. The novel H5N9 virus acquired a highly pathogenic H5 gene and an N9 gene from human-infecting subtype H7N9 but caused low mortality rates in mice. Whether this novel H5N9 virus will cause human infections from its avian host and become a pandemic subtype is not known yet. It is therefore imperative to assess the risk of emergence of this novel reassortant virus with potential transmissibility to public health.
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Xingbo
authors.initials: X
authors.lastname: Wang
authors.affiliation: BGI-Shenzhen, Shenzhen, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Jin
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Weiying
authors.initials: W
authors.lastname: Si
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Jiusheng
authors.initials: J
authors.lastname: Wu
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: BGI-Shenzhen, Shenzhen, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Liu
authors.affiliation: Changchun Institute of Veterinary Science, Chinese Academy of Agricultural Sciences, Changchun, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Sang
authors.affiliation: Changchun Institute of Veterinary Science, Chinese Academy of Agricultural Sciences, Changchun, China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Wu
authors.affiliation: Changchun Institute of Veterinary Science, Chinese Academy of Agricultural Sciences, Changchun, China.
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Changchun Institute of Veterinary Science, Chinese Academy of Agricultural Sciences, Changchun, China.
authors.forename: Xianzhu
authors.initials: X
authors.lastname: Xia
authors.affiliation: Hangzhou Center for Disease Control and Prevention, Zhejiang, China.
authors.forename: Xinfen
authors.initials: X
authors.lastname: Yu
authors.affiliation: Hangzhou Center for Disease Control and Prevention, Zhejiang, China.
authors.forename: Jingcao
authors.initials: J
authors.lastname: Pan
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou, People's Republic of China jyzhou@zju.edu.cn.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001483:Base Sequence; D001717:Birds; D005814:Genes, Viral / Q000235:genetics; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics / Q000302:isolation & purification; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics / Q000302:isolation & purification; D005585:Influenza in Birds / Q000821:virology; D007251:Influenza, Human / Q000821:virology; D051379:Mice; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000235:genetics*; D011485:Protein Binding; D016865:Reassortant Viruses / Q000235:genetics*; D011991:Receptors, Virus / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D053585:Virus Attachment
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011991:Receptors, Virus; D009439:Neuraminidase