title: Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus.
abstract: The emergence of human infection with a novel H7N9 influenza virus in China raises a pandemic concern. Chicken H9N2 viruses provided all six of the novel reassortant's internal genes. However, it is not fully understood how the prevalence and evolution of these H9N2 chicken viruses facilitated the genesis of the novel H7N9 viruses. Here we show that over more than 10 y of cocirculation of multiple H9N2 genotypes, a genotype (G57) emerged that had changed antigenicity and improved adaptability in chickens. It became predominant in vaccinated farm chickens in China, caused widespread outbreaks in 2010-2013 before the H7N9 viruses emerged in humans, and finally provided all of their internal genes to the novel H7N9 viruses. The prevalence and variation of H9N2 influenza virus in farmed poultry could provide an important early warning of the emergence of novel reassortants with pandemic potential.
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Juan
authors.initials: J
authors.lastname: Pu
authors.affiliation: Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Shuoguo
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China;
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Yin
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Guozhong
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Robert A
authors.initials: RA
authors.lastname: Carter
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Jinliang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Guanlong
authors.initials: G
authors.lastname: Xu
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Honglei
authors.initials: H
authors.lastname: Sun
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Chu
authors.initials: C
authors.lastname: Wen
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Yandi
authors.initials: Y
authors.lastname: Wei
authors.affiliation: College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China;
authors.forename: Dongdong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Chinese Academy of Sciences Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; and.
authors.forename: Baoli
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Gordon
authors.initials: G
authors.lastname: Lemmon
authors.affiliation: Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Yuannian
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Susu
authors.initials: S
authors.lastname: Duan
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Qian
authors.initials: Q
authors.lastname: Du
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Meng
authors.initials: M
authors.lastname: Sun
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Jinnan
authors.initials: J
authors.lastname: Bao
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
authors.forename: Jixun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN 38105.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; ljh@cau.edu.cn robert.webster@stjude.org.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105; ljh@cau.edu.cn robert.webster@stjude.org.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Webster
mesh_terms: D000818:Animals; D000940:Antigenic Variation / Q000235:genetics; D000956:Antigens, Viral / Q000235:genetics; D002645:Chickens / Q000821:virology*; D002681:China / Q000453:epidemiology; D019143:Evolution, Molecular; D005814:Genes, Viral; D040961:Genetic Drift; D005838:Genotype; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D005585:Influenza in Birds / Q000453:epidemiology / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology; D058873:Pandemics; D010802:Phylogeny; D016865:Reassortant Viruses / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity; D012189:Retrospective Studies
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus
keywords: H7N9; H9N2; chicken influenza virus; genotype; infectivity