title: Dissemination, divergence and establishment of H7N9 influenza viruses in China.
abstract: Since 2013 the occurrence of human infections by a novel avian H7N9 influenza virus in China has demonstrated the continuing threat posed by zoonotic pathogens. Although the first outbreak wave that was centred on eastern China was seemingly averted, human infections recurred in October 2013 (refs 3-7). It is unclear how the H7N9 virus re-emerged and how it will develop further; potentially it may become a long-term threat to public health. Here we show that H7N9 viruses have spread from eastern to southern China and become persistent in chickens, which has led to the establishment of multiple regionally distinct lineages with different reassortant genotypes. Repeated introductions of viruses from Zhejiang to other provinces and the presence of H7N9 viruses at live poultry markets have fuelled the recurrence of human infections. This rapid expansion of the geographical distribution and genetic diversity of the H7N9 viruses poses a direct challenge to current disease control systems. Our results also suggest that H7N9 viruses have become enzootic in China and may spread beyond the region, following the pattern previously observed with H5N1 and H9N2 influenza viruses.
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [3] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Tommy Tsan-Yuk
authors.initials: TT
authors.lastname: Lam
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China.
authors.forename: Boping
authors.initials: B
authors.lastname: Zhou
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Yujuan
authors.initials: Y
authors.lastname: Chai
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Yongyi
authors.initials: Y
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China.
authors.forename: Xinchun
authors.initials: X
authors.lastname: Chen
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Ma
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China.
authors.forename: Wenshan
authors.initials: W
authors.lastname: Hong
authors.affiliation: Key Laboratory of Emergency Detection for Public Health of Zhejiang Province, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang 310051, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory of Emergency Detection for Public Health of Zhejiang Province, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, Zhejiang 310051, China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [3] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Duan
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China.
authors.forename: Peiwen
authors.initials: P
authors.lastname: Chen
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Junfei
authors.initials: J
authors.lastname: Jiang
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Li
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Leo Lit Man
authors.initials: LL
authors.lastname: Poon
authors.affiliation: Division of Virology, Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Webby
authors.affiliation: 1] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: David K
authors.initials: DK
authors.lastname: Smith
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Joseph S M
authors.initials: JS
authors.lastname: Peiris
authors.affiliation: Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Holmes
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [3] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Guan
authors.affiliation: 1] State Key Laboratory of Emerging Infectious Diseases (HKU-Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen 518112, China [2] Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College (SUMC), Shantou 515041, China [3] Centre of Influenza Research, School of Public Health, The University of Hong Kong (HKU), Hong Kong, China.
authors.forename: Huachen
authors.initials: H
authors.lastname: Zhu
mesh_terms: D000818:Animals; D002645:Chickens / Q000821:virology*; D002681:China / Q000453:epidemiology; D017753:Ecosystem; D019143:Evolution, Molecular; D005838:Genotype; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000635:transmission / Q000821:virology*; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission / Q000821:virology; D008969:Molecular Sequence Data; D016865:Reassortant Viruses / Q000235:genetics / Q000302:isolation & purification; D015047:Zoonoses / Q000635:transmission / Q000821:virology