title: Emergence and evolution of H10 subtype influenza viruses in poultry in China.
abstract: The cases of human infections with H10N8 viruses identified in late 2013 and early 2014 in Jiangxi, China, have raised concerns over the origin, prevalence, and development of these viruses in this region. Our long-term influenza surveillance of poultry and migratory birds in southern China in the past 12 years showed that H10 influenza viruses have been introduced from migratory to domestic ducks over several winter seasons at sentinel duck farms at Poyang Lake, where domestic ducks share their water body with overwintering migratory birds. H10 viruses were never detected in terrestrial poultry in our survey areas until August 2013, when they were identified at live-poultry markets in Jiangxi. Since then, we have isolated 124 H10N8 or H10N6 viruses from chickens at local markets, revealing an ongoing outbreak. Phylogenetic analysis of H10 and related viruses showed that the chicken H10N8 viruses were generated through multiple reassortments between H10 and N8 viruses from domestic ducks and the enzootic chicken H9N2 viruses. These chicken reassortant viruses were highly similar to the human isolate, indicating that market chickens were the source of human infection. Recently, the H10 viruses further reassorted, apparently with H5N6 viruses, and generated an H10N6 variant. The emergence and prevalence of H10 viruses in chickens and the occurrence of human infections provide direct evidence of the threat from the current influenza ecosystem in China.
  
  
  OBJECTIVE
  After the outbreak of avian-origin H7N9 influenza viruses in China, fatal human infections with a novel H10N8 virus were reported. Utilizing data from 12 years of influenza surveillance in southern China, we showed that H10 viruses were regularly introduced by migratory ducks to domestic ducks on Poyang Lake, a major aggregative site of migratory birds in Asia. The H10 viruses were maintained and amplified in domestic ducks and then transmitted to chickens and reassorted with enzootic H9N2 viruses, leading to an outbreak and human infections at live-poultry markets. The emergence of the H10N8 virus, following a pathway similar to that of the recent H7N9 virus, highlights the role of domestic ducks and the current influenza ecosystem in China that facilitates influenza viruses moving from their reservoir hosts through the live-poultry system to cause severe consequences for public health.
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China State Key Laboratory of Emerging Infectious Diseases (Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Ma
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Tommy Tsan-Yuk
authors.initials: TT
authors.lastname: Lam
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yujuan
authors.initials: Y
authors.lastname: Chai
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Microbiology, Guangxi Medical University, Nanning, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Fan
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China.
authors.forename: Wenshan
authors.initials: W
authors.lastname: Hong
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Li
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: David K
authors.initials: DK
authors.lastname: Smith
authors.affiliation: Division of Virology, Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Webby
authors.affiliation: Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China State Key Laboratory of Emerging Infectious Diseases (Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen, China.
authors.forename: Joseph S M
authors.initials: JS
authors.lastname: Peiris
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China State Key Laboratory of Emerging Infectious Diseases (Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen, China zhuhch@hku.hk yguan@hku.hk.
authors.forename: Huachen
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Joint Influenza Research Centre (SUMC/HKU), Shantou University Medical College, Shantou, China Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China State Key Laboratory of Emerging Infectious Diseases (Shenzhen Branch), Shenzhen Third People's Hospital, Shenzhen, China zhuhch@hku.hk yguan@hku.hk.
authors.forename: Yi
authors.initials: Y
authors.lastname: Guan
mesh_terms: D000818:Animals; D002645:Chickens; D002681:China / Q000453:epidemiology; D004372:Ducks; D062665:Epidemiological Monitoring; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000032:analysis* / Q000235:genetics*; D006801:Humans; D009980:Influenza A virus / Q000145:classification* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000453:epidemiology / Q000821:virology*; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology*; D016865:Reassortant Viruses / Q000145:classification / Q000302:isolation & purification
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus