title: Human H7N9 virus induces a more pronounced pro-inflammatory cytokine but an attenuated interferon response in human bronchial epithelial cells when compared with an epidemiologically-linked chicken H7N9 virus.
abstract: BACKGROUND
  Avian influenza virus H7N9 has jumped species barrier, causing sporadic human infections since 2013. We have previously isolated an H7N9 virus from a patient, and an H7N9 virus from a chicken in a live poultry market where the patient visited during the incubation period. These two viruses were genetically highly similar. This study sought to use a human bronchial epithelial cell line model to infer the virulence of these H7N9 viruses in humans.
  
  
  METHODS
  Human bronchial epithelial cell line Calu-3 was infected with two H7N9 viruses (human H7N9-HU and chicken H7N9-CK), a human H5N1 virus and a human 2009 pandemic H1N1 virus. The infected cell lysate was collected at different time points post-infection for the determination of the levels of pro-inflammatory cytokines (tumor necrosis factor α [TNF-α] and interleukin 6 [IL-6]), anti-inflammatory cytokines (interleukin 10 [IL-10] and transforming growth factor beta [TGF-β]), chemokines (interleukin 8 [IL-8] and monocyte chemoattractant protein 1 [MCP-1]), and interferons (interferon β [IFN-β] and interferon lambda 1 [IFNL1]). The viral load in the cell lysate was also measured.
  
  
  RESULTS
  Comparison of the human and chicken H7N9 viruses showed that H7N9-HU induced significantly higher levels of TNF-α at 12 h post-infection, and significantly higher levels of IL-8 from 12 to 48 h post-infection than those of H7N9-CK. However, the level of IFNL1 was lower for H7N9-HU than that of H7N9-CK at 48 h post-infection (P < 0.001). H7N9-HU had significantly higher viral loads than H7N9-CK at 3 and 6 h post-infection. H5N1 induced significantly higher levels of TNF-α, IL-6, IL-8, IL-10 and MCP-1 than those of H7N9 viruses at 48 h post-infection. Conversely, H1N1 induced lower levels of TNF-α, IL-10, MCP-1, IFNL1 and IFN-β when compared with H7N9 viruses at the same time point.
  
  
  CONCLUSIONS
  H7N9-HU induced higher levels of pro-inflammatory IL-6 and IL-8 and exhibited a more rapid viral replication than H7N9-CK. However, the level of antiviral IFNL1 was lower for H7N9-HU than H7N9-CK. Our results suggest that the gained properties in modulating human innate immunity by H7N9-HU transformed it to be a more virulent virus in humans than H7N9-CK.
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Kelvin K W
authors.initials: KK
authors.lastname: To
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Candy C Y
authors.initials: CC
authors.lastname: Lau
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Jasper F W
authors.initials: JF
authors.lastname: Chan
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Anna J X
authors.initials: AJ
authors.lastname: Zhang
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China.|Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
authors.forename: Honglin
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China. kyyuen@hku.hk.|State Key Laboratory for Emerging Infectious Diseases, The University of Hong Kong, Hong Kong Special Administrative Region, China. kyyuen@hku.hk.|Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong Special Administrative Region, China. kyyuen@hku.hk.|Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong Special Administrative Region, China. kyyuen@hku.hk.|Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China. kyyuen@hku.hk.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D016207:Cytokines / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000821:virology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D064766:Influenza A Virus, H7N9 Subtype / Q000502:physiology*; D005585:Influenza in Birds / Q000378:metabolism* / Q000821:virology; D007251:Influenza, Human / Q000378:metabolism* / Q000821:virology; D007372:Interferons / Q000378:metabolism; D020545:Respiratory Mucosa / Q000378:metabolism / Q000821:virology; D019562:Viral Load; D014779:Virus Replication
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D007372:Interferons
keywords: Avian influenza virus; Chemokine; Chicken; Cytokine; H7N9; Human; IL-8; Interferon; Interferon lambda 1; Viral load