title: Avian influenza A H7N9 virus induces severe pneumonia in mice without prior adaptation and responds to a combination of zanamivir and COX-2 inhibitor.
abstract: BACKGROUND
  Human infection caused by the avian influenza A H7N9 virus has a case-fatality rate of over 30%. Systematic study of the pathogenesis of avian H7N9 isolate and effective therapeutic strategies are needed.
  
  
  METHODS
  BALB/c mice were inoculated intranasally with an H7N9 virus isolated from a chicken in a wet market epidemiologically linked to a fatal human case, (A/chicken/Zhejiang/DTID-ZJU01/2013 [CK1]), and with an H7N9 virus isolated from a human (A/Anhui/01/2013 [AH1]). The pulmonary viral loads, cytokine/chemokine profiles and histopathological changes of the infected mice were compared. The therapeutic efficacy of a non-steroidal anti-inflammatory drug (NSAID), celecoxib, was assessed.
  
  
  RESULTS
  Without prior adaptation, intranasal inoculation of 106 plaque forming units (PFUs) of CK1 caused a mortality rate of 82% (14/17) in mice. Viral nucleoprotein and RNA expression were limited to the respiratory system and no viral RNA could be detected from brain, liver and kidney tissues. CK1 caused heavy alveolar inflammatory exudation and pulmonary hemorrhage, associated with high pulmonary levels of proinflammatory cytokines. In the mouse lung cell line LA-4, CK1 also induced high levels of interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) mRNA. Administration of the antiviral zanamivir did not significantly improve survival in mice infected with CK1, but co-administration of the non-steroidal anti-inflammatory drug (NSAID) celecoxib in combination with zanamivir improved survival and lung pathology.
  
  
  CONCLUSIONS
  Our findings suggested that H7N9 viruses isolated from chicken without preceding trans-species adaptation can cause lethal mammalian pulmonary infection. The severe proinflammatory responses might be a factor contributing to the mortality. Treatment with combination of antiviral and NSAID could ameliorate pulmonary inflammation and may improve survival.
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China.
authors.forename: Can
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China.
authors.forename: Chuangen
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China.
authors.forename: Anna J X
authors.initials: AJ
authors.lastname: Zhang
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China.
authors.forename: Kelvin K W
authors.initials: KK
authors.lastname: To
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China.
authors.forename: Andrew C Y
authors.initials: AC
authors.lastname: Lee
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Houshun
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China.
authors.forename: Hazel W L
authors.initials: HW
authors.lastname: Wu
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China.
authors.forename: Jasper F W
authors.initials: JF
authors.lastname: Chan
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China; Zhejiang University, Hangzhou, China.
authors.forename: Honglin
authors.initials: H
authors.lastname: Chen
authors.affiliation: Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China; Department of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Ivan F N
authors.initials: IF
authors.lastname: Hung
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China; Zhejiang University, Hangzhou, China.
authors.forename: Lanjuan
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China; Zhejiang University, Hangzhou, China.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000222:Adaptation, Physiological / Q000276:immunology; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D016207:Cytokines / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D008168:Lung / Q000473:pathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D011024:Pneumonia, Viral / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D014779:Virus Replication; D053243:Zanamivir / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000998:Antiviral Agents; D052246:Cyclooxygenase 2 Inhibitors; D016207:Cytokines; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D053243:Zanamivir