title: Evaluation of the human adaptation of influenza A/H7N9 virus in PB2 protein using human and swine respiratory tract explant cultures.
abstract: Novel avian H7N9 virus emerged in China in 2013 resulting in a case fatality rate of around 39% and continues to pose zoonotic and pandemic risk. Amino acid substitutions in PB2 protein were shown to influence the pathogenicity and transmissibility of H7N9 following experimental infection of ferrets and mice. In this study, we evaluated the role of amino acid substitution PB2-627K or compensatory changes at PB2-591K and PB2-701N, on the tropism and replication competence of H7N9 viruses for human and swine respiratory tracts using ex vivo organ explant cultures. Recombinant viruses of A/Shanghai/2/2013 (rgH7N9) and its mutants with PB2-K627E, PB2-K627E + Q591K and PB2-K627E + D701N were generated by plasmid-based reverse genetics. PB2-E627K was essential for efficient replication of rgH7N9 in ex vivo cultures of human and swine respiratory tracts. Mutant rgPB2-K627E + D701N replicated better than rgPB2-K627E in human lung but not as well as rgH7N9 virus. The rgPB2-K627E mutant failed to replicate in human type I-like pneumocytes (ATI) and peripheral blood monocyte-derived macrophages (PMϕ) at 37 °C while the compensatory mutant rgPB2-K627E + Q591K and rgPB2-K627E + D701N had partly restored replication competence in PMϕ. Our results demonstrate that PB2-E627K was important for efficient replication of influenza H7N9 in both human and swine respiratory tracts.
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Louisa L Y
authors.initials: LL
authors.lastname: Chan
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Christine T H
authors.initials: CT
authors.lastname: Bui
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.|The HKU-Pasteur Research Pole, School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Chris K P
authors.initials: CK
authors.lastname: Mok
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Mandy M T
authors.initials: MM
authors.lastname: Ng
authors.affiliation: Department of Pathology, LKS Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: John M
authors.initials: JM
authors.lastname: Nicholls
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.|The HKU-Pasteur Research Pole, School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: J S Malik
authors.initials: JS
authors.lastname: Peiris
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Michael C W
authors.initials: MC
authors.lastname: Chan
authors.affiliation: Centre of Influenza Research and School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.|Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Renee W Y
authors.initials: RW
authors.lastname: Chan
mesh_terms: D000222:Adaptation, Physiological; D019943:Amino Acid Substitution; D000818:Animals; D002478:Cells, Cultured; D004285:Dogs; D006801:Humans; D064766:Influenza A Virus, H7N9 Subtype / Q000235:genetics* / Q000502:physiology; D008264:Macrophages / Q000821:virology; D061985:Madin Darby Canine Kidney Cells; D009154:Mutation; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D020545:Respiratory Mucosa / Q000821:virology*; D013552:Swine; D014764:Viral Proteins / Q000235:genetics*; D014779:Virus Replication
chemical_list: C057027:PB2 protein, Influenzavirus A; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase