title: A single point mutation (Y89F) within the non-structural protein 1 of influenza A viruses limits epithelial cell tropism and virulence in mice.
abstract: The nonstructural protein 1 (A/NS1) of influenza A viruses (IAV) harbors several src homology (SH)-binding motifs (bm) that mediate interactions with cellular proteins. In contrast to the sequence variability of the second SH3bm, tyrosine 89, within the SH2bm is a highly conserved residue among IAV strains. This prompted us to evaluate the necessity of this SH2bm for IAV virulence. In an in vivo mouse model, we observed drastic reductions in weight loss, mortality, and virus titers in lung and bronchoalveolar lavage fluid after infection with the mutant virus PR8 A/NS1-Y89F (PR8 Y89F) when compared with wild-type virus (PR8 wt). Concomitantly, we observed decreased inflammation and less severe pathologic changes, reflecting reduced levels of virus titers. At histologic analysis, lungs infected with PR8 wt virus showed widespread destruction of the bronchiolar epithelium, with extensive distribution of virus antigen within tracheal, bronchial, bronchiolar, and alveolar epithelium. In marked contrast, the bronchiolar epithelium after infection with the mutant PR8 Y89F virus was entirely intact, and the severity and extent of viral infection was reduced and strongly restricted to alveoli. These findings demonstrate that change of a single residue of the highly conserved SH2bm within the A/NS1 results in restricted virus spread in mouse lung and strongly reduced virulence, which illustrates the necessity of the SH2bm for IAV-induced pathogenicity.
authors.affiliation: Institute of Molecular Virology, Center of Molecular Biology of Inflammation, University of Muenster, Muenster, Germany.
authors.forename: Eike R
authors.initials: ER
authors.lastname: Hrincius
authors.forename: Ann-Katrin
authors.initials: AK
authors.lastname: Hennecke
authors.forename: Lisa
authors.initials: L
authors.lastname: Gensler
authors.forename: Carolin
authors.initials: C
authors.lastname: Nordhoff
authors.forename: Darisuren
authors.initials: D
authors.lastname: Anhlan
authors.forename: Peter
authors.initials: P
authors.lastname: Vogel
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: McCullers
authors.forename: Stephan
authors.initials: S
authors.lastname: Ludwig
authors.forename: Christina
authors.initials: C
authors.lastname: Ehrhardt
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology / Q000821:virology; D018925:Chemokines / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis; D004847:Epithelial Cells / Q000821:virology; D009980:Influenza A virus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology; D008168:Lung / Q000276:immunology / Q000473:pathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000473:pathology / Q000821:virology*; D017354:Point Mutation; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D056189:Viral Tropism / Q000235:genetics*; D014774:Virulence / Q000235:genetics; D014779:Virus Replication / Q000235:genetics; D015431:Weight Loss; D018909:src Homology Domains / Q000235:genetics
chemical_list: D018925:Chemokines; D016207:Cytokines; D017361:Viral Nonstructural Proteins