title: The 1918 Influenza Virus PB2 Protein Enhances Virulence through the Disruption of Inflammatory and Wnt-Mediated Signaling in Mice.
abstract: The 1918-1919 influenza pandemic remains the single greatest infectious disease outbreak in the past century. Mouse and nonhuman primate infection models have shown that the 1918 virus induces overly aggressive innate and proinflammatory responses. To understand the response to viral infection and the role of individual 1918 genes on the host response to the 1918 virus, we examined reassortant avian viruses nearly identical to the pandemic 1918 virus (1918-like avian virus) carrying either the 1918 hemagglutinin (HA) or PB2 gene. In mice, both genes enhanced 1918-like avian virus replication, but only the mammalian host adaptation of the 1918-like avian virus through reassortment of the 1918 PB2 led to increased lethality. Through the combination of viral genetics and host transcriptional profiling, we provide a multidimensional view of the molecular mechanisms by which the 1918 PB2 gene drives viral pathogenicity. We demonstrate that 1918 PB2 enhances immune and inflammatory responses concomitant with increased cellular infiltration in the lung. We also show for the first time, that 1918 PB2 expression results in the repression of both canonical and noncanonical Wnt signaling pathways, which are crucial for inflammation-mediated lung regeneration and repair. Finally, we utilize regulatory enrichment and network analysis to define the molecular regulators of inflammation, epithelial regeneration, and lung immunopathology that are dysregulated during influenza virus infection. Taken together, our data suggest that while both HA and PB2 are important for viral replication, only 1918 PB2 exacerbates lung damage in mice infected with a reassortant 1918-like avian virus.
  
  
  OBJECTIVE
  As viral pathogenesis is determined in part by the host response, understanding the key host molecular driver(s) of virus-mediated disease, in relation to individual viral genes, is a promising approach to host-oriented drug efforts in preventing disease. Previous studies have demonstrated the importance of host adaptive genes, HA and PB2, in mediating disease although the mechanisms by which they do so are still poorly understood. Here, we combine viral genetics and host transcriptional profiling to show that although both 1918 HA and 1918 PB2 are important mediators of efficient viral replication, only 1918 PB2 impacts the pathogenicity of an avian influenza virus sharing high homology to the 1918 pandemic influenza virus. We demonstrate that 1918 PB2 enhances deleterious inflammatory responses and the inhibition of regeneration and repair functions coordinated by Wnt signaling in the lungs of infected mice, thereby promoting virus-associated disease.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Adriana
authors.initials: A
authors.lastname: Forero
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tisoncik-Go
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Tokiko
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Gongxun
authors.initials: G
authors.lastname: Zhong
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Masato
authors.initials: M
authors.lastname: Hatta
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tchitchek
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Selinger
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Chang
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Kristi
authors.initials: K
authors.lastname: Barker
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA.
authors.forename: Juliet
authors.initials: J
authors.lastname: Morrison
authors.affiliation: Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, and Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Berndt
authors.affiliation: Howard Hughes Medical Institute, Institute for Stem Cell and Regenerative Medicine, and Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Randall T
authors.initials: RT
authors.lastname: Moon
authors.affiliation: Laboratory of Virology, National Influenza Centre (South of France), Hospices Civils de Lyon, Bron, France, and Laboratorie Virpath EA4610, Université Claude Bernard Lyon 1, Lyon, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Josset
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kawaoka
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, USA Washington National Primate Research Center, University of Washington, Seattle, Washington, USA honey@uw.edu.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Katze
mesh_terms: D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D005260:Female; D020869:Gene Expression Profiling; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000473:pathology; D053118:Influenza A Virus, H1N1 Subtype / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D008168:Lung / Q000473:pathology / Q000821:virology; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000473:pathology* / Q000821:virology*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D016865:Reassortant Viruses / Q000201:enzymology / Q000472:pathogenicity; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D060449:Wnt Signaling Pathway / Q000276:immunology*
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; C057027:PB2 protein, Influenzavirus A; D014764:Viral Proteins; D037521:Virulence Factors; C483468:hemagglutinin, human influenza A virus; D012324:RNA-Dependent RNA Polymerase