title: Vaccinia virus protein N2 is a nuclear IRF3 inhibitor that promotes virulence.
abstract: Vaccinia virus (VACV) expresses many proteins that are non-essential for virus replication but promote virulence by inhibiting components of the host immune response to infection. These immunomodulators include a family of proteins that have, or are predicted to have, a structure related to the B-cell lymphoma (Bcl)-2 protein. Five members of the VACV Bcl-2 family (N1, B14, A52, F1 and K7) have had their crystal structure solved, others have been characterized and a function assigned (C6, A46), and others are predicted to be Bcl-2 proteins but are uncharacterized hitherto (N2, B22, C1). Data presented here show that N2 is a nuclear protein that is expressed early during infection and inhibits the activation of interferon regulatory factor (IRF)3. Consistent with its nuclear localization, N2 inhibits IRF3 downstream of the TANK-binding kinase (TBK)-1 and after IRF3 translocation into the nucleus. A mutant VACV strain Western Reserve lacking the N2L gene (vΔN2) showed normal replication and spread in cultured cells compared to wild-type parental (vN2) and revertant (vN2-rev) viruses, but was attenuated in two murine models of infection. After intranasal infection, the vΔN2 mutant induced lower weight loss and signs of illness, and virus was cleared more rapidly from the infected tissue. In the intradermal model of infection, vΔN2 induced smaller lesions that were resolved more rapidly. In summary, the N2 protein is an intracellular virulence factor that inhibits IRF3 activity in the nucleus.
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Ferguson
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Camilla T O
authors.initials: CTO
authors.lastname: Benfield
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Ren
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Vivian H
authors.initials: VH
authors.lastname: Lee
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Gordon L
authors.initials: GL
authors.lastname: Frazer
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Pavla
authors.initials: P
authors.lastname: Strnadova
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Rebecca P
authors.initials: RP
authors.lastname: Sumner
authors.affiliation: Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, UK.|Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
authors.forename: Geoffrey L
authors.initials: GL
authors.lastname: Smith
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D054884:Host-Pathogen Interactions; D050838:Interferon Regulatory Factor-3 / Q000037:antagonists & inhibitors*; D051379:Mice; D008807:Mice, Inbred BALB C; D014615:Vaccinia / Q000473:pathology / Q000821:virology; D014616:Vaccinia virus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014764:Viral Proteins / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D050838:Interferon Regulatory Factor-3; C494233:Irf3 protein, mouse; D014764:Viral Proteins; D037521:Virulence Factors