55
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Vaccinia virus protein A46R targets multiple Toll-like–interleukin-1 receptor adaptors and contributes to virulence

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Viral immune evasion strategies target key aspects of the host antiviral response. Recently, it has been recognized that Toll-like receptors (TLRs) have a role in innate defense against viruses. Here, we define the function of the vaccinia virus (VV) protein A46R and show it inhibits intracellular signalling by a range of TLRs. TLR signalling is triggered by homotypic interactions between the Toll-like–interleukin-1 resistance (TIR) domains of the receptors and adaptor molecules. A46R contains a TIR domain and is the only viral TIR domain–containing protein identified to date. We demonstrate that A46R targets the host TIR adaptors myeloid differentiation factor 88 (MyD88), MyD88 adaptor-like, TIR domain–containing adaptor inducing IFN-β (TRIF), and the TRIF-related adaptor molecule and thereby interferes with downstream activation of mitogen-activated protein kinases and nuclear factor κB. TRIF mediates activation of interferon (IFN) regulatory factor 3 (IRF3) and induction of IFN-β by TLR3 and TLR4 and suppresses VV replication in macrophages. Here, A46R disrupted TRIF-induced IRF3 activation and induction of the TRIF-dependent gene regulated on activation, normal T cell expressed and secreted. Furthermore, we show that A46R is functionally distinct from another described VV TLR inhibitor, A52R. Importantly, VV lacking the A46R gene was attenuated in a murine intranasal model, demonstrating the importance of A46R for VV virulence.

          Related collections

          Most cited references41

          • Record: found
          • Abstract: found
          • Article: not found

          Innate antiviral responses by means of TLR7-mediated recognition of single-stranded RNA.

          Interferons (IFNs) are critical for protection from viral infection, but the pathways linking virus recognition to IFN induction remain poorly understood. Plasmacytoid dendritic cells produce vast amounts of IFN-alpha in response to the wild-type influenza virus. Here, we show that this requires endosomal recognition of influenza genomic RNA and signaling by means of Toll-like receptor 7 (TLR7) and MyD88. Single-stranded RNA (ssRNA) molecules of nonviral origin also induce TLR7-dependent production of inflammatory cytokines. These results identify ssRNA as a ligand for TLR7 and suggest that cells of the innate immune system sense endosomal ssRNA to detect infection by RNA viruses.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Recognition of single-stranded RNA viruses by Toll-like receptor 7.

            Viral infection of mammalian host results in the activation of innate immune responses. Toll-like receptors (TLRs) have been shown to mediate the recognition of many types of pathogens, including viruses. The genomes of viruses possess unique characteristics that are not found in mammalian genomes, such as high CpG content and double-stranded RNA. These genomic nucleic acids serve as molecular signatures associated with viral infections. Here we show that TLR7 recognizes the single-stranded RNA viruses, vesicular stomatitis virus and influenza virus. The recognition of these viruses by plasmacytoid dendritic cells and B cells through TLR7 results in their activation of costimulatory molecules and production of cytokines. Moreover, this recognition required intact endocytic pathways. Mice deficient in either the TLR7 or the TLR adaptor protein MyD88 demonstrated reduced responses to in vivo infection with vesicular stomatitis virus. These results demonstrate microbial ligand recognition by TLR7 and provide insights into the pathways used by the innate immune cells in the recognition of viral pathogens.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Targeted disruption of the MyD88 gene results in loss of IL-1- and IL-18-mediated function.

              MyD88, originally isolated as a myeloid differentiation primary response gene, is shown to act as an adaptor in interleukin-1 (IL-1) signaling by interacting with both the IL-1 receptor complex and IL-1 receptor-associated kinase (IRAK). Mice generated by gene targeting to lack MyD88 have defects in T cell proliferation as well as induction of acute phase proteins and cytokines in response to IL-1. Increases in interferon-gamma production and natural killer cell activity in response to IL-18 are abrogated. In vivo Th1 response is also impaired. Furthermore, IL-18-induced activation of NF-kappaB and c-Jun N-terminal kinase (JNK) is blocked in MyD88-/- Th1-developing cells. Taken together, these results demonstrate that MyD88 is a critical component in the signaling cascade that is mediated by IL-1 receptor as well as IL-18 receptor.
                Bookmark

                Author and article information

                Journal
                J Exp Med
                The Journal of Experimental Medicine
                The Rockefeller University Press
                0022-1007
                1540-9538
                21 March 2005
                : 201
                : 6
                : 1007-1018
                Affiliations
                [1 ]Department of Biochemistry, Trinity College, Dublin 2, Ireland
                [2 ]Department of Virology, Faculty of Medicine, Imperial College London, St. Mary's Campus, London W2 1PG, England, UK
                [3 ]Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01604
                Author notes

                CORRESPONDENCE Andrew Bowie: agbowie@ 123456tcd.ie

                Article
                20041442
                10.1084/jem.20041442
                2213104
                15767367
                6751076b-2d7b-427a-b95c-e7ceb5596dbf
                Copyright © 2005, The Rockefeller University Press
                History
                : 16 July 2004
                : 14 January 2005
                Categories
                Article

                Medicine
                Medicine

                Comments

                Comment on this article