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Khatiwada S, Delhon G, Nagendraprabhu P, Chaulagain S, Luo S, Diel DG, Flores EF, Rock DL. A parapoxviral virion protein inhibits NF-κB signaling early in infection. PLoS Pathog 2017; 13:e1006561. [PMID: 28787456 PMCID: PMC5560748 DOI: 10.1371/journal.ppat.1006561] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 08/17/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Poxviruses have evolved unique proteins and mechanisms to counteract the nuclear factor κB (NF-κB) signaling pathway, which is an essential regulatory pathway of host innate immune responses. Here, we describe a NF-κB inhibitory virion protein of orf virus (ORFV), ORFV073, which functions very early in infected cells. Infection with ORFV073 gene deletion virus (OV-IA82Δ073) led to increased accumulation of NF-κB essential modulator (NEMO), marked phosphorylation of IκB kinase (IKK) subunits IKKα and IKKβ, IκBα and NF-κB subunit p65 (NF-κB-p65), and to early nuclear translocation of NF-κB-p65 in virus-infected cells (≤ 30 min post infection). Expression of ORFV073 alone was sufficient to inhibit TNFα induced activation of the NF-κB signaling in uninfected cells. Consistent with observed inhibition of IKK complex activation, ORFV073 interacted with the regulatory subunit of the IKK complex NEMO. Infection of sheep with OV-IA82Δ073 led to virus attenuation, indicating that ORFV073 is a virulence determinant in the natural host. Notably, ORFV073 represents the first poxviral virion-associated NF-κB inhibitor described, highlighting the significance of viral inhibition of NF-κB signaling very early in infection.
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Affiliation(s)
- Sushil Khatiwada
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Gustavo Delhon
- School of Veterinary Medicine and Biomedical Science, Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Ponnuraj Nagendraprabhu
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Sabal Chaulagain
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Shuhong Luo
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Diego G. Diel
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Eduardo F. Flores
- Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Daniel L. Rock
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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Deletion of the K1L Gene Results in a Vaccinia Virus That Is Less Pathogenic Due to Muted Innate Immune Responses, yet Still Elicits Protective Immunity. J Virol 2017; 91:JVI.00542-17. [PMID: 28490586 DOI: 10.1128/jvi.00542-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/03/2017] [Indexed: 12/14/2022] Open
Abstract
All viruses strategically alter the antiviral immune response to their benefit. The vaccinia virus (VACV) K1 protein has multiple immunomodulatory effects in tissue culture models of infection, including NF-κB antagonism. However, the effect of K1 during animal infection is poorly understood. We determined that a K1L-less vaccinia virus (vΔK1L) was less pathogenic than wild-type VACV in intranasal and intradermal models of infection. Decreased pathogenicity was correlated with diminished virus replication in intranasally infected mice. However, in intradermally inoculated ears, vΔK1L replicated to levels nearly identical to those of VACV, implying that the decreased immune response to vΔK1L infection, not virus replication, dictated lesion size. Several lines of evidence support this theory. First, vΔK1L induced slightly less edema than vK1L, as revealed by histopathology and noninvasive quantitative ultrasound technology (QUS). Second, infiltrating immune cell populations were decreased in vΔK1L-infected ears. Third, cytokine and chemokine gene expression was decreased in vΔK1L-infected ears. While these results identified the biological basis for smaller lesions, they remained puzzling; because K1 antagonizes NF-κB in vitro, antiviral gene expression was expected to be higher during vΔK1L infection. Despite these diminished innate immune responses, vΔK1L vaccination induced a protective VACV-specific CD8+ T cell response and protected against a lethal VACV challenge. Thus, vΔK1L is the first vaccinia virus construct reported that caused a muted innate immune gene expression profile and decreased immune cell infiltration in an intradermal model of infection yet still elicited protective immunity.IMPORTANCE The vaccinia virus (VACV) K1 protein inhibits NF-κB activation among its other antagonistic functions. A virus lacking K1 (vΔK1L) was predicted to be less pathogenic because it would trigger a more robust antiviral immune response than VACV. Indeed, vΔK1L was less pathogenic in intradermally infected mouse ear pinnae. However, vΔK1L infection unexpectedly elicited dramatically reduced infiltration of innate immune cells into ears. This was likely due to decreased expression of cytokine and chemokine genes in vΔK1L-infected ears. As such, our finding contradicted observations from cell culture systems. Interestingly, vΔK1L conferred protective immunity against lethal VACV challenge. This suggests that the muted immune response triggered during vΔK1L infection remained sufficient to mount an effective protective response. Our results highlight the complexity and unpredictable nature of virus-host interactions, a relationship that must be understood to better comprehend virus pathogenesis or to manipulate viruses for use as vaccines.
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Susceptibility to Urinary Tract Infection: Benefits and Hazards of the Antibacterial Host Response. Microbiol Spectr 2017; 4. [PMID: 27337480 DOI: 10.1128/microbiolspec.uti-0019-2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A paradigm shift is needed to improve and personalize the diagnosis of infectious disease and to select appropriate therapies. For many years, only the most severe and complicated bacterial infections received more detailed diagnostic and therapeutic attention as the efficiency of antibiotic therapy has guaranteed efficient treatment of patients suffering from the most common infections. Indeed, treatability almost became a rationale not to analyze bacterial and host parameters in these larger patient groups. Due to the rapid spread of antibiotic resistance, common infections like respiratory tract- or urinary-tract infections (UTIs) now pose new and significant therapeutic challenges. It is fortunate and timely that infectious disease research can offer such a wealth of new molecular information that is ready to use for the identification of susceptible patients and design of new suitable therapies. Paradoxically, the threat of antibiotic resistance may become a window of opportunity, by encouraging the implementation of new diagnostic and therapeutic approaches. The frequency of antibiotic resistance is rising rapidly in uropathogenic organisms and the molecular and genetic understanding of UTI susceptibility is quite advanced. More bold translation of the new molecular diagnostic and therapeutic tools would not just be possible but of great potential benefit in this patient group. This chapter reviews the molecular basis for susceptibility to UTI, including recent advances in genetics, and discusses the consequences for diagnosis and therapy. By dissecting the increasingly well-defined molecular interactions between bacteria and host and the molecular features of excessive bacterial virulence or host-response malfunction, it is becoming possible to isolate the defensive from the damaging aspects of the host response. Distinguishing "good" from "bad" inflammation has been a long-term quest of biomedical science and in UTI, patients need the "good" aspects of the inflammatory response to resist infection while avoiding the "bad" aspects, causing chronicity and tissue damage.
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Tian T, Jin MQ, Dubin K, King SL, Hoetzenecker W, Murphy GF, Chen CA, Kupper TS, Fuhlbrigge RC. IL-1R Type 1-Deficient Mice Demonstrate an Impaired Host Immune Response against Cutaneous Vaccinia Virus Infection. THE JOURNAL OF IMMUNOLOGY 2017; 198:4341-4351. [PMID: 28468973 DOI: 10.4049/jimmunol.1500106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/05/2017] [Indexed: 01/08/2023]
Abstract
The IL-1 superfamily of cytokines and receptors has been studied extensively. However, the specific roles of IL-1 elements in host immunity to cutaneous viral infection remain elusive. In this study, we applied vaccinia virus (VACV) by scarification to IL-1R1 knockout mice (IL-1R1-/-) and found that these mice developed markedly larger lesions with higher viral genome copies in skin than did wild-type mice. The phenotype of infected IL-1R1-/- mice was similar to eczema vaccinatum, a severe side effect of VACV vaccination that may develop in humans with atopic dermatitis. Interestingly, the impaired cutaneous response of IL-1R1-/- mice did not reflect a systemic immune deficiency, because immunized IL-1R1-/- mice survived subsequent lethal VACV intranasal challenge, or defects of T cell activation or T cell homing to the site of inoculation. Histologic evaluation revealed that VACV infection and replication after scarification were limited to the epidermal layer of wild-type mice, whereas lack of IL-1R1 permitted extension of VACV infection into dermal layers of the skin. We explored the etiology of this discrepancy and determined that IL-1R1-/- mice contained significantly more macrophages and monocyte-derived dendritic cells in the dermis after VACV scarification. These cells were vulnerable to VACV infection and may augment the transmission of virus to adjacent skin, thus leading to larger skin lesions and satellite lesions in IL-1R1-/- mice. These results suggest new therapeutic strategies for treatment of eczema vaccinatum and inform assessment of risks in patients receiving IL-1 blocking Abs for treatment of chronic inflammatory disorders.
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Affiliation(s)
- Tian Tian
- Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115;
| | | | - Krista Dubin
- Weill Cornell Medical College, New York, NY 10065
| | - Sandra L King
- Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Wolfram Hoetzenecker
- Department of Dermatology, University Hospital of Zurich, 8091 Zurich, Switzerland
| | - George F Murphy
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | | | - Thomas S Kupper
- Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
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RNA-Seq Based Transcriptome Analysis of the Type I Interferon Host Response upon Vaccinia Virus Infection of Mouse Cells. J Immunol Res 2017; 2017:5157626. [PMID: 28280747 PMCID: PMC5322442 DOI: 10.1155/2017/5157626] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/09/2017] [Indexed: 11/26/2022] Open
Abstract
Vaccinia virus (VACV) encodes the soluble type I interferon (IFN) binding protein B18 that is secreted from infected cells and also attaches to the cell surface, as an immunomodulatory strategy to inhibit the host IFN response. By using next generation sequencing technologies, we performed a detailed RNA-seq study to dissect at the transcriptional level the modulation of the IFN based host response by VACV and B18. Transcriptome profiling of L929 cells after incubation with purified recombinant B18 protein showed that attachment of B18 to the cell surface does not trigger cell signalling leading to transcriptional activation. Consistent with its ability to bind type I IFN, B18 completely inhibited the IFN-mediated modulation of host gene expression. Addition of UV-inactivated virus particles to cell cultures altered the expression of a set of 53 cellular genes, including genes involved in innate immunity. Differential gene expression analyses of cells infected with replication competent VACV identified the activation of a broad range of host genes involved in multiple cellular pathways. Interestingly, we did not detect an IFN-mediated response among the transcriptional changes induced by VACV, even after the addition of IFN to cells infected with a mutant VACV lacking B18. This is consistent with additional viral mechanisms acting at different levels to block IFN responses during VACV infection.
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56
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Kuri P, Ellwanger K, Kufer TA, Leptin M, Bajoghli B. A high-sensitivity bi-directional reporter to monitor NF-κB activity in cell culture and zebrafish in real time. J Cell Sci 2016; 130:648-657. [PMID: 27980067 DOI: 10.1242/jcs.196485] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/08/2016] [Indexed: 12/12/2022] Open
Abstract
Nuclear factor (NF)-κB transcription factors play major roles in numerous biological processes including development and immunity. Here, we engineered a novel bi-directional NF-κB-responsive reporter, pSGNluc, in which a high-affinity NF-κB promoter fragment simultaneously drives expression of luciferase and GFP. Treatment with TNFα (also known as TNF) induced a strong, dose-dependent luciferase signal in cell culture. The degree of induction over background was comparable to that of other NF-κB-driven luciferase reporters, but the absolute level of expression was at least 20-fold higher. This extends the sensitivity range of otherwise difficult assays mediated exclusively by endogenously expressed receptors, as we show for Nod1 signaling in HEK293 cells. To measure NF-κB activity in the living organism, we established a transgenic zebrafish line carrying the pSGNluc construct. Live in toto imaging of transgenic embryos revealed the activation patterns of NF-κB signaling during embryonic development and as responses to inflammatory stimuli. Taken together, by integrating qualitative and quantitative NF-κB reporter activity, pSGNluc is a valuable tool for studying NF-κB signaling at high spatiotemporal resolution in cultured cells and living animals that goes beyond the possibilities provided by currently available reporters.
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Affiliation(s)
- Paola Kuri
- Directors' Research Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Kornelia Ellwanger
- Department of Immunology, Institute of Nutritional Medicine, University of Hohenheim, 70593 Stuttgart, Germany
| | - Thomas A Kufer
- Department of Immunology, Institute of Nutritional Medicine, University of Hohenheim, 70593 Stuttgart, Germany
| | - Maria Leptin
- Directors' Research Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany .,Institute of Genetics, University of Cologne, Zülpicherstrasse 47a, 50674 Cologne, Germany.,EMBO, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Baubak Bajoghli
- Directors' Research Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
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57
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Stuart JH, Sumner RP, Lu Y, Snowden JS, Smith GL. Vaccinia Virus Protein C6 Inhibits Type I IFN Signalling in the Nucleus and Binds to the Transactivation Domain of STAT2. PLoS Pathog 2016; 12:e1005955. [PMID: 27907166 PMCID: PMC5131898 DOI: 10.1371/journal.ppat.1005955] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/26/2016] [Indexed: 12/17/2022] Open
Abstract
The type I interferon (IFN) response is a crucial innate immune signalling pathway required for defense against viral infection. Accordingly, the great majority of mammalian viruses possess means to inhibit this important host immune response. Here we show that vaccinia virus (VACV) strain Western Reserve protein C6, is a dual function protein that inhibits the cellular response to type I IFNs in addition to its published function as an inhibitor of IRF-3 activation, thereby restricting type I IFN production from infected cells. Ectopic expression of C6 inhibits the induction of interferon stimulated genes (ISGs) in response to IFNα treatment at both the mRNA and protein level. C6 inhibits the IFNα-induced Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway at a late stage, downstream of STAT1 and STAT2 phosphorylation, nuclear translocation and binding of the interferon stimulated gene factor 3 (ISGF3) complex to the interferon stimulated response element (ISRE). Mechanistically, C6 associates with the transactivation domain of STAT2 and this might explain how C6 inhibits the type I IFN signalling very late in the pathway. During virus infection C6 reduces ISRE-dependent gene expression despite the presence of the viral protein phosphatase VH1 that dephosphorylates STAT1 and STAT2. The ability of a cytoplasmic replicating virus to dampen the immune response within the nucleus, and the ability of viral immunomodulators such as C6 to inhibit multiple stages of the innate immune response by distinct mechanisms, emphasizes the intricacies of host-pathogen interactions and viral immune evasion. In response to a viral infection, infected host cells mount an early, innate immune response to limit viral replication and spread. Type I interferons (IFNs) are produced by a cell when a viral infection is detected and are a crucial aspect of this early immune response. IFNs are released from the infected cell and can act on the infected cell itself or neighbouring cells to initiate a signalling pathway that results in the production of hundreds of anti-viral proteins. In this work we investigated a vaccinia virus protein called C6, a known inhibitor of type I IFN production. Here we show that C6 also inhibits signalling initiated in response to type I IFNs, therefore providing a dual defence against this essential immune response. The results show that, unlike the majority of viral inhibitors of IFN signalling, C6 inhibits the signalling pathway at a late stage once the proteins required for IFN-stimulated gene transcription have reached the nucleus and bound to the DNA. This work illustrates the complex relationship between infecting viruses and the host immune response and further investigation of the mechanism by which C6 inhibits this important immune pathway will likely increase our knowledge of the pathway itself.
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Affiliation(s)
- Jennifer H. Stuart
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Rebecca P. Sumner
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Yongxu Lu
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Joseph S. Snowden
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Geoffrey L. Smith
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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58
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Bravo Cruz AG, Shisler JL. Vaccinia virus K1 ankyrin repeat protein inhibits NF-κB activation by preventing RelA acetylation. J Gen Virol 2016; 97:2691-2702. [DOI: 10.1099/jgv.0.000576] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Ariana G. Bravo Cruz
- Department of Microbiology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - Joanna L. Shisler
- Department of Microbiology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA
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Torres AA, Albarnaz JD, Bonjardim CA, Smith GL. Multiple Bcl-2 family immunomodulators from vaccinia virus regulate MAPK/AP-1 activation. J Gen Virol 2016; 97:2346-2351. [PMID: 27312213 PMCID: PMC5042131 DOI: 10.1099/jgv.0.000525] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Vaccinia virus (VACV) is a poxvirus and encodes many proteins that modify the host cell metabolism or inhibit the host response to infection. For instance, it is known that VACV infection can activate the mitogen-activated protein kinase (MAPK)/activator protein 1 (AP-1) pathway and inhibit activation of the pro-inflammatory transcription factor NF-κB. Since NF-κB and MAPK/AP-1 share common upstream activators we investigated whether six different VACV Bcl-2-like NF-κB inhibitors can also influence MAPK/AP-1 activation. Data presented show that proteins A52, B14 and K7 each contribute to AP-1 activation during VACV infection, and when expressed individually outwith infection. B14 induced the greatest stimulation of AP-1 and further investigation showed B14 activated mainly the MAPKs ERK (extracellular signal-regulated kinase) and JNK (Jun N-terminal kinase), and their substrate c-Jun (a component of AP-1). These data indicate that the same viral protein can have different effects on distinct signalling pathways, in blocking NF-κB activation whilst leading to MAPK/AP-1 activation.
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Affiliation(s)
- Alice A Torres
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha, CEP 31270-901, Belo Horizonte, MG, Brazil.,Department of Pathology, University of Cambridge, Cambridge, UK
| | | | - Cláudio A Bonjardim
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha, CEP 31270-901, Belo Horizonte, MG, Brazil
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60
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Dahiya SS, Kumar S, Mehta SC, Narnaware SD, Singh R, Tuteja FC. Camelpox: A brief review on its epidemiology, current status and challenges. Acta Trop 2016; 158:32-38. [PMID: 26902797 DOI: 10.1016/j.actatropica.2016.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/12/2016] [Accepted: 02/18/2016] [Indexed: 11/17/2022]
Abstract
Camelpox caused by a Camelpox virus (CMLV) is a very important host specific viral disease of camel. It is highly contagious in nature and causes serious impact on health even mortality of camels and economic losses to the camel owners. It manifests itself either in the local/mild or generalized/severe form. Various outbreaks of different pathogenicity have been reported from camel dwelling areas of the world. CMLV has been characterized in embryonated chicken eggs with the production of characteristic pock lesions and in various cell lines with the capacity to induce giant cells. Being of Poxviridae family, CMLV employs various strategies to impede host immune system and facilitates its own pathogenesis. Both live and attenuated vaccine has been found effective against CMLV infection. The present review gives a comprehensive overview of camelpox disease with respect to its transmission, epidemiology, virion characteristics, viral life cycle, host interaction and its immune modulation.
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Affiliation(s)
- Shyam Singh Dahiya
- National Research Center on Camel, Jorbeer, Bikaner, Rajasthan 334001, India.
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | | | - Shirish D Narnaware
- National Research Center on Camel, Jorbeer, Bikaner, Rajasthan 334001, India
| | - Raghvendar Singh
- National Research Center on Camel, Jorbeer, Bikaner, Rajasthan 334001, India
| | - Fateh Chand Tuteja
- National Research Center on Camel, Jorbeer, Bikaner, Rajasthan 334001, India
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Holgado MP, Falivene J, Maeto C, Amigo M, Pascutti MF, Vecchione MB, Bruttomesso A, Calamante G, Del Médico-Zajac MP, Gherardi MM. Deletion of A44L, A46R and C12L Vaccinia Virus Genes from the MVA Genome Improved the Vector Immunogenicity by Modifying the Innate Immune Response Generating Enhanced and Optimized Specific T-Cell Responses. Viruses 2016; 8:E139. [PMID: 27223301 PMCID: PMC4885094 DOI: 10.3390/v8050139] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/02/2016] [Accepted: 05/11/2016] [Indexed: 12/31/2022] Open
Abstract
MVA is an attenuated vector that still retains immunomodulatory genes. We have previously reported its optimization after deleting the C12L gene, coding for the IL-18 binding-protein. Here, we analyzed the immunogenicity of MVA vectors harboring the simultaneous deletion of A44L, related to steroid synthesis and A46R, a TLR-signaling inhibitor (MVAΔA44L-A46R); or also including a deletion of C12L (MVAΔC12L/ΔA44L-A46R). The absence of biological activities of the deleted genes in the MVA vectors was demonstrated. Adaptive T-cell responses against VACV epitopes, evaluated in spleen and draining lymph-nodes of C57Bl/6 mice at acute/memory phases, were of higher magnitude in those animals that received deleted MVAs compared to MVAwt. MVAΔC12L/ΔA44L-A46R generated cellular specific memory responses of higher quality characterized by bifunctionality (CD107a/b⁺/IFN-γ⁺) and proliferation capacity. Deletion of selected genes from MVA generated innate immune responses with higher levels of determining cytokines related to T-cell response generation, such as IL-12, IFN-γ, as well as IL-1β and IFN-β. This study describes for the first time that simultaneous deletion of the A44L, A46R and C12L genes from MVA improved its immunogenicity by enhancing the host adaptive and innate immune responses, suggesting that this approach comprises an appropriate strategy to increase the MVA vaccine potential.
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Affiliation(s)
- María Pía Holgado
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
| | - Juliana Falivene
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
| | - Cynthia Maeto
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
| | - Micaela Amigo
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
| | - María Fernanda Pascutti
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
| | - María Belén Vecchione
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
- Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina.
| | - Andrea Bruttomesso
- Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina.
| | - Gabriela Calamante
- Instituto de Biotecnología, CICVyA-INTA Castelar, Buenos Aires 1686, Argentina.
| | | | - María Magdalena Gherardi
- Instituto de Investigaciones Biomédicas en Retrovirus y SIDA (INBIRS), Universidad de Buenos Aires-CONICET, Facultad de Medicina, Ciudad de Buenos Aires 1121, Argentina.
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Shah M, Anwar MA, Kim JH, Choi S. Advances in Antiviral Therapies Targeting Toll-like Receptors. Expert Opin Investig Drugs 2016; 25:437-53. [DOI: 10.1517/13543784.2016.1154040] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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63
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The Membrane Protein of Severe Acute Respiratory Syndrome Coronavirus Functions as a Novel Cytosolic Pathogen-Associated Molecular Pattern To Promote Beta Interferon Induction via a Toll-Like-Receptor-Related TRAF3-Independent Mechanism. mBio 2016; 7:e01872-15. [PMID: 26861016 PMCID: PMC4752600 DOI: 10.1128/mbio.01872-15] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Most of the intracellular pattern recognition receptors (PRRs) reside in either the endolysosome or the cytoplasm to sense pathogen-derived RNAs, DNAs, or synthetic analogs of double-stranded RNA (dsRNA), such as poly(I:C). However, it remains elusive whether or not a pathogen-derived protein can function as a cytosolic pathogen-associated molecular pattern (PAMP). In this study, we demonstrate that delivering the membrane gene of severe acute respiratory syndrome coronavirus (SARS-CoV) into HEK293T, HEK293ET, and immobilized murine bone marrow-derived macrophage (J2-Mφ) cells significantly upregulates beta interferon (IFN-β) production. Both NF-κB and TBK1-IRF3 signaling cascades are activated by M gene products. M protein rather than M mRNA is responsible for M-mediated IFN-β induction that is preferentially associated with the activation of the Toll-like receptor (TLR) adaptor proteins MyD88, TIRAP, and TICAM2 but not the RIG-I signaling cascade. Blocking the secretion of M protein by brefeldin A (BFA) failed to reverse the M-mediated IFN-β induction. The antagonist of both TLR2 and TLR4 did not impede M-mediated IFN-β induction, indicating that the driving force for the activation of IFN-β production was generated from inside the cells. Inhibition of TRAF3 expression by specific small interfering RNA (siRNA) did not prevent M-mediated IFN-β induction. SARS-CoV pseudovirus could induce IFN-β production in an M rather than M(V68A) dependent manner, since the valine-to-alanine alteration at residue 68 in M protein markedly inhibited IFN-β production. Overall, our study indicates for the first time that a pathogen-derived protein is able to function as a cytosolic PAMP to stimulate type I interferon production by activating a noncanonical TLR signaling cascade in a TRAF3-independent manner. Viral protein can serve as a pathogen-associated molecular pattern (PAMP) that is usually recognized by certain pathogen recognition receptors (PRRs) on the cell surface, such as Toll-like receptor 2 (TLR2) and TLR4. In this study, we demonstrate that the membrane (M) protein of SARS-CoV can directly promote the activation of both beta interferon (IFN-β) and NF-κB through a TLR-related signaling pathway independent of TRAF3. The driving force for M-mediated IFN-β production is most likely generated from inside the cells. M-mediated IFN-β induction was confirmed at the viral infection level since a point mutation at the V68 residue of M markedly inhibited SARS-CoV pseudovirally induced IFN-β production. Thus, the results indicate for the first time that SARS-CoV M protein may function as a cytosolic PAMP to stimulate IFN-β production by activating a TLR-related TRAF3-independent signaling cascade.
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Abstract
Viruses have evolved numerous mechanisms to evade the immune response, including proteins that target the function of cytokines. This article provides an overview of the different strategies used by viruses to block the induction of cytokines and immune signals triggered by cytokines. Examples of virus evasion proteins are presented, such as intracellular proteins that block signal transduction and immune activation mechanisms, secreted proteins that mimic cytokines, or viral decoy receptors that inhibit the binding of cytokines to their cognate receptors. Virus-encoded proteins that target cytokines play a major role in immune modulation, and their contributions to viral pathogenesis, promoting virus replication or preventing immunopathology, are discussed.
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Strnadova P, Ren H, Valentine R, Mazzon M, Sweeney TR, Brierley I, Smith GL. Inhibition of Translation Initiation by Protein 169: A Vaccinia Virus Strategy to Suppress Innate and Adaptive Immunity and Alter Virus Virulence. PLoS Pathog 2015; 11:e1005151. [PMID: 26334635 PMCID: PMC4559412 DOI: 10.1371/journal.ppat.1005151] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 08/13/2015] [Indexed: 12/19/2022] Open
Abstract
Vaccinia virus (VACV) is the prototypic orthopoxvirus and the vaccine used to eradicate smallpox. Here we show that VACV strain Western Reserve protein 169 is a cytoplasmic polypeptide expressed early during infection that is excluded from virus factories and inhibits the initiation of cap-dependent and cap-independent translation. Ectopic expression of protein 169 causes the accumulation of 80S ribosomes, a reduction of polysomes, and inhibition of protein expression deriving from activation of multiple innate immune signaling pathways. A virus lacking 169 (vΔ169) replicates and spreads normally in cell culture but is more virulent than parental and revertant control viruses in intranasal and intradermal murine models of infection. Intranasal infection by vΔ169 caused increased pro-inflammatory cytokines and chemokines, infiltration of pulmonary leukocytes, and lung weight. These alterations in innate immunity resulted in a stronger CD8+ T-cell memory response and better protection against virus challenge. This work illustrates how inhibition of host protein synthesis can be a strategy for virus suppression of innate and adaptive immunity. Long after smallpox was eradicated by vaccination with vaccinia virus, the study of this virus continues to reveal novel aspects of the interactions between a virus and the host in which it replicates. In this work we investigated the function of a previously uncharacterized VACV protein, called 169. The results show that protein 169 inhibits the synthesis of host proteins in cells and thereby provides a broad inhibition of the host innate immune response to infection. Unlike several other virus inhibitors of host protein synthesis, protein 169 acts by inhibiting the initiation of protein synthesis by both cap-dependent and cap-independent pathways. Also unlike several other virus protein synthesis inhibitors, the loss of protein 169 does not affect virus replication or spread, but the virus virulence was increased. This more severe infection is, however, cleared more rapidly and results in a stronger immunological memory response that is mediated by T-cells and provides better protection against re-infection. This work illustrates how shutting down host protein synthesis can be a strategy to block the host immune response to infection rather than a means to manufacture more virus particles.
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Affiliation(s)
- Pavla Strnadova
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Hongwei Ren
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Robert Valentine
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Michela Mazzon
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Trevor R. Sweeney
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Ian Brierley
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Geoffrey L. Smith
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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Connolly M, Rooney PR, McGarry T, Maratha AX, McCormick J, Miggin SM, Veale DJ, Fearon U. Acute serum amyloid A is an endogenous TLR2 ligand that mediates inflammatory and angiogenic mechanisms. Ann Rheum Dis 2015; 75:1392-8. [PMID: 26290589 DOI: 10.1136/annrheumdis-2015-207655] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 08/01/2015] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Acute-phase serum amyloid A (A-SAA) has cytokine-like properties and is expressed at sites of inflammation. We examined whether A-SAA-induced pro-inflammatory mechanisms are mediated through Toll-like receptor 2 (TLR2) in rheumatoid arthritis (RA). METHODS The effect of A-SAA on human embryonic kidney (HEK), TLR2 or TLR4 cells was quantified by nuclear factor (NF)-κB luciferase reporter assays. A-SAA-induced RASFC and dHMVEC function were performed in the presence of a specific neutralising anti-TLR2 mAb (OPN301) (1 μg/mL) and matched IgG isotype control Ab (1 μg/mL). Cell surface expression of intracellular adhesion molecule (ICAM)-1, chemokine expression, cell migration, invasion and angiogenesis were assessed by flow cytometry, ELISA, Matrigel invasion chambers and tube formation assays. MyD88 expression was assessed by real-time PCR and western blot. RESULTS A-SAA induced TLR2 activation through induction of NF-κB (p<0.05), but failed to induce NF-κB in HEK-TLR4 cells, confirming specificity for TLR2. A-SAA-induced proliferation, invasion and migration were significantly inhibited in the presence of anti-TLR2 (all p<0.05), with no significant effect observed for tumour necrosis factor-α-induced events. Additionally, A-SAA-induced ICAM-1, interleukin-8, monocyte chemoattractant protein-1, RANTES and GRO-α expression were significantly reduced in the presence of anti-TLR2 (all p<0.05), as was A-SAA induced angiogenesis (p<0.05). Finally, A-SAA induced MyD88 signalling in RASFC and dHMVEC (p<0.05). CONCLUSIONS A-SAA is an endogenous ligand for TLR2, inducing pro-inflammatory effects in RA. Blocking the A-SAA/TLR2 interaction may be a potential therapeutic intervention in RA.
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Affiliation(s)
- Mary Connolly
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
| | - Peter R Rooney
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
| | - Trudy McGarry
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
| | - Ashwini X Maratha
- Department of Biology, Institute of Immunology, National University of Ireland Maynooth, Maynooth, County Kildare, Ireland
| | - Jennifer McCormick
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
| | - Sinead M Miggin
- Department of Biology, Institute of Immunology, National University of Ireland Maynooth, Maynooth, County Kildare, Ireland
| | - Douglas J Veale
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
| | - Ursula Fearon
- Centre for Arthritis and Rheumatic Diseases, Dublin Academic Medical Centre and Conway Institute of Biomolecular and Biomedical Research, Dublin 4, Ireland
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Neidel S, Maluquer de Motes C, Mansur DS, Strnadova P, Smith GL, Graham SC. Vaccinia virus protein A49 is an unexpected member of the B-cell Lymphoma (Bcl)-2 protein family. J Biol Chem 2015; 290:5991-6002. [PMID: 25605733 PMCID: PMC4358236 DOI: 10.1074/jbc.m114.624650] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/11/2015] [Indexed: 12/18/2022] Open
Abstract
Vaccinia virus (VACV) encodes several proteins that inhibit activation of the proinflammatory transcription factor nuclear factor κB (NF-κB). VACV protein A49 prevents translocation of NF-κB to the nucleus by sequestering cellular β-TrCP, a protein required for the degradation of the inhibitor of κB. A49 does not share overall sequence similarity with any protein of known structure or function. We solved the crystal structure of A49 from VACV Western Reserve to 1.8 Å resolution and showed, surprisingly, that A49 has the same three-dimensional fold as Bcl-2 family proteins despite lacking identifiable sequence similarity. Whereas Bcl-2 family members characteristically modulate cellular apoptosis, A49 lacks a surface groove suitable for binding BH3 peptides and does not bind proapoptotic Bcl-2 family proteins Bax or Bak. The N-terminal 17 residues of A49 do not adopt a single well ordered conformation, consistent with their proposed role in binding β-TrCP. Whereas pairs of A49 molecules interact symmetrically via a large hydrophobic surface in crystallo, A49 does not dimerize in solution or in cells, and we propose that this hydrophobic interaction surface may mediate binding to a yet undefined cellular partner. A49 represents the eleventh VACV Bcl-2 family protein and, despite these proteins sharing very low sequence identity, structure-based phylogenetic analysis shows that all poxvirus Bcl-2 proteins are structurally more similar to each other than they are to any cellular or herpesvirus Bcl-2 proteins. This is consistent with duplication and diversification of a single BCL2 family gene acquired by an ancestral poxvirus.
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Affiliation(s)
- Sarah Neidel
- From the Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom and
| | - Carlos Maluquer de Motes
- From the Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom and
| | - Daniel S Mansur
- the Department of Microbiology, Immunology, and Parasitology, Universidade Federal de Santa Catarina, Florianopolis, 88040-900 Brazil
| | - Pavla Strnadova
- From the Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom and
| | - Geoffrey L Smith
- From the Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom and
| | - Stephen C Graham
- From the Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom and
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NFκB activation by modified vaccinia virus as a novel strategy to enhance neutrophil migration and HIV-specific T-cell responses. Proc Natl Acad Sci U S A 2015; 112:E1333-42. [PMID: 25739961 DOI: 10.1073/pnas.1424341112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Neutrophils are antigen-transporting cells that generate vaccinia virus (VACV)-specific T-cell responses, yet how VACV modulates neutrophil recruitment and its significance in the immune response are unknown. We generated an attenuated VACV strain that expresses HIV-1 clade C antigens but lacks three specific viral genes (A52R, K7R, and B15R). We found that these genes act together to inhibit the NFκB signaling pathway. Triple ablation in modified virus restored NFκB function in macrophages. After virus infection of mice, NFκB pathway activation led to expression of several cytokines/chemokines that increased the migration of neutrophil populations (Nα and Nβ) to the infection site. Nβ cells displayed features of antigen-presenting cells and activated virus-specific CD8 T cells. Enhanced neutrophil trafficking to the infection site correlated with an increased T-cell response to HIV vector-delivered antigens. These results identify a mechanism for poxvirus-induced immune response and alternatives for vaccine vector design.
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Rosadini CV, Kagan JC. Microbial strategies for antagonizing Toll-like-receptor signal transduction. Curr Opin Immunol 2015; 32:61-70. [PMID: 25615700 PMCID: PMC4336813 DOI: 10.1016/j.coi.2014.12.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/24/2014] [Accepted: 12/30/2014] [Indexed: 12/18/2022]
Abstract
Within a few years of the discovery of Toll-like receptors (TLRs) and their role in innate immunity, viral and bacterial proteins were recognized to antagonize TLR signal transduction. Since then, as TLR signaling networks were unraveled, microbial systems have been discovered that target nearly every component within these pathways. However, recent findings as well as some notable exceptions promote the idea that more of these systems have yet to be discovered. For example, we know very little about microbial systems for directly targeting non-cytoplasmic portions of TLR signaling pathways, that is, the ligand interacting portions of the receptor itself. In this review, we compare and contrast strategies by which bacteria and viruses antagonize TLR signaling networks to identify potential areas for future research.
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Affiliation(s)
- Charles V Rosadini
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jonathan C Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115, USA.
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Interferon induction by RNA viruses and antagonism by viral pathogens. Viruses 2014; 6:4999-5027. [PMID: 25514371 PMCID: PMC4276940 DOI: 10.3390/v6124999] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/04/2014] [Accepted: 12/04/2014] [Indexed: 12/22/2022] Open
Abstract
Interferons are a group of small proteins that play key roles in host antiviral innate immunity. Their induction mainly relies on host pattern recognition receptors (PRR). Host PRR for RNA viruses include Toll-like receptors (TLR) and retinoic acid-inducible gene I (RIG-I) like receptors (RLR). Activation of both TLR and RLR pathways can eventually lead to the secretion of type I IFNs, which can modulate both innate and adaptive immune responses against viral pathogens. Because of the important roles of interferons, viruses have evolved multiple strategies to evade host TLR and RLR mediated signaling. This review focuses on the mechanisms of interferon induction and antagonism of the antiviral strategy by RNA viruses.
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Stack J, Doyle SL, Connolly DJ, Reinert LS, O'Keeffe KM, McLoughlin RM, Paludan SR, Bowie AG. TRAM is required for TLR2 endosomal signaling to type I IFN induction. THE JOURNAL OF IMMUNOLOGY 2014; 193:6090-102. [PMID: 25385819 DOI: 10.4049/jimmunol.1401605] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Detection of microbes by TLRs on the plasma membrane leads to the induction of proinflammatory cytokines such as TNF-α, via activation of NF-κB. Alternatively, activation of endosomal TLRs leads to the induction of type I IFNs via IFN regulatory factors (IRFs). TLR4 signaling from the plasma membrane to NF-κB via the Toll/IL-1R (TIR) adaptor protein MyD88 requires the TIR sorting adaptor Mal, whereas endosomal TLR4 signaling to IRF3 via the TIR domain-containing adaptor-inducing IFN-β (TRIF) requires the TRIF-related adaptor molecule (TRAM). Similar to TLR4 homodimers, TLR2 heterodimers can also induce both proinflammatory cytokines and type I IFNs. TLR2 plasma membrane signaling to NF-κB is known to require MyD88 and Mal, whereas endosomal IRF activation by TLR2 requires MyD88. However, it was unclear whether TLR2 requires a sorting adaptor for endosomal signaling, like TLR4 does. In this study, we show that TLR2-dependent IRF7 activation at the endosome is both Mal- and TRAM-dependent, and that TRAM is required for the TLR2-dependent movement of MyD88 to endosomes following ligand engagement. TRAM interacted with both TLR2 and MyD88, suggesting that TRAM can act as a bridging adapter between these two molecules. Furthermore, infection of macrophages lacking TRAM with herpes viruses or the bacterium Staphylococcus aureus led to impaired induction of type I IFN, indicating a role for TRAM in TLR2-dependent responses to human pathogens. Our work reveals that TRAM acts as a sorting adaptor not only for TLR4, but also for TLR2, to facilitate signaling to IRF7 at the endosome, which explains how TLR2 is capable of causing type I IFN induction.
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Affiliation(s)
- Julianne Stack
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Sarah L Doyle
- School of Medicine, Trinity College Dublin, Dublin 2, Ireland; The National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland; and
| | - Dympna J Connolly
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Line S Reinert
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Kate M O'Keeffe
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Rachel M McLoughlin
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Søren R Paludan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Andrew G Bowie
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland;
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Ectromelia virus encodes a family of Ankyrin/F-box proteins that regulate NFκB. Virology 2014; 468-470:351-362. [DOI: 10.1016/j.virol.2014.08.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 08/17/2014] [Accepted: 08/29/2014] [Indexed: 12/18/2022]
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Siciliano NA, Hersperger AR, Lacuanan AM, Xu RH, Sidney J, Sette A, Sigal LJ, Eisenlohr LC. Impact of distinct poxvirus infections on the specificities and functionalities of CD4+ T cell responses. J Virol 2014; 88:10078-91. [PMID: 24965457 PMCID: PMC4136331 DOI: 10.1128/jvi.01150-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/13/2014] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The factors that determine CD4+ T cell (TCD4+) specificities, functional capacity, and memory persistence in response to complex pathogens remain unclear. We explored these parameters in the C57BL/6 mouse through comparison of two highly related (>92% homology) poxviruses: ectromelia virus (ECTV), a natural mouse pathogen, and vaccinia virus (VACV), a heterologous virus that nevertheless elicits potent immune responses. In addition to elucidating several previously unidentified major histocompatibility complex class II (MHC-II)-restricted epitopes, we observed many qualitative and quantitative differences between the TCD4+ repertoires, including responses not elicited by VACV despite complete sequence conservation. In addition, we observed functional heterogeneity between ECTV- and VACV-specific TCD4+ at both a global and individual epitope level, particularly greater expression of the cytolytic marker CD107a from TCD4+ following ECTV infection. Most striking were differences during the late memory phase where, in contrast to ECTV, VACV infection failed to elicit measurable epitope-specific TCD4+ as determined by intracellular cytokine staining. These findings illustrate the strong influence of epitope-extrinsic factors on TCD4+ responses and memory. IMPORTANCE Much of our understanding concerning host-pathogen relationships in the context of poxvirus infections stems from studies of VACV in mice. However, VACV is not a natural mouse pathogen, and therefore, the relevance of results obtained using this model may be limited. Here, we explored the MHC class II-restricted TCD4+ repertoire induced by mousepox (ECTV) infection and the functional profile of the responding epitope-specific TCD4+, comparing these results to those induced by VACV infection under matched conditions. Despite a high degree of homology between the two viruses, we observed distinct specificity and functional profiles of TCD4+ responses at both acute and memory time points, with VACV-specific TCD4+ memory being notably compromised. These data offer insight into the impact of epitope-extrinsic factors on the resulting TCD4+ responses.
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Affiliation(s)
- Nicholas A Siciliano
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Adam R Hersperger
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA Department of Biology, Albright College, Reading, Pennsylvania, USA
| | - Aimee M Lacuanan
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Ren-Huan Xu
- Fox Chase Cancer Center, Immune Cell Development and Host Defense Program, Philadelphia, Pennsylvania, USA
| | - John Sidney
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California, USA
| | - Luis J Sigal
- Fox Chase Cancer Center, Immune Cell Development and Host Defense Program, Philadelphia, Pennsylvania, USA
| | - Laurence C Eisenlohr
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Patel MC, Shirey KA, Pletneva LM, Boukhvalova MS, Garzino-Demo A, Vogel SN, Blanco JC. Novel drugs targeting Toll-like receptors for antiviral therapy. Future Virol 2014; 9:811-829. [PMID: 25620999 DOI: 10.2217/fvl.14.70] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Toll-like receptors (TLRs) are sentinel receptors of the host innate immune system that recognize conserved 'pathogen-associated molecular patterns' of invading microbes, including viruses. The activation of TLRs establishes antiviral innate immune responses and coordinates the development of long-lasting adaptive immunity in order to control viral pathogenesis. However, microbe-induced damage to host tissues may release 'danger-associated molecular patterns' that also activate TLRs, leading to an overexuberant inflammatory response and, ultimately, to tissue damage. Thus, TLRs have proven to be promising targets as therapeutics for the treatment of viral infections that result in inflammatory damage or as adjuvants in order to enhance the efficacy of vaccines. Here, we explore recent advances in TLR biology with a focus on novel drugs that target TLRs (agonists and antagonists) for antiviral therapy.
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Affiliation(s)
- Mira C Patel
- Department of Microbiology & Immunology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA
| | - Kari Ann Shirey
- Department of Microbiology & Immunology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA
| | | | | | - Alfredo Garzino-Demo
- Department of Microbiology & Immunology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA ; Institute of Human Virology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA
| | - Stefanie N Vogel
- Department of Microbiology & Immunology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA
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Zeng X, Chi X, Li W, Hao W, Li M, Huang X, Huang Y, Rock DL, Luo S, Wang S. Complete genome sequence analysis of goatpox virus isolated from China shows high variation. Vet Microbiol 2014; 173:38-49. [DOI: 10.1016/j.vetmic.2014.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/07/2014] [Accepted: 07/13/2014] [Indexed: 10/25/2022]
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EVM005: an ectromelia-encoded protein with dual roles in NF-κB inhibition and virulence. PLoS Pathog 2014; 10:e1004326. [PMID: 25122471 PMCID: PMC4133408 DOI: 10.1371/journal.ppat.1004326] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/07/2014] [Indexed: 11/19/2022] Open
Abstract
Poxviruses contain large dsDNA genomes encoding numerous open reading frames that manipulate cellular signalling pathways and interfere with the host immune response. The NF-κB signalling cascade is an important mediator of innate immunity and inflammation, and is tightly regulated by ubiquitination at several key points. A critical step in NF-κB activation is the ubiquitination and degradation of the inhibitor of kappaB (IκBα), by the cellular SCFβ-TRCP ubiquitin ligase complex. We show here that upon stimulation with TNFα or IL-1β, Orthopoxvirus-infected cells displayed an accumulation of phosphorylated IκBα, indicating that NF-κB activation was inhibited during poxvirus infection. Ectromelia virus is the causative agent of lethal mousepox, a natural disease that is fatal in mice. Previously, we identified a family of four ectromelia virus genes (EVM002, EVM005, EVM154 and EVM165) that contain N-terminal ankyrin repeats and C-terminal F-box domains that interact with the cellular SCF ubiquitin ligase complex. Since degradation of IκBα is catalyzed by the SCFβ-TRCP ubiquitin ligase, we investigated the role of the ectromelia virus ankyrin/F-box protein, EVM005, in the regulation of NF-κB. Expression of Flag-EVM005 inhibited both TNFα- and IL-1β-stimulated IκBα degradation and p65 nuclear translocation. Inhibition of the NF-κB pathway by EVM005 was dependent on the F-box domain, and interaction with the SCF complex. Additionally, ectromelia virus devoid of EVM005 was shown to inhibit NF-κB activation, despite lacking the EVM005 open reading frame. Finally, ectromelia virus devoid of EVM005 was attenuated in both A/NCR and C57BL/6 mouse models, indicating that EVM005 is required for virulence and immune regulation in vivo. Poxviruses are large dsDNA viruses that are renowned for regulating cellular pathways and manipulating the host immune response, including the NF-κB pathway. NF-κB inhibition by poxviruses is a growing area of interest and this family of viruses has developed multiple mechanisms to manipulate the pathway. Here, we focus on regulation of the NF-κB pathway by ectromelia virus, the causative agent of mousepox. We demonstrate that ectromelia virus is a potent inhibitor of the NF-κB pathway. Previously, we identified a family of four ectromelia virus genes that contain N-terminal ankyrin repeats and a C-terminal F-box domain that interacts with the cellular SCF ubiquitin ligase. Significantly, expression of the ankyrin/F-box protein, EVM005, inhibited NF-κB, and the F-box domain was critical for NF-κB inhibition and interaction with the SCF complex. Ectromelia virus devoid of EVM005 still inhibited NF-κB, indicating that multiple gene products contribute to NF-κB inhibition. Importantly, mice infected with ectromelia virus lacking EVM005 had a robust immune response, leading to viral clearance during infection. The data present two mechanisms, one in which EVM005 inhibits NF-κB activation through manipulation of the host SCF ubiquitin ligase complex, and an additional, NF-κB-independent mechanism that drives virulence.
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79
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Brady G, Bowie AG. Innate immune activation of NFκB and its antagonism by poxviruses. Cytokine Growth Factor Rev 2014; 25:611-20. [PMID: 25081317 DOI: 10.1016/j.cytogfr.2014.07.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/03/2014] [Indexed: 12/18/2022]
Abstract
In recent years there has been an acceleration of discovery in the field of innate anti-viral immunity to the point that many of the key events in early virus sensing and the discrete anti-viral responses they trigger have been elucidated in detail. In particular, pattern recognition receptors (PRRs) that detect viruses at the plasma membrane, in endosomes, and within the cytosol have been characterized. Upon stimulation by viruses, most of these PRRs trigger signal transduction pathways culminating in NFκB activation. NFκB contributes both to type I interferon induction, and to production of pro-inflammatory cytokines from infected cells. Our understanding of host anti-viral innate immunity has been greatly aided by an appreciation of the ways in which poxviruses have evolved strategies to inhibit both innate sensing and effector responses. A recurring feature of poxviral immunomodulation is the apparent necessity for poxviruses to evolve multiple, non-redundant inhibitors of NFκB activation which often appear to act on the same innate signalling pathway. The reason for such apparent over-targeting of one transcription factor is not clear. Here we describe the current understanding of how host cells sense poxvirus infection to trigger signalling pathways leading to NFκB activation and pro-inflammatory cytokine induction, and the ways in which poxviruses have evolved to concisely antagonize these systems.
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Affiliation(s)
- Gareth Brady
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
| | - Andrew G Bowie
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
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Mavian C, López-Bueno A, Bryant NA, Seeger K, Quail MA, Harris D, Barrell B, Alcami A. The genome sequence of ectromelia virus Naval and Cornell isolates from outbreaks in North America. Virology 2014; 462-463:218-26. [PMID: 24999046 PMCID: PMC4139192 DOI: 10.1016/j.virol.2014.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 04/11/2014] [Accepted: 06/10/2014] [Indexed: 01/01/2023]
Abstract
Ectromelia virus (ECTV) is the causative agent of mousepox, a disease of laboratory mouse colonies and an excellent model for human smallpox. We report the genome sequence of two isolates from outbreaks in laboratory mouse colonies in the USA in 1995 and 1999: ECTV-Naval and ECTV-Cornell, respectively. The genome of ECTV-Naval and ECTV-Cornell was sequenced by the 454-Roche technology. The ECTV-Naval genome was also sequenced by the Sanger and Illumina technologies in order to evaluate these technologies for poxvirus genome sequencing. Genomic comparisons revealed that ECTV-Naval and ECTV-Cornell correspond to the same virus isolated from independent outbreaks. Both ECTV-Naval and ECTV-Cornell are extremely virulent in susceptible BALB/c mice, similar to ECTV-Moscow. This is consistent with the ECTV-Naval genome sharing 98.2% DNA sequence identity with that of ECTV-Moscow, and indicates that the genetic differences with ECTV-Moscow do not affect the virulence of ECTV-Naval in the mousepox model of footpad infection. We describe the genome sequence of two highly virulent ectromelia virus isolates. The outbreak of ectromelia virus in USA was caused by Chinese viral isolates. We describe a clade of ectromelia virus isolates from China. We compare three different sequencing technologies to sequence large DNA viruses.
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Affiliation(s)
- Carla Mavian
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Nicolas Cabrera 1, Campus de Cantoblanco, Madrid, Spain
| | - Alberto López-Bueno
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Nicolas Cabrera 1, Campus de Cantoblanco, Madrid, Spain
| | - Neil A Bryant
- Department of Medicine, University of Cambridge, United Kingdom
| | - Kathy Seeger
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, United Kingdom
| | - Michael A Quail
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, United Kingdom
| | - David Harris
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, United Kingdom
| | - Bart Barrell
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, United Kingdom
| | - Antonio Alcami
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Nicolas Cabrera 1, Campus de Cantoblanco, Madrid, Spain; Department of Medicine, University of Cambridge, United Kingdom.
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81
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A loss of function analysis of host factors influencing Vaccinia virus replication by RNA interference. PLoS One 2014; 9:e98431. [PMID: 24901222 PMCID: PMC4047015 DOI: 10.1371/journal.pone.0098431] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/23/2014] [Indexed: 02/08/2023] Open
Abstract
Vaccinia virus (VACV) is a large, cytoplasmic, double-stranded DNA virus that requires complex interactions with host proteins in order to replicate. To explore these interactions a functional high throughput small interfering RNA (siRNA) screen targeting 6719 druggable cellular genes was undertaken to identify host factors (HF) influencing the replication and spread of an eGFP-tagged VACV. The experimental design incorporated a low multiplicity of infection, thereby enhancing detection of cellular proteins involved in cell-to-cell spread of VACV. The screen revealed 153 pro- and 149 anti-viral HFs that strongly influenced VACV replication. These HFs were investigated further by comparisons with transcriptional profiling data sets and HFs identified in RNAi screens of other viruses. In addition, functional and pathway analysis of the entire screen was carried out to highlight cellular mechanisms involved in VACV replication. This revealed, as anticipated, that many pro-viral HFs are involved in translation of mRNA and, unexpectedly, suggested that a range of proteins involved in cellular transcriptional processes and several DNA repair pathways possess anti-viral activity. Multiple components of the AMPK complex were found to act as pro-viral HFs, while several septins, a group of highly conserved GTP binding proteins with a role in sequestering intracellular bacteria, were identified as strong anti-viral VACV HFs. This screen has identified novel and previously unexplored roles for cellular factors in poxvirus replication. This advancement in our understanding of the VACV life cycle provides a reliable knowledge base for the improvement of poxvirus-based vaccine vectors and development of anti-viral theraputics.
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82
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Downregulation of interleukin-18-mediated cell signaling and interferon gamma expression by the hepatitis B virus e antigen. J Virol 2014; 88:10412-20. [PMID: 24872585 DOI: 10.1128/jvi.00111-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED The mechanisms by which hepatitis B virus (HBV) establishes and maintains chronic hepatitis B infection (CHB) are poorly defined. Innate immune responses play an important role in reducing HBV replication and pathogenesis. HBV has developed numerous mechanisms to escape these responses, including the production of the secreted hepatitis B e antigen (HBeAg), which has been shown to regulate antiviral toll-like receptor (TLR) and interleukin-1 (IL-1) signaling. IL-18 is a related cytokine that inhibits HBV replication in hepatoma cell lines and in the liver through the induction of gamma interferon (IFN-γ) by NK cells and T cells. We hypothesized that HBV or HBV proteins inhibit IFN-γ expression by NK cells as an accessory immunomodulatory function. We show that HBeAg protein inhibits the NF-κB pathway and thereby downregulates NK cell IFN-γ expression. Additionally, IFN-γ expression was significantly inhibited by exposure to serum from individuals with HBeAg-positive but not HBeAg-negative chronic HBV infection. Further, we show that the HBeAg protein suppresses IL-18-mediated NF-κB signaling in NK and hepatoma cells via modulation of the NF-κB pathway. Together, these findings show that the HBeAg inhibits IL-18 signaling and IFN-γ expression, which may play an important role in the establishment and/or maintenance of persistent HBV infection. IMPORTANCE It is becoming increasingly apparent that NK cells play a role in the establishment and/or maintenance of chronic hepatitis B infection. The secreted HBeAg is an important regulator of innate and adaptive immune responses. We now show that the HBeAg downregulates NK cell-mediated IFN-γ production and IL-18 signaling, which may contribute to the establishment of infection and/or viral persistence. Our findings build on previous studies showing that the HBeAg also suppresses the TLR and IL-1 signaling pathways, suggesting that this viral protein is a key regulator of antiviral innate immune responses.
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83
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Kim Y, Lee H, Heo L, Seok C, Choe J. Structure of vaccinia virus A46, an inhibitor of TLR4 signaling pathway, shows the conformation of VIPER motif. Protein Sci 2014; 23:906-14. [PMID: 24723367 DOI: 10.1002/pro.2472] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 01/05/2023]
Abstract
Vaccinia virus (VACV) encodes many proteins that interfere with the host immune system. Vaccinia virus A46 protein specifically targets the BB-loop motif of TIR-domain-containing proteins to disrupt receptor:adaptor (e.g., TLR4:MAL and TLR4:TRAM) interactions of the toll-like receptor signaling. The crystal structure of A46 (75-227) determined at 2.58 Å resolution showed that A46 formed a homodimer and adopted a Bcl-2-like fold similar to other VACV proteins such as A52, B14, and K7. Our structure also revealed that VIPER (viral inhibitory peptide of TLR4) motif resides in the α1-helix and six residues of the VIPER region were exposed to surface for binding to target proteins. In vitro binding assays between wild type and six mutants A46 (75-227) and full-length MAL identified critical residues in the VIPER motif. Computational modeling of the A46:MAL complex structure showed that the VIPER region of A46 and AB loop of MAL protein formed a major binding interface. In summary, A46 is a homodimer with a Bcl-2-like fold and VIPER motif is believed to be involved in the interaction with MAL protein based on our binding assays.
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Affiliation(s)
- Yongwoon Kim
- Department of Life Sciences, University of Seoul, Seoul, 130-743, Republic of Korea
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84
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Dai P, Wang W, Cao H, Avogadri F, Dai L, Drexler I, Joyce JA, Li XD, Chen Z, Merghoub T, Shuman S, Deng L. Modified vaccinia virus Ankara triggers type I IFN production in murine conventional dendritic cells via a cGAS/STING-mediated cytosolic DNA-sensing pathway. PLoS Pathog 2014; 10:e1003989. [PMID: 24743339 PMCID: PMC3990710 DOI: 10.1371/journal.ppat.1003989] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 01/26/2014] [Indexed: 11/23/2022] Open
Abstract
Modified vaccinia virus Ankara (MVA) is an attenuated poxvirus that has been engineered as a vaccine against infectious agents and cancers. Our goal is to understand how MVA modulates innate immunity in dendritic cells (DCs), which can provide insights to vaccine design. In this study, using murine bone marrow-derived dendritic cells, we assessed type I interferon (IFN) gene induction and protein secretion in response to MVA infection. We report that MVA infection elicits the production of type I IFN in murine conventional dendritic cells (cDCs), but not in plasmacytoid dendritic cells (pDCs). Transcription factors IRF3 (IFN regulatory factor 3) and IRF7, and the positive feedback loop mediated by IFNAR1 (IFN alpha/beta receptor 1), are required for the induction. MVA induction of type I IFN is fully dependent on STING (stimulator of IFN genes) and the newly discovered cytosolic DNA sensor cGAS (cyclic guanosine monophosphate-adenosine monophosphate synthase). MVA infection of cDCs triggers phosphorylation of TBK1 (Tank-binding kinase 1) and IRF3, which is abolished in the absence of cGAS and STING. Furthermore, intravenous delivery of MVA induces type I IFN in wild-type mice, but not in mice lacking STING or IRF3. Treatment of cDCs with inhibitors of endosomal and lysosomal acidification or the lysosomal enzyme Cathepsin B attenuated MVA-induced type I IFN production, indicating that lysosomal enzymatic processing of virions is important for MVA sensing. Taken together, our results demonstrate a critical role of the cGAS/STING-mediated cytosolic DNA-sensing pathway for type I IFN induction in cDCs by MVA. We present evidence that vaccinia virulence factors E3 and N1 inhibit the activation of IRF3 and the induction of IFNB gene in MVA-infected cDCs.
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Affiliation(s)
- Peihong Dai
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Weiyi Wang
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Hua Cao
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Francesca Avogadri
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Lianpan Dai
- Institute for Virology, Düsseldorf University Hospital, Heinrich-Heine-University, Düsseldorf, Germany
| | - Ingo Drexler
- Institute for Virology, Düsseldorf University Hospital, Heinrich-Heine-University, Düsseldorf, Germany
| | - Johanna A. Joyce
- Cancer Biology & Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Xiao-Dong Li
- Department of Molecular Biology, University of Texas, Southwestern Medical Center, Dallas, Texas, United States of America
| | - Zhijian Chen
- Department of Molecular Biology, University of Texas, Southwestern Medical Center, Dallas, Texas, United States of America
| | - Taha Merghoub
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Liang Deng
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
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85
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Ectromelia virus encodes a BTB/kelch protein, EVM150, that inhibits NF-κB signaling. J Virol 2014; 88:4853-65. [PMID: 24522926 DOI: 10.1128/jvi.02923-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED The NF-κB signaling pathway plays a critical role in inflammation and innate immunity. Consequently, many viruses have evolved strategies to inhibit NF-κB in order to facilitate replication and evasion of the host immune response. Recently, we determined that ectromelia virus, the causative agent of mousepox, contains a family of four BTB/kelch proteins that interact with cullin-3-based ubiquitin ligases. We demonstrate here that expression of EVM150, one of the four BTB/kelch proteins, inhibited NF-κB activation induced by tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β). Although EVM150 inhibited NF-κB p65 nuclear translocation, IκBα degradation was observed, indicating that EVM150 functioned downstream of IκBα degradation. Significantly, expression of the BTB-only domain of EVM150 blocked NF-κB activation, demonstrating that EVM150 functioned independently of the kelch domain and its role as an adapter for cullin-3-based ubiquitin ligases. Furthermore, cullin-3 knockdown by small interfering RNA demonstrated that cullin-3-based ubiquitin ligases are dispensable for TNF-α-induced NF-κB activation. Interestingly, nuclear translocation of IRF3 and STAT1 still occurred in the presence of EVM150, indicating that EVM150 prevented NF-κB nuclear translocation specifically. In addition to identifying EVM150 as an inhibitor of the NF-κB pathway, this study provides new insights into the role of BTB/kelch proteins during virus infection. IMPORTANCE With the exception of virulence studies, little work has been done to determine the role of poxviral BTB/kelch proteins during infection. This study, for the first time, has identified a mechanism for the ectromelia virus BTB/kelch protein EVM150. Here, we show that EVM150 is a novel inhibitor of the cellular NF-κB pathway, an important component of the antiviral response. This study adds EVM150 to the growing list of NF-κB inhibitors in poxviruses and provides new insights into the role of BTB/kelch proteins during virus infection.
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86
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Fedosyuk S, Grishkovskaya I, de Almeida Ribeiro E, Skern T. Characterization and structure of the vaccinia virus NF-κB antagonist A46. J Biol Chem 2014; 289:3749-62. [PMID: 24356965 PMCID: PMC3916572 DOI: 10.1074/jbc.m113.512756] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 12/14/2013] [Indexed: 01/07/2023] Open
Abstract
Successful vaccinia virus (VACV) replication in the host requires expression of viral proteins that interfere with host immunity, such as antagonists of the activation of the proinflammatory transcription factor NF-κB. Two such VACV proteins are A46 and A52. A46 interacts with the Toll-like receptor/interleukin-1R (TIR) domain of Toll-like receptors and intracellular adaptors such as MAL (MyD88 adapter-like), TRAM (TIR domain-containing adapter-inducing interferon-β (TRIF)-related adaptor molecule), TRIF, and MyD88, whereas A52 binds to the downstream signaling components TRAF6 and IRAK2. Here, we characterize A46 biochemically, determine by microscale thermophoresis binding constants for the interaction of A46 with the TIR domains of MyD88 and MAL, and present the 2.0 Å resolution crystal structure of A46 residues 87-229. Full-length A46 behaves as a tetramer; variants lacking the N-terminal 80 residues are dimeric. Nevertheless, both bind to the Toll-like receptor domains of MAL and MyD88 with KD values in the low μm range. Like A52, A46 also shows a Bcl-2-like fold but with biologically relevant differences from that of A52. Thus, A46 uses helices α4 and α6 to dimerize, compared with the α1-α6 face used by A52 and other Bcl-2 like VACV proteins. Furthermore, the loop between A46 helices α4-α5 is flexible and shorter than in A52; there is also evidence for an intramolecular disulfide bridge between consecutive cysteine residues. We used molecular docking to propose how A46 interacts with the BB loop of the TRAM TIR domain. Comparisons of A46 and A52 exemplify how subtle changes in viral proteins with the same fold lead to crucial differences in biological activity.
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Affiliation(s)
- Sofiya Fedosyuk
- From the Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, A-1030 Vienna, Austria and
| | - Irina Grishkovskaya
- Max F. Perutz Laboratories, University of Vienna, Department of Structural and Computational Biology, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Euripedes de Almeida Ribeiro
- Max F. Perutz Laboratories, University of Vienna, Department of Structural and Computational Biology, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Tim Skern
- From the Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, A-1030 Vienna, Austria and
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87
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Bhanuprakash V, Prabhu M, Venkatesan G, Balamurugan V, Hosamani M, Pathak KML, Singh RK. Camelpox: epidemiology, diagnosis and control measures. Expert Rev Anti Infect Ther 2014; 8:1187-201. [DOI: 10.1586/eri.10.105] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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88
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Cole JE, Mitra AT, Monaco C. Treating atherosclerosis: the potential of Toll-like receptors as therapeutic targets. Expert Rev Cardiovasc Ther 2014; 8:1619-35. [DOI: 10.1586/erc.10.149] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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89
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Deletion of the vaccinia virus N2L gene encoding an inhibitor of IRF3 improves the immunogenicity of modified vaccinia virus Ankara expressing HIV-1 antigens. J Virol 2014; 88:3392-410. [PMID: 24390336 DOI: 10.1128/jvi.02723-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
UNLABELLED A modified vaccinia virus Ankara poxvirus vector expressing the HIV-1 Env, Gag, Pol, and Nef antigens from clade B (MVA-B) is currently being tested in clinical trials. To improve its immunogenicity, we have generated and characterized the immune profile of MVA-B containing a deletion of the vaccinia viral gene N2L, which codes for an inhibitor of IRF3 (MVA-B ΔN2L). Deletion of N2L had no effect on virus growth kinetics or on the expression of HIV-1 antigens; hence, the N2 protein is not essential for MVA replication. The innate immune responses triggered by MVA-B ΔN2L revealed an increase in beta interferon, proinflammatory cytokines, and chemokines. Mouse prime-boost protocols showed that MVA-B ΔN2L improves the magnitude and polyfunctionality of HIV-1-specific CD4(+) and CD8(+) T cell adaptive and memory immune responses, with most of the HIV-1 responses mediated by CD8(+) T cells. In the memory phase, HIV-1-specific CD8(+) T cells with an effector phenotype were predominant and in a higher percentage with MVA-B ΔN2L than with MVA-B. In both immunization groups, CD4(+) and CD8(+) T cell responses were directed mainly against Env. Furthermore, MVA-B ΔN2L in the memory phase enhanced levels of antibody against Env. For the vector immune responses, MVA-B ΔN2L induced a greater magnitude and polyfunctionality of VACV-specific CD8(+) T memory cells than MVA-B, with an effector phenotype. These results revealed the immunomodulatory role of N2L, whose deletion enhanced the innate immunity and improved the magnitude and quality of HIV-1-specific T cell adaptive and memory immune responses. These findings are relevant for the optimization of poxvirus vectors as vaccines. IMPORTANCE On the basis of the limited efficacy of the RV144 phase III clinical trial, new optimized poxvirus vectors as vaccines against HIV/AIDS are needed. Here we have generated and characterized a new HIV/AIDS vaccine candidate on the basis of the poxvirus MVA vector expressing HIV-1 Env, Gag, Pol, and Nef antigens (MVA-B) and containing a deletion in the vaccinia virus N2L gene. Our findings revealed the immunomodulatory role of N2L and proved that its deletion from the MVA-B vector triggered an enhanced innate immune response in human macrophages and monocyte-derived dendritic cells. Furthermore, in immunized mice, MVA-B ΔN2L induced improvements in the magnitude and quality of adaptive and memory HIV-1-specific CD4(+) and CD8(+) T cell immune responses, together with an increase in the memory phase of levels of antibody against Env. Thus, the selective deletion of the N2L viral immunomodulatory gene is important for the optimization of MVA vectors as HIV-1 vaccines.
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90
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MyD88 adaptor-like (Mal) functions in the epithelial barrier and contributes to intestinal integrity via protein kinase C. Mucosal Immunol 2014; 7:57-67. [PMID: 23612054 DOI: 10.1038/mi.2013.24] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 03/19/2013] [Indexed: 02/07/2023]
Abstract
MyD88 adapter-like (Mal)-deficient mice displayed increased susceptibility to oral but not intraperitoneal infection with Salmonella Typhimurium. Bone marrow chimeras demonstrated that mice with Mal-deficient non-hematopoietic cells were more susceptible to infection, indicating a role for Mal in non-myeloid cells. We observed perturbed barrier function in Mal(-/-) mice, as indicated by reduced electrical resistance and increased mucosa blood permeability following infection. Altered expression of occludin, Zonula occludens-1, and claudin-3 in intestinal epithelia from Mal(-/-) mice suggest that Mal regulates tight junction formation, which may in part contribute to intestinal integrity. Mal interacted with several protein kinase C (PKC) isoforms in a Caco-2 model of intestinal epithelia and inhibition of Mal or PKC increased permeability and bacterial invasion via a paracellular route, while a pan-PKC inhibitor increased susceptibility to oral infection in mice. Mal signaling is therefore beneficial to the integrity of the intestinal barrier during infection.
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Abstract
The transcription factor nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) plays a critical role in host defense against viral infection by inducing the production of proinflammatory mediators and type I interferon. Consequently, viruses have evolved many mechanisms to block its activation. The poxvirus vaccinia virus (VACV) encodes numerous inhibitors of NF-κB activation that target multiple points in the signaling pathway. A derivative of VACV strain Copenhagen, called vv811, lacking 55 open reading frames in the left and right terminal regions of the genome was reported to still inhibit NF-κB activation downstream of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), suggesting the presence of one or more additional inhibitors. In this study, we constructed a recombinant vv811 lacking the recently described NF-κB inhibitor A49 (vv811ΔA49), yielding a virus that lacked all currently described inhibitors downstream of TNF-α and IL-1β. Unlike vv811, vv811ΔA49 no longer inhibited degradation of the phosphorylated inhibitor of κBα and p65 translocated into the nucleus. However, despite this translocation, vv811ΔA49 still inhibited TNF-α- and IL-1β-induced NF-κB-dependent reporter gene expression and the transcription and production of cytokines induced by these agonists. This inhibition did not require late viral gene expression. These findings indicate the presence of another inhibitor of NF-κB that is expressed early during infection and acts by a novel mechanism downstream of p65 translocation into the nucleus.
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92
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Evasion of antiviral immunity through sequestering of TBK1/IKKε/IRF3 into viral inclusion bodies. J Virol 2013; 88:3067-76. [PMID: 24335286 DOI: 10.1128/jvi.03510-13] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cells are equipped with pattern recognition receptors (PRRs) such as the Toll-like and RIG-I-like receptors that mount innate defenses against viruses. However, viruses have evolved multiple strategies to evade or thwart host antiviral responses. Viral inclusion bodies (IBs), which are accumulated aggregates of viral proteins, are commonly formed during the replication of some viruses in infected cells, but their role in viral immune evasion has rarely been explored. Severe fever with thrombocytopenia syndrome (SFTS) is an emerging febrile illness caused by a novel phlebovirus in the Bunyaviridae. The SFTS viral nonstructural protein NSs can suppress host beta interferon (IFN-β) responses. NSs can form IBs in infected and transfected cells. Through interaction with tank-binding kinase 1 (TBK1), viral NSs was able to sequester the IKK complex, including IKKε and IRF3, into IBs, although NSs did not interact with IKKε or IRF3 directly. When cells were infected with influenza A virus, IRF3 was phosphorylated and active phosphorylated IRF3 (p-IRF3) was translocated into the nucleus. In the presence of NSs, IRF3 could still be phosphorylated, but p-IRF3 was trapped in cytoplasmic IBs, resulting in reduced IFN-β induction and enhanced viral replication. Sequestration of the IKK complex and active IRF3 into viral IBs through the interaction of NSs and TBK1 is a novel mechanism for viral evasion of innate immunity.
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93
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Priya R, Dhanwani R, Patro IK, Rao PVL, Parida MM. Differential regulation of TLR mediated innate immune response of mouse neuronal cells following infection with novel ECSA genotype of Chikungunya virus with and without E1:A226V mutation. INFECTION GENETICS AND EVOLUTION 2013; 20:396-406. [PMID: 24126361 DOI: 10.1016/j.meegid.2013.09.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/27/2013] [Accepted: 09/30/2013] [Indexed: 02/01/2023]
Abstract
Chikungunya virus (CHIKV) has received global attention due to the series of large-scale outbreaks in different parts of the world including Africa, Indian Ocean Islands, India and South-East Asia. The appearance of many unusual severe manifestations including neurological disorders was reported in post resurgence epidemics with implication of novel East Central South African (ECSA) genotype with E1:A226V mutation. The molecular mechanism of CHIKV neuropathogenesis is not yet understood and very little is known about the host-pathogen interactions. In the present study replication kinetics and innate immune response of ECSA genotype of CHIKV with and without A226V mutation were determined in mouse neuroblastoma cell line (N2a). The 226V mutant strain was more replication competent in N2a cells with a peak titer of 10(8)PFU/ml compared to 10(6)PFU/ml for A226 virus. Besides, the 226V mutant virus showed relatively less induction of antiviral genes i.e. IFN-β, OAS-3, MX-2, ISG-15 and Toll like receptors 3 and 7 as compared to non mutant strain (A226). Further pretreatment of N2a cells either with Poly I: C, IFN-β or TNF-α resulted in inhibition of CHIKV replication hence confirming the role of TLR mediated innate immune response in CHIKV pathogenesis. Differential regulation of TLRs and associated down stream antiviral genes might have attributed for increased pathogenesis of the 226V mutant novel ECSA genotype of CHIKV during the recent epidemics.
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Affiliation(s)
- Raj Priya
- Division of Virology, Defence Research & Development Establishment, Gwalior 474002, India
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94
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Stack J, Hurst TP, Flannery SM, Brennan K, Rupp S, Oda SI, Khan AR, Bowie AG. Poxviral protein A52 stimulates p38 mitogen-activated protein kinase (MAPK) activation by causing tumor necrosis factor receptor-associated factor 6 (TRAF6) self-association leading to transforming growth factor β-activated kinase 1 (TAK1) recruitment. J Biol Chem 2013; 288:33642-33653. [PMID: 24114841 DOI: 10.1074/jbc.m113.485490] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vaccinia virus encodes a number of proteins that inhibit and manipulate innate immune signaling pathways that also have a role in virulence. These include A52, a protein shown to inhibit IL-1- and Toll-like receptor-stimulated NFκB activation, via interaction with interleukin-1 receptor-associated kinase 2 (IRAK2). Interestingly, A52 was also found to activate p38 MAPK and thus enhance Toll-like receptor-dependent IL-10 induction, which was TRAF6-dependent, but the manner in which A52 manipulates TRAF6 to stimulate p38 activation was unclear. Here, we show that A52 has a non-canonical TRAF6-binding motif that is essential for TRAF6 binding and p38 activation but dispensable for NFκB inhibition and IRAK2 interaction. Wild-type A52, but not a mutant defective in p38 activation and TRAF6 binding (F154A), caused TRAF6 oligomerization and subsequent TRAF6-TAK1 association. The crystal structure of A52 shows that it adopts a Bcl2-like fold and exists as a dimer in solution. Residue Met-65 was identified as being located in the A52 dimer interface, and consistent with that, A52-M65E was impaired in its ability to dimerize. A52-M65E although capable of interacting with TRAF6, was unable to cause either TRAF6 self-association, induce the TRAF6-TAK1 association, or activate p38 MAPK. The results suggest that an A52 dimer causes TRAF6 self-association, leading to TAK1 recruitment and p38 activation. This reveals a molecular mechanism whereby poxviruses manipulate TRAF6 to activate MAPKs (which can be proviral) without stimulating antiviral NFκB activation.
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Affiliation(s)
- Julianne Stack
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Tara P Hurst
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Sinead M Flannery
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Kiva Brennan
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Sebastian Rupp
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Shun-Ichiro Oda
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Amir R Khan
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Andrew G Bowie
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
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95
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Peters NE, Ferguson BJ, Mazzon M, Fahy AS, Krysztofinska E, Arribas-Bosacoma R, Pearl LH, Ren H, Smith GL. A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus. PLoS Pathog 2013; 9:e1003649. [PMID: 24098118 PMCID: PMC3789764 DOI: 10.1371/journal.ppat.1003649] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 08/06/2013] [Indexed: 12/17/2022] Open
Abstract
The innate immune system is critical in the response to infection by pathogens and it is activated by pattern recognition receptors (PRRs) binding to pathogen associated molecular patterns (PAMPs). During viral infection, the direct recognition of the viral nucleic acids, such as the genomes of DNA viruses, is very important for activation of innate immunity. Recently, DNA-dependent protein kinase (DNA-PK), a heterotrimeric complex consisting of the Ku70/Ku80 heterodimer and the catalytic subunit DNA-PKcs was identified as a cytoplasmic PRR for DNA that is important for the innate immune response to intracellular DNA and DNA virus infection. Here we show that vaccinia virus (VACV) has evolved to inhibit this function of DNA-PK by expression of a highly conserved protein called C16, which was known to contribute to virulence but by an unknown mechanism. Data presented show that C16 binds directly to the Ku heterodimer and thereby inhibits the innate immune response to DNA in fibroblasts, characterised by the decreased production of cytokines and chemokines. Mechanistically, C16 acts by blocking DNA-PK binding to DNA, which correlates with reduced DNA-PK-dependent DNA sensing. The C-terminal region of C16 is sufficient for binding Ku and this activity is conserved in the variola virus (VARV) orthologue of C16. In contrast, deletion of 5 amino acids in this domain is enough to knockout this function from the attenuated vaccine strain modified vaccinia virus Ankara (MVA). In vivo a VACV mutant lacking C16 induced higher levels of cytokines and chemokines early after infection compared to control viruses, confirming the role of this virulence factor in attenuating the innate immune response. Overall this study describes the inhibition of DNA-PK-dependent DNA sensing by a poxvirus protein, adding to the evidence that DNA-PK is a critical component of innate immunity to DNA viruses.
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Affiliation(s)
- Nicholas E. Peters
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Brian J. Ferguson
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Michela Mazzon
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Aodhnait S. Fahy
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Ewelina Krysztofinska
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Raquel Arribas-Bosacoma
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, United Kingdom
| | - Laurence H. Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, United Kingdom
| | - Hongwei Ren
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Geoffrey L. Smith
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
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96
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Fekonja O, Avbelj M, Jerala R. Suppression of TLR signaling by targeting TIR domain-containing proteins. Curr Protein Pept Sci 2013; 13:776-88. [PMID: 23305364 PMCID: PMC3594740 DOI: 10.2174/138920312804871148] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/20/2012] [Accepted: 08/03/2012] [Indexed: 02/06/2023]
Abstract
Toll-like receptors (TLRs) recognize molecules specific to pathogens and endogenous danger signals. Binding of agonists to the ectodomain of the receptor initiates TLR activation and is followed by the association of receptor cytosolic Toll/Interleukin-1 receptor (TIR) domains with TIR domains of adapter proteins leading to the assembly of signaling cascade of protein kinases that ultimately trigger the activation of transcription factors and expression of genes involved in the immune response. Excessive activation of TIR-domain mediated signaling has been implicated in inflammatory diseases (e.g. rheumatoid arthritis, systemic lupus erythematosus, colitis) as well as in the development of cancer. Targeting receptor-adapter interactions represents a potential strategy for the therapeutic TLR/IL-1R-specific inhibition due to the unique interacting domains involved. Peptide and protein-domain binding TLR inhibitors originating from the interacting surfaces of TIR-domain containing proteins can bind to the site on their target interacting protein thereby preventing the assembly of the functional signaling complex. Here we review protein-domain, peptide and peptidomimetic inhibitors targeting TIR-domain mediated interactions and their application demonstrated on in vitro and in vivo models. Recent structural data and elucidation of the molecular mechanisms of TIR-domain mediated signaling enabled the development of peptide inhibitors from TIR domains of TLRs and adapters, MyD88 intermediary domain as well as improved protein inhibitors based on TIR domain dimerization, mimicking bacterial TIR-domain containing immunosuppressors (TCPs) which we discuss with challenges concerning the delivery and specificity of inhibitors targeting TLR adapters.
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Affiliation(s)
- Ota Fekonja
- Laboratory of Biotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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97
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Perdiguero B, Gómez CE, Di Pilato M, Sorzano COS, Delaloye J, Roger T, Calandra T, Pantaleo G, Esteban M. Deletion of the vaccinia virus gene A46R, encoding for an inhibitor of TLR signalling, is an effective approach to enhance the immunogenicity in mice of the HIV/AIDS vaccine candidate NYVAC-C. PLoS One 2013; 8:e74831. [PMID: 24069354 PMCID: PMC3775734 DOI: 10.1371/journal.pone.0074831] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/06/2013] [Indexed: 01/07/2023] Open
Abstract
Viruses have developed strategies to counteract signalling through Toll-like receptors (TLRs) that are involved in the detection of viruses and induction of proinflammatory cytokines and IFNs. Vaccinia virus (VACV) encodes A46 protein which disrupts TLR signalling by interfering with TLR: adaptor interactions. Since the innate immune response to viruses is critical to induce protective immunity, we studied whether deletion of A46R gene in a NYVAC vector expressing HIV-1 Env, Gag, Pol and Nef antigens (NYVAC-C) improves immune responses against HIV-1 antigens. This question was examined in human macrophages and in mice infected with a single A46R deletion mutant of the vaccine candidate NYVAC-C (NYVAC-C-ΔA46R). The viral gene A46R is not required for virus replication in primary chicken embryo fibroblast (CEF) cells and its deletion in NYVAC-C markedly increases TNF, IL-6 and IL-8 secretion by human macrophages. Analysis of the immune responses elicited in BALB/c mice after DNA prime/NYVAC boost immunization shows that deletion of A46R improves the magnitude of the HIV-1-specific CD4 and CD8 T cell immune responses during adaptive and memory phases, maintains the functional profile observed with the parental NYVAC-C and enhances anti-gp120 humoral response during the memory phase. These findings establish the immunological role of VACV A46R on innate immune responses of macrophages in vitro and antigen-specific T and B cell immune responses in vivo and suggest that deletion of viral inhibitors of TLR signalling is a useful approach for the improvement of poxvirus-based vaccine candidates.
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Affiliation(s)
- Beatriz Perdiguero
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Carmen Elena Gómez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Mauro Di Pilato
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Carlos Oscar S. Sorzano
- Biocomputing Unit, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Julie Delaloye
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Thierry Roger
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Thierry Calandra
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Giuseppe Pantaleo
- Division of Immunology and Allergy, Department of Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Mariano Esteban
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- * E-mail:
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98
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Smith GL, Benfield CTO, Maluquer de Motes C, Mazzon M, Ember SWJ, Ferguson BJ, Sumner RP. Vaccinia virus immune evasion: mechanisms, virulence and immunogenicity. J Gen Virol 2013; 94:2367-2392. [PMID: 23999164 DOI: 10.1099/vir.0.055921-0] [Citation(s) in RCA: 255] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Virus infection of mammalian cells is sensed by pattern recognition receptors and leads to an innate immune response that restricts virus replication and induces adaptive immunity. In response, viruses have evolved many countermeasures that enable them to replicate and be transmitted to new hosts, despite the host innate immune response. Poxviruses, such as vaccinia virus (VACV), have large DNA genomes and encode many proteins that are dedicated to host immune evasion. Some of these proteins are secreted from the infected cell, where they bind and neutralize complement factors, interferons, cytokines and chemokines. Other VACV proteins function inside cells to inhibit apoptosis or signalling pathways that lead to the production of interferons and pro-inflammatory cytokines and chemokines. In this review, these VACV immunomodulatory proteins are described and the potential to create more immunogenic VACV strains by manipulation of the gene encoding these proteins is discussed.
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Affiliation(s)
- Geoffrey L Smith
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Camilla T O Benfield
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | | | - Michela Mazzon
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Stuart W J Ember
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Brian J Ferguson
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Rebecca P Sumner
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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99
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Camelpox, an emerging orthopox viral disease. INDIAN JOURNAL OF VIROLOGY : AN OFFICIAL ORGAN OF INDIAN VIROLOGICAL SOCIETY 2013; 24:295-305. [PMID: 24426291 DOI: 10.1007/s13337-013-0145-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
Abstract
Camelpox is considered as emerging public health problem during this decade due to increased reported cases and outbreaks in camels. Camelpox is a contagious, often sporadic, and notifiable skin disease of camelids and is socio-economically significant as it incurs considerable loss in terms of morbidity, mortality, loss of weight and reduction in milk yield and confined to camel-rearing countries. The causative agent, camelpox virus (CMLV) is genetically closely related to variola virus and has gained much attention from researchers due to its recent emergence in human. The virus carrying genes responsible for host immune evasion mechanisms owing to the threat posed by potential bio-warfare agents. Although the disease can be diagnosed based on clinical features, the similar confounding skin lesions necessitate identification, detection and differentiation of the CMLV by molecular techniques. Vaccines are available in some countries and the available live attenuated vaccine provides long-lasting immunity. Further, novel highly sensitive and specific techniques would be useful in the identification of emerging and re-emerging virus, thereby therapeutic, prophylactic, preventive measures would be applied in time to curtail further spread of camelpox like other zoonotic diseases. This review provide overview of the camelpox particularly on its epidemiology, pathogenesis and biology of the disease, diagnostic approaches and control measures.
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100
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Patterson NJ, Werling D. To con protection: TIR-domain containing proteins (Tcp) and innate immune evasion. Vet Immunol Immunopathol 2013; 155:147-54. [PMID: 23871438 DOI: 10.1016/j.vetimm.2013.06.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 06/17/2013] [Accepted: 06/26/2013] [Indexed: 01/07/2023]
Abstract
The innate immune system provides the host's first line of defence against invading pathogens. Key to the stimulation of the innate immune response is pattern-recognition receptors (PRRs), such as Toll-like receptors (TLRs), which recognize microbial-associated molecular patterns (MAMPs). Binding of MAMPs to TLRs triggers a signalling cascade resulting in the production of pro-inflammatory mediators. Central to this TLR signalling pathway are heterotypic protein-protein interactions mediated through Toll/interleukin-1 receptor (TIR) domains found in both the cytoplasmic regions of TLRs and several key adaptor proteins. Interestingly, TIR-domain containing proteins (Tcps) do not seem to be unique to the mammalian TLR system, but occurs in abundance in many biological forms. Recent evidence suggests that pathogenic bacteria have developed a range of ingenuous strategies to evade the host immune mechanisms involving Tcps. There is increasing evidence to suggest that these pathogen-encoded Tcps interfere directly with the TLR signalling pathway and thus inhibit the activation of NF-κB, with different modes of action and roles in virulence. Here, we review the current state of knowledge on the possible roles and mechanisms of action of bacterial encoded Tcp.
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Affiliation(s)
- Nicholas J Patterson
- Molecular Immunology Group, Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, Hatfield AL9 7TA, UK
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