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Iyer M, Ravichandran N, Karuppusamy PA, Gnanarajan R, Yadav MK, Narayanasamy A, Vellingiri B. Molecular insights and promise of oncolytic virus based immunotherapy. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2024; 140:419-492. [PMID: 38762277 DOI: 10.1016/bs.apcsb.2023.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2024]
Abstract
Discovering a therapeutic that can counteract the aggressiveness of this disease's mechanism is crucial for improving survival rates for cancer patients and for better understanding the most different types of cancer. In recent years, using these viruses as an anticancer therapy has been thought to be successful. They mostly work by directly destroying cancer cells, activating the immune system to fight cancer, and expressing exogenous effector genes. For the treatment of tumors, oncolytic viruses (OVs), which can be modified to reproduce only in tumor tissues and lyse them while preserving the healthy non-neoplastic host cells and reinstating antitumor immunity which present a novel immunotherapeutic strategy. OVs can exist naturally or be created in a lab by altering existing viruses. These changes heralded the beginning of a new era of less harmful virus-based cancer therapy. We discuss three different types of oncolytic viruses that have already received regulatory approval to treat cancer as well as clinical research using oncolytic adenoviruses. The primary therapeutic applications, mechanism of action of oncolytic virus updates, future views of this therapy will be covered in this chapter.
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Affiliation(s)
- Mahalaxmi Iyer
- Department of Microbiology, Central University of Punjab, Bathinda, India
| | - Nandita Ravichandran
- Disease Proteomics Laboratory, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India
| | | | - Roselin Gnanarajan
- Disease Proteomics Laboratory, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India
| | - Mukesh Kumar Yadav
- Department of Microbiology, Central University of Punjab, Bathinda, India
| | - Arul Narayanasamy
- Disease Proteomics Laboratory, Department of Zoology, Bharathiar University, Coimbatore, Tamil Nadu, India.
| | - Balachandar Vellingiri
- Human Cytogenetics and Stem Cell Laboratory, Department of Zoology, School of Basic Sciences, Central University of Punjab, Bathinda, Punjab, India.
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2
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Jih J, Liu YT, Liu W, Zhou ZH. The incredible bulk: Human cytomegalovirus tegument architectures uncovered by AI-empowered cryo-EM. SCIENCE ADVANCES 2024; 10:eadj1640. [PMID: 38394211 PMCID: PMC10889378 DOI: 10.1126/sciadv.adj1640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 01/22/2024] [Indexed: 02/25/2024]
Abstract
The compartmentalization of eukaryotic cells presents considerable challenges to the herpesvirus life cycle. The herpesvirus tegument, a bulky proteinaceous aggregate sandwiched between herpesviruses' capsid and envelope, is uniquely evolved to address these challenges, yet tegument structure and organization remain poorly characterized. We use deep-learning-enhanced cryogenic electron microscopy to investigate the tegument of human cytomegalovirus virions and noninfectious enveloped particles (NIEPs; a genome packaging-aborted state), revealing a portal-biased tegumentation scheme. We resolve atomic structures of portal vertex-associated tegument (PVAT) and identify multiple configurations of PVAT arising from layered reorganization of pUL77, pUL48 (large tegument protein), and pUL47 (inner tegument protein) assemblies. Analyses show that pUL77 seals the last-packaged viral genome end through electrostatic interactions, pUL77 and pUL48 harbor a head-linker-capsid-binding motif conducive to PVAT reconfiguration, and pUL47/48 dimers form 45-nm-long filaments extending from the portal vertex. These results provide a structural framework for understanding how herpesvirus tegument facilitates and evolves during processes spanning viral genome packaging to delivery.
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Affiliation(s)
- Jonathan Jih
- Molecular Biology Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Yun-Tao Liu
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Wei Liu
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Z. Hong Zhou
- Molecular Biology Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
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Thomas ECM, Finnen RL, Mewburn JD, Archer SL, Banfield BW. The Herpes Simplex Virus pUL16 and pUL21 Proteins Prevent Capsids from Docking at Nuclear Pore Complexes. PLoS Pathog 2023; 19:e1011832. [PMID: 38039340 PMCID: PMC10718459 DOI: 10.1371/journal.ppat.1011832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 12/13/2023] [Accepted: 11/16/2023] [Indexed: 12/03/2023] Open
Abstract
After entry into cells, herpes simplex virus (HSV) nucleocapsids dock at nuclear pore complexes (NPCs) through which viral genomes are released into the nucleoplasm where viral gene expression, genome replication, and early steps in virion assembly take place. After their assembly, nucleocapsids are translocated to the cytoplasm for final virion maturation. Nascent cytoplasmic nucleocapsids are prevented from binding to NPCs and delivering their genomes to the nucleus from which they emerged, but how this is accomplished is not understood. Here we report that HSV pUL16 and pUL21 deletion mutants accumulate empty capsids at the cytoplasmic face of NPCs late in infection. Additionally, prior expression of pUL16 and pUL21 prevented incoming nucleocapsids from docking at NPCs, delivering their genomes to the nucleus and initiating viral gene expression. Both pUL16 and pUL21 localized to the nuclear envelope, placing them in an appropriate location to interfere with nucleocapsid/NPC interactions.
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Affiliation(s)
- Ethan C. M. Thomas
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Renée L. Finnen
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | | | - Stephen L. Archer
- Department of Medicine, Queen’s University, Kingston, Ontario, Canada
| | - Bruce W. Banfield
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
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Sucharita S, Krishnagopal A, van Drunen Littel-van den Hurk S. Comprehensive Analysis of the Tegument Proteins Involved in Capsid Transport and Virion Morphogenesis of Alpha, Beta and Gamma Herpesviruses. Viruses 2023; 15:2058. [PMID: 37896835 PMCID: PMC10611259 DOI: 10.3390/v15102058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/21/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
Herpesviruses are enveloped and have an amorphous protein layer surrounding the capsid, which is termed the tegument. Tegument proteins perform critical functions throughout the viral life cycle. This review provides a comprehensive and comparative analysis of the roles of specific tegument proteins in capsid transport and virion morphogenesis of selected, well-studied prototypes of each of the three subfamilies of Herpesviridae i.e., human herpesvirus-1/herpes simplex virus-1 (Alphaherpesvirinae), human herpesvirus-5/cytomegalovirus (Betaherpesvirinae) and human herpesvirus -8/Kaposi's sarcomavirus (Gammaherpesvirinae). Most of the current knowledge is based on alpha herpesviruses, in particular HSV-1. While some tegument proteins are released into the cytoplasm after virus entry, several tegument proteins remain associated with the capsid and are responsible for transport to and docking at the nucleus. After replication and capsid formation, the capsid is enveloped at the nuclear membrane, which is referred to as primary envelopment, followed by de-envelopment and release into the cytoplasm. This requires involvement of at least three tegument proteins. Subsequently, multiple interactions between tegument proteins and capsid proteins, other tegument proteins and glycoproteins are required for assembly of the virus particles and envelopment at the Golgi, with certain tegument proteins acting as the central hub for these interactions. Some redundancy in these interactions ensures appropriate morphogenesis.
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Affiliation(s)
- Soumya Sucharita
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
| | - Akshaya Krishnagopal
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
| | - Sylvia van Drunen Littel-van den Hurk
- Biochemistry, Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; (S.S.); (A.K.)
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
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5
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Döhner K, Serrero MC, Sodeik B. The role of nuclear pores and importins for herpes simplex virus infection. Curr Opin Virol 2023; 62:101361. [PMID: 37672874 DOI: 10.1016/j.coviro.2023.101361] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 07/31/2023] [Accepted: 08/08/2023] [Indexed: 09/08/2023]
Abstract
Microtubule transport and nuclear import are functionally connected, and the nuclear pore complex (NPC) can interact with microtubule motors. For several alphaherpesvirus proteins, nuclear localization signals (NLSs) and their interactions with specific importin-α proteins have been characterized. Here, we review recent insights on the roles of microtubule motors, capsid-associated NLSs, and importin-α proteins for capsid transport, capsid docking to NPCs, and genome release into the nucleoplasm, as well as the role of importins for nuclear viral transcription, replication, capsid assembly, genome packaging, and nuclear capsid egress. Moreover, importin-α proteins exert antiviral effects by promoting the nuclear import of transcription factors inducing the expression of interferons (IFN), cytokines, and IFN-stimulated genes, and the IFN-inducible MxB restricts capsid docking to NPCs.
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Affiliation(s)
- Katinka Döhner
- Institute of Virology, Hannover Medical School, Hannover, Germany; Department of Dermatology and Allergy, Hannover Medical School, Hannover, Germany; RESIST - Cluster of Excellence, Hannover Medical School, Hannover, Germany.
| | - Manutea C Serrero
- Institute of Virology, Hannover Medical School, Hannover, Germany; RESIST - Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Beate Sodeik
- Institute of Virology, Hannover Medical School, Hannover, Germany; RESIST - Cluster of Excellence, Hannover Medical School, Hannover, Germany; DZIF - German Centre for Infection Research, Braunschweig, Hannover, Germany.
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6
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Sausen DG, Shechter O, Gallo ES, Dahari H, Borenstein R. Herpes Simplex Virus, Human Papillomavirus, and Cervical Cancer: Overview, Relationship, and Treatment Implications. Cancers (Basel) 2023; 15:3692. [PMID: 37509353 PMCID: PMC10378257 DOI: 10.3390/cancers15143692] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023] Open
Abstract
There is a significant body of research examining the role of human papillomavirus (HPV) in the pathogenesis of cervical cancer, with a particular emphasis on the oncogenic proteins E5, E6, and E7. What is less well explored, however, is the relationship between cervical cancer and herpes simplex virus (HSV). To date, studies examining the role of HSV in cervical cancer pathogenesis have yielded mixed results. While several experiments have determined that HPV/HSV-2 coinfection results in a higher risk of developing cervical cancer, others have questioned the validity of this association. However, clarifying the potential role of HSV in the pathogenesis of cervical cancer may have significant implications for both the prevention and treatment of this disease. Should this relationship be clarified, treating and preventing HSV could open another avenue with which to prevent cervical cancer. The importance of this is highlighted by the fact that, despite the creation of an effective vaccine against HPV, cervical cancer still impacts 604,000 women and is responsible for 342,000 deaths annually. This review provides an overview of HSV and HPV infections and then delves into the possible links between HPV, HSV, and cervical cancer. It concludes with a summary of preventive measures against and recent treatment advances in cervical cancer.
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Affiliation(s)
- Daniel G. Sausen
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23501, USA; (D.G.S.); (O.S.)
| | - Oren Shechter
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23501, USA; (D.G.S.); (O.S.)
| | - Elisa S. Gallo
- Division of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv 64239, Israel
| | - Harel Dahari
- The Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA;
| | - Ronen Borenstein
- The Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA;
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Murata T. Tegument proteins of Epstein-Barr virus: Diverse functions, complex networks, and oncogenesis. Tumour Virus Res 2023; 15:200260. [PMID: 37169175 DOI: 10.1016/j.tvr.2023.200260] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/02/2023] [Accepted: 05/04/2023] [Indexed: 05/13/2023] Open
Abstract
The tegument is the structure between the envelope and nucleocapsid of herpesvirus particles. Viral (and cellular) proteins accumulate to create the layers of the tegument. Some Epstein-Barr virus (EBV) tegument proteins are conserved widely in Herpesviridae, but others are shared only by members of the gamma-herpesvirus subfamily. As the interface to envelope and nucleocapsid, the tegument functions in virion morphogenesis and budding of the nucleocapsid during progeny production. When a virus particle enters a cell, enzymes such as kinase and deubiquitinase, and transcriptional activators are released from the virion to promote virus infection. Moreover, some EBV tegument proteins are involved in oncogenesis. Here, we summarize the roles of EBV tegument proteins, in comparison to those of other herpesviruses.
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Affiliation(s)
- Takayuki Murata
- Department of Virology, Fujita Health University School of Medicine, Toyoake, Japan.
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8
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Ozhelvaci F, Steczkiewicz K. Identification and Classification of Papain-like Cysteine Proteinases. J Biol Chem 2023:104801. [PMID: 37164157 DOI: 10.1016/j.jbc.2023.104801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/11/2023] [Accepted: 05/05/2023] [Indexed: 05/12/2023] Open
Abstract
Papain-like cysteine peptidases form a big and highly diverse superfamily of proteins involved in many important biological functions, such as protein turnover, deubiquitination, tissue remodeling, blood clotting, virulence, defense, and cell wall remodeling. High sequence and structure diversity observed within these proteins hinders their comprehensive classification as well as the identification of new representatives. Moreover, in general protein databases, many families already classified as papain-like lack details regarding their mechanism of action or biological function. Here, we use transitive remote homology searches and 3D modeling to newly classify 21 families to the papain-like cysteine peptidase superfamily. We attempt to predict their biological function, and provide structural chacterization of 89 protein clusters defined based on sequence similarity altogether spanning 106 papain-like families. Moreover, we systematically discuss observed diversity in sequences, structures, and catalytic sites. Eventually, we expand the list of human papain-related proteins by seven representatives, including dopamine receptor-interacting protein (DRIP1) as potential deubiquitinase, and centriole duplication regulating CEP76 as retaining catalytically active peptidase-like domain. The presented results not only provide structure-based rationales to already existing peptidase databases but also may inspire further experimental research focused on peptidase-related biological processes.
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Affiliation(s)
- Fatih Ozhelvaci
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Kamil Steczkiewicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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9
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Krawczyk E, Kangas C, He B. HSV Replication: Triggering and Repressing STING Functionality. Viruses 2023; 15:226. [PMID: 36680267 PMCID: PMC9864509 DOI: 10.3390/v15010226] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/06/2023] [Accepted: 01/10/2023] [Indexed: 01/19/2023] Open
Abstract
Herpes simplex virus (HSV) has persisted within human populations due to its ability to establish both lytic and latent infection. Given this, human hosts have evolved numerous immune responses to protect against HSV infection. Critical in this defense against HSV, the host protein stimulator of interferon genes (STING) functions as a mediator of the antiviral response by inducing interferon (IFN) as well as IFN-stimulated genes. Emerging evidence suggests that during HSV infection, dsDNA derived from either the virus or the host itself ultimately activates STING signaling. While a complex regulatory circuit is in operation, HSV has evolved several mechanisms to neutralize the STING-mediated antiviral response. Within this review, we highlight recent progress involving HSV interactions with the STING pathway, with a focus on how STING influences HSV replication and pathogenesis.
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Affiliation(s)
| | | | - Bin He
- Department of Microbiology and Immunology, College of Medicine, University of Illinois, Chicago, IL 60612, USA
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10
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Herpesvirus ubiquitin deconjugases. Semin Cell Dev Biol 2022; 132:185-192. [PMID: 34776333 DOI: 10.1016/j.semcdb.2021.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/15/2022]
Abstract
The covalent attachment of ubiquitin and ubiquitin-like polypeptides to cellular and viral proteins regulates numerous processes that enable virus infection, viral genome replication, and the spread of viruses to new hosts. The importance of these protein modifications in the regulation of the life cycle of herpesviruses is underscored by the discovery that all known members of this virus family encode at least one protease that specifically recognizes and disassembles ubiquitin conjugates. The structural and functional characterization of the viral enzymes and the identification of their viral and cellular substrates is providing valuable insights into the biology of viral infection and increasing evidence suggests that the viral deconjugases may also play a role in malignant transformation.
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Mohnke J, Stark I, Fischer M, Fischer PM, Schlosser A, Grothey A, O’Hare P, Sodeik B, Erhard F, Dölken L, Hennig T. pUL36 Deubiquitinase Activity Augments Both the Initiation and the Progression of Lytic Herpes Simplex Virus Infection in IFN-Primed Cells. J Virol 2022; 96:e0096322. [PMID: 36314822 PMCID: PMC9683058 DOI: 10.1128/jvi.00963-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 09/15/2022] [Indexed: 11/24/2022] Open
Abstract
The evolutionarily conserved, structural HSV-1 tegument protein pUL36 is essential for both virus entry and assembly. While its N-terminal deubiquitinase (DUB) activity is dispensable for infection in cell culture, it is required for efficient virus spread in vivo, as it acts as a potent viral immune evasin. Interferon (IFN) induces the expression of hundreds of antiviral factors, including many ubiquitin modulators, which HSV-1 needs to neutralize to efficiently initiate a productive infection. Herein, we discover two functions of the conserved pUL36 DUB during lytic replication in cell culture in an understudied but equally important scenario of HSV-1 infection in IFN-treated cells. Our data indicate that the pUL36 DUB contributes to overcoming the IFN-mediated suppression of productive infection in both the early and late phases of HSV-1 infection. We show that incoming tegument-derived pUL36 DUB activity contributes to the IFN resistance of HSV-1 in IFN-primed cells to efficiently initiate lytic virus replication. Subsequently, the de novo expressed DUB augmented the efficiency of virus replication and increased the output of infectious virus. Notably, the DUB defect was only apparent when IFN was applied prior to infection. Our data indicate that IFN-induced defense mechanisms exist and that they work to both neutralize infectivity early on and slow the progression of HSV-1 replication in the late stages of infection. Also, our data indicate that pUL36 DUB activity contributes to the disarming of these host responses. IMPORTANCE HSV-1 is a ubiquitous human pathogen that is responsible for common cold sores and may also cause life-threatening disease. pUL36 is an essential, conserved herpesvirus protein with N-terminal deubiquitinating (DUB) activity. The DUB is dispensable for HSV-1 replication in cell culture but represents an important viral immune evasin in vivo. IFN plays a pivotal role in HSV-1 infection and suppresses viral replication both in vitro and in vivo. Here, we show that DUB activity contributes to overcoming IFN-induced cellular resistance in order to more efficiently initiate lytic replication and produce infectious virions. As such, DUB activity in the incoming virions increases their infectivity, while the de novo synthesized DUB augments productive infection. Thus, the HSV-1 DUB antagonizes the activity of IFN-inducible effector proteins to facilitate productive infection at multiple levels. Our findings underscore the importance of using more challenging cell culture systems to fully understand virus protein functions.
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Affiliation(s)
- Jonas Mohnke
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Irmgard Stark
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Mara Fischer
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Patrick M. Fischer
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Andreas Schlosser
- Rudolf-Virchow-Zentrum - Center for Integrative and Translational Bioimaging, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Arnhild Grothey
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Peter O’Hare
- Department of Virology, Imperial College London, Norfolk Place, London, United Kingdom
| | - Beate Sodeik
- Institut für Virologie, Medizinische Hochschule Hannover, Hannover, Germany
- RESIST Exzellenzcluster, Medizinische Hochschule Hannover, Hannover, Germany
| | - Florian Erhard
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Lars Dölken
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Thomas Hennig
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
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12
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Hong B, Sahu U, Mullarkey MP, Kaur B. Replication and Spread of Oncolytic Herpes Simplex Virus in Solid Tumors. Viruses 2022; 14:v14010118. [PMID: 35062322 PMCID: PMC8778098 DOI: 10.3390/v14010118] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/11/2022] Open
Abstract
Oncolytic herpes simplex virus (oHSV) is a highly promising treatment for solid tumors. Intense research and development efforts have led to first-in-class approval for an oHSV for melanoma, but barriers to this promising therapy still exist that limit efficacy. The process of infection, replication and transmission of oHSV in solid tumors is key to obtaining a good lytic destruction of infected cancer cells to kill tumor cells and release tumor antigens that can prime anti-tumor efficacy. Intracellular tumor cell signaling and tumor stromal cells present multiple barriers that resist oHSV activity. Here, we provide a review focused on oncolytic HSV and the essential viral genes that allow for virus replication and spread in order to gain insight into how manipulation of these pathways can be exploited to potentiate oHSV infection and replication among tumor cells.
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13
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Horníková L, Bruštíková K, Huérfano S, Forstová J. Nuclear Cytoskeleton in Virus Infection. Int J Mol Sci 2022; 23:ijms23010578. [PMID: 35009004 PMCID: PMC8745530 DOI: 10.3390/ijms23010578] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 02/04/2023] Open
Abstract
The nuclear lamina is the main component of the nuclear cytoskeleton that maintains the integrity of the nucleus. However, it represents a natural barrier for viruses replicating in the cell nucleus. The lamina blocks viruses from being trafficked to the nucleus for replication, but it also impedes the nuclear egress of the progeny of viral particles. Thus, viruses have evolved mechanisms to overcome this obstacle. Large viruses induce the assembly of multiprotein complexes that are anchored to the inner nuclear membrane. Important components of these complexes are the viral and cellular kinases phosphorylating the lamina and promoting its disaggregation, therefore allowing virus egress. Small viruses also use cellular kinases to induce lamina phosphorylation and the subsequent disruption in order to facilitate the import of viral particles during the early stages of infection or during their nuclear egress. Another component of the nuclear cytoskeleton, nuclear actin, is exploited by viruses for the intranuclear movement of their particles from the replication sites to the nuclear periphery. This study focuses on exploitation of the nuclear cytoskeleton by viruses, although this is just the beginning for many viruses, and promises to reveal the mechanisms and dynamic of physiological and pathological processes in the nucleus.
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Role of HSV-1 Capsid Vertex-Specific Component (CVSC) and Viral Terminal DNA in Capsid Docking at the Nuclear Pore. Viruses 2021; 13:v13122515. [PMID: 34960783 PMCID: PMC8704396 DOI: 10.3390/v13122515] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 01/18/2023] Open
Abstract
Penetration of the viral genome into a host cell nucleus is critical for initiation of viral replication for most DNA viruses and a few RNA viruses. For herpesviruses, viral DNA ejection into a nucleus occurs when the capsid docks at the nuclear pore complex (NPC) basket with the correct orientation of the unique capsid portal vertex. It has been shown that capsid vertex-specific component (CVSC) proteins, which are located at the twelve vertices of the human herpes simplex virus type 1 (HSV-1) capsid, interact with nucleoporins (Nups) of NPCs. However, it remained unclear whether CVSC proteins determine capsid-to-NPC binding. Furthermore, it has been speculated that terminal DNA adjacent to the portal complex of DNA-filled C-capsids forms a structural motif with the portal cap (which retains DNA in the capsid), which mediates capsid-NPC binding. We demonstrate that terminal viral DNA adjacent to the portal proteins does not present a structural element required for capsid-NPC binding. Our data also show that level of CVSC proteins on the HSV-1 capsid affects level of NPC binding. To elucidate the capsid-binding process, we use an isolated, reconstituted cell nucleus system that recapitulates capsid-nucleus binding in vivo without interference from trafficking kinetics of capsids moving toward the nucleus. This allows binding of non-infectious capsid maturation intermediates with varying levels of vertex-specific components. This experimental system provides a platform for investigating virus-host interaction at the nuclear membrane.
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Li D, Xie L, Qiao Z, Zhu J, Yao H, Qin Y, Yan Y, Chen Z, Ma F. IFI16 Isoforms with Cytoplasmic and Nuclear Locations Play Differential Roles in Recognizing Invaded DNA Viruses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 207:2699-2709. [PMID: 34750204 DOI: 10.4049/jimmunol.2100398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/27/2021] [Indexed: 11/19/2022]
Abstract
IFN-γ-inducible protein 16 (IFI16) recognizes viral DNAs from both nucleus-replicating viruses and cytoplasm-replicating viruses. Isoform 2 of IFI16 (IFI16-iso2) with nuclear localization sequence (NLS) has been studied extensively as a well-known DNA sensor. However, the characteristics and functions of other IFI16 isoforms are almost unknown. Here, we find that IFI16-iso1, with exactly the same length as IFI16-iso2, lacks the NLS and locates in the cytoplasm. To distinguish the functions of IFI16-iso1 and IFI16-iso2, we have developed novel nuclear viral DNA mimics that can be recognized by the nuclear DNA sensors, including IFI16-iso2 and hnRNPA2B1. The hexanucleotide motif 5'-AGTGTT-3' DNA form of the nuclear localization sequence (DNLS) effectively drives cytoplasmic viral DNA nuclear translocation. These nuclear viral DNA mimics potently induce IFN-β and antiviral IFN-stimulated genes in human A549 cells, HEK293T cells, and mouse macrophages. The subcellular location difference of IFI16 isoforms determines their differential functions in recognizing viral DNA and activating type I IFN-dependent antiviral immunity. IFI16-iso1 preferentially colocalizes with cytoplasmic HSV60mer and cytoplasm-replicating vaccinia virus (VACV), whereas IFI16-iso2 mainly colocalizes with nuclear HSV60-DNLS and nucleus-replicating HSV-1. Compared with IFI16-iso2, IFI16-iso1 induces more transcription of IFN-β and IFN-stimulated genes, as well as stronger antiviral immunity upon HSV60mer transfection or VACV infection. IFI16-iso2, with the ability of nuclear-cytoplasmic shuttling, clears both invaded HSV type 1 and VACV significantly. However, IFI16-iso2 induces more type I IFN-dependent antiviral immunity than IFI16-iso1 upon HSV60-DNLS transfection or HSV type 1 infection. Our study has developed potent agonists for nuclear DNA sensors and also has demonstrated that IFI16 isoforms with cytoplasmic and nuclear locations play differential roles in innate immunity against DNA viruses.
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Affiliation(s)
- Dapei Li
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; .,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Lifen Xie
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Zigang Qiao
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Jingfei Zhu
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Haiping Yao
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Suzhou Institute of Systems Medicine, Suzhou, China
| | - Yanghua Qin
- Department of Laboratory Diagnosis, Changhai Hospital of the Second Military Medical University, Shanghai, China; and
| | - Yongdong Yan
- Department of Pulmonary Medicine, Children's Hospital of Soochow University, Suzhou, 215025, China
| | - Zhengrong Chen
- Department of Pulmonary Medicine, Children's Hospital of Soochow University, Suzhou, 215025, China
| | - Feng Ma
- CAMS Key Laboratory of Synthetic Biology Regulatory Elements, Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; .,Suzhou Institute of Systems Medicine, Suzhou, China
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16
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Shen Q, Wang YE, Palazzo AF. Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection. J Biol Chem 2021; 297:100856. [PMID: 34097873 PMCID: PMC8254040 DOI: 10.1016/j.jbc.2021.100856] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/24/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.
| | - Yifan E Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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The Portal Vertex of KSHV Promotes Docking of Capsids at the Nuclear Pores. Viruses 2021; 13:v13040597. [PMID: 33807444 PMCID: PMC8065994 DOI: 10.3390/v13040597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a cancer-related herpesvirus. Like other herpesviruses, the KSHV icosahedral capsid includes a portal vertex, composed of 12 protein subunits encoded by open reading frame (ORF) 43, which enables packaging and release of the viral genome into the nucleus through the nuclear pore complex (NPC). Capsid vertex-specific component (CVSC) tegument proteins, which directly mediate docking at the NPCs, are organized on the capsid vertices and are enriched on the portal vertex. Whether and how the portal vertex is selected for docking at the NPC is unknown. Here, we investigated the docking of incoming ORF43-null KSHV capsids at the NPCs, and describe a significantly lower fraction of capsids attached to the nuclear envelope compared to wild-type (WT) capsids. Like WT capsids, nuclear envelope-associated ORF43-null capsids co-localized with different nucleoporins (Nups) and did not detach upon salt treatment. Inhibition of nuclear export did not alter WT capsid docking. As ORF43-null capsids exhibit lower extent of association with the NPCs, we conclude that although not essential, the portal has a role in mediating the interaction of the CVSC proteins with Nups, and suggest a model whereby WT capsids can dock at the nuclear envelope through a non-portal penton vertex, resulting in an infection 'dead end'.
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18
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Lee JH, Shim J, Kim SJ. Stunning symmetries involved in the self-assembly of the HSV-1 capsid. THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY 2021; 78:357-364. [PMID: 33584000 PMCID: PMC7871024 DOI: 10.1007/s40042-020-00044-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/29/2020] [Accepted: 10/29/2020] [Indexed: 06/12/2023]
Abstract
Herpes simplex virus-1 (HSV-1) is an enveloped dsDNA virus, infecting ~ 67% of humans. Here, we present the essential components of the HSV-1, focusing on stunning symmetries on the capsid. However, little is known about how the symmetries are involved dynamically in the self-assembly process. We suggest small angle X-ray scattering as a suitable method to capture the dynamics of self-assembly. Furthermore, our understanding of the viruses can be expanded by using an integrative approach that combines heterogeneous types of data, thus promoting new diagnostic tools and a cure for viral infections.
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Affiliation(s)
- Joo-hyeon Lee
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
| | - Jaehyu Shim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
| | - Seung Joong Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
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19
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Bauer M, Flatt JW, Seiler D, Cardel B, Emmenlauer M, Boucke K, Suomalainen M, Hemmi S, Greber UF. The E3 Ubiquitin Ligase Mind Bomb 1 Controls Adenovirus Genome Release at the Nuclear Pore Complex. Cell Rep 2020; 29:3785-3795.e8. [PMID: 31851912 DOI: 10.1016/j.celrep.2019.11.064] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/15/2019] [Accepted: 11/14/2019] [Indexed: 01/06/2023] Open
Abstract
Adenoviruses (AdVs) cause respiratory, ocular, and gastrointestinal tract infection and inflammation in immunocompetent people and life-threatening disease upon immunosuppression. AdV vectors are widely used in gene therapy and vaccination. Incoming particles attach to nuclear pore complexes (NPCs) of post-mitotic cells, then rupture and deliver viral DNA (vDNA) to the nucleus or misdeliver to the cytosol. Our genome-wide RNAi screen in AdV-infected cells identified the RING-type E3 ubiquitin ligase Mind bomb 1 (Mib1) as a proviral host factor for AdV infection. Mib1 is implicated in Notch-Delta signaling, ciliary biogenesis, and RNA innate immunity. Mib1 depletion arrested incoming AdVs at NPCs. Induced expression of full-length but not ligase-defective Mib1 in knockout cells triggered vDNA uncoating from NPC-tethered virions, nuclear import, misdelivery of vDNA, and vDNA expression. Mib1 is an essential host factor for AdV uncoating in human cells, and it provides a new concept for licensing virion DNA delivery through the NPC.
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Affiliation(s)
- Michael Bauer
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland; Life Science Zurich Graduate School, ETH and University of Zurich, 8057 Zurich, Switzerland
| | - Justin W Flatt
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland; Institute of Biotechnology, University of Helsinki, 00790 Helsinki, Finland; Department of Biosciences, University of Helsinki, 00790 Helsinki, Finland
| | - Daria Seiler
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Bettina Cardel
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | | | - Karin Boucke
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Maarit Suomalainen
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Silvio Hemmi
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Urs F Greber
- Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.
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20
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Masucci MG. Viral Ubiquitin and Ubiquitin-Like Deconjugases-Swiss Army Knives for Infection. Biomolecules 2020; 10:E1137. [PMID: 32752270 PMCID: PMC7464072 DOI: 10.3390/biom10081137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 12/16/2022] Open
Abstract
Posttranslational modifications of cellular proteins by covalent conjugation of ubiquitin and ubiquitin-like polypeptides regulate numerous cellular processes that are captured by viruses to promote infection, replication, and spreading. The importance of these protein modifications for the viral life cycle is underscored by the discovery that many viruses encode deconjugases that reverse their functions. The structural and functional characterization of these viral enzymes and the identification of their viral and cellular substrates is providing valuable insights into the biology of viral infections and the host's antiviral defense. Given the growing body of evidence demonstrating their key contribution to pathogenesis, the viral deconjugases are now recognized as attractive targets for the design of novel antiviral therapeutics.
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Affiliation(s)
- Maria Grazia Masucci
- Department of Cell and Molecular Biology, Karolinska Institutet, S-17177 Stockholm, Sweden
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21
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Diwaker D, Wilson DW. Microtubule-Dependent Trafficking of Alphaherpesviruses in the Nervous System: The Ins and Outs. Viruses 2019; 11:v11121165. [PMID: 31861082 PMCID: PMC6950448 DOI: 10.3390/v11121165] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/13/2019] [Accepted: 12/15/2019] [Indexed: 12/12/2022] Open
Abstract
The Alphaherpesvirinae include the neurotropic pathogens herpes simplex virus and varicella zoster virus of humans and pseudorabies virus of swine. These viruses establish lifelong latency in the nuclei of peripheral ganglia, but utilize the peripheral tissues those neurons innervate for productive replication, spread, and transmission. Delivery of virions from replicative pools to the sites of latency requires microtubule-directed retrograde axonal transport from the nerve terminus to the cell body of the sensory neuron. As a corollary, during reactivation newly assembled virions must travel along axonal microtubules in the anterograde direction to return to the nerve terminus and infect peripheral tissues, completing the cycle. Neurotropic alphaherpesviruses can therefore exploit neuronal microtubules and motors for long distance axonal transport, and alternate between periods of sustained plus end- and minus end-directed motion at different stages of their infectious cycle. This review summarizes our current understanding of the molecular details by which this is achieved.
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Affiliation(s)
- Drishya Diwaker
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
| | - Duncan W. Wilson
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
- Correspondence: ; Tel.: +1-(718)-430-2305
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22
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MXB inhibits murine cytomegalovirus. Virology 2018; 522:158-167. [DOI: 10.1016/j.virol.2018.07.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/09/2018] [Accepted: 07/13/2018] [Indexed: 01/02/2023]
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23
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Infection and Transport of Herpes Simplex Virus Type 1 in Neurons: Role of the Cytoskeleton. Viruses 2018; 10:v10020092. [PMID: 29473915 PMCID: PMC5850399 DOI: 10.3390/v10020092] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 02/16/2018] [Accepted: 02/20/2018] [Indexed: 12/22/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) is a neuroinvasive human pathogen that has the ability to infect and replicate within epithelial cells and neurons and establish a life-long latent infection in sensory neurons. HSV-1 depends on the host cellular cytoskeleton for entry, replication, and exit. Therefore, HSV-1 has adapted mechanisms to promote its survival by exploiting the microtubule and actin cytoskeletons to direct its active transport, infection, and spread between neurons and epithelial cells during primary and recurrent infections. This review will focus on the currently known mechanisms utilized by HSV-1 to harness the neuronal cytoskeleton, molecular motors, and the secretory and exocytic pathways for efficient virus entry, axonal transport, replication, assembly, and exit from the distinct functional compartments (cell body and axon) of the highly polarized sensory neurons.
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24
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Wu XM, Chen QY, Chen RJ, Che YL, Wang LB, Wang CY, Yan S, Liu YT, Xiu JS, Zhou LJ. Pathogenicity and Whole Genome Sequence Analysis of a Pseudorabies Virus Strain FJ-2012 Isolated from Fujian, Southern China. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2017; 2017:9073172. [PMID: 29527230 PMCID: PMC5804112 DOI: 10.1155/2017/9073172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 09/18/2017] [Accepted: 09/26/2017] [Indexed: 01/03/2023]
Abstract
The outbreaks of pseudorabies have been frequently reported in Bartha-K61-vaccinated farms in China since 2011. To study the pathogenicity and evolution of the circulating pseudorabies viruses in Fujian Province, mainland China, we isolated and sequenced the whole genome of a wild-type pseudorabies virus strain named "FJ-2012." We then conducted a few downstream bioinformatics analyses including phylogenetic analysis and pathogenic analysis and used the virus to infect 6 pseudorabies virus-free piglets. FJ-2012-infected piglets developed symptoms like high body temperature and central nervous system disorders and had high mortality rate. In addition, we identified typical micropathological changes such as multiple gross lesions in infected piglets through pathological analysis and conclude that the FJ-2012 genome is significantly different from known pseudorabies viruses, in which insertions, deletions, and substitutions are observed in multiple immune and virulence genes. In summary, this study shed lights on the molecular basis of the prevalence and pathology of the pseudorabies virus strain FJ-2012. The genome of FJ-2012 could be used as a reference to study the evolution of pseudorabies viruses, which is critical to the vaccine development of new emerging pseudorabies viruses.
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Affiliation(s)
- Xue-min Wu
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Qiu-yong Chen
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Ru-jing Chen
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Yong-liang Che
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Long-bai Wang
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Chen-yan Wang
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Shan Yan
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Yu-tao Liu
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
| | - Jin-sheng Xiu
- College of Animal Sciences, Fujian Agricultural and Forestry University, Fuzhou, Fujian 350002, China
| | - Lun-jiang Zhou
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences/Fujian Animal Disease Control Technology Development Center, Fuzhou 350013, China
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25
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Richards AL, Sollars PJ, Pitts JD, Stults AM, Heldwein EE, Pickard GE, Smith GA. The pUL37 tegument protein guides alpha-herpesvirus retrograde axonal transport to promote neuroinvasion. PLoS Pathog 2017; 13:e1006741. [PMID: 29216315 PMCID: PMC5749899 DOI: 10.1371/journal.ppat.1006741] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/02/2018] [Accepted: 11/10/2017] [Indexed: 01/07/2023] Open
Abstract
A hallmark property of the neurotropic alpha-herpesvirinae is the dissemination of infection to sensory and autonomic ganglia of the peripheral nervous system following an initial exposure at mucosal surfaces. The peripheral ganglia serve as the latent virus reservoir and the source of recurrent infections such as cold sores (herpes simplex virus type I) and shingles (varicella zoster virus). However, the means by which these viruses routinely invade the nervous system is not fully understood. We report that an internal virion component, the pUL37 tegument protein, has a surface region that is an essential neuroinvasion effector. Mutation of this region rendered herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV) incapable of spreading by retrograde axonal transport to peripheral ganglia both in culture and animals. By monitoring the axonal transport of individual viral particles by time-lapse fluorescence microscopy, the mutant viruses were determined to lack the characteristic sustained intracellular capsid motion along microtubules that normally traffics capsids to the neural soma. Consistent with the axonal transport deficit, the mutant viruses did not reach sites of latency in peripheral ganglia, and were avirulent. Despite this, viral propagation in peripheral tissues and in cultured epithelial cell lines remained robust. Selective elimination of retrograde delivery to the nervous system has long been sought after as a means to develop vaccines against these ubiquitous, and sometimes devastating viruses. In support of this potential, we find that HSV-1 and PRV mutated in the effector region of pUL37 evoked effective vaccination against subsequent nervous system challenges and encephalitic disease. These findings demonstrate that retrograde axonal transport of the herpesviruses occurs by a virus-directed mechanism that operates by coordinating opposing microtubule motors to favor sustained retrograde delivery of the virus to the peripheral ganglia. The ability to selectively eliminate the retrograde axonal transport mechanism from these viruses will be useful in trans-synaptic mapping studies of the mammalian nervous system, and affords a new vaccination paradigm for human and veterinary neurotropic herpesviruses.
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MESH Headings
- Amino Acid Sequence
- Animals
- Axonal Transport/genetics
- Axonal Transport/physiology
- Axons/virology
- Ganglia/virology
- Genes, Viral
- Herpesvirus 1, Human/genetics
- Herpesvirus 1, Human/pathogenicity
- Herpesvirus 1, Human/physiology
- Herpesvirus 1, Suid/genetics
- Herpesvirus 1, Suid/pathogenicity
- Herpesvirus 1, Suid/physiology
- Host-Pathogen Interactions/genetics
- Host-Pathogen Interactions/physiology
- Humans
- Male
- Mice
- Mice, Inbred DBA
- Models, Molecular
- Mutation
- Neurons/virology
- Rats
- Rats, Long-Evans
- Viral Structural Proteins/chemistry
- Viral Structural Proteins/genetics
- Viral Structural Proteins/physiology
- Viral Vaccines/genetics
- Virulence/genetics
- Virulence/physiology
- Virus Release/genetics
- Virus Release/physiology
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Affiliation(s)
- Alexsia L. Richards
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Patricia J. Sollars
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Jared D. Pitts
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Austin M. Stults
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Ekaterina E. Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Gary E. Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska
| | - Gregory A. Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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26
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Ralph M, Bednarchik M, Tomer E, Rafael D, Zargarian S, Gerlic M, Kobiler O. Promoting Simultaneous Onset of Viral Gene Expression Among Cells Infected with Herpes Simplex Virus-1. Front Microbiol 2017; 8:2152. [PMID: 29163436 PMCID: PMC5671993 DOI: 10.3389/fmicb.2017.02152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 10/20/2017] [Indexed: 11/30/2022] Open
Abstract
Synchronous viral infection facilitates the study of viral gene expression, viral host interactions, and viral replication processes. However, the protocols for achieving synchronous infections were hardly ever tested in proper temporal resolution at the single-cell level. We set up a fluorescence-based, time lapse microscopy assay to study sources of variability in the timing of gene expression during herpes simplex virus-1 (HSV-1) infection. We found that with the common protocol, the onset of gene expression within different cells can vary by more than 3 h. We showed that simultaneous viral genome entry to the nucleus can be achieved with a derivative of the previously characterized temperature sensitive mutant tsB7, however, this did not improve gene expression synchrony. We found that elevating the temperature in which the infection is done and increasing the multiplicity of infection (MOI) significantly promoted simultaneous onset of viral gene expression among infected cells. Further, elevated temperature result in a decrease in the coefficient of variation (a standardized measure of dispersion) of viral replication compartments (RCs) sizes among cells as well as a slight increment of viral late gene expression synchrony. We conclude that simultaneous viral gene expression can be improved by simple modifications to the infection process and may reduce the effect of single-cell variability on population-based assays.
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Affiliation(s)
| | | | | | | | | | | | - Oren Kobiler
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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27
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Liu YT, Jiang J, Bohannon KP, Dai X, Gant Luxton GW, Hui WH, Bi GQ, Smith GA, Zhou ZH. A pUL25 dimer interfaces the pseudorabies virus capsid and tegument. J Gen Virol 2017; 98:2837-2849. [PMID: 29035172 DOI: 10.1099/jgv.0.000903] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inside the virions of α-herpesviruses, tegument protein pUL25 anchors the tegument to capsid vertices through direct interactions with tegument proteins pUL17 and pUL36. In addition to promoting virion assembly, both pUL25 and pUL36 are critical for intracellular microtubule-dependent capsid transport. Despite these essential roles during infection, the stoichiometry and precise organization of pUL25 and pUL36 on the capsid surface remain controversial due to the insufficient resolution of existing reconstructions from cryo-electron microscopy (cryoEM). Here, we report a three-dimensional (3D) icosahedral reconstruction of pseudorabies virus (PRV), a varicellovirus of the α-herpesvirinae subfamily, obtained by electron-counting cryoEM at 4.9 Å resolution. Our reconstruction resolves a dimer of pUL25 forming a capsid-associated tegument complex with pUL36 and pUL17 through a coiled coil helix bundle, thus correcting previous misinterpretations. A comparison between reconstructions of PRV and the γ-herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV) reinforces their similar architectures and establishes important subfamily differences in the capsid-tegument interface.
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Affiliation(s)
- Yun-Tao Liu
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.,Center for Integrative Imaging, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Brain Science and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, PR China
| | - Jiansen Jiang
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.,California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Kevin Patrick Bohannon
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA.,Present address: Department of Pharmacology, University of Michigan Medical School, University of Michigan, Ann Arbor, MI, USA
| | - Xinghong Dai
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.,California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - G W Gant Luxton
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA.,Present address: College of Biological Sciences, University of Minnesota, 420 Washington, Avenue SE, Minneapolis, MN 55455, USA
| | - Wong Hoi Hui
- California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Guo-Qiang Bi
- Center for Integrative Imaging, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Brain Science and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, PR China
| | - Gregory Allan Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.,California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
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The C Terminus of the Herpes Simplex Virus UL25 Protein Is Required for Release of Viral Genomes from Capsids Bound to Nuclear Pores. J Virol 2017; 91:JVI.00641-17. [PMID: 28490590 DOI: 10.1128/jvi.00641-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 05/03/2017] [Indexed: 12/27/2022] Open
Abstract
The herpes simplex virus (HSV) capsid is released into the cytoplasm after fusion of viral and host membranes, whereupon dynein-dependent trafficking along microtubules targets it to the nuclear envelope. Binding of the capsid to the nuclear pore complex (NPC) is mediated by the capsid protein pUL25 and the capsid-tethered tegument protein pUL36. Temperature-sensitive mutants in both pUL25 and pUL36 dock at the NPC but fail to release DNA. The uncoating reaction has been difficult to study due to the rapid release of the genome once the capsid interacts with the nuclear pore. In this study, we describe the isolation and characterization of a truncation mutant of pUL25. Live-cell imaging and immunofluorescence studies demonstrated that the mutant was not impaired in penetration of the host cell or in trafficking of the capsid to the nuclear membrane. However, expression of viral proteins was absent or significantly delayed in cells infected with the pUL25 mutant virus. Transmission electron microscopy revealed capsids accumulated at nuclear pores that retained the viral genome for at least 4 h postinfection. In addition, cryoelectron microscopy (cryo-EM) reconstructions of virion capsids did not detect any obvious differences in the location or structural organization for the pUL25 or pUL36 proteins on the pUL25 mutant capsids. Further, in contrast to wild-type virus, the antiviral response mediated by the viral DNA-sensing cyclic guanine adenine synthase (cGAS) was severely compromised for the pUL25 mutant. These results demonstrate that the pUL25 capsid protein has a critical role in releasing viral DNA from NPC-bound capsids.IMPORTANCE Herpes simplex virus 1 (HSV-1) is the causative agent of several pathologies ranging in severity from the common cold sore to life-threatening encephalitic infection. Early steps in infection include release of the capsid into the cytoplasm, docking of the capsid at a nuclear pore, and release of the viral genome into the nucleus. A key knowledge gap is how the capsid engages the NPC and what triggers release of the viral genome into the nucleus. Here we show that the C-terminal region of the HSV-1 pUL25 protein is required for releasing the viral genome from capsids docked at nuclear pores. The significance of our research is in identifying pUL25 as a key viral factor for genome uncoating. pUL25 is found at each of the capsid vertices as part of the capsid vertex-specific component and implicates the importance of this complex for NPC binding and genome release.
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Flatt JW, Greber UF. Viral mechanisms for docking and delivering at nuclear pore complexes. Semin Cell Dev Biol 2017; 68:59-71. [PMID: 28506891 DOI: 10.1016/j.semcdb.2017.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 05/11/2017] [Indexed: 12/22/2022]
Abstract
Some viruses possess the remarkable ability to transport their genomes across nuclear pore complexes (NPCs) for replication inside the host cell's intact nuclear compartment. Viral mechanisms for crossing the restrictive NPC passageway are highly complex and astonishingly diverse, requiring in each case stepwise interaction between incoming virus particles and components of the nuclear transport machinery. Exactly how a large viral genome loaded with accessory proteins is able to pass through the relatively narrow central channel of the NPC without causing catastrophic structural damage is not yet fully understood. It appears likely, however, that the overall structure of the NPC changes in response to the cargo. Translocation may result in nucleic acids being misdelivered to the cytoplasm. Here we consider in detail the diverse strategies that viruses have evolved to target and subvert NPCs during infection. For decades, this process has both captivated and confounded researchers in the fields of virology, cell biology, and structural biology.
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Affiliation(s)
- Justin W Flatt
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Urs F Greber
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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30
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Nuclear Import of Hepatitis B Virus Capsids and Genome. Viruses 2017; 9:v9010021. [PMID: 28117723 PMCID: PMC5294990 DOI: 10.3390/v9010021] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 02/07/2023] Open
Abstract
Hepatitis B virus (HBV) is an enveloped pararetrovirus with a DNA genome, which is found in an up to 36 nm-measuring capsid. Replication of the genome occurs via an RNA intermediate, which is synthesized in the nucleus. The virus must have thus ways of transporting its DNA genome into this compartment. This review summarizes the data on hepatitis B virus genome transport and correlates the finding to those from other viruses.
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31
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Assembly and Egress of an Alphaherpesvirus Clockwork. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 223:171-193. [PMID: 28528444 PMCID: PMC5768427 DOI: 10.1007/978-3-319-53168-7_8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
All viruses produce infectious particles that possess some degree of stability in the extracellular environment yet disassemble upon cell contact and entry. For the alphaherpesviruses, which include many neuroinvasive viruses of mammals, these metastable virions consist of an icosahedral capsid surrounded by a protein matrix (referred to as the tegument) and a lipid envelope studded with glycoproteins. Whereas the capsid of these viruses is a rigid structure encasing the DNA genome, the tegument and envelope are dynamic assemblies that orchestrate a sequential series of events that ends with the delivery of the genome into the nucleus. These particles are adapted to infect two different polarized cell types in their hosts: epithelial cells and neurons of the peripheral nervous system. This review considers how the virion is assembled into a primed state and is targeted to infect these cell types such that the incoming particles can subsequently negotiate the diverse environments they encounter on their way from plasma membrane to nucleus and thereby achieve their remarkably robust neuroinvasive infectious cycle.
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Conserved Tryptophan Motifs in the Large Tegument Protein pUL36 Are Required for Efficient Secondary Envelopment of Herpes Simplex Virus Capsids. J Virol 2016; 90:5368-5383. [PMID: 27009950 DOI: 10.1128/jvi.03167-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/15/2016] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED Herpes simplex virus (HSV) replicates in the skin and mucous membranes, and initiates lytic or latent infections in sensory neurons. Assembly of progeny virions depends on the essential large tegument protein pUL36 of 3,164 amino acid residues that links the capsids to the tegument proteins pUL37 and VP16. Of the 32 tryptophans of HSV-1-pUL36, the tryptophan-acidic motifs (1766)WD(1767) and (1862)WE(1863) are conserved in all HSV-1 and HSV-2 isolates. Here, we characterized the role of these motifs in the HSV life cycle since the rare tryptophans often have unique roles in protein function due to their large hydrophobic surface. The infectivity of the mutants HSV-1(17(+))Lox-pUL36-WD/AA-WE/AA and HSV-1(17(+))Lox-CheVP26-pUL36-WD/AA-WE/AA, in which the capsid has been tagged with the fluorescent protein Cherry, was significantly reduced. Quantitative electron microscopy shows that there were a larger number of cytosolic capsids and fewer enveloped virions compared to their respective parental strains, indicating a severe impairment in secondary capsid envelopment. The capsids of the mutant viruses accumulated in the perinuclear region around the microtubule-organizing center and were not dispersed to the cell periphery but still acquired the inner tegument proteins pUL36 and pUL37. Furthermore, cytoplasmic capsids colocalized with tegument protein VP16 and, to some extent, with tegument protein VP22 but not with the envelope glycoprotein gD. These results indicate that the unique conserved tryptophan-acidic motifs in the central region of pUL36 are required for efficient targeting of progeny capsids to the membranes of secondary capsid envelopment and for efficient virion assembly. IMPORTANCE Herpesvirus infections give rise to severe animal and human diseases, especially in young, immunocompromised, and elderly individuals. The structural hallmark of herpesvirus virions is the tegument, which contains evolutionarily conserved proteins that are essential for several stages of the herpesvirus life cycle. Here we characterized two conserved tryptophan-acidic motifs in the central region of the large tegument protein pUL36 of herpes simplex virus. When we mutated these motifs, secondary envelopment of cytosolic capsids and the production of infectious particles were severely impaired. Our data suggest that pUL36 and its homologs in other herpesviruses, and in particular such tryptophan-acidic motifs, could provide attractive targets for the development of novel drugs to prevent herpesvirus assembly and spread.
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Yamauchi Y, Greber UF. Principles of Virus Uncoating: Cues and the Snooker Ball. Traffic 2016; 17:569-92. [PMID: 26875443 PMCID: PMC7169695 DOI: 10.1111/tra.12387] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/10/2016] [Accepted: 02/10/2016] [Indexed: 12/17/2022]
Abstract
Viruses are spherical or complex shaped carriers of proteins, nucleic acids and sometimes lipids and sugars. They are metastable and poised for structural changes. These features allow viruses to communicate with host cells during entry, and to release the viral genome, a process known as uncoating. Studies have shown that hundreds of host factors directly or indirectly support this process. The cell provides molecules that promote stepwise virus uncoating, and direct the virus to the site of replication. It acts akin to a snooker player who delivers accurate and timely shots (cues) to the ball (virus) to score. The viruses, on the other hand, trick (snooker) the host, hijack its homeostasis systems, and dampen innate immune responses directed against danger signals. In this review, we discuss how cellular cues, facilitators, and built‐in viral mechanisms promote uncoating. Cues come from receptors, enzymes and chemicals that act directly on the virus particle to alter its structure, trafficking and infectivity. Facilitators are defined as host factors that are involved in processes which indirectly enhance entry or uncoating. Unraveling the mechanisms of virus uncoating will continue to enhance understanding of cell functions, and help counteracting infections with chemicals and vaccines.
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Affiliation(s)
- Yohei Yamauchi
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Urs F Greber
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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34
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Jovasevic V, Naghavi MH, Walsh D. Microtubule plus end-associated CLIP-170 initiates HSV-1 retrograde transport in primary human cells. J Cell Biol 2016; 211:323-37. [PMID: 26504169 PMCID: PMC4621836 DOI: 10.1083/jcb.201505123] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Herpes simplex virus particles that enter the cell do not randomly associate with microtubule filaments, but require plus end–binding proteins EB1, CLIP-170, and dynactin to initiate retrograde transport to the nucleus. Dynamic microtubules (MTs) continuously explore the intracellular environment and, through specialized plus end–tracking proteins (+TIPs), engage a variety of targets. However, the nature of cargoes that require +TIP-mediated capture for their movement on MTs remains poorly understood. Using RNA interference and dominant-negative approaches, combined with live cell imaging, we show that herpes simplex virus particles that have entered primary human cells exploit a +TIP complex comprising end-binding protein 1 (EB1), cytoplasmic linker protein 170 (CLIP-170), and dynactin-1 (DCTN1) to initiate retrograde transport. Depletion of these +TIPs completely blocked post-entry long-range transport of virus particles and suppressed infection ∼5,000-fold, whereas transferrin uptake, early endosome organization, and dynein-dependent movement of lysosomes and mitochondria remained unaffected. These findings provide the first insights into the earliest stages of viral engagement of MTs through specific +TIPs, akin to receptors, with therapeutic implications, and identify herpesvirus particles as one of a very limited number of cargoes absolutely dependent on CLIP-170–mediated capture to initiate transport in primary human cells.
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Affiliation(s)
- Vladimir Jovasevic
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Derek Walsh
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 Department of Microbiology, School of Medicine, New York University, New York, NY 10016
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35
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Involvement of the N-Terminal Deubiquitinating Protease Domain of Human Cytomegalovirus UL48 Tegument Protein in Autoubiquitination, Virion Stability, and Virus Entry. J Virol 2016; 90:3229-42. [PMID: 26764006 DOI: 10.1128/jvi.02766-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/05/2016] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Human cytomegalovirus (HCMV) protein pUL48 is closely associated with the capsid and has a deubiquitinating protease (DUB) activity in its N-terminal region. Although this DUB activity moderately increases virus replication in cultured fibroblast cells, the requirements of the N-terminal region of pUL48 in the viral replication cycle are not fully understood. In this study, we characterized the recombinant viruses encoding UL48(ΔDUB/NLS), which lacks the DUB domain and the adjacent nuclear localization signal (NLS), UL48(ΔDUB), which lacks only the DUB, and UL48(Δ360-1200), which lacks the internal region (amino acids 360 to 1200) downstream of the DUB/NLS. While ΔDUB/NLS and Δ360-1200 mutant viruses did not grow in fibroblasts, the ΔDUB virus replicated to titers 100-fold lower than those for wild-type virus and showed substantially reduced viral gene expression at low multiplicities of infection. The DUB domain contained ubiquitination sites, and DUB activity reduced its own proteasomal degradation in trans. Deletion of the DUB domain did not affect the nuclear and cytoplasmic localization of pUL48, whereas the internal region (360-1200) was necessary for cytoplasmic distribution. In coimmunoprecipitation assays, pUL48 interacted with three tegument proteins (pUL47, pUL45, and pUL88) and two capsid proteins (pUL77 and pUL85) but the DUB domain contributed to only pUL85 binding. Furthermore, we found that the ΔDUB virus showed reduced virion stability and less efficiently delivered its genome into the cell than the wild-type virus. Collectively, our results demonstrate that the N-terminal DUB domain of pUL48 contributes to efficient viral growth by regulating its own stability and promoting virion stabilization and virus entry. IMPORTANCE HCMV pUL48 and its herpesvirus homologs play key roles in virus entry, regulation of immune signaling pathways, and virion assembly. The N terminus of pUL48 contains the DUB domain, which is well conserved among all herpesviruses. Although studies using the active-site mutant viruses revealed that the DUB activity promotes viral growth, the exact role of this region in the viral life cycle is not fully understood. In this study, using the mutant virus lacking the entire DUB domain, we demonstrate that the DUB domain of pUL48 contributes to viral growth by regulating its own stability via autodeubiquitination and promoting virion stability and virus entry. This report is the first to demonstrate the characteristics of the mutant virus with the entire DUB domain deleted, which, along with information on the functions of this region, is useful in dissecting the functions associated with pUL48.
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36
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Mettenleiter TC. Breaching the Barrier-The Nuclear Envelope in Virus Infection. J Mol Biol 2015; 428:1949-61. [PMID: 26522933 DOI: 10.1016/j.jmb.2015.10.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 09/22/2015] [Accepted: 10/04/2015] [Indexed: 11/16/2022]
Abstract
Many DNA and a few RNA viruses use the host cell nucleus for virion formation and/or genome replication. To this end, the nuclear envelope (NE) barrier has to be overcome for entry into and egress from the intranuclear replication compartment. Different virus families have devised ingenious ways of entering and leaving the nucleus usurping cellular transport pathways through the nuclear pore complex but also translocating directly through both membranes of the NE. This intriguing diversity in nuclear entry and egress of viruses also highlights different ways nucleocytoplasmic transport can occur. Thus, the study of interactions between viruses and the NE also helps to unravel hitherto unknown cellular pathways such as vesicular nucleocytoplasmic transfer.
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Affiliation(s)
- Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany.
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37
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Nakashima H, Kaufmann JK, Wang PY, Nguyen T, Speranza MC, Kasai K, Okemoto K, Otsuki A, Nakano I, Fernandez S, Goins WF, Grandi P, Glorioso JC, Lawler S, Cripe TP, Chiocca EA. Histone deacetylase 6 inhibition enhances oncolytic viral replication in glioma. J Clin Invest 2015; 125:4269-80. [PMID: 26524593 DOI: 10.1172/jci80713] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 09/10/2015] [Indexed: 12/15/2022] Open
Abstract
Oncolytic viral (OV) therapy, which uses genetically engineered tumor-targeting viruses, is being increasingly used in cancer clinical trials due to the direct cytolytic effects of this treatment that appear to provoke a robust immune response against the tumor. As OVs enter tumor cells, intrinsic host defenses have the potential to hinder viral replication and spread within the tumor mass. In this report, we show that histone deacetylase 6 (HDAC6) in tumor cells appears to alter the trafficking of post-entry OVs from the nucleus toward lysosomes. In glioma cell lines and glioma-stem-like cells, HDAC6 inhibition (HDAC6i) by either pharmacologic or genetic means substantially increased replication of oncolytic herpes simplex virus type 1 (oHSV). Moreover, HDAC6i increased shuttling of post-entry oHSV to the nucleus. In addition, electron microscopic analysis revealed that post-entry oHSVs are preferentially taken up into glioma cells through the endosomal pathway rather than via fusion at the cell surface. Together, these findings illustrate a mechanism of glioma cell defense against an incoming infection by oHSV and identify possible approaches to enhance oHSV replication and subsequent lysis of tumor cells.
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Abstract
Neuroinvasive herpesviruses display a remarkable propensity to enter the nervous system of healthy individuals in the absence of obvious trauma at the site of inoculation. We document a repurposing of cellular ubiquitin during infection to switch the virus between two invasive states. The states act sequentially to defeat consecutive host barriers of the peripheral nervous system and together promote the potent neuroinvasive phenotype. The first state directs virus access to nerve endings in peripheral tissue, whereas the second delivers virus particles within nerve fibers to the neural ganglia. Mutant viruses locked in either state remain competent to overcome the corresponding barrier but fail to invade the nervous system. The herpesvirus "ubiquitin switch" may explain the unusual ability of these viruses to routinely enter the nervous system and, as a consequence, their prevalence in human and veterinary hosts.
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Herpes Simplex Virus Capsid-Organelle Association in the Absence of the Large Tegument Protein UL36p. J Virol 2015; 89:11372-82. [PMID: 26339048 DOI: 10.1128/jvi.01893-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 08/25/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED UL36p (VP1/2) is the largest protein encoded by herpes simplex virus 1 (HSV-1) and resides in the innermost layer of the viral tegument, lying between the capsid and the envelope. UL36p performs multiple functions in the HSV life cycle, including an essential role in cytoplasmic envelopment. We earlier described the isolation of a virion-associated cytoplasmic membrane fraction from HSV-infected cells. Biochemical and ultrastructural analyses showed that the organelles in this buoyant fraction contain enveloped infectious HSV particles in their lumens and naked capsids docked to their cytoplasmic surfaces. These organelles can also recruit molecular motors and transport their cargo virions along microtubules in vitro. Here we examine the properties of these HSV-associated organelles in the absence of UL36p. We find that while capsid envelopment is clearly defective, a subpopulation of capsids nevertheless still associate with the cytoplasmic faces of these organelles. The existence of these capsid-membrane structures was confirmed by subcellular fractionation, immunocytochemistry, lipophilic dye fluorescence microscopy, thin-section electron microscopy, and correlative light and electron microscopy. We conclude that capsid-membrane binding can occur in the absence of UL36p and propose that this association may precede the events of UL36p-driven envelopment. IMPORTANCE Membrane association and envelopment of the HSV capsid are essential for the assembly of an infectious virion. Envelopment involves the complex interplay of a large number of viral and cellular proteins; however, the function of most of them is unknown. One example of this is the viral protein UL36p, which is clearly essential for envelopment but plays a poorly understood role. Here we demonstrate that organelles utilized for HSV capsid envelopment still accumulate surface-bound capsids in the absence of UL36p. We propose that UL36p-independent binding of capsids to organelles occurs prior to the function of UL36p in capsid envelopment.
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40
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Genomic characterization of emergent pseudorabies virus in China reveals marked sequence divergence: Evidence for the existence of two major genotypes. Virology 2015; 483:32-43. [DOI: 10.1016/j.virol.2015.04.013] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 02/08/2015] [Accepted: 04/11/2015] [Indexed: 01/13/2023]
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41
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Abstract
Many viruses deliver their genomes into the host cell’s nucleus before they replicate. While onco-retroviruses and papillomaviruses tether their genomes to host chromatin upon mitotic breakdown of the nuclear envelope, lentiviruses, such as human immunodeficiency virus, adenoviruses, herpesviruses, parvoviruses, influenza viruses, hepatitis B virus, polyomaviruses, and baculoviruses deliver their genomes into the nucleus of post-mitotic cells. This poses the significant challenge of slipping a DNA or RNA genome past the nuclear pore complex (NPC) embedded in the nuclear envelope. Quantitative fluorescence imaging is shedding new light on this process, with recent data implicating misdelivery of viral genomes at nuclear pores as a bottleneck to virus replication. Here, we infer NPC functions for nuclear import of viral genomes from cell biology experiments and explore potential causes of misdelivery, including improper virus docking at NPCs, incomplete translocation, virus-induced stress and innate immunity reactions. We conclude by discussing consequences of viral genome misdelivery for viruses and host cells, and lay out future questions to enhance our understanding of this phenomenon. Further studies into viral genome misdelivery may reveal unexpected aspects about NPC structure and function, as well as aid in developing strategies for controlling viral infections to improve human health.
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Abstract
DNA viruses undertake their replication within the cell nucleus, and therefore they must first deliver their genome into the nucleus of their host cells. Thus, trafficking across the nuclear envelope is at the basis of DNA virus infections. Nuclear transport of molecules with diameters up to 39 nm is a tightly regulated process that occurs through the nuclear pore complex (NPC). Due to the enormous diversity of virus size and structure, each virus has developed its own strategy for entering the nucleus of their host cells, with no two strategies alike. For example, baculoviruses target their DNA-containing capsid to the NPC and subsequently enter the nucleus intact, while the hepatitis B virus capsid crosses the NPC but disassembles at the nuclear side of the NPC. For other viruses such as herpes simplex virus and adenovirus, although both dock at the NPC, they have each developed a distinct mechanism for the subsequent delivery of their genome into the nucleus. Remarkably, other DNA viruses, such as parvoviruses and human papillomaviruses, access the nucleus through an NPC-independent mechanism. This review discusses our current understanding of the mechanisms used by DNA viruses to deliver their genome into the nucleus, and further presents the experimental evidence for such mechanisms.
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Affiliation(s)
- Nikta Fay
- Department of Zoology, University of British Columbia Vancouver, BC, Canada
| | - Nelly Panté
- Department of Zoology, University of British Columbia Vancouver, BC, Canada
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43
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Abstract
Virus genomes are condensed and packaged inside stable proteinaceous capsids that serve to protect them during transit from one cell or host organism, to the next. During virus entry, capsid shells are primed and disassembled in a complex, tightly-regulated, multi-step process termed uncoating. Here we compare the uncoating-programs of DNA viruses of the pox-, herpes-, adeno-, polyoma-, and papillomavirus families. Highlighting the chemical and mechanical cues virus capsids respond to, we review the conformational changes that occur during stepwise disassembly of virus capsids and how these culminate in the release of viral genomes at the right time and cellular location to assure successful replication.
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44
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Scrima N, Lepault J, Boulard Y, Pasdeloup D, Bressanelli S, Roche S. Insights into herpesvirus tegument organization from structural analyses of the 970 central residues of HSV-1 UL36 protein. J Biol Chem 2015; 290:8820-33. [PMID: 25678705 DOI: 10.1074/jbc.m114.612838] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Indexed: 11/06/2022] Open
Abstract
The tegument of all herpesviruses contains a capsid-bound large protein that is essential for multiple viral processes, including capsid transport, decapsidation at the nuclear pore complex, particle assembly, and secondary envelopment, through mechanisms that are still incompletely understood. We report here a structural characterization of the central 970 residues of this protein for herpes simplex virus type 1 (HSV-1 UL36, 3164 residues). This large fragment is essentially a 34-nm-long monomeric fiber. The crystal structure of its C terminus shows an elongated domain-swapped dimer. Modeling and molecular dynamics simulations give a likely molecular organization for the monomeric form and extend our findings to alphaherpesvirinae. Hence, we propose that an essential feature of UL36 is the existence in its central region of a stalk capable of connecting capsid and membrane across the tegument and that the ability to switch between monomeric and dimeric forms may help UL36 fulfill its multiple functions.
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Affiliation(s)
- Nathalie Scrima
- From the Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette
| | - Jean Lepault
- From the Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette
| | - Yves Boulard
- From the Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, the Institute of Biology and Technologies of Saclay, Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, and
| | - David Pasdeloup
- the Faculté de Pharmacie, INSERM UMR 984, 5 Rue J. B. Clément, 92290 Châtenay-Malabry, France
| | - Stéphane Bressanelli
- From the Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette,
| | - Stéphane Roche
- From the Institute for Integrative Biology of the Cell (I2BC), 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette,
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Kukhanova MK, Korovina AN, Kochetkov SN. Human herpes simplex virus: Life cycle and development of inhibitors. BIOCHEMISTRY (MOSCOW) 2015; 79:1635-52. [DOI: 10.1134/s0006297914130124] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Anderson F, Savulescu AF, Rudolph K, Schipke J, Cohen I, Ibiricu I, Rotem A, Grünewald K, Sodeik B, Harel A. Targeting of viral capsids to nuclear pores in a cell-free reconstitution system. Traffic 2014; 15:1266-81. [PMID: 25131140 DOI: 10.1111/tra.12209] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 08/13/2014] [Accepted: 08/13/2014] [Indexed: 11/28/2022]
Abstract
Many viruses deliver their genomes into the nucleoplasm for viral transcription and replication. Here, we describe a novel cell-free system to elucidate specific interactions between viruses and nuclear pore complexes (NPCs). Nuclei reconstituted in vitro from egg extracts of Xenopus laevis, an established biochemical system to decipher nuclear functions, were incubated with GFP-tagged capsids of herpes simplex virus, an alphaherpesvirus replicating in the nucleus. Capsid binding to NPCs was analyzed using fluorescence and field emission scanning electron microscopy. Tegument-free capsids or viral capsids exposing inner tegument proteins on their surface bound to nuclei, while capsids inactivated by a high-salt treatment or covered by inner and outer tegument showed less binding. There was little binding of the four different capsid types to nuclei lacking functional NPCs. This novel approach provides a powerful system to elucidate the molecular mechanisms that enable viral structures to engage with NPCs. Furthermore, this assay could be expanded to identify molecular cues triggering viral genome uncoating and nuclear import of viral genomes.
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Affiliation(s)
- Fenja Anderson
- Institute of Virology, OE 5230, Hannover Medical School, Carl-Neuberg-Straße 1, D-30623, Hannover, Germany
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Kelly BJ, Bauerfeind R, Binz A, Sodeik B, Laimbacher AS, Fraefel C, Diefenbach RJ. The interaction of the HSV-1 tegument proteins pUL36 and pUL37 is essential for secondary envelopment during viral egress. Virology 2014; 454-455:67-77. [PMID: 24725933 DOI: 10.1016/j.virol.2014.02.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 11/29/2013] [Accepted: 02/04/2014] [Indexed: 12/25/2022]
Abstract
The herpes simplex virus type 1 (HSV-1) tegument proteins pUL36 (VP1/2) and pUL37 are essential for viral egress. We previously defined a minimal domain in HSV-1 pUL36, residues 548-572, as important for binding pUL37. Here, we investigated the role of this region in binding to pUL37 and facilitating viral replication. We deleted residues 548-572 in frame in a virus containing a mRFP tag at the N-terminus of the capsid protein VP26 and an eGFP tag at the C-terminus of pUL37 (HSV-1pUL36∆548-572). This mutant virus was unable to generate plaques in Vero cells, indicating that deletion of this region of pUL36 blocks viral replication. Imaging of HSV-1pUL36∆548-572-infected Vero cells, in comparison to parental and resucant, revealed a block in secondary envelopment of cytoplasmic capsids. In addition, immunoblot analysis suggested that failure to bind pUL37 affected the stability of pUL36. This study provides further insight into the role of this essential interaction.
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Affiliation(s)
- Barbara J Kelly
- Centre for Virus Research, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia
| | - Rudolf Bauerfeind
- Institute of Cell Biology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Anne Binz
- Institute of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Beate Sodeik
- Institute of Virology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | | | - Cornel Fraefel
- Institute of Virology, University of Zurich, 8057 Zurich, Switzerland
| | - Russell J Diefenbach
- Centre for Virus Research, Westmead Millennium Institute, The University of Sydney and Westmead Hospital, Westmead, NSW 2145, Australia.
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Epstein-Barr virus large tegument protein BPLF1 contributes to innate immune evasion through interference with toll-like receptor signaling. PLoS Pathog 2014; 10:e1003960. [PMID: 24586164 PMCID: PMC3930590 DOI: 10.1371/journal.ppat.1003960] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 01/14/2014] [Indexed: 01/04/2023] Open
Abstract
Viral infection triggers an early host response through activation of pattern recognition receptors, including Toll-like receptors (TLR). TLR signaling cascades induce production of type I interferons and proinflammatory cytokines involved in establishing an anti-viral state as well as in orchestrating ensuing adaptive immunity. To allow infection, replication, and persistence, (herpes)viruses employ ingenious strategies to evade host immunity. The human gamma-herpesvirus Epstein-Barr virus (EBV) is a large, enveloped DNA virus persistently carried by more than 90% of adults worldwide. It is the causative agent of infectious mononucleosis and is associated with several malignant tumors. EBV activates TLRs, including TLR2, TLR3, and TLR9. Interestingly, both the expression of and signaling by TLRs is attenuated during productive EBV infection. Ubiquitination plays an important role in regulating TLR signaling and is controlled by ubiquitin ligases and deubiquitinases (DUBs). The EBV genome encodes three proteins reported to exert in vitro deubiquitinase activity. Using active site-directed probes, we show that one of these putative DUBs, the conserved herpesvirus large tegument protein BPLF1, acts as a functional DUB in EBV-producing B cells. The BPLF1 enzyme is expressed during the late phase of lytic EBV infection and is incorporated into viral particles. The N-terminal part of the large BPLF1 protein contains the catalytic site for DUB activity and suppresses TLR-mediated activation of NF-κB at, or downstream of, the TRAF6 signaling intermediate. A catalytically inactive mutant of this EBV protein did not reduce NF-κB activation, indicating that DUB activity is essential for attenuating TLR signal transduction. Our combined results show that EBV employs deubiquitination of signaling intermediates in the TLR cascade as a mechanism to counteract innate anti-viral immunity of infected hosts. Epstein-Barr virus (EBV) is a human herpesvirus that persistently infects >90% of adults worldwide. One factor underlying the ability of EBV to establish such widespread and lifelong infections is its capacity to escape elimination by the human immune system. Among the first lines of defense against viral infection is the human Toll-like receptor (TLR) system. These receptors can detect the presence of viruses and initiate an intracellular protein signaling cascade that leads to the expression of immune response genes. The activation status of many proteins in this signaling cascade is regulated by the addition of ubiquitin tags. EBV has previously been reported to encode enzymes, called deubiquitinases (DUBs), which are capable of removing such ubiquitin tags from substrate proteins. In our study, we found that one of these enzymes, BPLF1, functions as an active DUB during EBV production in infected cells before being packaged into newly produced viral particles. Furthermore, our study provides insight into the way in which EBV can subvert the human immune response, as we show that BPLF1 can remove ubiquitin tags from proteins in the TLR signaling cascade. This inhibits TLR signaling and decreases the expression of immune response genes.
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Viral subversion of the nuclear pore complex. Viruses 2013; 5:2019-42. [PMID: 23959328 PMCID: PMC3761240 DOI: 10.3390/v5082019] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 08/08/2013] [Indexed: 12/17/2022] Open
Abstract
The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses.
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Zaichick SV, Bohannon KP, Hughes A, Sollars PJ, Pickard GE, Smith GA. The herpesvirus VP1/2 protein is an effector of dynein-mediated capsid transport and neuroinvasion. Cell Host Microbe 2013; 13:193-203. [PMID: 23414759 DOI: 10.1016/j.chom.2013.01.009] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 11/13/2012] [Accepted: 01/11/2013] [Indexed: 12/23/2022]
Abstract
Microtubule transport of herpesvirus capsids from the cell periphery to the nucleus is imperative for viral replication and, in the case of many alphaherpesviruses, transmission into the nervous system. Using the neuroinvasive herpesvirus, pseudorabies virus (PRV), we show that the viral protein 1/2 (VP1/2) tegument protein associates with the dynein/dynactin microtubule motor complex and promotes retrograde microtubule transport of PRV capsids. Functional activation of VP1/2 requires binding to the capsid protein pUL25 or removal of the capsid-binding domain. A proline-rich sequence within VP1/2 is required for the efficient interaction with the dynein/dynactin microtubule motor complex as well as for PRV virulence and retrograde axon transport in vivo. Additionally, in the absence of infection, functionally active VP1/2 is sufficient to move large surrogate cargoes via the dynein/dynactin microtubule motor complex. Thus, VP1/2 tethers PRV capsids to dynein/dynactin to enhance microtubule transport, neuroinvasion, and pathogenesis.
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Affiliation(s)
- Sofia V Zaichick
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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