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Langsjoen RM, Auguste AJ, Rossi SL, Roundy CM, Penate HN, Kastis M, Schnizlein MK, Le KC, Haller SL, Chen R, Watowich SJ, Weaver SC. Host oxidative folding pathways offer novel anti-chikungunya virus drug targets with broad spectrum potential. Antiviral Res 2017; 143:246-251. [PMID: 28461071 DOI: 10.1016/j.antiviral.2017.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 04/05/2017] [Indexed: 11/15/2022]
Abstract
Alphaviruses require conserved cysteine residues for proper folding and assembly of the E1 and E2 envelope glycoproteins, and likely depend on host protein disulfide isomerase-family enzymes (PDI) to aid in facilitating disulfide bond formation and isomerization in these proteins. Here, we show that in human HEK293 cells, commercially available inhibitors of PDI or modulators thereof (thioredoxin reductase, TRX-R; endoplasmic reticulum oxidoreductin-1, ERO-1) inhibit the replication of CHIKV chikungunya virus (CHIKV) in vitro in a dose-dependent manner. Further, the TRX-R inhibitor auranofin inhibited Venezuelan equine encephalitis virus and the flavivirus Zika virus replication in vitro, while PDI inhibitor 16F16 reduced replication but demonstrated notable toxicity. 16F16 significantly altered the viral genome: plaque-forming unit (PFU) ratio of CHIKV in vitro without affecting relative intracellular viral RNA quantities and inhibited CHIKV E1-induced cell-cell fusion, suggesting that PDI inhibitors alter progeny virion infectivity through altered envelope function. Auranofin also increased the extracellular genome:PFU ratio but decreased the amount of intracellular CHIKV RNA, suggesting an alternative mechanism of action. Finally, auranofin reduced footpad swelling and viremia in the C57BL/6 murine model of CHIKV infection. Our results suggest that targeting oxidative folding pathways represents a potential new anti-alphavirus therapeutic strategy.
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Affiliation(s)
- Rose M Langsjoen
- Institute for Translational Science, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Albert J Auguste
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Shannan L Rossi
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Christopher M Roundy
- Institute for Translational Science, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Heidy N Penate
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Maria Kastis
- Center in Environmental Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | | | - Kevin C Le
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Sherry L Haller
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Rubing Chen
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
| | - Stanley J Watowich
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Center in Environmental Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Scott C Weaver
- Institute for Translational Science, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.
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Structural differences observed in arboviruses of the alphavirus and flavivirus genera. Adv Virol 2014; 2014:259382. [PMID: 25309597 PMCID: PMC4182009 DOI: 10.1155/2014/259382] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/28/2014] [Accepted: 08/18/2014] [Indexed: 12/22/2022] Open
Abstract
Arthropod borne viruses have developed a complex life cycle adapted to alternate between insect and vertebrate hosts. These arthropod-borne viruses belong mainly to the families Togaviridae, Flaviviridae, and Bunyaviridae. This group of viruses contains many pathogens that cause febrile, hemorrhagic, and encephalitic disease or arthritic symptoms which can be persistent. It has been appreciated for many years that these viruses were evolutionarily adapted to function in the highly divergent cellular environments of both insect and mammalian phyla. These viruses are hybrid in nature, containing viral-encoded RNA and proteins which are glycosylated by the host and encapsulate viral nucleocapsids in the context of a host-derived membrane. From a structural perspective, these virus particles are macromolecular machines adapted in design to assemble into a packaging and delivery system for the virus genome and, only when associated with the conditions appropriate for a productive infection, to disassemble and deliver the RNA cargo. It was initially assumed that the structures of the virus from both hosts were equivalent. New evidence that alphaviruses and flaviviruses can exist in more than one conformation postenvelopment will be discussed in this review. The data are limited but should refocus the field of structural biology on the metastable nature of these viruses.
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Hernandez R, Sinodis C, Brown DT. Sindbis virus: propagation, quantification, and storage. ACTA ACUST UNITED AC 2010; Chapter 15:Unit15B.1. [PMID: 20131223 DOI: 10.1002/9780471729259.mc15b01s16] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The prototype of the Alphaviruses, Sindbis virus, has a broad host range. In nature, Sindbis virus shuttles from an insect vector to a vertebrate host and back to the insect vector in a complex transmission cycle. Sindbis virus must, therefore, be able to replicate in two biochemically and genetically divergent hosts, invertebrates and vertebrates. In the laboratory, Sindbis grows to high titers in a large variety of cultured cells of both vertebrate and invertebrate origin. Sindbis virus is easily titered for infectivity on several mammalian cell lines as well as certain mosquito cells. Full-length cDNA clones of several strains of Sindbis virus are available from which infectious RNA can be synthesized, making possible the genetic manipulation of the virus. Transfection of mammalian and insect cells by electroporation has facilitated expression of RNA mutants in the cell lines of choice.
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Hernandez R, Sinodis C, Brown DT. Sindbis virus: propagation, quantification, and storage. CURRENT PROTOCOLS IN MICROBIOLOGY 2008; Chapter 15:Unit 15B.1. [PMID: 18770557 DOI: 10.1002/9780471729259.mc15b01s00] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The prototype of the Alphaviruses, Sindbis virus, has a broad host range. In nature, Sindbis virus shuttles from an insect vector to a vertebrate host and back to the insect vector in a complex transmission cycle. Sindbis virus must, therefore, be able to replicate in two biochemically and genetically divergent hosts, invertebrates and vertebrates. In the laboratory, Sindbis grows to high titers in a large variety of cultured cells of both vertebrate and invertebrate origin. Sindbis virus is easily titered for infectivity on several mammalian cell lines as well as certain mosquito cells. Full-length cDNA clones of several strains of Sindbis virus are available from which infectious RNA can be synthesized, making possible the genetic manipulation of the virus. Transfection of mammalian and insect cells by electroporation has facilitated expression of RNA mutants in the cell lines of choice.
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Hernandez R, Paredes A, Brown DT. Sindbis virus conformational changes induced by a neutralizing anti-E1 monoclonal antibody. J Virol 2008; 82:5750-60. [PMID: 18417595 PMCID: PMC2395122 DOI: 10.1128/jvi.02673-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 04/06/2008] [Indexed: 02/04/2023] Open
Abstract
A rare Sindbis virus anti-E1 neutralizing monoclonal antibody, Sin-33, was investigated to determine the mechanism of in vitro neutralization. A cryoelectron microscopic reconstruction of Sindbis virus (SVHR) neutralized with FAb from Sin-33 (FAb-33) revealed conformational changes on the surface of the virion at a resolution of 24 A. FAb-33 was found to bind E1 in less than 1:1 molar ratios, as shown by the absence of FAb density in the reconstruction and stoichiometric measurements using radiolabeled FAb-33, which determined that about 60 molecules of FAb-33 bound to the 240 possible sites in a single virus particle. FAb-33-neutralized virus particles became sensitive to digestion by endoproteinase Glu-C, providing further evidence of antibody-induced structural changes within the virus particle. The treatment of FAb-33-neutralized or Sin-33-neutralized SVHR with low pH did not induce the conformational rearrangements required for virus membrane-cell membrane fusion. Exposure to low pH, however, increased the amount of Sin-33 or FAb-33 that bound to the virus particles, indicating the exposure of additional epitopes. The neutralization of SVHR infection by FAb-33 or Sin-33 did not prevent the association of virus with host cells. These data are in agreement with the results of previous studies that demonstrated that specific antibodies can inactivate the infectious state of a metastable virus in vitro by the induction of conformational changes to produce an inactive structure. A model is proposed which postulates that the induction of conformational changes in the infectious state of a metastable enveloped virus may be a general mechanism of antibody inactivation of virus infectivity.
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Affiliation(s)
- Raquel Hernandez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27608, USA.
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Sharp JS, Nelson S, Brown D, Tomer KB. Structural characterization of the E2 glycoprotein from Sindbis by lysine biotinylation and LC-MS/MS. Virology 2006; 348:216-23. [PMID: 16443253 DOI: 10.1016/j.virol.2005.12.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Revised: 12/04/2005] [Accepted: 12/12/2005] [Indexed: 10/25/2022]
Abstract
Sindbis is an Alphavirus capable of infecting and replicating in both vertebrate and invertebrate hosts. Mature Sindbis virus particles consist of an inner capsid surrounded by a host-derived lipid bilayer, which in turn is surrounded by a protein shell consisting of the E1 and E2 glycoproteins. While a homolog of the E1 glycoprotein has been structurally characterized, the amount of structural data on the E2 glycoprotein is considerably less. In this study, the organization of the E2 glycoprotein was probed by surface biotinylation of intact virions. The virus remained fully infectious, demonstrating that the biotinylation did not alter the topology of the proteins involved in infection. Seven sites of modification were identified in the E2 glycoprotein (K70, K76, K97, K131, K149, K202, and K235), while one site of modification in the E1 glycoprotein (K16) was identified, confirming that the E1 protein is almost completely buried in the virus structure.
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Affiliation(s)
- Joshua S Sharp
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, 111 T.W. Alexander Dr., P.O. Box 12233, MD F0-04, Research Triangle Park, NC 27709, USA.
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Nelson S, Hernandez R, Ferreira D, Brown DT. In vivo processing and isolation of furin protease-sensitive alphavirus glycoproteins: a new technique for producing mutations in virus assembly. Virology 2005; 332:629-39. [PMID: 15680428 DOI: 10.1016/j.virol.2004.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 11/29/2004] [Accepted: 12/14/2004] [Indexed: 12/19/2022]
Abstract
Sindbis virus particles are composed of three structural proteins (Capsid/E2/E1). In the mature virion the E1 glycoprotein is organized in a highly constrained, energy-rich conformation. It is hypothesized that this energy is utilized to drive events that deliver the viral genome to the cytoplasm of a host cell. The extraction of the E1 glycoprotein from virus membranes with detergent results in disulfide-bridge rearrangement and the collapse of the protein to a number of low-energy, non-native configurations. In a new approach to the production of membrane-free membrane glycoproteins, furin protease recognition motifs were installed at various positions in the E1 glycoprotein ectodomain. Proteins containing the furin-sensitive sites undergo normal folding and assembly in the endoplasmic reticulum and only experience the consequence of the mutation during transport to the cell surface. Processing by furin in the Golgi results in the release of the protein from the membrane. Processing of the proteins also impacts the envelopment of the nucleocapsid in the modified plasma membrane. This technique provides a unique method for studying the mechanism of virus assembly and protein structure without altering crucial early events in protein assembly, folding, and maturation.
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Affiliation(s)
- Steevenson Nelson
- Department of Molecular and Structural Biochemistry, North Carolina State University, Campus Box 7622, Raleigh NC 27695-7622, USA
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