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Schiffman Z, Garnett L, Tran KN, Cao W, He S, Emeterio K, Tierney K, Azaransky K, Strong JE, Banadyga L. The Inability of Marburg Virus to Cause Disease in Ferrets Is Not Solely Linked to the Virus Glycoprotein. J Infect Dis 2023; 228:S594-S603. [PMID: 37288605 DOI: 10.1093/infdis/jiad206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/30/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023] Open
Abstract
Ebola virus (EBOV) causes lethal disease in ferrets, whereas Marburg virus (MARV) does not. To investigate this difference, we first evaluated viral entry by infecting ferret spleen cells with vesicular stomatitis viruses pseudotyped with either MARV or EBOV glycoprotein (GP). Both viruses were capable of infecting ferret spleen cells, suggesting that lack of disease is not due to a block in MARV entry. Next, we evaluated replication kinetics of authentic MARV and EBOV in ferret cell lines and demonstrated that, unlike EBOV, MARV was only capable of low levels of replication. Finally, we inoculated ferrets with a recombinant EBOV expressing MARV GP in place of EBOV GP. Infection resulted in uniformly lethal disease within 7-9 days postinfection, while MARV-inoculated animals survived until study endpoint. Together these data suggest that the inability of MARV to cause disease in ferrets is not entirely linked to GP.
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Affiliation(s)
- Zachary Schiffman
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Lauren Garnett
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Kaylie N Tran
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Wenguang Cao
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Shihua He
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Karla Emeterio
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Kevin Tierney
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Kim Azaransky
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - James E Strong
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Logan Banadyga
- Special Pathogens Program, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
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2
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Santos RI, Ilinykh PA, Pietzsch CA, Ronk AJ, Huang K, Kuzmina NA, Zhou F, Crowe JE, Bukreyev A. Blocking of ebolavirus spread through intercellular connections by an MPER-specific antibody depends on BST2/tetherin. Cell Rep 2023; 42:113254. [PMID: 37858466 PMCID: PMC10664807 DOI: 10.1016/j.celrep.2023.113254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 08/10/2023] [Accepted: 09/27/2023] [Indexed: 10/21/2023] Open
Abstract
Ebola virus (EBOV) and Bundibugyo virus (BDBV) belong to the family Filoviridae and cause a severe disease in humans. We previously isolated a large panel of monoclonal antibodies from B cells of human survivors from the 2007 Uganda BDBV outbreak, 16 survivors from the 2014 EBOV outbreak in the Democratic Republic of the Congo, and one survivor from the West African 2013-2016 EBOV epidemic. Here, we demonstrate that EBOV and BDBV are capable of spreading to neighboring cells through intercellular connections in a process that depends upon actin and T cell immunoglobulin and mucin 1 protein. We quantify spread through intercellular connections by immunofluorescence microscopy and flow cytometry. One of the antibodies, BDBV223, specific to the membrane-proximal external region, induces virus accumulation at the plasma membrane. The inhibiting activity of BDBV223 depends on BST2/tetherin.
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Affiliation(s)
- Rodrigo I Santos
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Philipp A Ilinykh
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Colette A Pietzsch
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Adam J Ronk
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Kai Huang
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Natalia A Kuzmina
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - Fuchun Zhou
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA
| | - James E Crowe
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Alexander Bukreyev
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, Galveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.
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3
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Unique Mode of Antiviral Action of a Marine Alkaloid against Ebola Virus and SARS-CoV-2. Viruses 2022; 14:v14040816. [PMID: 35458549 PMCID: PMC9028129 DOI: 10.3390/v14040816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/24/2022] [Accepted: 04/02/2022] [Indexed: 11/16/2022] Open
Abstract
Lamellarin α 20-sulfate is a cell-impenetrable marine alkaloid that can suppress infection that is mediated by the envelope glycoprotein of human immunodeficiency virus type 1. We explored the antiviral action and mechanisms of this alkaloid against emerging enveloped RNA viruses that use endocytosis for infection. The alkaloid inhibited the infection of retroviral vectors that had been pseudotyped with the envelope glycoprotein of Ebola virus and SARS-CoV-2. The antiviral effects of lamellarin were independent of the retrovirus Gag-Pol proteins. Interestingly, although heparin and dextran sulfate suppressed the cell attachment of vector particles, lamellarin did not. In silico structural analyses of the trimeric glycoprotein of the Ebola virus disclosed that the principal lamellarin-binding site is confined to a previously unappreciated cavity near the NPC1-binding site and fusion loop, whereas those for heparin and dextran sulfate were dispersed across the attachment and fusion subunits of the glycoproteins. Notably, lamellarin binding to this cavity was augmented under conditions where the pH was 5.0. These results suggest that the final action of the alkaloid against Ebola virus is specific to events following endocytosis, possibly during conformational glycoprotein changes in the acidic environment of endosomes. Our findings highlight the unique biological and physicochemical features of lamellarin α 20-sulfate and should lead to the further use of broadly reactive antivirals to explore the structural mechanisms of virus replication.
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Abstract
Retroviral elements from endogenous retroviruses have functions in mammalian physiology. The best-known examples are the envelope proteins that function in placenta development and immune suppression. Porcine endogenous retroviruses (PERVs) are an understudied class of endogenous retroviruses that infect cultured human cells, raising concern regarding porcine xenografts. The PERV envelope glycoprotein has also been proposed as a possible swine syncytin with a role in placental development. Despite the growing interest in PERVs, their envelope glycoproteins remain poorly characterized. Here, we successfully determined the postfusion crystal structure of the PERV core fusion ectodomain. The PERV fusion protein structure reveals a conserved class I viral fusion protein six-helix bundle. Biophysical experiments demonstrated that the thermodynamic stability of the PERV fusion protein secondary structure was the same at physiological and acidic pHs. A conserved surface analysis highlights the high degree of sequence conservation among retroviral fusogens in the chain reversal region that facilitates the large-scale conformational change required for membrane fusion. Further structural alignment of class I viral fusogens revealed a phylogenetic clustering that shows evolution into various lineages that correlate with virus mechanisms of cell entry. Our work indicates that structural dendrograms can be used to qualitatively infer insights into the fusion mechanisms of newly discovered class I viral fusogen structures. IMPORTANCE Class I viral fusion proteins represent a diverse group of fusogens that catalyze membrane fusion. Although structural studies have focused on those from exogenous viruses, ancient retroviral infections of germ line cells have immortalized ancient fusogens in eukaryotic genomes. These "fossilized" glycoproteins are poorly defined compared to modern fusogens. In this study, we characterized and determined the structure of the porcine endogenous retrovirus fusogen, an ancient retroviral element captured by swine. This fusion protein revealed remarkable alignment to exogenous retroviral fusion proteins, suggesting that fossil fusogens utilize similar structural determinants to perform membrane fusion. Moreover, structural phylogenetic analysis demonstrates that class I viral fusogens cluster into distinct lineages defined by mechanism of membrane fusion. Our results suggest that structural dendrograms can be used to infer mechanistic insights for uncharacterized fusion proteins.
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Düzgüneş N, Fernandez-Fuentes N, Konopka K. Inhibition of Viral Membrane Fusion by Peptides and Approaches to Peptide Design. Pathogens 2021; 10:1599. [PMID: 34959554 PMCID: PMC8709411 DOI: 10.3390/pathogens10121599] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 12/06/2021] [Accepted: 12/06/2021] [Indexed: 12/29/2022] Open
Abstract
Fusion of lipid-enveloped viruses with the cellular plasma membrane or the endosome membrane is mediated by viral envelope proteins that undergo large conformational changes following binding to receptors. The HIV-1 fusion protein gp41 undergoes a transition into a "six-helix bundle" after binding of the surface protein gp120 to the CD4 receptor and a co-receptor. Synthetic peptides that mimic part of this structure interfere with the formation of the helix structure and inhibit membrane fusion. This approach also works with the S spike protein of SARS-CoV-2. Here we review the peptide inhibitors of membrane fusion involved in infection by influenza virus, HIV-1, MERS and SARS coronaviruses, hepatitis viruses, paramyxoviruses, flaviviruses, herpesviruses and filoviruses. We also describe recent computational methods used for the identification of peptide sequences that can interact strongly with protein interfaces, with special emphasis on SARS-CoV-2, using the PePI-Covid19 database.
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Affiliation(s)
- Nejat Düzgüneş
- Department of Biomedical Sciences, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, CA 94103, USA;
| | - Narcis Fernandez-Fuentes
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth SY23 3EE, UK;
| | - Krystyna Konopka
- Department of Biomedical Sciences, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, CA 94103, USA;
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Yamaoka S, Ebihara H. Pathogenicity and Virulence of Ebolaviruses with Species- and Variant-specificity. Virulence 2021; 12:885-901. [PMID: 33734027 PMCID: PMC7993122 DOI: 10.1080/21505594.2021.1898169] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/10/2021] [Accepted: 02/19/2021] [Indexed: 01/05/2023] Open
Abstract
Ebola virus (EBOV), belonging to the species Zaire ebolavirus in the genus Ebolavirus, causes a severe febrile illness in humans with case fatality rates (CFRs) up to 90%. While there have been six virus species classified, which each have a single type virus in the genus Ebolavirus, CFRs of ebolavirus infections vary among viruses belonging to each distinct species. In this review, we aim to define the ebolavirus species-specific virulence on the basis of currently available laboratory and experimental findings. In addition, this review will also cover the variant-specific virulence of EBOV by referring to the unique biological and pathogenic characteristics of EBOV variant Makona, a new EBOV variant isolated from the 2013-2016 EBOV disease outbreak in West Africa. A better definition of species-specific and variant-specific virulence of ebolaviruses will facilitate our comprehensive knowledge on genus Ebolavirus biology, leading to the development of therapeutics against well-focused pathogenic mechanisms of each Ebola disease.
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Affiliation(s)
- Satoko Yamaoka
- Department of Molecular Medicine, Mayo Clinic, Rochester, USA
| | - Hideki Ebihara
- Department of Molecular Medicine, Mayo Clinic, Rochester, USA
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7
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Potential pharmacological strategies targeting the Niemann-Pick C1 receptor and Ebola virus glycoprotein interaction. Eur J Med Chem 2021; 223:113654. [PMID: 34175537 DOI: 10.1016/j.ejmech.2021.113654] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/27/2021] [Accepted: 06/13/2021] [Indexed: 10/21/2022]
Abstract
Niemann-Pick C1 (NPC1) receptor is an intracellular protein located in late endosomes and lysosomes whose main function is to regulate intracellular cholesterol trafficking. Besides being postulated as necessary for the infection of highly pathogenic viruses in which the integrity of cholesterol transport is required, this protein also allows the entry of the Ebola virus (EBOV) into the host cells acting as an intracellular receptor. EBOV glycoprotein (EBOV-GP) interaction with NPC1 at the endosomal membrane triggers the release of the viral material into the host cell, starting the infective cycle. Disruption of the NPC1/EBOV-GP interaction could represent an attractive strategy for the development of drugs aimed at inhibiting viral entry and thus infection. Some of the today available EBOV inhibitors were proposed to interrupt this interaction, but molecular and structural details about their mode of action are still preliminary thus more efforts are needed to properly address these points. Here, we provide a critical discussion of the potential of NPC1 and its interaction with EBOV-GP as a therapeutic target for viral infections.
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Hansen F, Feldmann H, Jarvis MA. Targeting Ebola virus replication through pharmaceutical intervention. Expert Opin Investig Drugs 2021; 30:201-226. [PMID: 33593215 DOI: 10.1080/13543784.2021.1881061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Introduction. The consistent emergence/reemergence of filoviruses into a world that previously lacked an approved pharmaceutical intervention parallels an experience repeatedly played-out for most other emerging pathogenic zoonotic viruses. Investment to preemptively develop effective and low-cost prophylactic and therapeutic interventions against viruses that have high potential for emergence and societal impact should be a priority.Areas covered. Candidate drugs can be characterized into those that interfere with cellular processes required for Ebola virus (EBOV) replication (host-directed), and those that directly target virally encoded functions (direct-acting). We discuss strategies to identify pharmaceutical interventions for EBOV infections. PubMed/Web of Science databases were searched to establish a detailed catalog of these interventions.Expert opinion. Many drug candidates show promising in vitro inhibitory activity, but experience with EBOV shows the general lack of translation to in vivo efficacy for host-directed repurposed drugs. Better translation is seen for direct-acting antivirals, in particular monoclonal antibodies. The FDA-approved monoclonal antibody treatment, Inmazeb™ is a success story that could be improved in terms of impact on EBOV-associated disease and mortality, possibly by combination with other direct-acting agents targeting distinct aspects of the viral replication cycle. Costs need to be addressed given EBOV emergence primarily in under-resourced countries.
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Affiliation(s)
- Frederick Hansen
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Heinz Feldmann
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Michael A Jarvis
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA.,School of Biomedical Sciences, University of Plymouth, Plymouth, Devon, UK.,The Vaccine Group, Ltd, Plymouth, Devon, UK
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9
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Length of mucin-like domains enhances cell-Ebola virus adhesion by increasing binding probability. Biophys J 2021; 120:781-790. [PMID: 33539790 DOI: 10.1016/j.bpj.2021.01.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 11/20/2022] Open
Abstract
The Ebola virus (EBOV) hijacks normal physiological processes by apoptotic mimicry to be taken up by the cell it infects. The initial adhesion of the virus to the cell is based on the interaction between T cell immunoglobulin and mucin domain protein, TIM, on the cell surface and phosphatidylserine (PS) on the viral outer surface. Therefore, it is important to understand the interaction between EBOV and PS and TIM, with selective blocking of the interaction as a potential therapy. Recent experimental studies have shown that for TIM-dependent EBOV entry, a mucin-like domain with a length of at least 120 amino acids is required, possibly because of the increase of area of the PS-coated surface sampled. We examine this hypothesis by modeling the process of TIM-PS adhesion using a coarse-grained molecular model. We find that the strength of individual bound PS-TIM pairs is essentially independent of TIM length. TIMs with longer mucin-like domains collectively have higher average binding strengths because of an increase in the probability of binding between EBOV and TIM proteins. Similarly, we find that for larger persistence length (less flexible), the average binding force decreases, again because of a reduction in the probability of binding.
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10
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Bessières M, Plebanek E, Chatterjee P, Shrivastava-Ranjan P, Flint M, Spiropoulou CF, Warszycki D, Bojarski AJ, Roy V, Agrofoglio LA. Design, synthesis and biological evaluation of 2-substituted-6-[(4-substituted-1-piperidyl)methyl]-1H-benzimidazoles as inhibitors of ebola virus infection. Eur J Med Chem 2021; 214:113211. [PMID: 33548632 DOI: 10.1016/j.ejmech.2021.113211] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/20/2020] [Accepted: 01/12/2021] [Indexed: 11/17/2022]
Abstract
Novel 2-substituted-6-[(4-substituted-1-piperidyl)methyl]-1H-benzimidazoles were designed and synthesized as Ebola virus inhibitors. The proposed structures of the new prepared benzimidazole-piperidine hybrids were confirmed based on their spectral data and CHN analyses. The target compounds were screened in vitro for their anti-Ebola activity. Among tested molecules, compounds 26a (EC50=0.93 μM, SI = 10) and 25a (EC50=0.64 μM, SI = 20) were as potent as and more selective than Toremifene reference drug (EC50 = 0.38 μM, SI = 7) against cell line. Data suggests that the mechanism by which 25a and 26a block EBOV infection is through the inhibition of viral entry at the level of NPC1. Furthermore, a docking study revealed that several of the NPC1 amino acids that participate in binding to GP are involved in the binding of the most active compounds 25a and 26a. Finally, in silico ADME prediction indicates that 26a is an idealy drug-like candidate. Our results could enable the development of small molecule drug capable of inhibiting Ebola virus, especially at the viral entry step.
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Affiliation(s)
| | | | - Payel Chatterjee
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Mike Flint
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Christina F Spiropoulou
- Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Dawid Warszycki
- May Institute of Pharmacology Polish Academy of Sciences, Kraków, Poland
| | - Andrzej J Bojarski
- May Institute of Pharmacology Polish Academy of Sciences, Kraków, Poland
| | - Vincent Roy
- Univ. Orléans, CNRS, ICOA, UMR 7311, F-45067, Orléans, France.
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[The latest research findings on Ebola virus]. Uirusu 2021; 71:137-150. [PMID: 37245976 DOI: 10.2222/jsv.71.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
013-2016 Ebola virus disease (EVD) outbreak was the largest EVD outbreak ever documented that started earlier in Guinea and later widely spread throughout West Africa, ending up a total of > 28,000 human infections. In this review, we outline research findings on Ebola virus (EBOV) variant Makona, a new EBOV variant isolated from the 2013-2016 EVD outbreak, and introduce the unique biological and pathogenic characteristics of Makona variant. We also discuss about the relevance of persistent infection of EBOV in EVD survivors with resurgence of EVD outbreak in Guinea in 2021. Moreover, this review covers a recent case report of EVD relapse and deliberates new interpretations of EBOV biology and EVD outbreak.
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A Virion-Based Assay for Glycoprotein Thermostability Reveals Key Determinants of Filovirus Entry and Its Inhibition. J Virol 2020; 94:JVI.00336-20. [PMID: 32611759 DOI: 10.1128/jvi.00336-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/26/2020] [Indexed: 11/20/2022] Open
Abstract
Ebola virus (EBOV) entry into cells is mediated by its spike glycoprotein (GP). Following attachment and internalization, virions traffic to late endosomes where GP is cleaved by host cysteine proteases. Cleaved GP then binds its cellular receptor, Niemann-Pick C1. In response to an unknown cellular trigger, GP undergoes conformational rearrangements that drive fusion of viral and endosomal membranes. The temperature-dependent stability (thermostability) of the prefusion conformers of class I viral fusion glycoproteins, including those of filovirus GPs, has provided insights into their propensity to undergo fusion-related rearrangements. However, previously described assays have relied on soluble glycoprotein ectodomains. Here, we developed a simple enzyme-linked immunosorbent assay (ELISA)-based assay that uses the temperature-dependent loss of conformational epitopes to measure thermostability of GP embedded in viral membranes. The base and glycan cap subdomains of all filovirus GPs tested suffered a concerted loss of prefusion conformation at elevated temperatures but did so at different temperature ranges, indicating virus-specific differences in thermostability. Despite these differences, all of these GPs displayed reduced thermostability upon cleavage to GP conformers (GPCL). Surprisingly, acid pH enhanced, rather than decreased, GP thermostability, suggesting it could enhance viral survival in hostile endo/lysosomal compartments. Finally, we confirmed and extended previous findings that some small-molecule inhibitors of filovirus entry destabilize EBOV GP and uncovered evidence that the most potent inhibitors act through multiple mechanisms. We establish the epitope-loss ELISA as a useful tool for studies of filovirus entry, engineering of GP variants with enhanced stability for use in vaccine development, and discovery of new stability-modulating antivirals.IMPORTANCE The development of Ebola virus countermeasures is challenged by our limited understanding of cell entry, especially at the step of membrane fusion. The surface-exposed viral protein, GP, mediates membrane fusion and undergoes major structural rearrangements during this process. The stability of GP at elevated temperatures (thermostability) can provide insights into its capacity to undergo these rearrangements. Here, we describe a new assay that uses GP-specific antibodies to measure GP thermostability under a variety of conditions relevant to viral entry. We show that proteolytic cleavage and acid pH have significant effects on GP thermostability that shed light on their respective roles in viral entry. We also show that the assay can be used to study how small-molecule entry inhibitors affect GP stability. This work provides a simple and readily accessible assay to engineer stabilized GP variants for antiviral vaccines and to discover and improve drugs that act by modulating GP stability.
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Gold AS, Feitosa-Suntheimer F, Asad S, Adeoye B, Connor JH, Colpitts TM. Examining the Role of Niemann-Pick C1 Protein in the Permissiveness of Aedes Mosquitoes to Filoviruses. ACS Infect Dis 2020; 6:2023-2028. [PMID: 32609483 DOI: 10.1021/acsinfecdis.0c00018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aedes mosquitoes vector many viruses with divergent characteristics, yet the criteria needed for a virus to be vectored by an arthropod remain unknown. The intracellular cholesterol transporter protein Niemann-Pick C1 (NPC1) has been identified as the necessary entry receptor for filoviruses such as Ebola and Marburg viruses. While homologues of NPC1 are observed in mosquitoes, currently no filovirus has been identified as circulating in mosquitoes. This work aimed at increasing the understanding of the mosquito vector by examining the capability of a virus to gain the ability to enter mosquito cells. We developed a model system of Aedes cells expressing human NPC1 (hNPC1) and attempted to infect these cells with recombinant vesicular stomatitis virus expressing the Ebola virus glycoprotein. As compared to the control cells, no significant increase in infection was observed in cells expressing hNPC1, demonstrating that the expression of human NPC1 alone is not sufficient to support filovirus infection, and that host factors other than NPC1 determine filovirus susceptibility of mosquito cells.
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Affiliation(s)
- Alexander S. Gold
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
| | - Fabiana Feitosa-Suntheimer
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
| | - Sultan Asad
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
| | - Bukola Adeoye
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
| | - John H. Connor
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
| | - Tonya M. Colpitts
- Department of Microbiology, Boston University School of Medicine, National Emerging Infectious Diseases Laboratories, 620 Albany Street, Boston, Massachusetts 02118, United States
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14
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Zhang Q, Tian F, Wang F, Guo Z, Cai M, Xu H, Wang H, Yang G, Shi X, Shan Y, Cui Z. Entry Dynamics of Single Ebola Virus Revealed by Force Tracing. ACS NANO 2020; 14:7046-7054. [PMID: 32383590 DOI: 10.1021/acsnano.0c01739] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Infections by the Ebola virus (EBOV) rapidly cause fatal hemorrhagic fever in humans. Viral entry into host cells is the most critical step in infection and an attractive target for therapeutic intervention. Herein, the invagination behavior and entry dynamics of filamentous Ebola virus-like particles (EBO-VLPs) were investigated using a force tracing technique based on atomic force microscopy and single-particle fluorescence tracking in real time. The filamentous EBOV-VLPs might enter cells in both horizontal and vertical modes, and the virus-receptor interactions during endocytic uptake were analyzed. In addition, molecular dynamics simulations and engulfment energy analysis further depicted EBO-VLP entry in the horizontal and vertical directions and suggested that internalization in the vertical direction requires a larger force and more time. This report provides useful information for further revealing the mechanism of viral infection, which is important for understanding viral pathogenesis.
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Affiliation(s)
- Qingrong Zhang
- School of Chemistry and Life Science, Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, P.R. China
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
| | - Falin Tian
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory for Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Fei Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, P.R. China
| | - Zhengyuan Guo
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
| | - Haijiao Xu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
| | - Guocheng Yang
- School of Chemistry and Life Science, Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, P.R. China
| | - Xinghua Shi
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory for Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Yuping Shan
- School of Chemistry and Life Science, Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, P.R. China
| | - Zongqiang Cui
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
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15
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Liu N, Girvin ME, Brenowitz M, Lai JR. Conformational and lipid bilayer-perturbing properties of Marburg virus GP2 segments containing the fusion loop and membrane-proximal external region/transmembrane domain. Heliyon 2019; 5:e03018. [PMID: 31890962 PMCID: PMC6926192 DOI: 10.1016/j.heliyon.2019.e03018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 11/04/2019] [Accepted: 12/06/2019] [Indexed: 12/13/2022] Open
Abstract
Fusion of host and viral membranes is a crucial step during infection by enveloped viruses. In the structurally-defined "class I″ viral glycoproteins, the formation of a highly stable α-helical bundle by the ectodomain of the fusion subunit (e.g., GP2 for Marburg virus, MARV) is postulated to provide the energetic driving force to overcome barriers associated with membrane fusion. Upon cell binding, the fusion subunit is proposed to form an extended intermediate that bridges both the viral and host membranes, and collapse of this extended intermediate brings the two membranes into proximity. While there is much high-resolution structural data available for prefusion and post-fusion structures of viral glycoproteins, little information is available about intermediate conformations especially in the context of the fusion loop/peptide (FL or FP) and membrane-proximal external region (MPER)/transmembrane (TM) segments. We present structural and functional studies on segments of MARV GP2 that encompass the FL and MPER/TM in detergent micelles and lipid bicelles. A protein that contains most elements of GP2 ("MGP2-full") is α-helical in membrane-mimicking environments and has pH-dependent membrane lytic activity. MGP2-full is monomeric under such conditions, contrasting with the trimeric species that has been described previously for MARV GP2 ectodomain in aqueous buffer. Variants of MARV GP2 containing the N- and C-terminal halves ("MGP2-FNL" and "MGP2-CMT", respectively) have similar properties. This work provides novel insight into conformational and membrane-perturbing properties of the MARV fusion subunit and how they may relate to viral membrane fusion.
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Affiliation(s)
- Nina Liu
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Mark E Girvin
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Michael Brenowitz
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.,Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Jonathan R Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
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16
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Efficient Expression and Processing of Ebola Virus Glycoprotein Induces Morphological Changes in BmN Cells but Cannot Rescue Deficiency of Bombyx Mori Nucleopolyhedrovirus GP64. Viruses 2019; 11:v11111067. [PMID: 31731691 PMCID: PMC6893839 DOI: 10.3390/v11111067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 01/08/2023] Open
Abstract
Ebola virus (EBOV) disease outbreaks have resulted in many fatalities, yet no licensed vaccines are available to prevent infection. Recombinant glycoprotein (GP) production may contribute to finding a cure for Ebola virus disease, which is the key candidate protein for vaccine preparation. To explore GP1,2 expression in BmN cells, EBOV-GP1,2 with its native signal peptide or the GP64 signal peptide was cloned and transferred into a normal or gp64 null Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid via transposition. The infectivity of the recombinant bacmids was investigated after transfection, expression and localization of EBOV-GP were investigated, and cell morphological changes were analyzed by TEM. The GP64 signal peptide, but not the GP1,2 native signal peptide, caused GP1,2 localization to the cell membrane, and the differentially localized GP1,2 proteins were cleaved into GP1 and GP2 fragments in BmN cells. GP1,2 expression resulted in dramatic morphological changes in BmN cells in the early stage of infection. However, GP1,2 expression did not rescue GP64 deficiency in BmNPV infection. This study provides a better understanding of GP expression and processing in BmN cells, which may lay a foundation for EBOV-GP expression using the BmNPV baculovirus expression system.
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17
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Wendt L, Bostedt L, Hoenen T, Groseth A. High-throughput screening for negative-stranded hemorrhagic fever viruses using reverse genetics. Antiviral Res 2019; 170:104569. [PMID: 31356830 DOI: 10.1016/j.antiviral.2019.104569] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/28/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023]
Abstract
Viral hemorrhagic fevers (VHFs) cause thousands of fatalities every year, but the treatment options for their management remain very limited. In particular, the development of therapeutic interventions is restricted by the lack of commercial viability of drugs targeting individual VHF agents. This makes approaches like drug repurposing and/or the identification of broad range therapies (i.e. those directed at host responses or common proviral factors) highly attractive. However, the identification of candidates for such antiviral repurposing or of host factors/pathways important for the virus life cycle is reliant on high-throughput screening (HTS). Recently, such screening work has been increasingly facilitated by the availability of reverse genetics-based approaches, including tools such as full-length clone (FLC) systems to generate reporter-expressing viruses or various life cycle modelling (LCM) systems, many of which have been developed and/or greatly improved during the last years. In particular, since LCM systems are capable of modelling specific steps in the life cycle, they are a valuable tool for both targeted screening (i.e. for inhibitors of a specific pathway) and mechanism of action studies. This review seeks to summarize the currently available reverse genetics systems for negative-sense VHF causing viruses (i.e. arenaviruses, bunyaviruses and filoviruses), and to highlight the recent advancements made in applying these systems for HTS to identify either antivirals or new virus-host interactions that might hold promise for the development of future treatments for the infections caused by these deadly but neglected virus groups.
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Affiliation(s)
- Lisa Wendt
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Linus Bostedt
- Junior Research Group - Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Thomas Hoenen
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
| | - Allison Groseth
- Junior Research Group - Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
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18
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Abstract
This chapter reviews our current knowledge about the spatiotemporal assembly of filoviral particles. We will follow particles from nucleocapsid entry into the cytoplasm until the nucleocapsids are enveloped at the plasma membrane. We will also highlight the currently open scientific questions surrounding filovirus assembly.
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19
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Pleet ML, DeMarino C, Stonier SW, Dye JM, Jacobson S, Aman MJ, Kashanchi F. Extracellular Vesicles and Ebola Virus: A New Mechanism of Immune Evasion. Viruses 2019; 11:v11050410. [PMID: 31052499 PMCID: PMC6563240 DOI: 10.3390/v11050410] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/29/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023] Open
Abstract
Ebola virus (EBOV) disease can result in a range of symptoms anywhere from virtually asymptomatic to severe hemorrhagic fever during acute infection. Additionally, spans of asymptomatic persistence in recovering survivors is possible, during which transmission of the virus may occur. In acute infection, substantial cytokine storm and bystander lymphocyte apoptosis take place, resulting in uncontrolled, systemic inflammation in affected individuals. Recently, studies have demonstrated the presence of EBOV proteins VP40, glycoprotein (GP), and nucleoprotein (NP) packaged into extracellular vesicles (EVs) during infection. EVs containing EBOV proteins have been shown to induce apoptosis in recipient immune cells, as well as contain pro-inflammatory cytokines. In this manuscript, we review the current field of knowledge on EBOV EVs including the mechanisms of their biogenesis, their cargo and their effects in recipient cells. Furthermore, we discuss some of the effects that may be induced by EBOV EVs that have not yet been characterized and highlight the remaining questions and future directions.
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Affiliation(s)
- Michelle L Pleet
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA.
| | - Catherine DeMarino
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA.
| | - Spencer W Stonier
- Department, Emergent BioSolutions, Gaithersburg, MD 20879, USA.
- Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA.
| | - John M Dye
- Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA.
| | - Steven Jacobson
- Viral Immunology Section, Neuroimmunology Branch, National Institute for Neurological Disease and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - M Javad Aman
- Department. Integrated BioTherapeutics, Inc., Gaithersburg, MD 20850, USA.
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA.
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20
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Flint M, Chatterjee P, Lin DL, McMullan LK, Shrivastava-Ranjan P, Bergeron É, Lo MK, Welch SR, Nichol ST, Tai AW, Spiropoulou CF. A genome-wide CRISPR screen identifies N-acetylglucosamine-1-phosphate transferase as a potential antiviral target for Ebola virus. Nat Commun 2019; 10:285. [PMID: 30655525 PMCID: PMC6336797 DOI: 10.1038/s41467-018-08135-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 12/19/2018] [Indexed: 12/28/2022] Open
Abstract
There are no approved therapies for Ebola virus infection. Here, to find potential therapeutic targets, we perform a screen for genes essential for Ebola virus (EBOV) infection. We identify GNPTAB, which encodes the α and β subunits of N-acetylglucosamine-1-phosphate transferase. We show that EBOV infection of a GNPTAB knockout cell line is impaired, and that this is reversed by reconstituting GNPTAB expression. Fibroblasts from patients with mucolipidosis II, a disorder associated with mutations in GNPTAB, are refractory to EBOV, whereas cells from their healthy parents support infection. Impaired infection correlates with loss of the expression of cathepsin B, known to be essential for EBOV entry. GNPTAB activity is dependent upon proteolytic cleavage by the SKI-1/S1P protease. Inhibiting this protease with the small-molecule PF-429242 blocks EBOV entry and infection. Disruption of GNPTAB function may represent a strategy for a host-targeted therapy for EBOV. Genetic screens are important tools to identify host factors associated with viral infections. Here, Flint et al. perform a genome-wide CRISPR screen using infectious Ebola virus (EBOV) and show that the host transferase GNPTAB is required for EBOV infection and a potential target for antiviral therapies
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Affiliation(s)
- Mike Flint
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA.
| | - Payel Chatterjee
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - David L Lin
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Laura K McMullan
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Punya Shrivastava-Ranjan
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Éric Bergeron
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Michael K Lo
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Stephen R Welch
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Stuart T Nichol
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA
| | - Andrew W Tai
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.,Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Christina F Spiropoulou
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA, 30329, USA.
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21
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Post-exposure immunotherapy for two ebolaviruses and Marburg virus in nonhuman primates. Nat Commun 2019; 10:105. [PMID: 30631063 PMCID: PMC6328579 DOI: 10.1038/s41467-018-08040-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/12/2018] [Indexed: 11/09/2022] Open
Abstract
The 2013-2016 Ebola virus (EBOV) disease epidemic demonstrated the grave consequences of filovirus epidemics in the absence of effective therapeutics. Besides EBOV, two additional ebolaviruses, Sudan (SUDV) and Bundibugyo (BDBV) viruses, as well as multiple variants of Marburg virus (MARV), have also caused high fatality epidemics. Current experimental EBOV monoclonal antibodies (mAbs) are ineffective against SUDV, BDBV, or MARV. Here, we report that a cocktail of two broadly neutralizing ebolavirus mAbs, FVM04 and CA45, protects nonhuman primates (NHPs) against EBOV and SUDV infection when delivered four days post infection. This cocktail when supplemented by the anti-MARV mAb MR191 exhibited 100% efficacy in MARV-infected NHPs. These findings provide a solid foundation for clinical development of broadly protective immunotherapeutics for use in future filovirus epidemics.
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22
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Martins DP, Barros MT, Pierobon M, Kandhavelu M, Lio' P, Balasubramaniam S. Computational Models for Trapping Ebola Virus Using Engineered Bacteria. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2018; 15:2017-2027. [PMID: 29994771 DOI: 10.1109/tcbb.2018.2836430] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The outbreak of the Ebola virus in recent years has resulted in numerous research initiatives to seek new solutions to contain the virus. A number of approaches that have been investigated include new vaccines to boost the immune system. An alternative post-exposure treatment is presented in this paper. The proposed approach for clearing the Ebola virus can be developed through a microfluidic attenuator, which contains the engineered bacteria that traps Ebola flowing through the blood onto its membrane. The paper presents the analysis of the chemical binding force between the virus and a genetically engineered bacterium considering the opposing forces acting on the attachment point, including hydrodynamic tension and drag force. To test the efficacy of the technique, simulations of bacterial motility within a confined area to trap the virus were performed. More than 60 percent of the displaced virus could be collected within 15 minutes. While the proposed approach currently focuses on in vitro environments for trapping the virus, the system can be further developed into a future treatment system whereby blood can be cycled out of the body into a microfluidic device that contains the engineered bacteria to trap viruses.
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23
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Ilinykh PA, Santos RI, Gunn BM, Kuzmina NA, Shen X, Huang K, Gilchuk P, Flyak AI, Younan P, Alter G, Crowe JE, Bukreyev A. Asymmetric antiviral effects of ebolavirus antibodies targeting glycoprotein stem and glycan cap. PLoS Pathog 2018; 14:e1007204. [PMID: 30138408 PMCID: PMC6107261 DOI: 10.1371/journal.ppat.1007204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 07/08/2018] [Indexed: 01/24/2023] Open
Abstract
Recent studies suggest that some monoclonal antibodies (mAbs) specific for ebolavirus glycoprotein (GP) can protect experimental animals against infections. Most mAbs isolated from ebolavirus survivors appeared to target the glycan cap or the stalk region of the viral GP, which is the envelope protein and the only antigen inducing virus-neutralizing antibody response. Some of the mAbs were demonstrated to be protective in vivo. Here, a panel of mAbs from four individual survivors of ebolavirus infection that target the glycan cap or stem region were selected for investigation of the mechanisms of their antiviral effect. Comparative characterization of the inhibiting effects on multiple steps of viral replication was performed, including attachment, post-attachment, entry, binding at low pH, post-cleavage neutralization of virions, viral trafficking to endosomes, cell-to-cell transmission, viral egress, and inhibition when added early at various time points post-infection. In addition, Fc-domain related properties were characterized, including activation and degranulation of NK cells, antibody-dependent cellular phagocytosis and glycan content. The two groups of mAbs (glycan cap versus stem) demonstrated very different profiles of activities suggesting usage of mAbs with different epitope specificity could coordinate inhibition of multiple steps of filovirus infection through Fab- and Fc-mediated mechanisms, and provide a reliable therapeutic approach.
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Affiliation(s)
- Philipp A. Ilinykh
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
| | - Rodrigo I. Santos
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
| | - Bronwyn M. Gunn
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Natalia A. Kuzmina
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
| | - Xiaoli Shen
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
| | - Kai Huang
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
| | - Pavlo Gilchuk
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Andrew I. Flyak
- Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Patrick Younan
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
| | - Galit Alter
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, United States of America
| | - James E. Crowe
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Department of Pediatrics (Infectious Diseases), Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Alexander Bukreyev
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States of America
- Galveston National Laboratory, Galveston, TX, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States of America
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24
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Cui Q, Du R, Anantpadma M, Schafer A, Hou L, Tian J, Davey RA, Cheng H, Rong L. Identification of Ellagic Acid from Plant Rhodiola rosea L. as an Anti-Ebola Virus Entry Inhibitor. Viruses 2018; 10:v10040152. [PMID: 29584652 PMCID: PMC5923446 DOI: 10.3390/v10040152] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 11/16/2022] Open
Abstract
The recent 2014-2016 West African Ebola virus epidemic underscores the need for the development of novel anti-Ebola therapeutics, due to the high mortality rates of Ebola virus infections and the lack of FDA-approved vaccine or therapy that is available for the prevention and treatment. Traditional Chinese medicines (TCMs) represent a huge reservoir of bioactive chemicals and many TCMs have been shown to have antiviral activities. 373 extracts from 128 TCMs were evaluated using a high throughput assay to screen for inhibitors of Ebola virus cell entry. Extract of Rhodiola rosea displayed specific and potent inhibition against cell entry of both Ebola virus and Marburg virus. In addition, twenty commercial compounds that were isolated from Rhodiola rosea were evaluated using the pseudotyped Ebola virus entry assay, and it was found that ellagic acid and gallic acid, which are two structurally related compounds, are the most effective ones. The activity of the extract and the two pure compounds were validated using infectious Ebola virus. The time-of-addition experiments suggest that, mechanistically, the Rhodiola rosea extract and the effective compounds act at an early step in the infection cycle following initial cell attachment, but prior to viral/cell membrane fusion. Our findings provide evidence that Rhodiola rosea has potent anti-filovirus properties that may be developed as a novel anti-Ebola treatment.
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Affiliation(s)
- Qinghua Cui
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Ruikun Du
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Manu Anantpadma
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX 78227, USA.
| | - Adam Schafer
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Lin Hou
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
| | - Jingzhen Tian
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
| | - Robert A Davey
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX 78227, USA.
| | - Han Cheng
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Lijun Rong
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
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25
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Piloni A, Walther A, Stenzel MH. Compartmentalized nanoparticles in aqueous solution through hierarchical self-assembly of triblock glycopolymers. Polym Chem 2018. [DOI: 10.1039/c8py00792f] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Amphiphilic block copolymers can elegantly assemble in water to form well-defined nano-objects and through smart design of the polymers it is possible to efficiently prepare functional materials for biomedical applications such as drug carriers.
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Affiliation(s)
- Alberto Piloni
- Centre for Advanced Macromolecular Design
- School of Chemistry
- UNSW
- Sydney
- Australia
| | - Andreas Walther
- Institute for Macromolecular Chemistry
- Stefan-Meier-Strasse 31
- University of Freiburg
- 79104 Freiburg
- Germany
| | - Martina H. Stenzel
- Centre for Advanced Macromolecular Design
- School of Chemistry
- UNSW
- Sydney
- Australia
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26
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Structure of the Ebola virus envelope protein MPER/TM domain and its interaction with the fusion loop explains their fusion activity. Proc Natl Acad Sci U S A 2017; 114:E7987-E7996. [PMID: 28874543 DOI: 10.1073/pnas.1708052114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ebolavirus (EBOV), an enveloped filamentous RNA virus causing severe hemorrhagic fever, enters cells by macropinocytosis and membrane fusion in a late endosomal compartment. Fusion is mediated by the EBOV envelope glycoprotein GP, which consists of subunits GP1 and GP2. GP1 binds to cellular receptors, including Niemann-Pick C1 (NPC1) protein, and GP2 is responsible for low pH-induced membrane fusion. Proteolytic cleavage and NPC1 binding at endosomal pH lead to conformational rearrangements of GP2 that include exposing the hydrophobic fusion loop (FL) for insertion into the cellular target membrane and forming a six-helix bundle structure. Although major portions of the GP2 structure have been solved in pre- and postfusion states and although current models place the transmembrane (TM) and FL domains of GP2 in close proximity at critical steps of membrane fusion, their structures in membrane environments, and especially interactions between them, have not yet been characterized. Here, we present the structure of the membrane proximal external region (MPER) connected to the TM domain: i.e., the missing parts of the EBOV GP2 structure. The structure, solved by solution NMR and EPR spectroscopy in membrane-mimetic environments, consists of a helix-turn-helix architecture that is independent of pH. Moreover, the MPER region is shown to interact in the membrane interface with the previously determined structure of the EBOV FL through several critical aromatic residues. Mutation of aromatic and neighboring residues in both binding partners decreases fusion and viral entry, highlighting the functional importance of the MPER/TM-FL interaction in EBOV entry and fusion.
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27
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Antibodies from a Human Survivor Define Sites of Vulnerability for Broad Protection against Ebolaviruses. Cell 2017; 169:878-890.e15. [PMID: 28525755 DOI: 10.1016/j.cell.2017.04.037] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/16/2017] [Accepted: 04/26/2017] [Indexed: 12/19/2022]
Abstract
Experimental monoclonal antibody (mAb) therapies have shown promise for treatment of lethal Ebola virus (EBOV) infections, but their species-specific recognition of the viral glycoprotein (GP) has limited their use against other divergent ebolaviruses associated with human disease. Here, we mined the human immune response to natural EBOV infection and identified mAbs with exceptionally potent pan-ebolavirus neutralizing activity and protective efficacy against three virulent ebolaviruses. These mAbs recognize an inter-protomer epitope in the GP fusion loop, a critical and conserved element of the viral membrane fusion machinery, and neutralize viral entry by targeting a proteolytically primed, fusion-competent GP intermediate (GPCL) generated in host cell endosomes. Only a few somatic hypermutations are required for broad antiviral activity, and germline-approximating variants display enhanced GPCL recognition, suggesting that such antibodies could be elicited more efficiently with suitably optimized GP immunogens. Our findings inform the development of both broadly effective immunotherapeutics and vaccines against filoviruses.
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Zou Z, Misasi J, Sullivan N, Sun PD. Overexpression of Ebola virus envelope GP1 protein. Protein Expr Purif 2017; 135:45-53. [PMID: 28458053 DOI: 10.1016/j.pep.2017.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/13/2022]
Abstract
Ebola virus uses its envelope GP1 and GP2 for viral attachment and entry into host cells. Due to technical difficulty expressing full-length envelope, many structural and functional studies of Ebola envelope protein have been carried out primarily using GP1 lacking its mucin-like domain. As a result, the viral invasion mechanisms involving the mucin-like domain are not fully understood. To elucidate the role of the mucin-like domain of GP1 in Ebola-host attachment and infection and to facilitate vaccine development, we constructed a GP1 expression vector containing the entire attachment region (1-496). Cysteine 53 of GP1, which forms a disulfide bond with GP2, was mutated to serine to avoid potential disulfide bond mispairing. Stable expression clones using codon optimized open reading frame were developed in human 293-H cells with yields reaching ∼25 mg of GP1 protein per liter of spent medium. Purified GP1 was functional and bound to Ebola attachment receptors, DC-SIGN and DC-SIGNR. The over-expression and easy purification characteristic of this system has implications in Ebola research and vaccine development. To further understand the differential expression yields between the codon optimized and native GP1, we analyzed the presence of RNA structural motifs in the first 100 nucleotides of translational initiation AUG site. RNA structural prediction showed the codon optimization removed two potential RNA pseudoknot structures. This methodology is also applicable to the expression of other difficult virus envelope proteins.
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Affiliation(s)
- Zhongcheng Zou
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - John Misasi
- Biodefense Research Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nancy Sullivan
- Biodefense Research Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter D Sun
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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Pacheco DADMRA, Rodrigues AAG, Silva CMLD. Ebola virus - from neglected threat to global emergency state. Rev Assoc Med Bras (1992) 2017; 62:458-67. [PMID: 27656857 DOI: 10.1590/1806-9282.62.05.458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/11/2015] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE This review aims to update knowledge about Ebola virus disease (EVD) and recent advances in its diagnosis, treatment and prevention. METHOD A literature review was performed using the following databases: ISI Web of Knowledge, PubMed, IRIS, Scopus and the websites of the CDC and the WHO. Additionally, we have included articles and reports referenced in the basic literature search, and news that were considered relevant. RESULTS The Ebola virus, endemic in some parts of Africa, is responsible for a severe form of hemorrhagic fever in humans; bats are probably its natural reservoir. It is an extremely virulent virus and easily transmitted by bodily fluids. EVD's complex pathophysiology, characterized by immunosuppression as well as stimulation of an intense inflammatory response, results in a syndrome similar to septic shock. The diagnosis is difficult due to the initial symptoms that mimic other diseases. Despite the high mortality rates that can amount to 90%, a prophylaxis (chemical or vaccine) or effective treatment does not exist. Two vaccines and experimental therapies are being developed for the prevention and treatment of EVD. CONCLUSION Although the virus is known for about 40 years, the lack of knowledge obtained and the disinterest of government authorities in the countries involved justify the state of emergency currently exists regarding this infectious agent. Only the coordination of multiple entities and the effective commitment of the international community will facilitate the control and effective prevention of EVD.
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Affiliation(s)
| | - Acácio Agostinho Gonçalves Rodrigues
- PhD - Director of the Department and Laboratory of Microbiology, Faculdade de Medicina, Universidade do Porto. MD, Department of Anesthesiology and Intensive Care, Burns Unit, Hospital de São João, Porto, Portugal
| | - Carmen Maria Lisboa da Silva
- PhD - Professor of the Department and Laboratory of Microbiology, Faculdade de Medicina, Universidade do Porto. MD, Department of Dermatovenereology, Hospital São João, Porto, Portugal
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30
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An inter-residue network model to identify mutational-constrained regions on the Ebola coat glycoprotein. Sci Rep 2017; 7:45886. [PMID: 28397835 PMCID: PMC5387726 DOI: 10.1038/srep45886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 03/06/2017] [Indexed: 11/09/2022] Open
Abstract
Recently, progress has been made in the development of vaccines and monoclonal antibody cocktails that target the Ebola coat glycoprotein (GP). Based on the mutation rates for Ebola virus given its natural sequence evolution, these treatment strategies are likely to impose additional selection pressure to drive acquisition of mutations in GP that escape neutralization. Given the high degree of sequence conservation among GP of Ebola viruses, it would be challenging to determine the propensity of acquiring mutations in response to vaccine or treatment with one or a cocktail of monoclonal antibodies. In this study, we analyzed the mutability of each residue using an approach that captures the structural constraints on mutability based on the extent of its inter-residue interaction network within the three-dimensional structure of the trimeric GP. This analysis showed two distinct clusters of highly networked residues along the GP1-GP2 interface, part of which overlapped with epitope surfaces of known neutralizing antibodies. This network approach also permitted us to identify additional residues in the network of the known hotspot residues of different anti-Ebola antibodies that would impact antibody-epitope interactions.
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Davey RA, Shtanko O, Anantpadma M, Sakurai Y, Chandran K, Maury W. Mechanisms of Filovirus Entry. Curr Top Microbiol Immunol 2017; 411:323-352. [PMID: 28601947 DOI: 10.1007/82_2017_14] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Filovirus entry into cells is complex, perhaps as complex as any viral entry mechanism identified to date. However, over the past 10 years, the important events required for filoviruses to enter into the endosomal compartment and fuse with vesicular membranes have been elucidated (Fig. 1). Here, we highlight the important steps that are required for productive entry of filoviruses into mammalian cells.
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Affiliation(s)
- R A Davey
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - O Shtanko
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - M Anantpadma
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Y Sakurai
- Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - K Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - W Maury
- Department of Microbiology, The University of Iowa, Iowa City, IA, USA.
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32
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Hoenen T, Brandt J, Caì Y, Kuhn JH, Finch C. Reverse Genetics of Filoviruses. Curr Top Microbiol Immunol 2017; 411:421-445. [PMID: 28918537 DOI: 10.1007/82_2017_55] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Reverse genetics systems are used for the generation of recombinant viruses. For filoviruses, this technology has been available for more than 15 years and has been used to investigate questions regarding the molecular biology, pathogenicity, and host adaptation determinants of these viruses. Further, reporter-expressing, recombinant viruses are increasingly used as tools for screening for and characterization of candidate medical countermeasures. Thus, reverse genetics systems represent powerful research tools. Here we provide an overview of available reverse genetics systems for the generation of recombinant filoviruses, potential applications, and the achievements that have been made using these systems.
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Affiliation(s)
- Thomas Hoenen
- Friedrich-Loeffler-Institut, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
| | - Janine Brandt
- Friedrich-Loeffler-Institut, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Yíngyún Caì
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD, 21702, USA
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD, 21702, USA.
| | - Courtney Finch
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD, 21702, USA
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Balmith M, Faya M, Soliman MES. Ebola virus: A gap in drug design and discovery - experimental and computational perspective. Chem Biol Drug Des 2016; 89:297-308. [PMID: 27637475 DOI: 10.1111/cbdd.12870] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The Ebola virus, formally known as the Ebola hemorrhagic fever, is an acute viral syndrome causing sporadic outbreaks that have ravaged West Africa. Due to its extreme virulence and highly transmissible nature, Ebola has been classified as a category A bioweapon organism. Only recently have vaccine or drug regimens for the Ebola virus been developed, including Zmapp and peptides. In addition, existing drugs which have been repurposed toward anti-Ebola virus activity have been re-examined and are seen to be promising candidates toward combating Ebola. Drug development involving computational tools has been widely employed toward target-based drug design. Screening large libraries have greatly stimulated research toward effective anti-Ebola virus drug regimens. Current emphasis has been placed on the investigation of host proteins and druggable viral targets. There is a huge gap in the literature regarding guidelines in the discovery of Ebola virus inhibitors, which may be due to the lack of information on the Ebola drug targets, binding sites, and mechanism of action of the virus. This review focuses on Ebola virus inhibitors, drugs which could be repurposed to combat the Ebola virus, computational methods which study drug-target interactions as well as providing further insight into the mode of action of the Ebola virus.
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Affiliation(s)
- Marissa Balmith
- Molecular Modeling and Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Mbuso Faya
- Molecular Modeling and Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Mahmoud E S Soliman
- Molecular Modeling and Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
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34
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Schmidt KM, Mühlberger E. Marburg Virus Reverse Genetics Systems. Viruses 2016; 8:E178. [PMID: 27338448 PMCID: PMC4926198 DOI: 10.3390/v8060178] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 12/16/2022] Open
Abstract
The highly pathogenic Marburg virus (MARV) is a member of the Filoviridae family and belongs to the group of nonsegmented negative-strand RNA viruses. Reverse genetics systems established for MARV have been used to study various aspects of the viral replication cycle, analyze host responses, image viral infection, and screen for antivirals. This article provides an overview of the currently established MARV reverse genetic systems based on minigenomes, infectious virus-like particles and full-length clones, and the research that has been conducted using these systems.
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Affiliation(s)
- Kristina Maria Schmidt
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Greifswald-Insel Riems 17493, Germany.
| | - Elke Mühlberger
- Department of Microbiology, School of Medicine, Boston University, 620 Albany Street, Boston, MA 02118, USA.
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, 620 Albany Street, Boston, MA 02118, USA.
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Howell KA, Qiu X, Brannan JM, Bryan C, Davidson E, Holtsberg FW, Wec AZ, Shulenin S, Biggins JE, Douglas R, Enterlein SG, Turner HL, Pallesen J, Murin CD, He S, Kroeker A, Vu H, Herbert AS, Fusco ML, Nyakatura EK, Lai JR, Keck ZY, Foung SKH, Saphire EO, Zeitlin L, Ward AB, Chandran K, Doranz BJ, Kobinger GP, Dye JM, Aman MJ. Antibody Treatment of Ebola and Sudan Virus Infection via a Uniquely Exposed Epitope within the Glycoprotein Receptor-Binding Site. Cell Rep 2016; 15:1514-1526. [PMID: 27160900 PMCID: PMC4871745 DOI: 10.1016/j.celrep.2016.04.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/07/2016] [Accepted: 04/03/2016] [Indexed: 12/02/2022] Open
Abstract
Previous efforts to identify cross-neutralizing antibodies to the receptor-binding site (RBS) of ebolavirus glycoproteins have been unsuccessful, largely because the RBS is occluded on the viral surface. We report a monoclonal antibody (FVM04) that targets a uniquely exposed epitope within the RBS; cross-neutralizes Ebola (EBOV), Sudan (SUDV), and, to a lesser extent, Bundibugyo viruses; and shows protection against EBOV and SUDV in mice and guinea pigs. The antibody cocktail ZMapp™ is remarkably effective against EBOV (Zaire) but does not cross-neutralize other ebolaviruses. By replacing one of the ZMapp™ components with FVM04, we retained the anti-EBOV efficacy while extending the breadth of protection to SUDV, thereby generating a cross-protective antibody cocktail. In addition, we report several mutations at the base of the ebolavirus glycoprotein that enhance the binding of FVM04 and other cross-reactive antibodies. These findings have important implications for pan-ebolavirus vaccine development and defining broadly protective antibody cocktails.
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Affiliation(s)
- Katie A Howell
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA
| | - Xiangguo Qiu
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R3E 3R2, Canada; Deparment of Medical Microbiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Jennifer M Brannan
- U.S. Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA
| | | | | | | | - Anna Z Wec
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Sergey Shulenin
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA
| | - Julia E Biggins
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA
| | - Robin Douglas
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA
| | | | - Hannah L Turner
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jesper Pallesen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Charles D Murin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Shihua He
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R3E 3R2, Canada; Deparment of Medical Microbiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Andrea Kroeker
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R3E 3R2, Canada; Deparment of Medical Microbiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Hong Vu
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA
| | - Andrew S Herbert
- U.S. Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA
| | - Marnie L Fusco
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Elisabeth K Nyakatura
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jonathan R Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Zhen-Yong Keck
- Department of Pathology, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Steven K H Foung
- Department of Pathology, School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Erica Ollmann Saphire
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA; Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kartik Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | - Gary P Kobinger
- Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R3E 3R2, Canada; Deparment of Medical Microbiology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - John M Dye
- U.S. Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA
| | - M Javad Aman
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20878, USA.
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White JM, Whittaker GR. Fusion of Enveloped Viruses in Endosomes. Traffic 2016; 17:593-614. [PMID: 26935856 PMCID: PMC4866878 DOI: 10.1111/tra.12389] [Citation(s) in RCA: 259] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 12/12/2022]
Abstract
Ari Helenius launched the field of enveloped virus fusion in endosomes with a seminal paper in the Journal of Cell Biology in 1980. In the intervening years, a great deal has been learned about the structures and mechanisms of viral membrane fusion proteins as well as about the endosomes in which different enveloped viruses fuse and the endosomal cues that trigger fusion. We now recognize three classes of viral membrane fusion proteins based on structural criteria and four mechanisms of fusion triggering. After reviewing general features of viral membrane fusion proteins and viral fusion in endosomes, we delve into three characterized mechanisms for viral fusion triggering in endosomes: by low pH, by receptor binding plus low pH and by receptor binding plus the action of a protease. We end with a discussion of viruses that may employ novel endosomal fusion‐triggering mechanisms. A key take‐home message is that enveloped viruses that enter cells by fusing in endosomes traverse the endocytic pathway until they reach an endosome that has all of the environmental conditions (pH, proteases, ions, intracellular receptors and lipid composition) to (if needed) prime and (in all cases) trigger the fusion protein and to support membrane fusion.
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Affiliation(s)
- Judith M White
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Gary R Whittaker
- Department of Microbiology & Immunology, Cornell University, Ithaca, NY, USA
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37
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Lee J, Gregory SM, Nelson EA, White JM, Tamm LK. The Roles of Histidines and Charged Residues as Potential Triggers of a Conformational Change in the Fusion Loop of Ebola Virus Glycoprotein. PLoS One 2016; 11:e0152527. [PMID: 27023721 PMCID: PMC4811418 DOI: 10.1371/journal.pone.0152527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/15/2016] [Indexed: 11/23/2022] Open
Abstract
Ebola virus (EBOV) enters cells from late endosomes/lysosomes under mildly acidic conditions. Entry by fusion with the endosomal membrane requires the fusion loop (FL, residues 507–560) of the EBOV surface glycoprotein to undergo a pH-dependent conformational change. To find the pH trigger for this reaction we mutated multiple conserved histidines and charged and uncharged hydrophilic residues in the FL and measured their activity by liposome fusion and cell entry of virus-like particles. The FL location in the membrane was assessed by NMR using soluble and lipid-bound paramagnetic relaxation agents. While we could not identify a single residue to be alone responsible for pH triggering, we propose that a distributed pH effect over multiple residues induces the conformational change that enhances membrane insertion and triggers the fusion activity of the EBOV FL.
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Affiliation(s)
- Jinwoo Lee
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia 22908, United States of America.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, United States of America
| | - Sonia M Gregory
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia 22908, United States of America.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, United States of America
| | - Elizabeth A Nelson
- Department Cell Biology, University of Virginia, Charlottesville, Virginia 22908, United States of America
| | - Judith M White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia 22908, United States of America.,Department Cell Biology, University of Virginia, Charlottesville, Virginia 22908, United States of America
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia 22908, United States of America.,Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, United States of America
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Host-Primed Ebola Virus GP Exposes a Hydrophobic NPC1 Receptor-Binding Pocket, Revealing a Target for Broadly Neutralizing Antibodies. mBio 2016; 7:e02154-15. [PMID: 26908579 PMCID: PMC4791852 DOI: 10.1128/mbio.02154-15] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED The filovirus surface glycoprotein (GP) mediates viral entry into host cells. Following viral internalization into endosomes, GP is cleaved by host cysteine proteases to expose a receptor-binding site (RBS) that is otherwise hidden from immune surveillance. Here, we present the crystal structure of proteolytically cleaved Ebola virus GP to a resolution of 3.3 Å. We use this structure in conjunction with functional analysis of a large panel of pseudotyped viruses bearing mutant GP proteins to map the Ebola virus GP endosomal RBS at molecular resolution. Our studies indicate that binding of GP to its endosomal receptor Niemann-Pick C1 occurs in two distinct stages: the initial electrostatic interactions are followed by specific interactions with a hydrophobic trough that is exposed on the endosomally cleaved GP1 subunit. Finally, we demonstrate that monoclonal antibodies targeting the filovirus RBS neutralize all known filovirus GPs, making this conserved pocket a promising target for the development of panfilovirus therapeutics. IMPORTANCE Ebola virus uses its glycoprotein (GP) to enter new host cells. During entry, GP must be cleaved by human enzymes in order for receptor binding to occur. Here, we provide the crystal structure of the cleaved form of Ebola virus GP. We demonstrate that cleavage exposes a site at the top of GP and that this site binds the critical domain C of the receptor, termed Niemann-Pick C1 (NPC1). We perform mutagenesis to find parts of the site essential for binding NPC1 and map distinct roles for an upper, charged crest and lower, hydrophobic trough in cleaved GP. We find that this 3-dimensional site is conserved across the filovirus family and that antibody directed against this site is able to bind cleaved GP from every filovirus tested and neutralize viruses bearing those GPs.
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Ng M, Ndungo E, Kaczmarek ME, Herbert AS, Binger T, Kuehne AI, Jangra RK, Hawkins JA, Gifford RJ, Biswas R, Demogines A, James RM, Yu M, Brummelkamp TR, Drosten C, Wang LF, Kuhn JH, Müller MA, Dye JM, Sawyer SL, Chandran K. Filovirus receptor NPC1 contributes to species-specific patterns of ebolavirus susceptibility in bats. eLife 2015; 4. [PMID: 26698106 PMCID: PMC4709267 DOI: 10.7554/elife.11785] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 11/19/2015] [Indexed: 12/13/2022] Open
Abstract
Biological factors that influence the host range and spillover of Ebola virus (EBOV) and other filoviruses remain enigmatic. While filoviruses infect diverse mammalian cell lines, we report that cells from African straw-colored fruit bats (Eidolon helvum) are refractory to EBOV infection. This could be explained by a single amino acid change in the filovirus receptor, NPC1, which greatly reduces the affinity of EBOV-NPC1 interaction. We found signatures of positive selection in bat NPC1 concentrated at the virus-receptor interface, with the strongest signal at the same residue that controls EBOV infection in Eidolon helvum cells. Our work identifies NPC1 as a genetic determinant of filovirus susceptibility in bats, and suggests that some NPC1 variations reflect host adaptations to reduce filovirus replication and virulence. A single viral mutation afforded escape from receptor control, revealing a pathway for compensatory viral evolution and a potential avenue for expansion of filovirus host range in nature. DOI:http://dx.doi.org/10.7554/eLife.11785.001 Ebola virus and other filoviruses can cause devastating diseases in humans and other apes. Numerous small outbreaks of Ebola virus disease have occurred in Africa over the past 40 years. However, in 2013–2015, the largest outbreak on record took place in three Western African nations with no previous history of the disease. Human outbreaks of Ebola virus disease likely begin when a person encounters an infected wild animal. Though it remains unclear precisely which animals harbor Ebola virus between outbreaks, and how they transmit the virus to humans or other primates, recent work showed that some filoviruses do infect specific types of bats in nature. Ng, Ndungo, Kaczmarek et al. sought to identify the genes that influence whether or not a type of bat is susceptible to infection by Ebola virus and other filoviruses. Several filoviruses, including Ebola virus, were tested to see if they could infect cells that had been collected from four types of African fruit bats. These bats are all found in areas where outbreaks have occurred in the past. The tests revealed that a small change in the sequence of the NPC1 gene in some bat cells greatly reduced their susceptibility to Ebola virus. NPC1 encodes a protein that mammals need in order to move cholesterol within their cells. In humans, the loss of the protein encoded by NPC1 causes a rare but very severe disease called Niemann-Pick type C disease. This protein also turns out to be a receptor that the filoviruses must bind to before they can infect the cells. Further analysis then revealed that NPC1 has evolved rapidly in bats, with changes concentrated in the parts of the receptor that interact with Ebola virus. Ng, Ndungo, Kaczmarek et al. went on to discover some changes in the genome sequence of Ebola virus that could compensate for the changes in the bat’s NPC1 gene. These findings hint at one way that a filovirus could evolve to better infect a host with receptors that were less than optimal. Following on from this work, the next challenges will be to expand the investigation to include additional types of bats, other types of mammals, and other host genes that could influence filovirus infection and disease. Further studies could also examine the other side of the arms race – that is, the evolution of viral genes in bats. However, such studies would be complicated by the lack of viral sequences that have been collected from bats, because to date most have been isolated from humans and other primates instead. DOI:http://dx.doi.org/10.7554/eLife.11785.002
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Affiliation(s)
- Melinda Ng
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Esther Ndungo
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Maria E Kaczmarek
- Department of Integrative Biology, University of Texas at Austin, Austin, United States
| | - Andrew S Herbert
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, United States
| | - Tabea Binger
- Institute of Virology, University of Bonn Medical Center, Bonn, Germany
| | - Ana I Kuehne
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, United States
| | - Rohit K Jangra
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - John A Hawkins
- Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, United States
| | - Robert J Gifford
- University of Glasgow MRC Virology Unit, Glasgow, United Kingdom
| | - Rohan Biswas
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Ann Demogines
- Department of Molecular Biosciences, University of Texas at Austin, Austin, United States
| | - Rebekah M James
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, United States
| | - Meng Yu
- Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, , Singapore
| | | | - Christian Drosten
- Institute of Virology, University of Bonn Medical Center, Bonn, Germany.,German Centre for Infectious Diseases Research, Bonn, Germany
| | - Lin-Fa Wang
- Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, , Singapore
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, United States
| | - Marcel A Müller
- Institute of Virology, University of Bonn Medical Center, Bonn, Germany
| | - John M Dye
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, United States
| | - Sara L Sawyer
- Department of Molecular Biosciences, University of Texas at Austin, Austin, United States.,BioFrontiers Institute, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Kartik Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
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40
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Ebolavirus Glycoprotein Directs Fusion through NPC1+ Endolysosomes. J Virol 2015; 90:605-10. [PMID: 26468524 PMCID: PMC4702577 DOI: 10.1128/jvi.01828-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 10/06/2015] [Indexed: 12/31/2022] Open
Abstract
Ebolavirus, a deadly hemorrhagic fever virus, was thought to enter cells through endolysosomes harboring its glycoprotein receptor, Niemann-Pick C1. However, an alternate model was recently proposed in which ebolavirus enters through a later NPC1-negative endosome that contains two-pore Ca(2+) channel 2 (TPC2), a newly identified ebolavirus entry factor. Here, using live cell imaging, we obtained evidence that in contrast to the new model, ebolavirus enters cells through endolysosomes that contain both NPC1 and TPC2.
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41
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Rhein BA, Maury WJ. Ebola virus entry into host cells: identifying therapeutic strategies. CURRENT CLINICAL MICROBIOLOGY REPORTS 2015; 2:115-124. [PMID: 26509109 PMCID: PMC4617201 DOI: 10.1007/s40588-015-0021-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Filoviruses cause severe hemorrhagic fever in humans. The archetypal virus of this group, Ebola virus, is responsible for the current filovirus epidemic in West Africa. Filoviruses infect most mammalian cells, resulting in broad species tropism and likely contributing to rapid spread of virus throughout the body. A thorough understanding of filovirus entry events will facilitate the development of therapeutics against these critical steps in the viral life cycle. This review summarizes the current understanding of filovirus entry and discusses some of the recent advancements in therapeutic strategies that target entry.
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Affiliation(s)
- Bethany A. Rhein
- Department of Microbiology, University of Iowa, 3-701 Bowen Science Building, 51 Newton Rd, Iowa City, IA 52242 USA
| | - Wendy J. Maury
- Department of Microbiology, University of Iowa, 3-701 Bowen Science Building, 51 Newton Rd, Iowa City, IA 52242 USA
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42
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Mathys L, Balzarini J. The role of cellular oxidoreductases in viral entry and virus infection-associated oxidative stress: potential therapeutic applications. Expert Opin Ther Targets 2015; 20:123-43. [PMID: 26178644 DOI: 10.1517/14728222.2015.1068760] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Cellular oxidoreductases catalyze thiol/disulfide exchange reactions in susceptible proteins and contribute to the cellular defense against oxidative stress. Oxidoreductases and oxidative stress are also involved in viral infections. In this overview, different aspects of the role of cellular oxidoreductases and oxidative stress during viral infections are discussed from a chemotherapeutic viewpoint. AREAS COVERED Entry of enveloped viruses into their target cells is triggered by the interaction of viral envelope glycoproteins with cellular (co)receptor(s) and depends on obligatory conformational changes in these viral envelope glycoproteins and/or cellular receptors. For some viruses, these conformational changes are mediated by cell surface-associated cellular oxidoreductases, which mediate disulfide bridge reductions in viral envelope glycoprotein(s). Therefore, targeting these oxidoreductases using oxidoreductase inhibitors might yield an interesting strategy to block viral entry of these viruses. Furthermore, since viral infections are often associated with systemic oxidative stress, contributing to disease progression, the enhancement of the cellular antioxidant defense systems might have potential as an adjuvant antiviral strategy, slowing down disease progression. EXPERT OPINION Promising antiviral data were obtained for both strategies. However, potential pitfalls have also been identified for these strategies, indicating that it is important to carefully assess the benefits versus risks of these antiviral strategies.
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Affiliation(s)
- Leen Mathys
- a 1 Rega Institute for Medical Research, KU Leuven , Minderbroedersstraat 10 blok x - bus 1030, Leuven, Belgium
| | - Jan Balzarini
- b 2 Rega Institute for Medical Research, KU Leuven , Minderbroedersstraat 10 blok x - bus 1030, Leuven, Belgium +32 16 3 37352 ; +32 16 3 37340 ;
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43
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Jae LT, Brummelkamp TR. Emerging intracellular receptors for hemorrhagic fever viruses. Trends Microbiol 2015; 23:392-400. [PMID: 26004032 DOI: 10.1016/j.tim.2015.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/10/2015] [Accepted: 04/21/2015] [Indexed: 01/05/2023]
Abstract
Ebola virus and Lassa virus belong to different virus families that can cause viral hemorrhagic fever, a life-threatening disease in humans with limited treatment options. To infect a target cell, Ebola and Lassa viruses engage receptors at the cell surface and are subsequently shuttled into the endosomal compartment. Upon arrival in late endosomes/lysosomes, the viruses trigger membrane fusion to release their genome into the cytoplasm. Although contact sites at the cell surface were recognized for Ebola virus and Lassa virus, it was postulated that Ebola virus requires a critical receptor inside the cell. Recent screens for host factors identified such internal receptors for both viruses: Niemann-Pick disease type C1 protein (NPC1) for Ebola virus and lysosome-associated membrane protein 1 (LAMP1) for Lassa virus. A cellular trigger is needed to permit binding of the viral envelope protein to these intracellular receptors. This 'receptor switch' represents a previously unnoticed step in virus entry with implications for host-pathogen interactions and viral tropism.
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Affiliation(s)
- Lucas T Jae
- Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, CX, 1066 The Netherlands
| | - Thijn R Brummelkamp
- Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, CX, 1066 The Netherlands.
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44
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Liu N, Tao Y, Brenowitz MD, Girvin ME, Lai JR. Structural and Functional Studies on the Marburg Virus GP2 Fusion Loop. J Infect Dis 2015; 212 Suppl 2:S146-53. [PMID: 25786917 DOI: 10.1093/infdis/jiv030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Marburg virus (MARV) and the ebolaviruses belong to the family Filoviridae (the members of which are filoviruses) that cause severe hemorrhagic fever. Infection requires fusion of the host and viral membranes, a process that occurs in the host cell endosomal compartment and is facilitated by the envelope glycoprotein fusion subunit, GP2. The N-terminal fusion loop (FL) of GP2 is a hydrophobic disulfide-bonded loop that is postulated to insert and disrupt the host endosomal membrane during fusion. Here, we describe the first structural and functional studies of a protein corresponding to the MARV GP2 FL. We found that this protein undergoes a pH-dependent conformational change, as monitored by circular dichroism and nuclear magnetic resonance. Furthermore, we report that, under low pH conditions, the MARV GP2 FL can induce content leakage from liposomes. The general aspects of this pH-dependent structure and lipid-perturbing behavior are consistent with previous reports on Ebola virus GP2 FL. However, nuclear magnetic resonance studies in lipid bicelles and mutational analysis indicate differences in structure exist between MARV and Ebola virus GP2 FL. These results provide new insight into the mechanism of MARV GP2-mediated cell entry.
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Affiliation(s)
- Nina Liu
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Yisong Tao
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Michael D Brenowitz
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Mark E Girvin
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Jonathan R Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
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Abstract
The current Ebola virus disease (EVD) outbreak in West Africa is the largest with over 5100 deaths in four West African countries as of 14 November 2014. EVD has high case-fatality rates but no licensed treatment or vaccine is yet available. Several vaccine candidates that protected nonhuman primates are not yet available for clinical use. Slow development of vaccine-stimulated immunity, sporadic nature and fast progression of EVD underlines the need for the development of effective postexposure therapeutic drugs. WHO encouraged the use of untested drugs for EVD to curb the fast-spreading outbreak. Here, we summarize therapeutics for EVD including monoclonal antibody-based therapy and inhibitors of viral replication including our recently developed small-molecule inhibitors of VP30 dephosphorylation.
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Affiliation(s)
- Marina Jerebtsova
- Department of Microbiology, Howard University, Washington, DC 20059, USA
| | - Sergei Nekhai
- Department of Microbiology, Howard University, Washington, DC 20059, USA ; Center for Sickle Cell Disease, Howard University, Washington, DC 20059, USA ; Department of Medicine, Howard University, Washington, DC 20059, USA ; Department of Pharmacology, Howard University, Washington, DC 20059, USA
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46
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Bickler SW, Lizardo RE, De Maio A. The transition from a rural to an urban environment alters expression of the human Ebola virus receptor Neiman-Pick C1: implications for the current epidemic in West Africa. Cell Stress Chaperones 2015; 20:203-6. [PMID: 25477151 PMCID: PMC4326391 DOI: 10.1007/s12192-014-0557-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 11/06/2014] [Accepted: 11/11/2014] [Indexed: 01/06/2023] Open
Affiliation(s)
- Stephen W. Bickler
- />Center for Investigations of Health and Education Disparities, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA 92093-0739 USA
- />Department of Surgery, School of Medicine, University of California, La Jolla, CA 92093 USA
- />Division of Pediatric Surgery, Rady Children’s Hospital, San Diego, CA 92123 USA
| | - Radhames E. Lizardo
- />Center for Investigations of Health and Education Disparities, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA 92093-0739 USA
- />Department of Surgery, Naval Medical Center San Diego, San Diego, CA 92134 USA
- />Division of Pediatric Surgery, Rady Children’s Hospital, San Diego, CA 92123 USA
| | - Antonio De Maio
- />Center for Investigations of Health and Education Disparities, University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA 92093-0739 USA
- />Department of Surgery, School of Medicine, University of California, La Jolla, CA 92093 USA
- />Department of Neurosciences, School of Medicine, University of California, La Jolla, CA 92093 USA
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47
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Abstract
![]()
The
Ebolaviruses are members of the family Filoviridae (“filoviruses”) and cause severe hemhorragic fever
with human case fatality rates as high as 90%. Infection requires
attachment of the viral particle to cells and triggering of membrane
fusion between the host and viral membranes, a process that occurs
in the host endosome and is facilitated by the envelope glycoprotein
(GP). One potential strategy for therapeutic intervention is the development
of agents (antibodies, peptides, and small molecules) that can interfere
with viral entry aspects such as attachment, uptake, priming, or membrane
fusion. This paper highlights recent developments in the discovery
and evaluation of therapeutic entry inhibitors and identifies opportunities
moving forward.
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Affiliation(s)
- Elisabeth K. Nyakatura
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Julia C. Frei
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Jonathan R. Lai
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
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48
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Ebola virus and severe acute respiratory syndrome coronavirus display late cell entry kinetics: evidence that transport to NPC1+ endolysosomes is a rate-defining step. J Virol 2014; 89:2931-43. [PMID: 25552710 DOI: 10.1128/jvi.03398-14] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED Ebola virus (EBOV) causes hemorrhagic fevers with high mortality rates. During cellular entry, the virus is internalized by macropinocytosis and trafficked through endosomes until fusion between the viral and an endosomal membrane is triggered, releasing the RNA genome into the cytoplasm. We found that while macropinocytotic uptake of filamentous EBOV viruslike particles (VLPs) expressing the EBOV glycoprotein (GP) occurs relatively quickly, VLPs only begin to enter the cytoplasm after a 30-min lag, considerably later than particles bearing the influenza hemagglutinin or GP from lymphocytic choriomeningitis virus, which enter through late endosomes (LE). For EBOV, the long lag is not due to the large size or unusual shape of EBOV filaments, the need to prime EBOV GP to the 19-kDa receptor-binding species, or a need for unusually low endosomal pH. In contrast, since we observed that EBOV entry occurs upon arrival in Niemann-Pick C1 (NPC1)-positive endolysosomes (LE/Lys), we propose that trafficking to LE/Lys is a key rate-defining step. Additional experiments revealed, unexpectedly, that severe acute respiratory syndrome (SARS) S-mediated entry also begins only after a 30-min lag. Furthermore, although SARS does not require NPC1 for entry, SARS entry also begins after colocalization with NPC1. Since the only endosomal requirement for SARS entry is cathepsin L activity, we tested and provide evidence that NPC1(+) LE/Lys have higher cathepsin L activity than LE, with no detectable activity in earlier endosomes. Our findings suggest that both EBOV and SARS traffic deep into the endocytic pathway for entry and that they do so to access higher cathepsin activity. IMPORTANCE Ebola virus is a hemorrhagic fever virus that causes high fatality rates when it spreads from zoonotic vectors into the human population. Infection by severe acute respiratory syndrome coronavirus (SARS-CoV) causes severe respiratory distress in infected patients. A devastating outbreak of EBOV occurred in West Africa in 2014, and there was a significant outbreak of SARS in 2003. No effective vaccine or treatment has yet been approved for either virus. We present evidence that both viruses traffic late into the endocytic pathway, to NPC1(+) LE/Lys, in order to enter host cells, and that they do so to access high levels of cathepsin activity, which both viruses use in their fusion-triggering mechanisms. This unexpected similarity suggests an unexplored vulnerability, trafficking to NPC1(+) LE/Lys, as a therapeutic target for SARS and EBOV.
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49
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Less is more: Ebola virus surface glycoprotein expression levels regulate virus production and infectivity. J Virol 2014; 89:1205-17. [PMID: 25392212 DOI: 10.1128/jvi.01810-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED The Ebola virus (EBOV) surface glycoprotein (GP1,2) mediates host cell attachment and fusion and is the primary target for host neutralizing antibodies. Expression of GP1,2 at high levels disrupts normal cell physiology, and EBOV uses an RNA-editing mechanism to regulate expression of the GP gene. In this study, we demonstrate that high levels of GP1,2 expression impair production and release of EBOV virus-like particles (VLPs) as well as infectivity of GP1,2-pseudotyped viruses. We further show that this effect is mediated through two mechanisms. First, high levels of GP1,2 expression reduce synthesis of other proteins needed for virus assembly. Second, viruses containing high levels of GP1,2 are intrinsically less infectious, possibly due to impaired receptor binding or endosomal processing. Importantly, proteolysis can rescue the infectivity of high-GP1,2-containing viruses. Taken together, our findings indicate that GP1,2 expression levels have a profound effect on factors that contribute to virus fitness and that RNA editing may be an important mechanism employed by EBOV to regulate GP1,2 expression in order to optimize virus production and infectivity. IMPORTANCE The Ebola virus (EBOV), as well as other members of the Filoviridae family, causes severe hemorrhagic fever that is highly lethal, with up to 90% mortality. The EBOV surface glycoprotein (GP1,2) plays important roles in virus infection and pathogenesis, and its expression is tightly regulated by an RNA-editing mechanism during virus replication. Our study demonstrates that the level of GP1,2 expression profoundly affects virus particle production and release and uncovers a new mechanism by which Ebola virus infectivity is regulated by the level of GP1,2 expression. These findings extend our understanding of EBOV infection and replication in adaptation of host environments, which will aid the development of countermeasures against EBOV infection.
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50
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Chen G, Koellhoffer JF, Zak SE, Frei JC, Liu N, Long H, Ye W, Nagar K, Pan G, Chandran K, Dye JM, Sidhu SS, Lai JR. Synthetic antibodies with a human framework that protect mice from lethal Sudan ebolavirus challenge. ACS Chem Biol 2014; 9:2263-73. [PMID: 25140871 PMCID: PMC4201348 DOI: 10.1021/cb5006454] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
The ebolaviruses cause severe and
rapidly progressing hemorrhagic
fever. There are five ebolavirus species; although much is known about
Zaire ebolavirus (EBOV) and its neutralization by antibodies, little
is known about Sudan ebolavirus (SUDV), which is emerging with increasing
frequency. Here we describe monoclonal antibodies containing a human
framework that potently inhibit infection by SUDV and protect mice
from lethal challenge. The murine antibody 16F6, which binds the SUDV
envelope glycoprotein (GP), served as the starting point for design.
Sequence and structural alignment revealed similarities between 16F6
and YADS1, a synthetic antibody with a humanized scaffold. A focused
phage library was constructed and screened to impart 16F6-like recognition
properties onto the YADS1 scaffold. A panel of 17 antibodies were
characterized and found to have a range of neutralization potentials
against a pseudotype virus infection model. Neutralization correlated
with GP binding as determined by ELISA. Two of these clones, E10 and
F4, potently inhibited authentic SUDV and conferred protection and
memory immunity in mice from lethal SUDV challenge. E10 and F4 were
further shown to bind to the same epitope on GP as 16F6 with comparable
affinities. These antibodies represent strong immunotherapeutic candidates
for treatment of SUDV infection.
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Affiliation(s)
- Gang Chen
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
| | | | - Samantha E. Zak
- Virology
Division, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Maryland 21702, United States
| | | | | | - Hua Long
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
| | - Wei Ye
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
| | - Kaajal Nagar
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
| | - Guohua Pan
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
| | | | - John M. Dye
- Virology
Division, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Maryland 21702, United States
| | - Sachdev S. Sidhu
- Banting
and Best Department of Medical Research, Terrence Donnelly Centre
for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON, Canada M5S 3E1
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