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Narkhede YB, Bhardwaj A, Motsa BB, Saxena R, Sharma T, Chapagain PP, Stahelin RV, Wiest O. Elucidating Residue-Level Determinants Affecting Dimerization of Ebola Virus Matrix Protein Using High-Throughput Site Saturation Mutagenesis and Biophysical Approaches. J Phys Chem B 2023; 127:6449-6461. [PMID: 37458567 DOI: 10.1021/acs.jpcb.3c01759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The Ebola virus (EBOV) is a filamentous virus that acquires its lipid envelope from the plasma membrane of the host cell it infects. EBOV assembly and budding from the host cell plasma membrane are mediated by a peripheral protein, known as the matrix protein VP40. VP40 is a 326 amino acid protein with two domains that are loosely linked. The VP40 N-terminal domain (NTD) contains a hydrophobic α-helix, which mediates VP40 dimerization. The VP40 C-terminal domain has a cationic patch, which mediates interactions with anionic lipids and a hydrophobic region that mediates VP40 dimer-dimer interactions. The VP40 dimer is necessary for trafficking to the plasma membrane inner leaflet and interactions with anionic lipids to mediate the VP40 assembly and oligomerization. Despite significant structural information available on the VP40 dimer structure, little is known on how the VP40 dimer is stabilized and how residues outside the NTD hydrophobic portion of the α-helical dimer interface contribute to dimer stability. To better understand how VP40 dimer stability is maintained, we performed computational studies using per-residue energy decomposition and site saturation mutagenesis. These studies revealed a number of novel keystone residues for VP40 dimer stability just adjacent to the α-helical dimer interface as well as distant residues in the VP40 CTD that can stabilize the VP40 dimer form. Experimental studies with representative VP40 mutants in vitro and in cells were performed to test computational predictions that reveal residues that alter VP40 dimer stability. Taken together, these studies provide important biophysical insights into VP40 dimerization and may be useful in strategies to weaken or alter the VP40 dimer structure as a means of inhibiting the EBOV assembly.
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Affiliation(s)
- Yogesh B Narkhede
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Atul Bhardwaj
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Balindile B Motsa
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, Indiana 47907, United States
| | - Roopashi Saxena
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, Indiana 47907, United States
| | | | | | - Robert V Stahelin
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, Indiana 47907, United States
| | - Olaf Wiest
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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WWOX-Mediated Degradation of AMOTp130 Negatively Affects Egress of Filovirus VP40 VLPs. J Virol 2022; 96:e0202621. [PMID: 35107375 DOI: 10.1128/jvi.02026-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ebola (EBOV) and Marburg (MARV) viruses continue to emerge and cause severe hemorrhagic disease in humans. A comprehensive understanding of the filovirus-host interplay will be crucial for identifying and developing antiviral strategies. The filoviral VP40 matrix protein drives virion assembly and egress, in part by recruiting specific WW-domain-containing host interactors via its conserved PPxY Late (L) domain motif to positively regulate virus egress and spread. In contrast to these positive regulators of virus budding, a growing list of WW-domain-containing interactors that negatively regulate virus egress and spread have been identified, including BAG3, YAP/TAZ and WWOX. In addition to host WW-domain regulators of virus budding, host PPxY-containing proteins also contribute to regulating this late stage of filovirus replication. For example, angiomotin (AMOT) is a multi-PPxY-containing host protein that functionally interacts with many of the same WW-domain-containing proteins that regulate virus egress and spread. In this report, we demonstrate that host WWOX, which negatively regulates egress of VP40 VLPs and recombinant VSV-M40 virus, interacts with and suppresses the expression of AMOT. We found that WWOX disrupts AMOT's scaffold-like tubular distribution and reduces AMOT localization at the plasma membrane via lysosomal degradation. In sum, our findings reveal an indirect and novel mechanism by which modular PPxY/WW-domain interactions between AMOT and WWOX regulate PPxY-mediated egress of filovirus VP40 VLPs. A better understanding of this modular network and competitive nature of protein-protein interactions will help to identify new antiviral targets and therapeutic strategies. IMPORTANCE Filoviruses (Ebola [EBOV] and Marburg [MARV]) are zoonotic, emerging pathogens that cause outbreaks of severe hemorrhagic fever in humans. A fundamental understanding of the virus-host interface is critical for understanding the biology of these viruses and for developing future strategies for therapeutic intervention. Here, we reveal a novel mechanism by which host proteins WWOX and AMOTp130 interact with each other and with the EBOV matrix protein VP40 to regulate VP40-mediated egress of virus like particles (VLPs). Our results highlight the biological impact of competitive interplay of modular virus-host interactions on both the virus lifecycle and the host cell.
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Abstract
Marburg virus (MARV) VP40 protein (mVP40) directs egress and spread of MARV, in part, by recruiting specific host WW domain-containing proteins via its conserved PPxY late (L) domain motif to facilitate efficient virus-cell separation. We reported previously that small-molecule compounds targeting the viral PPxY/host WW domain interaction inhibited VP40-mediated egress and spread. Here, we report on the antiviral potency of novel compound FC-10696, which emerged from extensive structure-activity relationship (SAR) of a previously described series of PPxY inhibitors. We show that FC-10696 inhibits egress of mVP40 virus-like particles (VLPs) and egress of authentic MARV from HeLa cells and primary human macrophages. Moreover, FC-10696 treated-mice displayed delayed onset of weight loss and clinical signs and significantly lower viral loads compared to controls, with 14% of animals surviving 21 days following a lethal MARV challenge. Thus, FC-10696 represents a first-in-class, host-oriented inhibitor effectively targeting late stages of the MARV life cycle.
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Amiar S, Husby ML, Wijesinghe KJ, Angel S, Bhattarai N, Gerstman BS, Chapagain PP, Li S, Stahelin RV. Lipid-specific oligomerization of the Marburg virus matrix protein VP40 is regulated by two distinct interfaces for virion assembly. J Biol Chem 2021; 296:100796. [PMID: 34019871 PMCID: PMC8191294 DOI: 10.1016/j.jbc.2021.100796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 02/03/2023] Open
Abstract
Marburg virus (MARV) is a lipid-enveloped virus harboring a negative-sense RNA genome, which has caused sporadic outbreaks of viral hemorrhagic fever in sub-Saharan Africa. MARV assembles and buds from the host cell plasma membrane where MARV matrix protein (mVP40) dimers associate with anionic lipids at the plasma membrane inner leaflet and undergo a dynamic and extensive self-oligomerization into the structural matrix layer. The MARV matrix layer confers the virion filamentous shape and stability but how host lipids modulate mVP40 oligomerization is mostly unknown. Using in vitro and cellular techniques, we present a mVP40 assembly model highlighting two distinct oligomerization interfaces: the (N-terminal domain [NTD] and C-terminal domain [CTD]) in mVP40. Cellular studies of NTD and CTD oligomerization interface mutants demonstrate the importance of each interface in matrix assembly. The assembly steps include protein trafficking to the plasma membrane, homo-multimerization that induced protein enrichment, plasma membrane fluidity changes, and elongations at the plasma membrane. An ascorbate peroxidase derivative (APEX)-transmission electron microscopy method was employed to closely assess the ultrastructural localization and formation of viral particles for wildtype mVP40 and NTD and CTD oligomerization interface mutants. Taken together, these studies present a mechanistic model of mVP40 oligomerization and assembly at the plasma membrane during virion assembly that requires interactions with phosphatidylserine for NTD–NTD interactions and phosphatidylinositol-4,5-bisphosphate for proper CTD–CTD interactions. These findings have broader implications in understanding budding of lipid-enveloped viruses from the host cell plasma membrane and potential strategies to target protein–protein or lipid–protein interactions to inhibit virus budding.
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Affiliation(s)
- Souad Amiar
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Monica L Husby
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Kaveesha J Wijesinghe
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Stephanie Angel
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
| | - Nisha Bhattarai
- Department of Physics, Florida International University, Miami, Florida, USA
| | - Bernard S Gerstman
- Department of Physics, Florida International University, Miami, Florida, USA; Biomolecular Sciences Institute, Florida International University, Miami, Florida, USA
| | - Prem P Chapagain
- Department of Physics, Florida International University, Miami, Florida, USA; Biomolecular Sciences Institute, Florida International University, Miami, Florida, USA
| | - Sheng Li
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Robert V Stahelin
- Department of Medicinal Chemistry & Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA.
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Angiomotin Counteracts the Negative Regulatory Effect of Host WWOX on Viral PPxY-Mediated Egress. J Virol 2021; 95:JVI.00121-21. [PMID: 33536174 PMCID: PMC8103691 DOI: 10.1128/jvi.00121-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Filoviridae family members Ebola (EBOV) and Marburg (MARV) viruses and Arenaviridae family member Lassa virus (LASV) are emerging pathogens that can cause hemorrhagic fever and high rates of mortality in humans. A better understanding of the interplay between these viruses and the host will inform about the biology of these pathogens, and may lead to the identification of new targets for therapeutic development. Notably, expression of the filovirus VP40 and LASV Z matrix proteins alone drives assembly and egress of virus-like particles (VLPs). The conserved PPxY Late (L) domain motifs in the filovirus VP40 and LASV Z proteins play a key role in the budding process by mediating interactions with select host WW-domain containing proteins that then regulate virus egress and spread. To identify the full complement of host WW-domain interactors, we utilized WT and PPxY mutant peptides from EBOV and MARV VP40 and LASV Z proteins to screen an array of GST-WW-domain fusion proteins. We identified WW domain-containing oxidoreductase (WWOX) as a novel PPxY-dependent interactor, and we went on to show that full-length WWOX physically interacts with eVP40, mVP40 and LASV Z to negatively regulate egress of VLPs and of a live VSV/Ebola recombinant virus (M40). Interestingly, WWOX is a versatile host protein that regulates multiple signaling pathways and cellular processes via modular interactions between its WW-domains and PPxY motifs of select interacting partners, including host angiomotin (AMOT). Notably, we demonstrated recently that expression of endogenous AMOT not only positively regulates egress of VLPs, but also promotes egress and spread of live EBOV and MARV. Toward the mechanism of action, we show that the competitive and modular interplay among WWOX-AMOT-VP40/Z regulates VLP and M40 virus egress. Thus, WWOX is the newest member of an emerging group of host WW-domain interactors (e.g. BAG3; YAP/TAZ) that negatively regulate viral egress. These findings further highlight the complex interplay of virus-host PPxY/WW-domain interactions and their potential impact on the biology of both the virus and the host during infection.Author Summary Filoviruses (Ebola [EBOV] and Marburg [MARV]) and arenavirus (Lassa virus; LASV) are zoonotic, emerging pathogens that cause outbreaks of severe hemorrhagic fever in humans. A fundamental understanding of the virus-host interface is critical for understanding the biology of these viruses and for developing future strategies for therapeutic intervention. Here, we identified host WW-domain containing protein WWOX as a novel interactor with VP40 and Z, and showed that WWOX inhibited budding of VP40/Z virus-like particles (VLPs) and live virus in a PPxY/WW-domain dependent manner. Our findings are important to the field as they expand the repertoire of host interactors found to regulate PPxY-mediated budding of RNA viruses, and further highlight the competitive interplay and modular virus-host interactions that impact both the virus lifecycle and the host cell.
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Ubiquitin Ligase SMURF2 Interacts with Filovirus VP40 and Promotes Egress of VP40 VLPs. Viruses 2021; 13:v13020288. [PMID: 33673144 PMCID: PMC7918931 DOI: 10.3390/v13020288] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 01/17/2023] Open
Abstract
Filoviruses Ebola (EBOV) and Marburg (MARV) are devastating high-priority pathogens capable of causing explosive outbreaks with high human mortality rates. The matrix proteins of EBOV and MARV, as well as eVP40 and mVP40, respectively, are the key viral proteins that drive virus assembly and egress and can bud independently from cells in the form of virus-like particles (VLPs). The matrix proteins utilize proline-rich Late (L) domain motifs (e.g., PPxY) to hijack specific host proteins that contain WW domains, such as the HECT family E3 ligases, to facilitate the last step of virus–cell separation. We identified E3 ubiquitin ligase Smad Ubiquitin Regulatory Factor 2 (SMURF2) as a novel interactor with VP40 that positively regulates VP40 VLP release. Our results show that eVP40 and mVP40 interact with the three WW domains of SMURF2 via their PPxY motifs. We provide evidence that the eVP40–SMURF2 interaction is functional as the expression of SMURF2 positively regulates VLP egress, while siRNA knockdown of endogenous SMURF2 decreases VLP budding compared to controls. In sum, our identification of novel interactor SMURF2 adds to the growing list of identified host proteins that can regulate PPxY-mediated egress of VP40 VLPs. A more comprehensive understanding of the modular interplay between filovirus VP40 and host proteins may lead to the development of new therapies to combat these deadly infections.
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A Conserved Tryptophan in the Ebola Virus Matrix Protein C-Terminal Domain Is Required for Efficient Virus-Like Particle Formation. Pathogens 2020; 9:pathogens9050402. [PMID: 32455873 PMCID: PMC7281420 DOI: 10.3390/pathogens9050402] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 02/05/2023] Open
Abstract
The Ebola virus (EBOV) harbors seven genes, one of which is the matrix protein eVP40, a peripheral protein that is sufficient to induce the formation of virus-like particles from the host cell plasma membrane. eVP40 can form different structures to fulfil different functions during the viral life cycle, although the structural dynamics of eVP40 that warrant dimer, hexamer, and octamer formation are still poorly understood. eVP40 has two conserved Trp residues at positions 95 and 191. The role of Trp95 has been characterized in depth as it serves as an important residue in eVP40 oligomer formation. To gain insight into the functional role of Trp191 in eVP40, we prepared mutations of Trp191 (W191A or W191F) to determine the effects of mutation on eVP40 plasma membrane localization and budding as well as eVP40 oligomerization. These in vitro and cellular experiments were complemented by molecular dynamics simulations of the wild-type (WT) eVP40 structure versus that of W191A. Taken together, Trp is shown to be a critical amino acid at position 191 as mutation to Ala reduces the ability of VP40 to localize to the plasma membrane inner leaflet and form new virus-like particles. Further, mutation of Trp191 to Ala or Phe shifted the in vitro equilibrium to the octamer form by destabilizing Trp191 interactions with nearby residues. This study has shed new light on the importance of interdomain interactions in stability of the eVP40 structure and the critical nature of timing of eVP40 oligomerization for plasma membrane localization and viral budding.
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Jin C, Che B, Guo Z, Li C, Liu Y, Wu W, Wang S, Li D, Cui Z, Liang M. Single virus tracking of Ebola virus entry through lipid rafts in living host cells. BIOSAFETY AND HEALTH 2020; 2:25-31. [PMID: 32835208 PMCID: PMC7347359 DOI: 10.1016/j.bsheal.2019.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/24/2019] [Accepted: 12/25/2019] [Indexed: 12/20/2022] Open
Abstract
Ebola virus (EBOV) is one of the most pathogenic viruses in humans which can cause a lethal hemorrhagic fever. Understanding the cellular entry mechanisms of EBOV can promote the development of new therapeutic strategies to control virus replication and spread. It has been known that EBOV virions bind to factors expressed at the host cell surface. Subsequently, the virions are internalized by a macropinocytosis-like process, followed by being trafficked through early and late endosomes. Recent researches indicate that the entry of EBOV into cells requires integrated and functional lipid rafts. Whilst lipid rafts have been hypothesized to play a role in virus entry, there is a current lack of supporting data. One major technical hurdle is the lack of effective approaches for observing viral entry. To provide evidence on the involvement of lipid rafts in the entry process of EBOV, we generated the fluorescently labeled Ebola virus like particles (VLPs), and utilized single-particle tracking (SPT) to visualize the entry of fluorescent Ebola VLPs in live cells and the interaction of Ebola VLPs with lipid rafts. In this study, we demonstrate the compartmentalization of Ebola VLPs in lipid rafts during entry process, and inform the essential function of lipid rafts for the entry of Ebola virus. As such, our study provides evidence to show that the raft integrity is critical for Ebola virus pathogenesis and that lipid rafts can serve as potential targets for the development of novel therapeutic strategies.
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Affiliation(s)
- Cong Jin
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
- National Center for AIDS/STD Control and Prevention, China CDC, Beijing 102206, China
| | - Bin Che
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Zhengyuan Guo
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chuan Li
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Yang Liu
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Wei Wu
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Shiwen Wang
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Dexin Li
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
| | - Zongqiang Cui
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mifang Liang
- Key Laboratory of Medical Virology and Viral Diseases, Ministry of Health of People's Republic of China, National Institute for Viral Disease Control and Prevention (IVDC), Chinese Center for Disease control and Prevention (China CDC), Beijing 102206, China
- Center for Biosafety Mega-Science, Chinese Academy of Sciences, Beijing 100049, China
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Lin AE, Diehl WE, Cai Y, Finch CL, Akusobi C, Kirchdoerfer RN, Bollinger L, Schaffner SF, Brown EA, Saphire EO, Andersen KG, Kuhn JH, Luban J, Sabeti PC. Reporter Assays for Ebola Virus Nucleoprotein Oligomerization, Virion-Like Particle Budding, and Minigenome Activity Reveal the Importance of Nucleoprotein Amino Acid Position 111. Viruses 2020; 12:E105. [PMID: 31952352 PMCID: PMC7019320 DOI: 10.3390/v12010105] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/17/2023] Open
Abstract
For highly pathogenic viruses, reporter assays that can be rapidly performed are critically needed to identify potentially functional mutations for further study under maximal containment (e.g., biosafety level 4 [BSL-4]). The Ebola virus nucleoprotein (NP) plays multiple essential roles during the viral life cycle, yet few tools exist to study the protein under BSL-2 or equivalent containment. Therefore, we adapted reporter assays to measure NP oligomerization and virion-like particle (VLP) production in live cells and further measured transcription and replication using established minigenome assays. As a proof-of-concept, we examined the NP-R111C substitution, which emerged during the 2013‒2016 Western African Ebola virus disease epidemic and rose to high frequency. NP-R111C slightly increased NP oligomerization and VLP budding but slightly decreased transcription and replication. By contrast, a synthetic charge-reversal mutant, NP-R111E, greatly increased oligomerization but abrogated transcription and replication. These results are intriguing in light of recent structures of NP oligomers, which reveal that the neighboring residue, K110, forms a salt bridge with E349 on adjacent NP molecules. By developing and utilizing multiple reporter assays, we find that the NP-111 position mediates a complex interplay between NP's roles in protein structure, virion budding, and transcription and replication.
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Affiliation(s)
- Aaron E. Lin
- Harvard Program in Virology, Harvard Medical School, Boston, MA 02115, USA
- Department of Organismic and Evolutionary Biology, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; (S.F.S.); (E.A.B.)
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - William E. Diehl
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA; (W.E.D.); (J.L.)
| | - Yingyun Cai
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD 21702, USA; (Y.C.); (C.L.F.); (L.B.); (J.H.K.)
| | - Courtney L. Finch
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD 21702, USA; (Y.C.); (C.L.F.); (L.B.); (J.H.K.)
| | - Chidiebere Akusobi
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02120, USA;
| | | | - Laura Bollinger
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD 21702, USA; (Y.C.); (C.L.F.); (L.B.); (J.H.K.)
| | - Stephen F. Schaffner
- Department of Organismic and Evolutionary Biology, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; (S.F.S.); (E.A.B.)
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Elizabeth A. Brown
- Department of Organismic and Evolutionary Biology, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; (S.F.S.); (E.A.B.)
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Kristian G. Andersen
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA;
- Scripps Translational Science Institute, La Jolla, CA 92037, USA
| | - Jens H. Kuhn
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, MD 21702, USA; (Y.C.); (C.L.F.); (L.B.); (J.H.K.)
| | - Jeremy Luban
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA; (W.E.D.); (J.L.)
| | - Pardis C. Sabeti
- Harvard Program in Virology, Harvard Medical School, Boston, MA 02115, USA
- Department of Organismic and Evolutionary Biology, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; (S.F.S.); (E.A.B.)
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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Sarkar B, Ullah MA, Araf Y. A systematic and reverse vaccinology approach to design novel subunit vaccines against Dengue virus type-1 (DENV-1) and human Papillomavirus-16 (HPV-16). INFORMATICS IN MEDICINE UNLOCKED 2020. [DOI: 10.1016/j.imu.2020.100343] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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Nanbo A, Ohba Y. Budding of Ebola Virus Particles Requires the Rab11-Dependent Endocytic Recycling Pathway. J Infect Dis 2019; 218:S388-S396. [PMID: 30476249 PMCID: PMC6249604 DOI: 10.1093/infdis/jiy460] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The Ebola virus-encoded major matrix protein VP40 traffics to the plasma membrane, which leads to the formation of filamentous viral particles and subsequent viral egress. However, the cellular machineries underlying this process are not fully understood. In the present study, we have assessed the role of host endocytic recycling in Ebola virus particle formation. We found that a small GTPase Rab11, which regulates recycling of molecules among the trans-Golgi network, recycling endosomes, and the plasma membrane, was incorporated in Ebola virus-like particles. Although Rab11 predominantly localized in the perinuclear region, it distributed diffusely in the cytoplasm and partly localized in the periphery of the cells transiently expressing VP40. In contrast, Rab11 exhibited a perinuclear distribution when 2 VP40 derivatives that lack ability to traffic to the plasma membrane were expressed. Finally, expression of a dominant-negative form of Rab11 or knockdown of Rab11 inhibited both VP40-induced clusters at the plasma membrane and release of viral-like particles. Taken together, our findings demonstrate that Ebola virus exploits host endocytic recycling machinery to facilitate the trafficking of VP40 to the cell surface and the subsequent release of viral-like particles for its establishment of efficient viral egress.
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Affiliation(s)
- Asuka Nanbo
- Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yusuke Ohba
- Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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Gordon TB, Hayward JA, Marsh GA, Baker ML, Tachedjian G. Host and Viral Proteins Modulating Ebola and Marburg Virus Egress. Viruses 2019; 11:v11010025. [PMID: 30609802 PMCID: PMC6357148 DOI: 10.3390/v11010025] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/21/2018] [Accepted: 01/01/2019] [Indexed: 12/11/2022] Open
Abstract
The filoviruses Ebolavirus and Marburgvirus are among the deadliest viral pathogens known to infect humans, causing emerging diseases with fatality rates of up to 90% during some outbreaks. The replication cycles of these viruses are comprised of numerous complex molecular processes and interactions with their human host, with one key feature being the means by which nascent virions exit host cells to spread to new cells and ultimately to a new host. This review focuses on our current knowledge of filovirus egress and the viral and host factors and processes that are involved. Within the virus, these factors consist of the major matrix protein, viral protein 40 (VP40), which is necessary and sufficient for viral particle release, and nucleocapsid and glycoprotein that interact with VP40 to promote egress. In the host cell, some proteins are hijacked by filoviruses in order to enhance virion budding capacity that include members of the family of E3 ubiquitin ligase and the endosomal sorting complexes required for transport (ESCRT) pathway, while others such as tetherin inhibit viral egress. An understanding of these molecular interactions that modulate viral particle egress provides an important opportunity to identify new targets for the development of antivirals to prevent and treat filovirus infections.
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Affiliation(s)
- Tamsin B Gordon
- Health Security Program, Life Sciences Discipline, Burnet Institute, Melbourne, VIC 3004, Australia.
- Department of Microbiology, Monash University, Clayton, VIC 3168, Australia.
| | - Joshua A Hayward
- Health Security Program, Life Sciences Discipline, Burnet Institute, Melbourne, VIC 3004, Australia.
- Department of Microbiology, Monash University, Clayton, VIC 3168, Australia.
| | - Glenn A Marsh
- Department of Microbiology, Monash University, Clayton, VIC 3168, Australia.
- CSIRO Australian Animal Health Laboratory, Health and Biosecurity Business Unit, Geelong, VIC 3220, Australia.
| | - Michelle L Baker
- CSIRO Australian Animal Health Laboratory, Health and Biosecurity Business Unit, Geelong, VIC 3220, Australia.
| | - Gilda Tachedjian
- Health Security Program, Life Sciences Discipline, Burnet Institute, Melbourne, VIC 3004, Australia.
- Department of Microbiology, Monash University, Clayton, VIC 3168, Australia.
- Department of Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne VIC 3010, Australia.
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia.
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13
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Filovirus proteins for antiviral drug discovery: Structure/function of proteins involved in assembly and budding. Antiviral Res 2018; 150:183-192. [DOI: 10.1016/j.antiviral.2017.12.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/20/2017] [Accepted: 12/28/2017] [Indexed: 01/30/2023]
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14
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Ren S, Wei Q, Cai L, Yang X, Xing C, Tan F, Leavenworth JW, Liang S, Liu W. Alphavirus Replicon DNA Vectors Expressing Ebola GP and VP40 Antigens Induce Humoral and Cellular Immune Responses in Mice. Front Microbiol 2018; 8:2662. [PMID: 29375526 PMCID: PMC5767729 DOI: 10.3389/fmicb.2017.02662] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 12/20/2017] [Indexed: 11/13/2022] Open
Abstract
Ebola virus (EBOV) causes severe hemorrhagic fevers in humans, and no approved therapeutics or vaccine is currently available. Glycoprotein (GP) is the major protective antigen of EBOV, and can generate virus-like particles (VLPs) by co-expression with matrix protein (VP40). In this study, we constructed a recombinant Alphavirus Semliki Forest virus (SFV) replicon vector DREP to express EBOV GP and matrix viral protein (VP40). EBOV VLPs were successfully generated and achieved budding from 293 cells after co-transfection with DREP-based GP and VP40 vectors (DREP-GP+DREP-VP40). Vaccination of BALB/c mice with DREP-GP, DREP-VP40, or DREP-GP+DREP-VP40 vectors, followed by immediate electroporation resulted in a mixed IgG subclass production, which recognized EBOV GP and/or VP40 proteins. This vaccination regimen also led to the generation of both Th1 and Th2 cellular immune responses in mice. Notably, vaccination with DREP-GP and DREP-VP40, which produces both GP and VP40 antigens, induced a significantly higher level of anti-GP IgG2a antibody and increased IFN-γ secreting CD8+ T-cell responses relative to vaccination with DREP-GP or DREP-VP40 vector alone. Our study indicates that co-expression of GP and VP40 antigens based on the SFV replicon vector generates EBOV VLPs in vitro, and vaccination with recombinant DREP vectors containing GP and VP40 antigens induces Ebola antigen-specific humoral and cellular immune responses in mice. This novel approach provides a simple and efficient vaccine platform for Ebola disease prevention.
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Affiliation(s)
- Shoufeng Ren
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Qimei Wei
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China.,Institute of Pathogen and Immunology, Wenzhou Medical University, Wenzhou, China
| | - Liya Cai
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China.,Institute of Pathogen and Immunology, Wenzhou Medical University, Wenzhou, China
| | - Xuejing Yang
- Department of Laboratory Medicine, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Cuicui Xing
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Feng Tan
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China.,Institute of Pathogen and Immunology, Wenzhou Medical University, Wenzhou, China
| | - Jianmei W Leavenworth
- Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, United States.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Shaohui Liang
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China.,Institute of Pathogen and Immunology, Wenzhou Medical University, Wenzhou, China
| | - Wenquan Liu
- Department of Human Parasitology, Wenzhou Medical University, Wenzhou, China.,Institute of Pathogen and Immunology, Wenzhou Medical University, Wenzhou, China
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15
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Abstract
Independent expression of the VP40 or Z matrix proteins of filoviruses (marburgviruses and ebolaviruses) and arenaviruses (Lassa fever and Junín), respectively, gives rise to the production and release of virus-like particles (VLPs) that are morphologically identical to infectious virions. We can detect and quantify VLP production and egress in mammalian cells by transient transfection, SDS-PAGE, Western blotting, and live cell imaging techniques such as total internal reflection fluorescence (TIRF) microscopy. Since the VLP budding assay accurately mimics budding of infectious virus, this BSL-2 assay is safe and useful for the interrogation of both viral and host determinants required for budding and can be used as an initial screen to identify and validate small molecule inhibitors of virus release and spread.
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Affiliation(s)
- Ronald N Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St., Philadelphia, PA, 19104, USA.
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16
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Liang J, Sagum CA, Bedford MT, Sidhu SS, Sudol M, Han Z, Harty RN. Chaperone-Mediated Autophagy Protein BAG3 Negatively Regulates Ebola and Marburg VP40-Mediated Egress. PLoS Pathog 2017; 13:e1006132. [PMID: 28076420 PMCID: PMC5226679 DOI: 10.1371/journal.ppat.1006132] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/15/2016] [Indexed: 12/18/2022] Open
Abstract
Ebola (EBOV) and Marburg (MARV) viruses are members of the Filoviridae family which cause outbreaks of hemorrhagic fever. The filovirus VP40 matrix protein is essential for virus assembly and budding, and its PPxY L-domain motif interacts with WW-domains of specific host proteins, such as Nedd4 and ITCH, to facilitate the late stage of virus-cell separation. To identify additional WW-domain-bearing host proteins that interact with VP40, we used an EBOV PPxY-containing peptide to screen an array of 115 mammalian WW-domain-bearing proteins. Using this unbiased approach, we identified BCL2 Associated Athanogene 3 (BAG3), a member of the BAG family of molecular chaperone proteins, as a specific VP40 PPxY interactor. Here, we demonstrate that the WW-domain of BAG3 interacts with the PPxY motif of both EBOV and MARV VP40 and, unexpectedly, inhibits budding of both eVP40 and mVP40 virus-like particles (VLPs), as well as infectious VSV-EBOV recombinants. BAG3 is a stress induced protein that regulates cellular protein homeostasis and cell survival through chaperone-mediated autophagy (CMA). Interestingly, our results show that BAG3 alters the intracellular localization of VP40 by sequestering VP40 away from the plasma membrane. As BAG3 is the first WW-domain interactor identified that negatively regulates budding of VP40 VLPs and infectious virus, we propose that the chaperone-mediated autophagy function of BAG3 represents a specific host defense strategy to counteract the function of VP40 in promoting efficient egress and spread of virus particles.
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Affiliation(s)
- Jingjing Liang
- Department of Pathobiology, School Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- Laboratory of Animal Infectious Diseases, College of Animal Sciences and Veterinary Medicine; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi, China
| | - Cari A. Sagum
- Department of Epigenetics & Molecular Carcinogenesis, M.D. Anderson Cancer Center, University of Texas Smithville, Smithville, TX, United States of America
| | - Mark T. Bedford
- Department of Epigenetics & Molecular Carcinogenesis, M.D. Anderson Cancer Center, University of Texas Smithville, Smithville, TX, United States of America
| | - Sachdev S. Sidhu
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Marius Sudol
- Department of Physiology, National University of Singapore, Mechanobiology Institute and Institute for Molecular and Cell Biology (IMCB, A*STAR), Republic of Singapore
| | - Ziying Han
- Department of Pathobiology, School Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Ronald N. Harty
- Department of Pathobiology, School Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail:
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17
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Freedman BD, Harty RN. Calcium and filoviruses: a budding relationship. Future Microbiol 2016; 11:713-5. [DOI: 10.2217/fmb-2016-0057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Bruce D Freedman
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St, Philadelphia, PA 19104, USA
| | - Ronald N Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St, Philadelphia, PA 19104, USA
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18
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The Ebola Virus Matrix Protein VP40 Interacts With Several Host Protein Networks to Facilitate Viral Replication. CURRENT CLINICAL MICROBIOLOGY REPORTS 2015. [DOI: 10.1007/s40588-015-0022-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Madara JJ, Han Z, Ruthel G, Freedman BD, Harty RN. The multifunctional Ebola virus VP40 matrix protein is a promising therapeutic target. Future Virol 2015; 10:537-546. [PMID: 26120351 DOI: 10.2217/fvl.15.6] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The highly virulent nature of Ebola virus, evident from the 2014 West African pandemic, highlights the need to develop vaccines or therapeutic agents that limit the pathogenesis and spread of this virus. While vaccines represent an obvious approach, targeting virus interactions with host proteins that critically regulate the virus lifecycle also represent important therapeutic strategies. Among Ebola virus proteins at this critical interface is its matrix protein, VP40, which is abundantly expressed during infection and plays a number of critical roles in the viral lifecycle. In addition to regulating viral transcription, VP40 coordinates virion assembly and budding from infected cells. Details of the molecular mechanisms underpinning these essential functions are currently being elucidated, with a particular emphasis on its interactions with host proteins that control virion assembly and egress. This review focuses on the strategies geared toward developing novel therapeutic agents that target VP40-specific control of host functions critical to virion transcription, assembly and egress.
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Affiliation(s)
- Jonathan J Madara
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
| | - Ziying Han
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
| | - Gordon Ruthel
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
| | - Bruce D Freedman
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
| | - Ronald N Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
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20
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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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21
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Abstract
On 23 March 2014, the World Health Organization first announced a new Ebola virus outbreak that started in December 2013 in the eastern part of the Republic of Guinea. Human infections shortly emerged in Liberia, Sierra Leone, and Nigeria. On 30 September 2014, the Centers for Disease Control and Prevention confirmed through laboratory testing the first Ebola virus infection diagnosed in the USA, in a patient who travelled from West Africa to Texas. On 6 October 2014, the first human infection occurring outside of Africa was reported, in a Spanish nurse who treated two priests, both of whom died, and on 23 October 2014, the first human infection was reported in New York City. To date, the 2014 Ebola virus outbreak is the longest, largest, and most persistent one since 1976, when the virus was first identified in humans, and the number of human cases exceeded, as of mid-September 2014, the cumulative number of infections from all the previous outbreaks. The early clinical presentation overlaps with other infectious diseases, opening differential diagnosis difficulties. Understanding the transmission routes and identifying the natural reservoir of the virus are additional challenges in studying Ebola hemorrhagic fever outbreaks. Ebola virus is as much a public health challenge for developing countries as it is for the developed world, and previous outbreaks underscored that the relative contribution of the risk factors may differ among outbreaks. The implementation of effective preparedness plans is contingent on integrating teachings from previous Ebola virus outbreaks with those from the current outbreak and with lessons provided by other infectious diseases, along with developing a multifaceted inter-disciplinary and cross-disciplinary framework that should be established and shaped by biomedical as well as sociopolitical sciences.
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Affiliation(s)
- R A Stein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
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22
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A loop region in the N-terminal domain of Ebola virus VP40 is important in viral assembly, budding, and egress. Viruses 2014; 6:3837-54. [PMID: 25330123 PMCID: PMC4213565 DOI: 10.3390/v6103837] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 10/09/2014] [Accepted: 10/11/2014] [Indexed: 12/26/2022] Open
Abstract
Ebola virus (EBOV) causes viral hemorrhagic fever in humans and can have clinical fatality rates of ~60%. The EBOV genome consists of negative sense RNA that encodes seven proteins including viral protein 40 (VP40). VP40 is the major Ebola virus matrix protein and regulates assembly and egress of infectious Ebola virus particles. It is well established that VP40 assembles on the inner leaflet of the plasma membrane of human cells to regulate viral budding where VP40 can produce virus like particles (VLPs) without other Ebola virus proteins present. The mechanistic details, however, of VP40 lipid-interactions and protein-protein interactions that are important for viral release remain to be elucidated. Here, we mutated a loop region in the N-terminal domain of VP40 (Lys127, Thr129, and Asn130) and find that mutations (K127A, T129A, and N130A) in this loop region reduce plasma membrane localization of VP40. Additionally, using total internal reflection fluorescence microscopy and number and brightness analysis we demonstrate these mutations greatly reduce VP40 oligomerization. Lastly, VLP assays demonstrate these mutations significantly reduce VLP release from cells. Taken together, these studies identify an important loop region in VP40 that may be essential to viral egress.
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23
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The VP40 protein of Marburg virus exhibits impaired budding and increased sensitivity to human tetherin following mouse adaptation. J Virol 2014; 88:14440-50. [PMID: 25297995 DOI: 10.1128/jvi.02069-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
UNLABELLED The Marburg virus VP40 protein is a viral matrix protein that spontaneously buds from cells. It also functions as an interferon (IFN) signaling antagonist by targeting Janus kinase 1 (JAK1). A previous study demonstrated that the VP40 protein of the Ravn strain of Marburg virus (Ravn virus [RAVV]) failed to block IFN signaling in mouse cells, whereas the mouse-adapted RAVV (maRAVV) VP40 acquired the ability to inhibit IFN responses in mouse cells. The increased IFN antagonist function of maRAVV VP40 mapped to residues 57 and 165, which were mutated during the mouse adaptation process. In the present study, we demonstrate that maRAVV VP40 lost the capacity to efficiently bud from human cell lines, despite the fact that both parental and maRAVV VP40s bud efficiently from mouse cell lines. The impaired budding in human cells corresponds with the appearance of protrusions on the surface of maRAVV VP40-expressing Huh7 cells and with an increased sensitivity of maRAVV VP40 to restriction by human tetherin but not mouse tetherin. However, transfer of the human tetherin cytoplasmic tail to mouse tetherin restored restriction of maRAVV VP40. Residues 57 and 165 were demonstrated to contribute to the failure of maRAVV VP40 to bud from human cells, and residue 57 was demonstrated to alter VP40 oligomerization, as assessed by coprecipitation assay, and to determine sensitivity to human tetherin. This suggests that RAVV VP40 acquired, during adaptation to mice, changes in its oligomerization potential that enhanced IFN antagonist function. However, this new capacity impaired RAVV VP40 budding from human cells. IMPORTANCE Filoviruses, which include Marburg viruses and Ebola viruses, are zoonotic pathogens that cause severe disease in humans and nonhuman primates but do not cause similar disease in wild-type laboratory strains of mice unless first adapted to these animals. Although mouse adaptation has been used as a method to develop small animal models of pathogenesis, the molecular determinants associated with filovirus mouse adaptation are poorly understood. Our study demonstrates how genetic changes that accrued during mouse adaptation of the Ravn strain of Marburg virus have impacted the budding function of the viral VP40 matrix protein. Strikingly, we find impairment of mouse-adapted VP40 budding function in human but not mouse cell lines, and we correlate the impairment with an increased sensitivity of VP40 to restriction by human but not mouse tetherin and with changes in VP40 oligomerization. These data suggest that there are functional costs associated with filovirus adaptation to new hosts and implicate tetherin as a filovirus host restriction factor.
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24
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Small-molecule probes targeting the viral PPxY-host Nedd4 interface block egress of a broad range of RNA viruses. J Virol 2014; 88:7294-306. [PMID: 24741084 DOI: 10.1128/jvi.00591-14] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Budding of filoviruses, arenaviruses, and rhabdoviruses is facilitated by subversion of host proteins, such as Nedd4 E3 ubiquitin ligase, by viral PPxY late (L) budding domains expressed within the matrix proteins of these RNA viruses. As L domains are important for budding and are highly conserved in a wide array of RNA viruses, they represent potential broad-spectrum targets for the development of antiviral drugs. To identify potential competitive blockers, we used the known Nedd4 WW domain-PPxY interaction interface as the basis of an in silico screen. Using PPxY-dependent budding of Marburg (MARV) VP40 virus-like particles (VLPs) as our model system, we identified small-molecule hit 1 that inhibited Nedd4-PPxY interaction and PPxY-dependent budding. This lead candidate was subsequently improved with additional structure-activity relationship (SAR) analog testing which enhanced antibudding activity into the nanomolar range. Current lead compounds 4 and 5 exhibit on-target effects by specifically blocking the MARV VP40 PPxY-host Nedd4 interaction and subsequent PPxY-dependent egress of MARV VP40 VLPs. In addition, lead compounds 4 and 5 exhibited antibudding activity against Ebola and Lassa fever VLPs, as well as vesicular stomatitis and rabies viruses (VSV and RABV, respectively). These data provide target validation and suggest that inhibition of the PPxY-Nedd4 interaction can serve as the basis for the development of a novel class of broad-spectrum, host-oriented antivirals targeting viruses that depend on a functional PPxY L domain for efficient egress. IMPORTANCE There is an urgent and unmet need for the development of safe and effective therapeutics against biodefense and high-priority pathogens, including filoviruses (Ebola and Marburg) and arenaviruses (e.g., Lassa and Junin) which cause severe hemorrhagic fever syndromes with high mortality rates. We along with others have established that efficient budding of filoviruses, arenaviruses, and other viruses is critically dependent on the subversion of host proteins. As disruption of virus budding would prevent virus dissemination, identification of small-molecule compounds that block these critical viral-host interactions should effectively block disease progression and transmission. Our findings provide validation for targeting these virus-host interactions as we have identified lead inhibitors with broad-spectrum antiviral activity. In addition, such inhibitors might prove useful for newly emerging RNA viruses for which no therapeutics would be available.
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25
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Abstract
UNLABELLED There are currently no U.S. Food and Drug Administration (FDA)-approved vaccines or therapeutics to prevent or treat Argentine hemorrhagic fever (AHF). The causative agent of AHF is Junin virus (JUNV); a New World arenavirus classified as a National Institute of Allergy and Infectious Disease/Centers for Disease Control and Prevention category A priority pathogen. The PTAP late (L) domain motif within JUNV Z protein facilitates virion egress and transmission by recruiting host Tsg101 and other ESCRT complex proteins to promote scission of the virus particle from the plasma membrane. Here, we describe a novel compound (compound 0013) that blocks the JUNV Z-Tsg101 interaction and inhibits budding of virus-like particles (VLPs) driven by ectopic expression of the Z protein and live-attenuated JUNV Candid-1 strain in cell culture. Since inhibition of the PTAP-Tsg101 interaction inhibits JUNV egress, compound 0013 serves as a prototype therapeutic that could reduce virus dissemination and disease progression in infected individuals. Moreover, since PTAP l-domain-mediated Tsg101 recruitment is utilized by other RNA virus pathogens (e.g., Ebola virus and HIV-1), PTAP inhibitors such as compound 0013 have the potential to function as potent broad-spectrum, host-oriented antiviral drugs. IMPORTANCE There are currently no FDA-approved vaccines or therapeutics to prevent or treat Argentine hemorrhagic fever (AHF). The causative agent of AHF is Junin virus (JUNV); a New World arenavirus classified as an NIAID/CDC category A priority pathogen. Here, we describe a prototype therapeutic that blocks budding of JUNV and has the potential to function as a broad-spectrum antiviral drug.
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26
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Soni SP, Adu-Gyamfi E, Yong SS, Jee CS, Stahelin RV. The Ebola virus matrix protein deeply penetrates the plasma membrane: an important step in viral egress. Biophys J 2013; 104:1940-9. [PMID: 23663837 DOI: 10.1016/j.bpj.2013.03.021] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 02/24/2013] [Accepted: 03/12/2013] [Indexed: 10/26/2022] Open
Abstract
Ebola virus, from the Filoviridae family has a high fatality rate in humans and nonhuman primates and to date, to the best of our knowledge, has no FDA approved vaccines or therapeutics. Viral protein 40 (VP40) is the major Ebola virus matrix protein that regulates assembly and egress of infectious Ebola virus particles. It is well established that VP40 assembles on the inner leaflet of the plasma membrane; however, the mechanistic details of VP40 membrane binding that are important for viral release remain to be elucidated. In this study, we used fluorescence quenching of a tryptophan on the membrane-binding interface with brominated lipids along with mutagenesis of VP40 to understand the depth of membrane penetration into lipid bilayers. Experimental results indicate that VP40 penetrates 8.1 Å into the hydrocarbon core of the plasma membrane bilayer. VP40 also induces substantial changes to membrane curvature as it tubulates liposomes and induces vesiculation into giant unilamellar vesicles, effects that are abrogated by hydrophobic mutations. This is a critical step in viral egress as cellular assays demonstrate that hydrophobic residues that penetrate deeply into the plasma membrane are essential for plasma membrane localization and virus-like particle formation and release from cells.
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Affiliation(s)
- Smita P Soni
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, Indiana, USA
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27
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Lin AE, Greco TM, Döhner K, Sodeik B, Cristea IM. A proteomic perspective of inbuilt viral protein regulation: pUL46 tegument protein is targeted for degradation by ICP0 during herpes simplex virus type 1 infection. Mol Cell Proteomics 2013; 12:3237-52. [PMID: 23938468 DOI: 10.1074/mcp.m113.030866] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Much like the host cells they infect, viruses must also regulate their life cycles. Herpes simples virus type 1 (HSV-1), a prominent human pathogen, uses a promoter-rich genome in conjunction with multiple viral trans-activating factors. Following entry into host cells, the virion-associated outer tegument proteins pUL46 and pUL47 act to increase expression of viral immediate-early (α) genes, thereby helping initiate the infection life cycle. Because pUL46 has gone largely unstudied, we employed a hybrid mass spectrometry-based approach to determine how pUL46 exerts its functions during early stages of infection. For a spatio-temporal characterization of pUL46, time-lapse microscopy was performed in live cells to define its dynamic localization from 2 to 24 h postinfection. Next, pUL46-containing protein complexes were immunoaffinity purified during infection of human fibroblasts and analyzed by mass spectrometry to investigate virus-virus and virus-host interactions, as well as post-translational modifications. We demonstrated that pUL46 is heavily phosphorylated in at least 23 sites. One phosphorylation site matched the consensus 14-3-3 phospho-binding motif, consistent with our identification of 14-3-3 proteins and host and viral kinases as specific pUL46 interactions. Moreover, we determined that pUL46 specifically interacts with the viral E3 ubiquitin ligase ICP0. We demonstrated that pUL46 is partially degraded in a proteasome-mediated manner during infection, and that the catalytic activity of ICP0 is responsible for this degradation. This is the first evidence of a viral protein being targeted for degradation by another viral protein during HSV-1 infection. Together, these data indicate that pUL46 levels are tightly controlled and important for the temporal regulation of viral gene expression throughout the virus life cycle. The concept of a structural virion protein, pUL46, performing nonstructural roles is likely to reflect a theme common to many viruses, and a better understanding of these functions will be important for developing therapeutics.
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Affiliation(s)
- Aaron E Lin
- Department of Molecular Biology, Princeton University, Princeton, New Jersey
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28
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Adu-Gyamfi E, Soni SP, Xue Y, Digman MA, Gratton E, Stahelin RV. The Ebola virus matrix protein penetrates into the plasma membrane: a key step in viral protein 40 (VP40) oligomerization and viral egress. J Biol Chem 2013; 288:5779-89. [PMID: 23297401 DOI: 10.1074/jbc.m112.443960] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ebola, a fatal virus in humans and non-human primates, has no Food and Drug Administration-approved vaccines or therapeutics. The virus from the Filoviridae family causes hemorrhagic fever, which rapidly progresses and in some cases has a fatality rate near 90%. The Ebola genome encodes seven genes, the most abundantly expressed of which is viral protein 40 (VP40), the major Ebola matrix protein that regulates assembly and egress of the virus. It is well established that VP40 assembles on the inner leaflet of the plasma membrane; however, the mechanistic details of plasma membrane association by VP40 are not well understood. In this study, we used an array of biophysical experiments and cellular assays along with mutagenesis of VP40 to investigate the role of membrane penetration in VP40 assembly and egress. Here we demonstrate that VP40 is able to penetrate specifically into the plasma membrane through an interface enriched in hydrophobic residues in its C-terminal domain. Mutagenesis of this hydrophobic region consisting of Leu(213), Ile(293), Leu(295), and Val(298) demonstrated that membrane penetration is critical to plasma membrane localization, VP40 oligomerization, and viral particle egress. Taken together, VP40 membrane penetration is an important step in the plasma membrane localization of the matrix protein where oligomerization and budding are defective in the absence of key hydrophobic interactions with the membrane.
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Affiliation(s)
- Emmanuel Adu-Gyamfi
- Department of Chemistry and Biochemistry, the Eck Institute for Global Health, and the Center for Rare and Neglected Diseases, University of Notre Dame, South Bend, Indiana 46556, USA
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Mittler E, Kolesnikova L, Herwig A, Dolnik O, Becker S. Assembly of the Marburg virus envelope. Cell Microbiol 2012. [PMID: 23186212 DOI: 10.1111/cmi.12076] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The key player to assemble the filamentous Marburg virus particles is the matrix protein VP40 which orchestrates recruitment of nucleocapsid complexes and the viral glycoprotein GP to the budding sites at the plasma membrane. Here, VP40 induces the formation of the viral particles, determines their morphology and excludes cellular proteins from the virions. Budding takes place at filopodia in non-polarized cells and at the basolateral cell pole in polarized epithelial cells. Molecular basis of how VP40 exerts its multifunctional role in these different processes is currently under investigation. Here we summarize recent data on structure-function relationships of VP40 and GP in connection with their function in assembly. Questions concerning the complex particle assembly, budding and release remaining enigmatic are addressed. Cytoplasmic domains of viral surface proteins often serve as a connection to the viral matrix protein or as binding sites for further viral or cellular proteins. A cooperation of MARV GP and VP40 building up the viral envelope can be proposed and is discussed in more detail in this review, as the cytoplasmic domain of GP represents an obvious interaction candidate because of its localization adjacent to the VP40 layer. Interestingly, truncation of the short cytoplasmic domain of GP neither inhibited interaction with VP40 nor incorporation of GP into progeny viral particles. Based on reverse genetics we generated recombinant virions expressing a GP mutant without the cytoplasmic tail. Investigations revealed attenuation in virus growth and an obvious defect in entry. Further investigations showed that the truncation of the cytoplasmic domain of GP impaired the structural integrity of the ectodomain, whichconsequently had impact on entry steps downstream of virus binding. Our data indicated that changes in the cytoplasmic domain are relayed over the lipid membrane to alter the function of the ectodomain.
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Affiliation(s)
- Eva Mittler
- Institute of Virology, Philipps University Marburg, Hans-Meerwein-Strasse 2, 35043 Marburg, Germany
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30
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Kushnir N, Streatfield SJ, Yusibov V. Virus-like particles as a highly efficient vaccine platform: diversity of targets and production systems and advances in clinical development. Vaccine 2012; 31:58-83. [PMID: 23142589 PMCID: PMC7115575 DOI: 10.1016/j.vaccine.2012.10.083] [Citation(s) in RCA: 401] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/13/2012] [Accepted: 10/25/2012] [Indexed: 12/16/2022]
Abstract
Virus-like particles (VLPs) are a class of subunit vaccines that differentiate themselves from soluble recombinant antigens by stronger protective immunogenicity associated with the VLP structure. Like parental viruses, VLPs can be either non-enveloped or enveloped, and they can form following expression of one or several viral structural proteins in a recombinant heterologous system. Depending on the complexity of the VLP, it can be produced in either a prokaryotic or eukaryotic expression system using target-encoding recombinant vectors, or in some cases can be assembled in cell-free conditions. To date, a wide variety of VLP-based candidate vaccines targeting various viral, bacterial, parasitic and fungal pathogens, as well as non-infectious diseases, have been produced in different expression systems. Some VLPs have entered clinical development and a few have been licensed and commercialized. This article reviews VLP-based vaccines produced in different systems, their immunogenicity in animal models and their status in clinical development.
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Affiliation(s)
- Natasha Kushnir
- Fraunhofer USA Center for Molecular Biotechnology, Newark, DE 19711, USA
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31
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Abstract
In 1967, the first reported filovirus hemorrhagic fever outbreak took place in Germany and the former Yugoslavia. The causative agent that was identified during this outbreak, Marburg virus, is one of the most deadly human pathogens. This article provides a comprehensive overview of our current knowledge about Marburg virus disease ranging from ecology to pathogenesis and molecular biology.
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Affiliation(s)
- Kristina Brauburger
- Department of Microbiology, School of Medicine and National Emerging Infectious Diseases Laboratories Institute, Boston University, Boston, MA 02118, USA.
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32
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García M, Cooper A, Shi W, Bornmann W, Carrion R, Kalman D, Nabel GJ. Productive replication of Ebola virus is regulated by the c-Abl1 tyrosine kinase. Sci Transl Med 2012; 4:123ra24. [PMID: 22378924 DOI: 10.1126/scitranslmed.3003500] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ebola virus causes a fulminant infection in humans resulting in diffuse bleeding, vascular instability, hypotensive shock, and often death. Because of its high mortality and ease of transmission from human to human, Ebola virus remains a biological threat for which effective preventive and therapeutic interventions are needed. An understanding of the mechanisms of Ebola virus pathogenesis is critical for developing antiviral therapeutics. Here, we report that productive replication of Ebola virus is modulated by the c-Abl1 tyrosine kinase. Release of Ebola virus-like particles (VLPs) in a cell culture cotransfection system was inhibited by c-Abl1-specific small interfering RNA (siRNA) or by Abl-specific kinase inhibitors and required tyrosine phosphorylation of the Ebola matrix protein VP40. Expression of c-Abl1 stimulated an increase in phosphorylation of tyrosine 13 (Y(13)) of VP40, and mutation of Y(13) to alanine decreased the release of Ebola VLPs. Productive replication of the highly pathogenic Ebola virus Zaire strain was inhibited by c-Abl1-specific siRNAs or by the Abl-family inhibitor nilotinib by up to four orders of magnitude. These data indicate that c-Abl1 regulates budding or release of filoviruses through a mechanism involving phosphorylation of VP40. This step of the virus life cycle therefore may represent a target for antiviral therapy.
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Affiliation(s)
- Mayra García
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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33
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Demirov D, Gabriel G, Schneider C, Hohenberg H, Ludwig S. Interaction of influenza A virus matrix protein with RACK1 is required for virus release. Cell Microbiol 2012; 14:774-89. [PMID: 22289149 DOI: 10.1111/j.1462-5822.2012.01759.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The mechanism of budding of influenza A virus revealed important deviation from the consensus mechanism of budding of retroviruses and of a growing number of negative-strand RNA viruses. This study is focused on the role of the influenza A virus matrix protein M1 in virus release. We found that a mutation of the proline residue at position 16 of the matrix protein induces inhibition of virus detachment from cells. Depletion of the M1-binding protein RACK1 also impairs virus release and RACK1 binding requires the proline residue at position 16 of M1. The impaired M1-RACK1 interaction does not affect the plasma membrane binding of M1; in contrast, RACK1 is recruited to detergent-resistant membranes in a M1-proline-16-dependent manner. The proline-16 mutation in M1 and depletion of RACK1 impairs the pinching-off of the budding virus particles. These findings reveal the active role of the viral matrix protein in the release of influenza A virus particles that involves a cross-talk with a RACK1-mediated pathway.
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Affiliation(s)
- Dimiter Demirov
- Institute of Molecular Virology (IMV), Centre for Molecular Biology of Inflammation (ZMBE), University of Münster, 48149 Münster, Germany
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34
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Makino A, Yamayoshi S, Shinya K, Noda T, Kawaoka Y. Identification of amino acids in Marburg virus VP40 that are important for virus-like particle budding. J Infect Dis 2011; 204 Suppl 3:S871-7. [PMID: 21987763 DOI: 10.1093/infdis/jir309] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The matrix protein VP40 of Marburg virus promotes the formation and release of virus-like particles (VLPs). Marburg virus VP40 interacts with cellular Tsg101 via its L domain motif; however, mutation of this motif does not affect VLP budding or the accumulation of VP40 in multivesicular bodies (MVBs), which are platforms for virus particle formation. To identify regions of Marburg virus VP40 that are important for VLP budding, we examined deletion mutants and alanine-scanning mutants at the N- and C-terminus of VP40 for their involvement in VLP budding. VLPs were not detected in the presence of alanine-replacement mutants at Ile39 and Thr40, and the level of VLP budding for the alanine mutant at Asn297 was decreased. Moreover, these mutants did not accumulate in MVBs. Our results suggest the involvement of a novel host factor(s) in VLP budding and VP40 transport to MVBs.
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Affiliation(s)
- Akiko Makino
- Department of Microbiology and Infectious Diseases, Division of Zoonosis, Graduate School of Medicine, Kobe University, Japan
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35
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Liu Y, Stone S, Harty RN. Characterization of filovirus protein-protein interactions in mammalian cells using bimolecular complementation. J Infect Dis 2011; 204 Suppl 3:S817-24. [PMID: 21987757 DOI: 10.1093/infdis/jir293] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The virion protein 40 (VP40) and nucleoprotein (NP) of Ebola (EBOV) and Marburg viruses (MARV) play key roles during virion assembly and egress. The ability to detect interactions between VP40-VP40, VP40-NP, and NP-NP and follow these complexes as they traffic through mammalian cells would enhance our understanding of the molecular events leading to filovirus assembly and budding, and provide new insights into filovirus replication and pathogenesis. Here, we successfully employed a bimolecular complementation (BiMC) approach to visualize interactions between EBOV and MARV VP40-VP40, NP-NP, and VP40-NP proteins and localize these protein complexes in mammalian cells using confocal microscopy. We demonstrate that VP40-VP40 complexes localized predominantly at the plasma membrane, whereas VP40-NP and NP-NP complexes displayed a more dispersed pattern throughout the cytoplasm. As expected based on previous findings, efficient interactions between EBOV or MARV VP40-VP40 proteins were independent of L-domains PTAPPEY and PPPY, respectively. In contrast, the formation of EBOV or MARV VP40-VP40 complexes was dependent on the previously characterized LPLGVA and LPLGIM motifs of EBOV and MARV VP40 proteins, respectively, indicating that these motifs are important for VP40 oligomerization and subsequent budding. These results highlight the feasibility and usefulness of the BiMC approach as a strategy to further characterize both filovirus protein interactions as well as filovirus-host interactions in real time in the natural environment of the cell.
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Affiliation(s)
- Yuliang Liu
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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36
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Warfield KL, Aman MJ. Advances in virus-like particle vaccines for filoviruses. J Infect Dis 2011; 204 Suppl 3:S1053-9. [PMID: 21987741 DOI: 10.1093/infdis/jir346] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ebola virus (EBOV) and Marburg virus (MARV) are among the deadliest human pathogens, with no vaccines or therapeutics available. Multiple vaccine platforms have been tested for efficacy as prophylactic pretreatments or therapeutics for prevention of filovirus hemorrhagic fever. Most successful vaccines are based on a virus-vectored approach expressing the protective glycoprotein (GP); protein-based subunit and DNA vaccines have been tested with moderate success. Virus-like particle (VLP) vaccines have realized promising results when tested in both rodents and nonhuman primates. VLPs rely on the natural properties of the viral matrix protein (VP) 40 to drive budding of filamentous particles that can also incorporate ≥ 1 other filovirus protein, including GP, VP24, and nucleoprotein (NP). Filovirus VLP vaccines have used particles containing 2 or 3 (GP and VP40, with or without NP) viral proteins generated in either mammalian or insect cells. Early studies successfully demonstrated efficacy of bivalent VLP vaccines in rodents; more recent studies have shown the ability of the VLP vaccines containing GP, NP, and VP40 to confer complete homologous protection against Ebola virus and Marburg virus in a prophylactic setting against in macaques. This review will discuss published work to date regarding development of the VLP vaccines for prevention of lethal filovirus hemorrhagic fever.
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Affiliation(s)
- Kelly L Warfield
- Vaccine Development, Integrated Biotherapeutics, 21 Firstfield Rd, Ste 100, Gaithersburg, MD 20878, USA.
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37
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Abstract
Marburgviruses are zoonotic pathogens that cause lethal hemorrhagic fever in humans and nonhuman primates. However, they do not cause lethal disease in immunocompetent mice unless they are adapted to this species. The adaptation process can therefore provide insight into the specific virus-host interactions that determine virulence. In primate cells, the Lake Victoria marburgvirus Musoke strain (MARV) VP40 matrix protein antagonizes alpha/beta interferon (IFN-α/β) and IFN-γ signaling by inhibiting the activation of the cellular tyrosine kinase Jak1. Here, VP40 from the Ravn strain (RAVV VP40)-from a distinct Marburg virus clade-is demonstrated to also inhibit IFN signaling in human cells. However, neither MARV nor RAVV VP40 effectively inhibited IFN-signaling in mouse cells, as assessed by assays of the antiviral effects of IFN-α/β and the IFN-α/β-induced phosphorylation of Jak1, STAT1, and STAT2. In contrast, the VP40 from a mouse-adapted RAVV (maRAVV) did inhibit IFN signaling. Effective Jak1 inhibition correlated with the species from which the cells were derived and did not depend upon whether Jak1 was of human or mouse origin. Of the seven amino acid changes that accumulated in VP40 during mouse adaptation, two (V57A and T165A) are sufficient to allow efficient IFN signaling antagonism by RAVV VP40 in mouse cells. The same two changes also confer efficient IFN antagonist function upon MARV VP40 in mouse cells. The mouse-adaptive changes did not affect the budding of RAVV VP40 in mouse cells, suggesting that this second major function of VP40 did not undergo adaptation. These data identify an apparent determinant of RAVV host range and virulence and define specific genetic determinants of this function.
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Bimolecular Complementation to Visualize Filovirus VP40-Host Complexes in Live Mammalian Cells: Toward the Identification of Budding Inhibitors. Adv Virol 2011; 2011. [PMID: 22102845 PMCID: PMC3217271 DOI: 10.1155/2011/341816] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Virus-host interactions play key roles in promoting efficient egress of many RNA viruses, including Ebola virus (EBOV or “e”) and Marburg virus (MARV or “m”). Late- (L-) domains conserved in viral matrix proteins recruit specific host proteins, such as Tsg101 and Nedd4, to facilitate the budding process. These interactions serve as attractive targets for the development of broad-spectrum budding inhibitors. A major gap still exists in our understanding of the mechanism of filovirus budding due to the difficulty in detecting virus-host complexes and mapping their trafficking patterns in the natural environment of the cell. To address this gap, we used a bimolecular complementation (BiMC) approach to detect, localize, and follow the trafficking patterns of eVP40-Tsg101 complexes in live mammalian cells. In addition, we used the BiMC approach along with a VLP budding assay to test small molecule inhibitors identified by in silico screening for their ability to block eVP40 PTAP-mediated interactions with Tsg101 and subsequent budding of eVP40 VLPs. We demonstrated the potential broad spectrum activity of a lead candidate inhibitor by demonstrating its ability to block PTAP-dependent binding of HIV-1 Gag to Tsg101 and subsequent egress of HIV-1 Gag VLPs.
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Abstract
The filoviruses, Ebola and Marburg, utilize a multifaceted mechanism for assembly and budding of infectious virions from mammalian cells. Growing evidence not only demonstrates the importance of multiple viral proteins for efficient assembly and budding, but also the exploitation of various host proteins/pathways by the virus during this late stage of filovirus replication, including endocytic compartments, vacuolar protein sorting pathways, ubiquitination machinery, lipid rafts and cytoskeletal components. Continued elucidation of these complex and orchestrated virus-host interactions will provide a fundamental understanding of the molecular mechanisms of filovirus assembly/budding and ultimately lead to the development of novel viral- and/or host-oriented therapeutics to inhibit filovirus egress and spread. This article will focus on the most recent studies on host interactions and modulation of filovirus budding and summarize the key findings from these investigations.
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Affiliation(s)
- Yuliang Liu
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St., Philadelphia, PA 19104, USA
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40
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Oligomerization of Ebola virus VP40 is essential for particle morphogenesis and regulation of viral transcription. J Virol 2010; 84:7053-63. [PMID: 20463076 DOI: 10.1128/jvi.00737-10] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The morphogenesis and budding of virus particles represent an important stage in the life cycle of viruses. For Ebola virus, this process is driven by its major matrix protein, VP40. Like the matrix proteins of many other nonsegmented, negative-strand RNA viruses, VP40 has been demonstrated to oligomerize and to occur in at least two distinct oligomeric states: hexamers and octamers, which are composed of antiparallel dimers. While it has been shown that VP40 oligomers are essential for the viral life cycle, their function is completely unknown. Here we have identified two amino acids essential for oligomerization of VP40, the mutation of which blocked virus-like particle production. Consistent with this observation, oligomerization-deficient VP40 also showed impaired intracellular transport to budding sites and reduced binding to cellular membranes. However, other biological functions, such as the interaction of VP40 with the nucleoprotein, NP, remained undisturbed. Furthermore, both wild-type VP40 and oligomerization-deficient VP40 were found to negatively regulate viral genome replication, a novel function of VP40, which we have recently reported. Interestingly, while wild-type VP40 was also able to negatively regulate viral genome transcription, oligomerization-deficient VP40 was no longer able to fulfill this function, indicating that regulation of viral replication and transcription by VP40 are mechanistically distinct processes. These data indicate that VP40 oligomerization not only is a prerequisite for intracellular transport of VP40 and efficient membrane binding, and as a consequence virion morphogenesis, but also plays a critical role in the regulation of viral transcription by VP40.
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Harrison MS, Sakaguchi T, Schmitt AP. Paramyxovirus assembly and budding: building particles that transmit infections. Int J Biochem Cell Biol 2010; 42:1416-29. [PMID: 20398786 DOI: 10.1016/j.biocel.2010.04.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/05/2010] [Accepted: 04/07/2010] [Indexed: 01/16/2023]
Abstract
The paramyxoviruses define a diverse group of enveloped RNA viruses that includes a number of important human and animal pathogens. Examples include human respiratory syncytial virus and the human parainfluenza viruses, which cause respiratory illnesses in young children and the elderly; measles and mumps viruses, which have caused recent resurgences of disease in developed countries; the zoonotic Hendra and Nipah viruses, which have caused several outbreaks of fatal disease in Australia and Asia; and Newcastle disease virus, which infects chickens and other avian species. Like other enveloped viruses, paramyxoviruses form particles that assemble and bud from cellular membranes, allowing the transmission of infections to new cells and hosts. Here, we review recent advances that have improved our understanding of events involved in paramyxovirus particle formation. Contributions of viral matrix proteins, glycoproteins, nucleocapsid proteins, and accessory proteins to particle formation are discussed, as well as the importance of host factor recruitment for efficient virus budding. Trafficking of viral structural components within infected cells is described, together with mechanisms that allow for the selection of specific sites on cellular membranes for the coalescence of viral proteins in preparation of bud formation and virion release.
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Affiliation(s)
- Megan S Harrison
- Department of Veterinary and Biomedical Sciences, and Center for Molecular Immunology and Infectious Disease, The Pennsylvania State University, University Park, PA 16802, United States
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