1
|
Martin CK, Wan JJ, Yin P, Morrison TE, Messer WB, Rivera-Amill V, Lai JR, Grau N, Rey FA, Couderc T, Lecuit M, Kielian M. The alphavirus determinants of intercellular long extension formation. mBio 2024:e0198624. [PMID: 39699169 DOI: 10.1128/mbio.01986-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 11/26/2024] [Indexed: 12/20/2024] Open
Abstract
The alphavirus chikungunya virus (CHIKV) is a serious human pathogen that can cause large-scale epidemics characterized by fever and joint pain and often resulting in chronic arthritis. Infection by alphaviruses including CHIKV and the closely related Semliki Forest virus (SFV) can induce the formation of filopodia-like intercellular long extensions (ILEs). ILEs emanate from an infected cell, stably attach to a neighboring cell, and mediate cell-to-cell viral transmission that is resistant to neutralizing antibodies. However, our mechanistic understanding of ILE formation is limited, and the potential contribution of ILEs to CHIKV virulence or human CHIKV infection is unknown. Here, we used well-characterized virus mutants and monoclonal antibodies with known epitopes to dissect the virus requirements for ILE formation. Our results showed that both the viral E2 and E1 envelope proteins were required for ILE formation, while viral proteins 6K and transframe, and cytoplasmic nucleocapsid formation were dispensable. A subset of CHIKV monoclonal antibodies reduced ILE formation by masking specific regions particularly on the E2 A domain. Studies of the viral proteins from different CHIKV strains showed that ILE formation is conserved across the four major CHIKV lineages. Sera from convalescent human CHIKV patients inhibited ILE formation in cell culture, providing the first evidence for ILE inhibitory antibody production during human CHIKV infections.IMPORTANCEChikungunya virus (CHIKV) infections can cause severe fever and long-lasting joint pain in humans. CHIKV is disseminated by mosquitoes and is now found world-wide, including in the Americas, Asia, and Africa. In cultured cells, CHIKV can induce the formation of long intercellular extensions that can transmit virus to another cell. However, our understanding of the formation of extensions and their importance in human CHIKV infection is limited. We here identified viral protein requirements for extension formation. We demonstrated that specific monoclonal antibodies against the virus envelope proteins or sera from human CHIKV patients can inhibit extension formation. Our data highlight the importance of evaluation of extension formation in the context of human CHIKV infection.
Collapse
Affiliation(s)
- Caroline K Martin
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Judy J Wan
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Peiqi Yin
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Thomas E Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - William B Messer
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
- Department of Medicine, Division of Infectious Diseases, Oregon Health & Science University, Portland, Oregon, USA
| | | | - Jonathan R Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Nina Grau
- Institut Pasteur, Université Paris Cité, CNRS UMR 3569, Unité de Virologie Structurale, Paris, France
| | - Félix A Rey
- Institut Pasteur, Université Paris Cité, CNRS UMR 3569, Unité de Virologie Structurale, Paris, France
| | - Thérèse Couderc
- Institut Pasteur, Université Paris Cité, Inserm U1117, Biology of Infection Unit, Paris, France
| | - Marc Lecuit
- Institut Pasteur, Université Paris Cité, Inserm U1117, Biology of Infection Unit, Paris, France
- Department of Infectious Diseases and Tropical Medicine, Necker-Enfants Malades University Hospital, APHP, Institut Imagine, Paris, France
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| |
Collapse
|
2
|
Chmielewski D, Su GC, Kaelber JT, Pintilie GD, Chen M, Jin J, Auguste AJ, Chiu W. Cryogenic electron microscopy and tomography reveal imperfect icosahedral symmetry in alphaviruses. PNAS NEXUS 2024; 3:pgae102. [PMID: 38525304 PMCID: PMC10959069 DOI: 10.1093/pnasnexus/pgae102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 02/15/2024] [Indexed: 03/26/2024]
Abstract
Alphaviruses are spherical, enveloped RNA viruses with two-layered icosahedral architecture. The structures of many alphaviruses have been studied using cryogenic electron microscopy (cryo-EM) reconstructions, which impose icosahedral symmetry on the viral particles. Using cryogenic electron tomography (cryo-ET), we revealed a polarized symmetry defect in the icosahedral lattice of Chikungunya virus (CHIKV) in situ, similar to the late budding particles, suggesting the inherent imperfect symmetry originates from the final pinch-off of assembled virions. We further demonstrated this imperfect symmetry is also present in in vitro purified CHIKV and Mayaro virus, another arthritogenic alphavirus. We employed a subparticle-based single-particle analysis protocol to circumvent the icosahedral imperfection and boosted the resolution of the structure of the CHIKV to ∼3 Å resolution, which revealed detailed molecular interactions between glycoprotein E1-E2 heterodimers in the transmembrane region and multiple lipid-like pocket factors located in a highly conserved hydrophobic pocket. This complementary use of in situ cryo-ET and single-particle cryo-EM approaches provides a more precise structural description of near-icosahedral viruses and valuable insights to guide the development of structure-based antiviral therapies against alphaviruses.
Collapse
Affiliation(s)
- David Chmielewski
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Guan-Chin Su
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Grigore D Pintilie
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Muyuan Chen
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Jing Jin
- Vitalant Research Institute, San Francisco, CA 94118, USA
- Department of Laboratory Medicine, University of California, San Francisco, CA 94143, USA
| | - Albert J Auguste
- Department of Entomology, College of Agriculture and Life Sciences, Fralin Life Science Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Wah Chiu
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| |
Collapse
|
3
|
Kehn-Hall K, Bradfute SB. Understanding host responses to equine encephalitis virus infection: implications for therapeutic development. Expert Rev Anti Infect Ther 2022; 20:1551-1566. [PMID: 36305549 DOI: 10.1080/14787210.2022.2141224] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Venezuelan, eastern, and western equine encephalitis viruses (VEEV, EEEV, and WEEV) are mosquito-borne New World alphaviruses that cause encephalitis in equids and humans. These viruses can cause severe disease and death, as well as long-term severe neurological symptoms in survivors. Despite the pathogenesis and weaponization of these viruses, there are no approved therapeutics for treating infection. AREAS COVERED In this review, we describe the molecular pathogenesis of these viruses, discuss host-pathogen interactions needed for viral replication, and highlight new avenues for drug development with a focus on host-targeted approaches. EXPERT OPINION Current approaches have yielded some promising therapeutics, but additional emphasis should be placed on advanced development of existing small molecules and pursuit of pan-encephalitic alphavirus drugs. More research should be conducted on EEEV and WEEV, given their high lethality rates.
Collapse
Affiliation(s)
- Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.,Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, VA, USA
| | - Steven B Bradfute
- Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| |
Collapse
|
4
|
Elmasri Z, Nasal BL, Jose J. Alphavirus-Induced Membrane Rearrangements during Replication, Assembly, and Budding. Pathogens 2021; 10:984. [PMID: 34451448 PMCID: PMC8399458 DOI: 10.3390/pathogens10080984] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 01/01/2023] Open
Abstract
Alphaviruses are arthropod-borne viruses mainly transmitted by hematophagous insects that cause moderate to fatal disease in humans and other animals. Currently, there are no approved vaccines or antivirals to mitigate alphavirus infections. In this review, we summarize the current knowledge of alphavirus-induced structures and their functions in infected cells. Throughout their lifecycle, alphaviruses induce several structural modifications, including replication spherules, type I and type II cytopathic vacuoles, and filopodial extensions. Type I cytopathic vacuoles are replication-induced structures containing replication spherules that are sites of RNA replication on the endosomal and lysosomal limiting membrane. Type II cytopathic vacuoles are assembly induced structures that originate from the Golgi apparatus. Filopodial extensions are induced at the plasma membrane and are involved in budding and cell-to-cell transport of virions. This review provides an overview of the viral and host factors involved in the biogenesis and function of these virus-induced structures. Understanding virus-host interactions in infected cells will lead to the identification of new targets for antiviral discovery.
Collapse
Affiliation(s)
- Zeinab Elmasri
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Benjamin L. Nasal
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Joyce Jose
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
| |
Collapse
|
5
|
Silva LR, Rodrigues ÉEDS, Taniele-Silva J, Anderson L, Araújo-Júnior JXD, Bassi ÊJ, Silva-Júnior EFD. Targeting Chikungunya Virus Entry: alternatives for new inhibitors in drug discovery. Curr Med Chem 2021; 29:612-634. [PMID: 34165405 DOI: 10.2174/0929867328666210623165005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/06/2021] [Accepted: 05/11/2021] [Indexed: 11/22/2022]
Abstract
Chikungunya virus (CHIKV) is an Alphavirus (Togaviridae) responsible for Chikungunya fever (CHIKF) that is mainly characterized by a severe polyarthralgia, in which it is transmitted by the bite of infected Aedes aegypti and Ae. albopictus mosquitoes. Nowadays, there no licensed vaccines or approved drugs to specifically treat this viral disease. Structural viral proteins participate in key steps of its replication cycle, such as viral entry, membrane fusion, nucleocapsid assembly, and virus budding. In this context, envelope E3-E2-E1 glycoproteins complex could be targeted for designing new drug candidates. In this review, aspects of the CHIKV entry process are discussed to provide insights to assist the drug discovery process. Moreover, several natural, nature-based and synthetic compounds, as well as repurposed drugs and virtual screening, are also explored as alternatives for developing CHIKV entry inhibitors. Finally, we provided a complimentary analysis of studies involving inhibitors that were not explored by in silico methods. Based on this, Phe118, Val179, and Lys181 were found to be the most frequent residues, being present in 89.6, 82.7, and 93.1% of complexes, respectively. Lastly, some chemical aspects associated with interactions of these inhibitors and mature envelope E3-E2-E1 glycoproteins' complex were discussed to provide data for scientists worldwide, supporting their search for new inhibitors against this emerging arbovirus.
Collapse
Affiliation(s)
- Leandro Rocha Silva
- Chemistry and Biotechnology Institute, Federal University of Alagoas, Campus A.C. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - Érica Erlanny da Silva Rodrigues
- Chemistry and Biotechnology Institute, Federal University of Alagoas, Campus A.C. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - Jamile Taniele-Silva
- IMUNOREG - Immunoregulation Research Group, Laboratory of Research in Virology and Immunology, Institute of Biological Sciences and Health, Federal University of Alagoas, Campus AC. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - Letícia Anderson
- IMUNOREG - Immunoregulation Research Group, Laboratory of Research in Virology and Immunology, Institute of Biological Sciences and Health, Federal University of Alagoas, Campus AC. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - João Xavier de Araújo-Júnior
- Chemistry and Biotechnology Institute, Federal University of Alagoas, Campus A.C. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - Ênio José Bassi
- IMUNOREG - Immunoregulation Research Group, Laboratory of Research in Virology and Immunology, Institute of Biological Sciences and Health, Federal University of Alagoas, Campus AC. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| | - Edeildo F da Silva-Júnior
- Chemistry and Biotechnology Institute, Federal University of Alagoas, Campus A.C. Simões, Lourival Melo Mota Avenue, Maceió 57072-970, Brazil
| |
Collapse
|
6
|
Abstract
Alphaviruses cause severe human illnesses including persistent arthritis and fatal encephalitis. As alphavirus entry into target cells is the first step in infection, intensive research efforts have focused on elucidating aspects of this pathway, including attachment, internalization, and fusion. Herein, we review recent developments in the molecular understanding of alphavirus entry both in vitro and in vivo and how these advances might enable the design of therapeutics targeting this critical step in the alphavirus life cycle.
Collapse
|
7
|
Cunha MS, Costa PAG, Correa IA, de Souza MRM, Calil PT, da Silva GPD, Costa SM, Fonseca VWP, da Costa LJ. Chikungunya Virus: An Emergent Arbovirus to the South American Continent and a Continuous Threat to the World. Front Microbiol 2020; 11:1297. [PMID: 32670231 PMCID: PMC7332961 DOI: 10.3389/fmicb.2020.01297] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/20/2020] [Indexed: 01/23/2023] Open
Abstract
Chikungunya virus (CHIKV) is an arthropod-borne virus (arbovirus) of epidemic concern, transmitted by Aedes ssp. mosquitoes, and is the etiologic agent of a febrile and incapacitating arthritogenic illness responsible for millions of human cases worldwide. After major outbreaks starting in 2004, CHIKV spread to subtropical areas and western hemisphere coming from sub-Saharan Africa, South East Asia, and the Indian subcontinent. Even though CHIKV disease is self-limiting and non-lethal, more than 30% of the infected individuals will develop chronic disease with persistent severe joint pain, tenosynovitis, and incapacitating polyarthralgia that can last for months to years, negatively impacting an individual's quality of life and socioeconomic productivity. The lack of specific drugs or licensed vaccines to treat or prevent CHIKV disease associated with the global presence of the mosquito vector in tropical and temperate areas, representing a possibility for CHIKV to continually spread to different territories, make this virus an agent of public health burden. In South America, where Dengue virus is endemic and Zika virus was recently introduced, the impact of the expansion of CHIKV infections, and co-infection with other arboviruses, still needs to be estimated. In Brazil, the recent spread of the East/Central/South Africa (ECSA) and Asian genotypes of CHIKV was accompanied by a high morbidity rate and acute cases of abnormal disease presentation and severe neuropathies, which is an atypical outcome for this infection. In this review, we will discuss what is currently known about CHIKV epidemics, clinical manifestations of the human disease, the basic concepts and recent findings in the mechanisms underlying virus-host interaction, and CHIKV-induced chronic disease for both in vitro and in vivo models of infection. We aim to stimulate scientific debate on how the characterization of replication, host-cell interactions, and the pathogenic potential of the new epidemic viral strains can contribute as potential developments in the virology field and shed light on strategies for disease control.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Luciana J. da Costa
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| |
Collapse
|
8
|
New World alphavirus protein interactomes from a therapeutic perspective. Antiviral Res 2019; 163:125-139. [PMID: 30695702 DOI: 10.1016/j.antiviral.2019.01.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/18/2019] [Accepted: 01/23/2019] [Indexed: 12/30/2022]
Abstract
The New World alphaviruses, Venezuelan, eastern and western equine encephalitis viruses (VEEV, EEEV, and WEEV), are important human pathogens due to their ability to cause varying levels of morbidity and mortality in humans. There is also concern about VEEV and EEEV being used as bioweapons. Currently, a FDA-approved antiviral is lacking for New World alphaviruses. In this review, the function of each viral protein is discussed with an emphasis on how these functions can be targeted by therapeutics. Both direct acting antivirals as well as inhibitors that impact host protein interactions with viral proteins are described. Non-structural protein 3 (nsP3), capsid, and E2 proteins have garnered attention in recent years, whereas little is known regarding host protein interactions of the other viral proteins and is an important avenue for future study.
Collapse
|
9
|
Chen L, Wang M, Zhu D, Sun Z, Ma J, Wang J, Kong L, Wang S, Liu Z, Wei L, He Y, Wang J, Zhang X. Implication for alphavirus host-cell entry and assembly indicated by a 3.5Å resolution cryo-EM structure. Nat Commun 2018; 9:5326. [PMID: 30552337 PMCID: PMC6294011 DOI: 10.1038/s41467-018-07704-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/12/2018] [Indexed: 11/09/2022] Open
Abstract
Alphaviruses are enveloped RNA viruses that contain several human pathogens. Due to intrinsic heterogeneity of alphavirus particles, a high resolution structure of the virion is currently lacking. Here we provide a 3.5 Å cryo-EM structure of Sindbis virus, using block based reconstruction method that overcomes the heterogeneity problem. Our structural analysis identifies a number of conserved residues that play pivotal roles in the virus life cycle. We identify a hydrophobic pocket in the subdomain D of E2 protein that is stabilized by an unknown pocket factor near the viral membrane. Residues in the pocket are conserved in different alphaviruses. The pocket strengthens the interactions of the E1/E2 heterodimer and may facilitate virus assembly. Our study provides structural insights into alphaviruses that may inform the design of drugs and vaccines.
Collapse
Affiliation(s)
- Lihong Chen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China.,State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China.,University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China
| | - Ming Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China
| | - Dongjie Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China.,School of Life Science, University of Science and Technology of China, 230026, Hefei, People's Republic of China
| | - Zhenzhao Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China
| | - Jun Ma
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China
| | - Jinglin Wang
- Yunnan Tropical and Subtropical Animal Viral Disease Laboratory, Yunnan Animal Science and Veterinary Institute, Kunming, 650224, People's Republic of China
| | - Lingfei Kong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China
| | - Shida Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China
| | - Zaisi Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China
| | - Lili Wei
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China
| | - Yuwen He
- Yunnan Tropical and Subtropical Animal Viral Disease Laboratory, Yunnan Animal Science and Veterinary Institute, Kunming, 650224, People's Republic of China
| | - Jingfei Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 150069, Harbin, People's Republic of China.
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, People's Republic of China. .,University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China.
| |
Collapse
|
10
|
Wong KZ, Chu JJH. The Interplay of Viral and Host Factors in Chikungunya Virus Infection: Targets for Antiviral Strategies. Viruses 2018; 10:E294. [PMID: 29849008 PMCID: PMC6024654 DOI: 10.3390/v10060294] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/13/2018] [Accepted: 05/28/2018] [Indexed: 12/14/2022] Open
Abstract
Chikungunya virus (CHIKV) has re-emerged as one of the many medically important arboviruses that have spread rampantly across the world in the past decade. Infected patients come down with acute fever and rashes, and a portion of them suffer from both acute and chronic arthralgia. Currently, there are no targeted therapeutics against this debilitating virus. One approach to develop potential therapeutics is by understanding the viral-host interactions. However, to date, there has been limited research undertaken in this area. In this review, we attempt to briefly describe and update the functions of the different CHIKV proteins and their respective interacting host partners. In addition, we also survey the literature for other reported host factors and pathways involved during CHIKV infection. There is a pressing need for an in-depth understanding of the interaction between the host environment and CHIKV in order to generate potential therapeutics.
Collapse
Affiliation(s)
- Kai Zhi Wong
- Laboratory of Molecular RNA Virology & Antiviral Strategies, Department of Microbiology & Immunology, Yong Loo Lin School of Medicine, National University Health System, 5 Science Drive 2, National University of Singapore, Singapore 117597, Singapore.
| | - Justin Jang Hann Chu
- Laboratory of Molecular RNA Virology & Antiviral Strategies, Department of Microbiology & Immunology, Yong Loo Lin School of Medicine, National University Health System, 5 Science Drive 2, National University of Singapore, Singapore 117597, Singapore.
- Institute of Molecular & Cell Biology, Agency for Science, Technology & Research (A*STAR), 61 Biopolis Drive, Proteos #06-05, Singapore 138673, Singapore.
| |
Collapse
|
11
|
Brown RS, Wan JJ, Kielian M. The Alphavirus Exit Pathway: What We Know and What We Wish We Knew. Viruses 2018; 10:E89. [PMID: 29470397 PMCID: PMC5850396 DOI: 10.3390/v10020089] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/28/2022] Open
Abstract
Alphaviruses are enveloped positive sense RNA viruses and include serious human pathogens, such as the encephalitic alphaviruses and Chikungunya virus. Alphaviruses are transmitted to humans primarily by mosquito vectors and include species that are classified as emerging pathogens. Alphaviruses assemble highly organized, spherical particles that bud from the plasma membrane. In this review, we discuss what is known about the alphavirus exit pathway during a cellular infection. We describe the viral protein interactions that are critical for virus assembly/budding and the host factors that are involved, and we highlight the recent discovery of cell-to-cell transmission of alphavirus particles via intercellular extensions. Lastly, we discuss outstanding questions in the alphavirus exit pathway that may provide important avenues for future research.
Collapse
Affiliation(s)
- Rebecca S Brown
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Judy J Wan
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| |
Collapse
|
12
|
Silva LA, Dermody TS. Chikungunya virus: epidemiology, replication, disease mechanisms, and prospective intervention strategies. J Clin Invest 2017; 127:737-749. [PMID: 28248203 PMCID: PMC5330729 DOI: 10.1172/jci84417] [Citation(s) in RCA: 226] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Chikungunya virus (CHIKV), a reemerging arbovirus, causes a crippling musculoskeletal inflammatory disease in humans characterized by fever, polyarthralgia, myalgia, rash, and headache. CHIKV is transmitted by Aedes species of mosquitoes and is capable of an epidemic, urban transmission cycle with high rates of infection. Since 2004, CHIKV has spread to new areas, causing disease on a global scale, and the potential for CHIKV epidemics remains high. Although CHIKV has caused millions of cases of disease and significant economic burden in affected areas, no licensed vaccines or antiviral therapies are available. In this Review, we describe CHIKV epidemiology, replication cycle, pathogenesis and host immune responses, and prospects for effective vaccines and highlight important questions for future research.
Collapse
|
13
|
Abstract
The mosquito-borne Chikungunya virus (CHIKV) is a profound global threat due to its high rate of contagion and the lack of vaccine or effective treatment. Suramin is a symmetric polyanionic naphthylurea that is widely used in the clinical treatment of parasite infections. Numerous studies have reported the broad antiviral activities of suramin; however, inhibition effects against CHIKV have not yet been demonstrated. The aim of this study was thus to investigate the antiviral effect of suramin on CHIKV infection and to elucidate the molecular mechanism underlying inhibition using plaque reduction assay, RT-qPCR, western blot analysis, and plaque assay. Microneutralization assay was used to determine the EC50 of suramin in the CHIKV-S27 strain as well as in three other clinical strains (0611aTw, 0810bTw and 0706aTw). Time-of-addition was used to reveal the anti-CHIKV mechanism of suramin. We also evaluated anti-CHIKV activity with regard to viral entry, virus release, and cell-to-cell transmission. Cytopathic effect, viral RNA, viral protein, and the virus yield of CHIKV infection were shown to diminish in the presence of suramin in a dose-dependent manner. Suramin was also shown the inhibitory activities of the three clinical isolates. Suramin inhibited the early progression of CHIKV infection, due perhaps to interference with virus fusion and binding, which subsequently prevented viral entry. Results of a molecular docking simulation indicate that suramin may embed within the cavity of the E1/E2 heterodimer to interfere with their function. Suramin was also shown to reduce viral release and cell-to-cell transmission of CHIKV. In conclusion, Suramin shows considerable potential as a novel anti-CHIKV agent targeting viral entry, extracellular transmission, and cell-to-cell transmission.
Collapse
Affiliation(s)
- Yi-Jung Ho
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Ming Wang
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Jeng-wei Lu
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Tzong-Yuan Wu
- Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li, Taiwan
| | - Liang-In Lin
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Szu-Cheng Kuo
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Department of Pathology, and Graduate Institute of Pathology and Parasitology, National Defense Medical Center, Taipei, Taiwan
- * E-mail: (SCK); (CCL)
| | - Chang-Chi Lin
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Department and Graduate Institute of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
- * E-mail: (SCK); (CCL)
| |
Collapse
|
14
|
Noranate N, Takeda N, Chetanachan P, Sittisaman P, A-nuegoonpipat A, Anantapreecha S. Characterization of chikungunya virus-like particles. PLoS One 2014; 9:e108169. [PMID: 25265335 PMCID: PMC4180278 DOI: 10.1371/journal.pone.0108169] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/19/2014] [Indexed: 12/19/2022] Open
Abstract
Chikungunya virus (CHIKV) is becoming a global concern due to the increasing number of outbreaks throughout the world and the absence of any CHIKV-specific vaccine or treatment. Virus-like particles (VLPs) are multistructured proteins that mimic the organization and conformation of native viruses but lack the viral genome. They are noninfectious and potentially safer vaccine candidates. Recent studies demonstrated that the yield of CHIKV VLPs varies depending on the strains, despite the 95% amino acid similarity of the strains. This might be due to the codon usage, since protein expression is differently controlled by different organisms. We optimized the region encoding CHIKV structural proteins, C-E3-E2-6k-E1, inserted it into a mammalian expression vector, and used the resulting construct to transfect 293 cells. We detected 50-kDa proteins corresponding to E1 and/or E2 in the cell lysate and the supernatant. Transmission electron microscopy revealed spherical particles with a 50- to 60-nm diameter in the supernatant that resembled the native CHIKV virions. The buoyant density of the VLPs was 1.23 g/mL, and the yield was 20 µg purified VLPs per 108 cells. The VLPs aggregated when mixed with convalescent sera from chikungunya patients, indicating that their antigenicity is similar to that of native CHIKV. Antibodies elicited with the VLPs were capable of detecting native CHIKV, demonstrating that the VLPs retain immunogenicity similar to that of the native virion. These results indicated that CHIKV VLPs are morphologically, antigenically, and immunologically similar to the native CHIKV, suggesting that they have potential for use in chikungunya vaccines.
Collapse
Affiliation(s)
- Nitchakarn Noranate
- Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections (RCC-ERI), Nonthaburi, Thailand
- * E-mail:
| | - Naokazu Takeda
- Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections (RCC-ERI), Nonthaburi, Thailand
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Prukswan Chetanachan
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Pathompong Sittisaman
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Atchareeya A-nuegoonpipat
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Surapee Anantapreecha
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| |
Collapse
|
15
|
Masrinoul P, Puiprom O, Tanaka A, Kuwahara M, Chaichana P, Ikuta K, Ramasoota P, Okabayashi T. Monoclonal antibody targeting chikungunya virus envelope 1 protein inhibits virus release. Virology 2014; 464-465:111-117. [PMID: 25063884 DOI: 10.1016/j.virol.2014.05.038] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 03/28/2014] [Accepted: 05/29/2014] [Indexed: 10/25/2022]
Abstract
Chikungunya virus (CHIKV) causes an acute clinical illness characterized by sudden high fever, intense joint pain, and skin rash. Recent outbreaks of chikungunya disease in Africa and Asia are a major public health concern; however, there is currently no effective licensed vaccine or specific treatment. This study reported the development of a mouse monoclonal antibody (MAb), CK47, which recognizes domain III within the viral envelope 1 protein and inhibited the viral release process, thereby preventing the production of progeny virus. The MAb had no effect on virus entry and replication processes. Thus, CK47 may be a useful tool for studying the mechanisms underlying CHIKV release and may show potential as a therapeutic agent.
Collapse
Affiliation(s)
- Promsin Masrinoul
- Mahidol-Osaka Center for Infectious Diseases, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Orapim Puiprom
- Mahidol-Osaka Center for Infectious Diseases, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Atsushi Tanaka
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Miwa Kuwahara
- Mahidol-Osaka Center for Infectious Diseases, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand; Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Panjaporn Chaichana
- Mahidol-Osaka Center for Infectious Diseases, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Kazuyoshi Ikuta
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Pongrama Ramasoota
- Center of Excellence for Antibody Research, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Tamaki Okabayashi
- Mahidol-Osaka Center for Infectious Diseases, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand; Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
| |
Collapse
|
16
|
Crystal structure of aura virus capsid protease and its complex with dioxane: new insights into capsid-glycoprotein molecular contacts. PLoS One 2012; 7:e51288. [PMID: 23251484 PMCID: PMC3522669 DOI: 10.1371/journal.pone.0051288] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 11/01/2012] [Indexed: 12/25/2022] Open
Abstract
The nucleocapsid core interaction with endodomains of glycoproteins plays a critical role in the alphavirus life cycle that is essential to virus budding. Recent cryo-electron microscopy (cryo-EM) studies provide structural insights into key interactions between capsid protein (CP) and trans-membrane glycoproteins E1 and E2. CP possesses a chymotrypsin-like fold with a hydrophobic pocket at the surface responsible for interaction with glycoproteins. In the present study, crystal structures of the protease domain of CP from Aura virus and its complex with dioxane were determined at 1.81 and 1.98 Å resolution respectively. Due to the absence of crystal structures, homology models of E1 and E2 from Aura virus were generated. The crystal structure of CP and structural models of E1 and E2 were fitted into the cryo-EM density map of Venezuelan equine encephalitis virus (VEEV) for detailed analysis of CP-glycoprotein interactions. Structural analysis revealed that the E2 endodomain consists of a helix-loop-helix motif where the loop region fits into the hydrophobic pocket of CP. Our studies suggest that Cys397, Cys418 and Tyr401 residues of E2 are involved in stabilizing the structure of E2 endodomain. Density map fitting analysis revealed that Pro405, a conserved E2 residue is present in the loop region of the E2 endodomain helix-loop-helix structure and makes intermolecular hydrophobic contacts with the capsid. In the Aura virus capsid protease (AVCP)-dioxane complex structure, dioxane occupies the hydrophobic pocket on CP and structurally mimics the hydrophobic pyrollidine ring of Pro405 in the loop region of E2.
Collapse
|
17
|
Tang J, Jose J, Chipman P, Zhang W, Kuhn RJ, Baker TS. Molecular links between the E2 envelope glycoprotein and nucleocapsid core in Sindbis virus. J Mol Biol 2011; 414:442-59. [PMID: 22001018 DOI: 10.1016/j.jmb.2011.09.045] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 09/26/2011] [Accepted: 09/28/2011] [Indexed: 10/17/2022]
Abstract
A three-dimensional reconstruction of Sindbis virus at 7.0 Å resolution presented here provides a detailed view of the virion structure and includes structural evidence for key interactions that occur between the capsid protein (CP) and transmembrane (TM) glycoproteins E1 and E2. Based on crystal structures of component proteins and homology modeling, we constructed a nearly complete, pseudo-atomic model of the virus. Notably, this includes identification of the 33-residue cytoplasmic domain of E2 (cdE2), which follows a path from the E2 TM helix to the CP where it enters and exits the CP hydrophobic pocket and then folds back to contact the viral membrane. Modeling analysis identified three major contact regions between cdE2 and CP, and the roles of specific residues were probed by molecular genetics. This identified R393 and E395 of cdE2 and Y162 and K252 of CP as critical for virus assembly. The N-termini of the CPs form a contiguous network that interconnects 12 pentameric and 30 hexameric CP capsomers. A single glycoprotein spike cross-links three neighboring CP capsomers as might occur during initiation of virus budding.
Collapse
Affiliation(s)
- Jinghua Tang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378, USA
| | | | | | | | | | | |
Collapse
|
18
|
Zhang R, Hryc CF, Cong Y, Liu X, Jakana J, Gorchakov R, Baker ML, Weaver SC, Chiu W. 4.4 Å cryo-EM structure of an enveloped alphavirus Venezuelan equine encephalitis virus. EMBO J 2011; 30:3854-63. [PMID: 21829169 PMCID: PMC3173789 DOI: 10.1038/emboj.2011.261] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 07/08/2011] [Indexed: 11/09/2022] Open
Abstract
Venezuelan equine encephalitis virus (VEEV), a member of the membrane-containing Alphavirus genus, is a human and equine pathogen, and has been developed as a biological weapon. Using electron cryo-microscopy (cryo-EM), we determined the structure of an attenuated vaccine strain, TC-83, of VEEV to 4.4 Å resolution. Our density map clearly resolves regions (including E1, E2 transmembrane helices and cytoplasmic tails) that were missing in the crystal structures of domains of alphavirus subunits. These new features are implicated in the fusion, assembly and budding processes of alphaviruses. Furthermore, our map reveals the unexpected E3 protein, which is cleaved and generally thought to be absent in the mature VEEV. Our structural results suggest a mechanism for the initial stage of nucleocapsid core formation, and shed light on the virulence attenuation, host recognition and neutralizing activities of VEEV and other alphavirus pathogens.
Collapse
Affiliation(s)
- Rui Zhang
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
Alphaviruses are taken up into the endosome of the cell, where acidic conditions activate the spikes for membrane fusion. This involves dissociation of the three E2-E1 heterodimers of the spike and E1 interaction with the target membrane as a homotrimer. The biosynthesis of the heterodimer as a pH-resistant p62-E1 precursor appeared to solve the problem of premature activation in the late and acidic parts of the biosynthetic transport pathway in the cell. However, p62 cleavage into E2 and E3 by furin occurs before the spike has left the acidic compartments, accentuating the problem. In this work, we used a furin-resistant Semliki Forest virus (SFV) mutant, SFV(SQL), to study the role of E3 in spike activation. The cleavage was reconstituted with proteinase K in vitro using free virus or spikes on SFV(SQL)-infected cells. We found that E3 association with the spikes was pH dependent, requiring acidic conditions, and that the bound E3 suppressed spike activation. This was shown in an in vitro spike activation assay monitoring E1 trimer formation with liposomes and a fusion-from-within assay with infected cells. Furthermore, the wild type, SFV(wt), was found to bind significant amounts of E3, especially if produced in dense cultures, which lowered the pH of the culture medium. This E3 also suppressed spike activation. The results suggest that furin-cleaved E3 continues to protect the spike from premature activation in acidic compartments of the cell and that its release in the neutral extracellular space primes the spike for low-pH activation.
Collapse
|
20
|
Lin YJ, Peng JG, Wu SC. Characterization of the GXXXG motif in the first transmembrane segment of Japanese encephalitis virus precursor membrane (prM) protein. J Biomed Sci 2010; 17:39. [PMID: 20492732 PMCID: PMC2890656 DOI: 10.1186/1423-0127-17-39] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 05/24/2010] [Indexed: 12/11/2022] Open
Abstract
The interaction between prM and E proteins in flavivirus-infected cells is a major driving force for the assembly of flavivirus particles. We used site-directed mutagenesis to study the potential role of the transmembrane domains of the prM proteins of Japanese encephalitis virus (JEV) in prM-E heterodimerization as well as subviral particle formation. Alanine insertion scanning mutagenesis within the GXXXG motif in the first transmembrane segment of JEV prM protein affected the prM-E heterodimerization; its specificity was confirmed by replacing the two glycines of the GXXXG motif with alanine, leucine and valine. The GXXXG motif was found to be conserved in the JEV serocomplex viruses but not other flavivirus groups. These mutants with alanine inserted in the two prM transmembrane segments all impaired subviral particle formation in cell cultures. The prM transmembrane domains of JEV may play importation roles in prM-E heterodimerization and viral particle assembly.
Collapse
Affiliation(s)
- Ying-Ju Lin
- Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
| | | | | |
Collapse
|
21
|
Abstract
The study of enveloped animal viruses has greatly advanced our understanding of the general properties of membrane fusion and of the specific pathways that viruses use to infect the host cell. The membrane fusion proteins of the alphaviruses and flaviviruses have many similarities in structure and function. As reviewed here, alphaviruses use receptor-mediated endocytic uptake and low pH-triggered membrane fusion to deliver their RNA genomes into the cytoplasm. Recent advances in understanding the biochemistry and structure of the alphavirus membrane fusion protein provide a clearer picture of this fusion reaction, including the protein’s conformational changes during fusion and the identification of key domains. These insights into the alphavirus fusion mechanism suggest new areas for experimental investigation and potential inhibitor strategies for anti-viral therapy.
Collapse
Affiliation(s)
- Margaret Kielian
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-718-430-3638; Fax: +1-718-430-8574
| | | | | |
Collapse
|
22
|
Schibli DJ, Weissenhorn W. Class I and class II viral fusion protein structures reveal similar principles in membrane fusion (Review). Mol Membr Biol 2009; 21:361-71. [PMID: 15764366 DOI: 10.1080/09687860400017784] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Recent crystal structures of Flavivirus and Alphavirus fusion proteins (class II) confirm two major principles of protein machineries that mediate the merger of two opposing lipid bilayers. First, the fusion protein can bridge both membranes tethered by two membrane anchors. Second, refolding or domain rearrangement steps lead to the positioning of both anchors into close proximity at the same end of an elongated structure. Although these two steps are in principle sufficient to pull two opposing membranes together and initiate membrane fusion, accumulating evidence suggests that the process requires the concerted action of a number of fusion proteins at and outside the contact sites. This review will focus on the structures of viral class I and class II fusion proteins and their similarities in facilitating membrane fusion.
Collapse
|
23
|
Abstract
Several arenaviruses, including Lassa virus (LASV), are causative agents of hemorrhagic fever, for which effective therapeutic options are lacking. The LASV envelope glycoprotein (GP) gene was used to generate lentiviral pseudotypes to identify small-molecule inhibitors of viral entry. A benzimidazole derivative with potent antiviral activity was identified from a high-throughput screen utilizing this strategy. Subsequent lead optimization for antiviral activity identified a modified structure, ST-193, with a 50% inhibitory concentration (IC(50)) of 1.6 nM against LASV pseudotypes. ST-193 inhibited pseudotypes generated with other arenavirus envelopes as well, including the remaining four commonly associated with hemorrhagic fever (IC(50)s for Junín, Machupo, Guanarito, and Sabiá were in the 0.2 to 12 nM range) but exhibited no antiviral activity against pseudotypes incorporating either the GP from the LASV-related arenavirus lymphocytic choriomeningitis virus (LCMV) or the unrelated G protein from vesicular stomatitis virus, at concentrations of up to 10 microM. Determinants of ST-193 sensitivity were mapped through a combination of LASV-LCMV domain-swapping experiments, genetic selection of viral variants, and site-directed mutagenesis. Taken together, these studies demonstrate that sensitivity to ST-193 is dictated by a segment of about 30 amino acids within the GP2 subunit. This region includes the carboxy-terminal region of the ectodomain and the predicted transmembrane domain of the envelope protein, revealing a novel antiviral target within the arenavirus envelope GP.
Collapse
|
24
|
Ciczora Y, Callens N, Penin F, Pécheur EI, Dubuisson J. Transmembrane domains of hepatitis C virus envelope glycoproteins: residues involved in E1E2 heterodimerization and involvement of these domains in virus entry. J Virol 2006; 81:2372-81. [PMID: 17166909 PMCID: PMC1865936 DOI: 10.1128/jvi.02198-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transmembrane (TM) domains of hepatitis C virus (HCV) envelope glycoproteins E1 and E2 have been shown to play multiple roles during the biogenesis of the E1E2 heterodimer. By using alanine scanning insertion mutagenesis within the TM domains of HCV envelope glycoproteins, we have previously shown that the central regions of these domains as well as the N-terminal part of the TM domain of E1 are involved in heterodimerization. Here, we used a tryptophan replacement scan of these regions to identify individual residues that participate in those interactions. Our mutagenesis study identified at least four residues involved in heterodimerization: Gly 354, Gly 358, Lys 370, and Asp 728. Interestingly, Gly 354 and Gly 358 belong to a GXXXG oligomerization motif. Our tryptophan mutants were also used to generate retrovirus-based, HCV-pseudotyped particles (HCVpp) in order to analyze the effects of these mutations on virus entry. Surprisingly, two mutants consistently displayed higher infectivity compared to that of the wild type. In contrast, HCVpp infectivity was strongly affected for many mutants, despite normal E1E2 heterodimerization and normal levels of incorporation of HCV glycoproteins into HCVpp. The characterization of some of these HCVpp mutants in the recently developed in vitro fusion assay using fluorescent-labeled liposomes indicated that mutations reducing HCVpp infectivity without altering E1E2 heterodimerization affected the fusion properties of HCV envelope glycoproteins. In conclusion, this mutational analysis identified residues involved in E1E2 heterodimerization and revealed that the TM domains of HCV envelope glycoproteins play a major role in the fusion properties of these proteins.
Collapse
Affiliation(s)
- Yann Ciczora
- Hepatitis C Laboratory, CNRS-UMR8161, Institut de Biologie de Lille, 1 rue Calmette, BP447, 59021 Lille cedex, France
| | | | | | | | | |
Collapse
|
25
|
Liao M, Kielian M. Functions of the stem region of the Semliki Forest virus fusion protein during virus fusion and assembly. J Virol 2006; 80:11362-9. [PMID: 16971447 PMCID: PMC1642169 DOI: 10.1128/jvi.01679-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Membrane fusion of the alphaviruses is mediated by the E1 protein, a class II virus membrane fusion protein. During fusion, E1 dissociates from its heterodimer interaction with the E2 protein and forms a target membrane-inserted E1 homotrimer. The structure of the homotrimer is that of a trimeric hairpin in which E1 domain III and the stem region fold back toward the target membrane-inserted fusion peptide loop. The E1 stem region has a strictly conserved length and several highly conserved residues, suggesting the possibility of specific stem interactions along the trimer core and an important role in driving membrane fusion. Mutagenesis studies of the alphavirus Semliki Forest virus (SFV) here demonstrated that there was a strong requirement for the E1 stem in virus assembly and budding, probably reflecting its importance in lateral interactions of the envelope proteins. Surprisingly, however, neither the conserved length nor any specific residues of the stem were required for membrane fusion. Although the highest fusion activity was observed with wild-type E1, efficient fusion was mediated by stem mutants containing a variety of substitutions or deletions. A minimal stem length was required but could be conferred by a series of alanine residues. The lack of a specific stem sequence requirement during SFV fusion suggests that the interaction of domain III with the trimer core can provide sufficient driving force to mediate membrane merger.
Collapse
Affiliation(s)
- Maofu Liao
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | | |
Collapse
|
26
|
Mukhopadhyay S, Zhang W, Gabler S, Chipman PR, Strauss EG, Strauss JH, Baker TS, Kuhn RJ, Rossmann MG. Mapping the structure and function of the E1 and E2 glycoproteins in alphaviruses. Structure 2006; 14:63-73. [PMID: 16407066 PMCID: PMC2757649 DOI: 10.1016/j.str.2005.07.025] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 07/11/2005] [Accepted: 07/16/2005] [Indexed: 11/25/2022]
Abstract
The 9 A resolution cryo-electron microscopy map of Sindbis virus presented here provides structural information on the polypeptide topology of the E2 protein, on the interactions between the E1 and E2 glycoproteins in the formation of a heterodimer, on the difference in conformation of the two types of trimeric spikes, on the interaction between the transmembrane helices of the E1 and E2 proteins, and on the conformational changes that occur when fusing with a host cell. The positions of various markers on the E2 protein established the approximate topology of the E2 structure. The largest conformational differences between the icosahedral surface spikes at icosahedral 3-fold and quasi-3-fold positions are associated with the monomers closest to the 5-fold axes. The long E2 monomers, containing the cell receptor recognition motif at their extremities, are shown to rotate by about 180 degrees and to move away from the center of the spikes during fusion.
Collapse
Affiliation(s)
- Suchetana Mukhopadhyay
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Ciczora Y, Callens N, Montpellier C, Bartosch B, Cosset FL, De Beeck AO, Dubuisson J. Contribution of the charged residues of hepatitis C virus glycoprotein E2 transmembrane domain to the functions of the E1E2 heterodimer. J Gen Virol 2005; 86:2793-2798. [PMID: 16186234 DOI: 10.1099/vir.0.81140-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The envelope glycoproteins of Hepatitis C virus (HCV), E1 and E2, form a heterodimer that is retained in the endoplasmic reticulum (ER). The transmembrane (TM) domains play a major role in E1E2 heterodimerization and in ER retention. Two fully conserved charged residues in the middle of the TM domain of E2 (Asp and Arg) are crucial for these functions. Replacement of the Asp residue by a Leu impaired E1E2 heterodimerization, whereas the Arg-to-Leu mutation had a milder effect. Both Asp and Arg residues were shown to contribute to the ER retention function of E2. In addition, the entry function of HCV envelope glycoproteins was affected by these mutations. Together, these data indicate that the charged residues present in the TM domain of E2 play a major role in the biogenesis and the entry function of the E1E2 heterodimer. However, the Asp and Arg residues do not contribute equally to these functions.
Collapse
Affiliation(s)
- Yann Ciczora
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Nathalie Callens
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Claire Montpellier
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Birke Bartosch
- Laboratoire de Vectorologie Rétrovirale et Thérapie Génique, INSERM U412, IFR74, Ecole Normale Supérieure de Lyon, Lyon, France
| | - François-Loïc Cosset
- Laboratoire de Vectorologie Rétrovirale et Thérapie Génique, INSERM U412, IFR74, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Anne Op De Beeck
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Jean Dubuisson
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| |
Collapse
|
28
|
Liao M, Kielian M. The conserved glycine residues in the transmembrane domain of the Semliki Forest virus fusion protein are not required for assembly and fusion. Virology 2005; 332:430-7. [PMID: 15661173 DOI: 10.1016/j.virol.2004.11.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 11/17/2004] [Accepted: 11/29/2004] [Indexed: 11/30/2022]
Abstract
The alphavirus Semliki Forest virus (SFV) infects cells via a low pH-triggered fusion reaction mediated by the viral E1 protein. Both the E1 fusion peptide and transmembrane (TM) domain are essential for membrane fusion, but the functional requirements for the TM domain are poorly understood. Here we explored the role of the five TM domain glycine residues, including the highly conserved glycine pair at E1 residues 415/416. SFV mutants with alanine substitutions for individual or all five glycine residues (5G/A) showed growth kinetics and fusion pH dependence similar to those of wild-type SFV. Mutants with increasing substitution of glycine residues showed an increasingly more stringent requirement for cholesterol during fusion. The 5G/A mutant showed decreased fusion kinetics and extent in fluorescent lipid mixing assays. TM domain glycine residues thus are not required for efficient SFV fusion or assembly but can cause subtle effects on the properties of membrane fusion.
Collapse
Affiliation(s)
- Maofu Liao
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | | |
Collapse
|
29
|
Zaitseva E, Mittal A, Griffin DE, Chernomordik LV. Class II fusion protein of alphaviruses drives membrane fusion through the same pathway as class I proteins. ACTA ACUST UNITED AC 2005; 169:167-77. [PMID: 15809312 PMCID: PMC2171914 DOI: 10.1083/jcb.200412059] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Viral fusion proteins of classes I and II differ radically in their initial structures but refold toward similar conformations upon activation. Do fusion pathways mediated by alphavirus E1 and influenza virus hemagglutinin (HA) that exemplify classes II and I differ to reflect the difference in their initial conformations, or concur to reflect the similarity in the final conformations? Here, we dissected the pathway of low pH–triggered E1-mediated cell–cell fusion by reducing the numbers of activated E1 proteins and by blocking different fusion stages with specific inhibitors. The discovered progression from transient hemifusion to small, and then expanding, fusion pores upon an increase in the number of activated fusion proteins parallels that established for HA-mediated fusion. We conclude that proteins as different as E1 and HA drive fusion through strikingly similar membrane intermediates, with the most energy-intensive stages following rather than preceding hemifusion. We propose that fusion reactions catalyzed by all proteins of both classes follow a similar pathway.
Collapse
Affiliation(s)
- Elena Zaitseva
- Section on Membrane Biology, Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | |
Collapse
|
30
|
Abstract
Every enveloped virus fuses its membrane with a host cell membrane, thereby releasing its genome into the cytoplasm and initiating the viral replication cycle. In each case, one or a small set of viral surface transmembrane glycoproteins mediates fusion. Viral fusion proteins vary in their mode of activation and in structural class. These features combine to yield many different fusion mechanisms. Despite their differences, common principles for how fusion proteins function are emerging: In response to an activating trigger, the metastable fusion protein converts to an extended, in some cases rodlike structure, which inserts into the target membrane via its fusion peptide. A subsequent conformational change causes the fusion protein to fold back upon itself, thereby bringing its fusion peptide and its transmembrane domain-and their attached target and viral membranes-into intimate contact. Fusion ensues as the initial lipid stalk progresses through local hemifusion, and then opening and enlargement of a fusion pore. Here we review recent advances in our understanding of how fusion proteins are activated, how fusion proteins change conformation during fusion, and what is happening to the lipids during fusion. We also briefly discuss the therapeutic potential of fusion inhibitors in treating viral infections.
Collapse
Affiliation(s)
- Mark Marsh
- Cell Biology Unit, MRC-LMCB, University College London, Gower Street, London, WC1E 6BT UK
| |
Collapse
|
31
|
Affiliation(s)
- Richard J Kuhn
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
| | | |
Collapse
|
32
|
Abstract
Alphaviruses are small highly ordered enveloped RNA viruses, which replicate very efficiently in the infected cell. They consist of a nucleocapsid (NC) and a surrounding membrane with glycoproteins. In the NC the positive single stranded RNA genome of the virus is enclosed by a T=4 icosahedral shell of capsid (C) proteins. The glycoproteins form a second shell with corresponding symmetry on the outside of the lipid membrane. These viruses mature by budding at the plasma membrane (PM) of the infected cell and enter into new cells by acid-triggered membrane fusion in endosomes. The viral glycoprotein consists of two subunits, E1, which carries the membrane fusion function, and E2, which suppresses this function until acid activation occurs. In the infected cell the RNA replication and transcription are confined to the cytoplasmic surface of endosome-derived vesicles called cytopathic vacuoles type I (CPV I). These structures are closely associated with membranes of the endoplasmic reticulum (ER), thereby creating a microenvironment for synthesis of viral proteins, assembly of the glycoproteins and formation of genome-C complexes. The budding process of the virus is initiated by C-glycoprotein interactions, possibly already before the glycoproteins arrive at the PM. This might involve a premade, ordered NC or a less ordered form of the genome-C complex. In the latter case, the interactions in the glycoprotein shell provide the major driving force for budding. The nature of the C-glycoprotein interaction has been resolved at atomic resolution by modelling. It involves hydrophobic interactions between a Tyr-X-Leu tripeptide in the internal tail of the E2 subunit and a pocket on the surface of the C protein. When the virus enters the endosome of a new cell the acid conditions trigger rearrangements in the glycoprotein shell, which result in the dissociation of the interactions that drive budding and a concomitant activation of the membrane fusion function in the E1 subunit.
Collapse
Affiliation(s)
- Henrik Garoff
- Department of Biosciences at Novum, Karolinska Institute, S-141 57 Huddinge, Sweden.
| | | | | |
Collapse
|
33
|
Zhang X, Kielian M. Mutations that promote furin-independent growth of Semliki Forest virus affect p62-E1 interactions and membrane fusion. Virology 2004; 327:287-96. [PMID: 15351216 DOI: 10.1016/j.virol.2004.06.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 06/24/2004] [Indexed: 11/17/2022]
Abstract
The enveloped alphavirus Semliki Forest virus (SFV) infects cells via a low pH-triggered membrane fusion reaction mediated by the E1 protein. E1's fusion activity is regulated by its heterodimeric interaction with a companion membrane protein E2. Mature E2 protein is generated by furin processing of the precursor p62. Processing destabilizes the heterodimer, allowing dissociation at acidic pH, E1 conformational changes, and membrane fusion. We used a furin-deficient cell line, FD11, to select for SFV mutants that show increased growth in the absence of p62 processing. We isolated and characterized 7 such pci mutants (p62 cleavage independent), which retained the parental furin cleavage site but showed significant increases in their ability to carry out membrane fusion in the p62 form. Sequence analysis of the pci mutants identified mutations primarily on the E2 protein, and suggested sites important in the interaction of p62 with E1 and the regulation of fusion.
Collapse
Affiliation(s)
- Xinyong Zhang
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | |
Collapse
|
34
|
Caballero-Herrera A, Nilsson L. Molecular dynamics simulations of the E1/E2 transmembrane domain of the Semliki Forest virus. Biophys J 2004; 85:3646-58. [PMID: 14645057 PMCID: PMC1303669 DOI: 10.1016/s0006-3495(03)74782-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Transmembrane (TM) helix-helix interactions are important for virus budding and fusion. We have developed a simulation strategy that reveals the main features of the helical packing between the TM domains of the two glycoproteins E1 and E2 of the alpha-virus Semliki Forest virus and that can be extrapolated to sketch TM helical packing in other alpha-viruses. Molecular dynamics simulations were performed in wild-type and mutant peptides, both isolated and forming E1/E2 complexes. The simulations revealed that the isolated wild-type E1 peptide formed a more flexible helix than the rest of peptides and that the wild-type E1/E2 complex consists of two helices that intimately pack their N-terminals. The residues located at the interhelical interface displayed the typical motif of the left-handed coiled-coils. These were small and medium residues as Gly, Ala, Ser, and Leu, which also had the possibility to form interhelical Calpha-H...O hydrogen bonds. Results from the mutant complexes suggested that correct packing is a compromise between these residues at both E1 and E2 interhelical interfaces. This compromise allowed prediction of E1-E2 contact residues in the TM spanning domain of other alphaviruses even though the sequence identity of E2 peptides is low in this domain.
Collapse
Affiliation(s)
- Ana Caballero-Herrera
- Department of Biosciences at Novum, Karolinska Institutet, S-141 57 Huddinge, Sweden
| | | |
Collapse
|
35
|
Morozov SY, Solovyev AG. Triple gene block: modular design of a multifunctional machine for plant virus movement. J Gen Virol 2003; 84:1351-1366. [PMID: 12771402 DOI: 10.1099/vir.0.18922-0] [Citation(s) in RCA: 259] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many plant virus genera encode a 'triple gene block' (TGB), a specialized evolutionarily conserved gene module involved in the cell-to-cell and long-distance movement of viruses. The TGB-based transport system exploits the co-ordinated action of three polypeptides to deliver viral genomes to plasmodesmata and to accomplish virus entry into neighbouring cells. Although data obtained on both the TGB and well-studied single protein transport systems clearly demonstrate that plant viruses employ host cell pathways for intra- and intercellular trafficking of genomic nucleic acids and proteins, there is no integral picture of the details of molecular events during TGB-mediated virus movement. Undoubtedly, understanding the molecular basis of the concerted action of TGB-encoded proteins in transporting viral genomes from cell to cell should provide new insights into the general principles of movement protein function. This review describes the structure, phylogeny and expression of TGB proteins, their roles in virus cell-to-cell movement and potential influence on host antiviral defences.
Collapse
Affiliation(s)
- Sergey Yu Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| | - Andrey G Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
| |
Collapse
|