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Pichkur EB, Vorovitch MF, Ivanova AL, Protopopova EV, Loktev VB, Osolodkin DI, Ishmukhametov AA, Samygina VR. The structure of inactivated mature tick-borne encephalitis virus at 3.0 Å resolution. Emerg Microbes Infect 2024; 13:2313849. [PMID: 38465849 DOI: 10.1080/22221751.2024.2313849] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/30/2024] [Indexed: 03/12/2024]
Abstract
Tick-borne encephalitis virus (TBEV) causes a severe disease, tick-borne encephalitis (TBE), that has a substantial epidemiological importance for Northern Eurasia. Between 10,000 and 15,000 TBE cases are registered annually despite the availability of effective formaldehyde-inactivated full-virion vaccines due to insufficient vaccination coverage, as well as sporadic cases of vaccine breakthrough. The development of improved vaccines would benefit from the atomic resolution structure of the antigen. Here we report the refined single-particle cryo-electron microscopy (cryo-EM) structure of the inactivated mature TBEV vaccine strain Sofjin-Chumakov (Far-Eastern subtype) at a resolution of 3.0 Å. The increase of the resolution with respect to the previously published structures of TBEV strains Hypr and Kuutsalo-14 (European subtype) was reached due to improvement of the virus sample quality achieved by the optimized preparation methods. All the surface epitopes of TBEV were structurally conserved in the inactivated virions. ELISA studies with monoclonal antibodies supported the hypothesis of TBEV protein shell cross-linking upon inactivation with formaldehyde.
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Affiliation(s)
| | - Mikhail F Vorovitch
- FSASI "Chumakov FSC R&D IBP RAS" (Institute of Poliomyelitis), Moscow, Russian Federation
- Institute of Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Alla L Ivanova
- FSASI "Chumakov FSC R&D IBP RAS" (Institute of Poliomyelitis), Moscow, Russian Federation
| | - Elena V Protopopova
- State Research Center of Virology and Biotechnology "Vector", Novosibirsk, Russian Federation
| | - Valery B Loktev
- State Research Center of Virology and Biotechnology "Vector", Novosibirsk, Russian Federation
| | - Dmitry I Osolodkin
- FSASI "Chumakov FSC R&D IBP RAS" (Institute of Poliomyelitis), Moscow, Russian Federation
- Institute of Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Aydar A Ishmukhametov
- FSASI "Chumakov FSC R&D IBP RAS" (Institute of Poliomyelitis), Moscow, Russian Federation
- Institute of Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russian Federation
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2
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Feng Y. Recent advances in the study of zika virus structure, drug targets, and inhibitors. Front Pharmacol 2024; 15:1418516. [PMID: 39011504 PMCID: PMC11246971 DOI: 10.3389/fphar.2024.1418516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/30/2024] [Indexed: 07/17/2024] Open
Abstract
Zika Virus (ZIKV) is a positive-strand RNA virus that can lead to Guillain-Barré syndrome or encephalitis in some individuals and hence presents a serious public health risk. Since the first outbreak of ZIKV in Brazil in 2015, no effective clinical inhibitors have been developed, making the development of effective ZIKV drugs an urgent issue that needs to be addressed. ZIKV belongs to the Flaviviridae family, and its structure includes three structural proteins, namely, capsular (C), premembrane (prM), and envelope (E) proteins, as well as seven nonstructural proteins, namely, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. To provide a reference for the development of future ZIKV drugs, this paper reviews the structure of the ZIKV based on recent literature reports, analyzes the potential therapeutic targets of various proteins, and proposes feasible drug design strategies. Additionally, this paper reviews and classifies the latest research progress on several protease inhibitors, such as E protein inhibitors, NS2B-NS3 inhibitors, and NS5 inhibitors, so that researchers can quickly understand the current status of development and the interconnections among these inhibitors.
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Affiliation(s)
- Yingqi Feng
- Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemical Engineering, College of Materials Science & Engineering, Beijing University of Technology, Beijing, China
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3
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Das S, Sarma G, Panicker NJ, Sahu PP. Identifying citrus limonoids as a potential fusion inhibitor of DENV-2 virus through its in silico study and FTIR analysis. In Silico Pharmacol 2024; 12:35. [PMID: 38680655 PMCID: PMC11045700 DOI: 10.1007/s40203-024-00207-2] [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: 12/04/2023] [Accepted: 04/01/2024] [Indexed: 05/01/2024] Open
Abstract
Dengue virus type 2 (DENV-2) is an arthropod-borne deadly RNA human pathogen transmitted through the mosquito Aedes. The DENV-2 roots viral infection by facilitating entry with its envelope glycoprotein to the receptor protein Dendritic-cell-specific ICAM3-grabbing non-integrin (DC-SIGN) through membrane fusion. Here, an organizational path is reported for inhibiting the transition due to fusion activation and by blocking the residues of the DC-SIGN-E-Glyco protein complex through citrus limonoids with its antiviral effect. Based on lower binding affinity obtained with E-glycoprotein, and based on ADMET and drug-likeness study, limonin was selected as having effective interaction with DC-SIGN-E-glycoprotein complex in comparison to other citrus limonoids. The FTIR spectra performed with the limonin-E-glycoprotein sample provide evidence of hydrogen bond formation that indicates the formation of a strong limonin-E-glycoprotein conjugate. Further, the strong physical interaction between DC-SIGN and small limonin molecules in comparison to that of E-glyco with DC-SIGN assures the development of immunity against DENV-2. Supplementary Information The online version contains supplementary material available at 10.1007/s40203-024-00207-2.
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Affiliation(s)
- Satyajit Das
- Department of Electronics and Telecommunication Engineering, Jorhat Institute of Science and Technology, Jorhat, Assam 785010 India
| | - Geetartha Sarma
- Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam 784028 India
| | - Nithin J. Panicker
- Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam 784028 India
| | - Partha P. Sahu
- Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam 784028 India
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4
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Tam EH, Peng Y, Cheah MXY, Yan C, Xiao T. Neutralizing antibodies to block viral entry and for identification of entry inhibitors. Antiviral Res 2024; 224:105834. [PMID: 38369246 DOI: 10.1016/j.antiviral.2024.105834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/20/2024]
Abstract
Neutralizing antibodies (NAbs) are naturally produced by our immune system to combat viral infections. Clinically, neutralizing antibodies with potent efficacy and high specificity have been extensively used to prevent and treat a wide variety of viral infections, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Human Immunodeficiency Virus (HIV), Dengue Virus (DENV) and Hepatitis B Virus (HBV). An overwhelmingly large subset of clinically effective NAbs operates by targeting viral envelope proteins to inhibit viral entry into the host cell. Binding of viral envelope protein to the host receptor is a critical rate limiting step triggering a cascade of downstream events, including endocytosis, membrane fusion and pore formation to allow viral entry. In recent years, improved structural knowledge on these processes have allowed researchers to also leverage NAbs as an indispensable tool in guiding discovery of novel antiviral entry inhibitors, providing drug candidates with high efficacy and pan-genus specificity. This review will summarize the latest progresses on the applications of NAbs as effective entry inhibitors and as important tools to develop antiviral therapeutics by high-throughput drug screenings, rational design of peptidic entry inhibitor mimicking NAbs and in silico computational modeling approaches.
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Affiliation(s)
- Ee Hong Tam
- School of Biological Sciences, Nanyang Technological University 637551, Singapore; Institute of Structural Biology, Nanyang Technological University 636921, Singapore
| | - Yu Peng
- School of Biological Sciences, Nanyang Technological University 637551, Singapore; Institute of Structural Biology, Nanyang Technological University 636921, Singapore
| | - Megan Xin Yan Cheah
- Institute of Molecular and Cell Biology, A*STAR (Agency of Science, Technology and Research) 138673, Singapore
| | - Chuan Yan
- Institute of Molecular and Cell Biology, A*STAR (Agency of Science, Technology and Research) 138673, Singapore
| | - Tianshu Xiao
- School of Biological Sciences, Nanyang Technological University 637551, Singapore; Institute of Structural Biology, Nanyang Technological University 636921, Singapore.
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5
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Guo J, Mi Y, Guo Y, Bai Y, Wang M, Wang W, Wang Y. Current Advances in Japanese Encephalitis Virus Drug Development. Viruses 2024; 16:202. [PMID: 38399978 PMCID: PMC10892782 DOI: 10.3390/v16020202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/14/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Japanese encephalitis virus (JEV) belongs to the Flaviviridae family and is a representative mosquito-borne flavivirus responsible for acute encephalitis and meningitis in humans. Despite the availability of vaccines, JEV remains a major public health threat with the potential to spread globally. According to the World Health Organization (WHO), there are an estimated 69,000 cases of JE each year, and this figure is probably an underestimate. The majority of JE victims are children in endemic areas, and almost half of the surviving patients have motor or cognitive sequelae. Thus, the absence of a clinically approved drug for the treatment of JE defines an urgent medical need. Recently, several promising and potential drug candidates were reported through drug repurposing studies, high-throughput drug library screening, and de novo design. This review focuses on the historical aspects of JEV, the biology of JEV replication, targets for therapeutic strategies, a target product profile, and drug development initiatives.
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Affiliation(s)
- Jiao Guo
- The Xi’an Key Laboratory of Pathogenic Microorganism and Tumor Immunity, School of Basic Medicine, Xi’an Medical University, Xi’an 710021, China; (J.G.); (Y.M.); (Y.B.)
| | - Yunqi Mi
- The Xi’an Key Laboratory of Pathogenic Microorganism and Tumor Immunity, School of Basic Medicine, Xi’an Medical University, Xi’an 710021, China; (J.G.); (Y.M.); (Y.B.)
| | - Yan Guo
- College of Animal Science and Technology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Yang Bai
- The Xi’an Key Laboratory of Pathogenic Microorganism and Tumor Immunity, School of Basic Medicine, Xi’an Medical University, Xi’an 710021, China; (J.G.); (Y.M.); (Y.B.)
| | - Meihua Wang
- Faculty of Life Science and Medicine, University of Science and Technology of China, Hefei 230026, China;
| | - Wei Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yang Wang
- The Xi’an Key Laboratory of Pathogenic Microorganism and Tumor Immunity, School of Basic Medicine, Xi’an Medical University, Xi’an 710021, China; (J.G.); (Y.M.); (Y.B.)
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6
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Stiasny K, Medits I, Roßbacher L, Heinz FX. Impact of structural dynamics on biological functions of flaviviruses. FEBS J 2023; 290:1973-1985. [PMID: 35246954 PMCID: PMC10952610 DOI: 10.1111/febs.16419] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 11/30/2022]
Abstract
Flaviviruses comprise a number of mosquito- or tick-transmitted human pathogens of global public health importance. Advances in structural biology techniques have contributed substantially to our current understanding of the life cycle of these small enveloped RNA viruses and led to deep insights into details of virus assembly, maturation and cell entry. In addition to large-scale conformational changes and oligomeric rearrangements of envelope proteins during these processes, there is increasing evidence that smaller-scale protein dynamics (referred to as virus "breathing") can confer extra flexibility to these viruses for the fine-tuning of their interactions with the immune system and possibly with cellular factors they encounter in their complex ecological cycles in arthropod and vertebrate hosts. In this review, we discuss how work with tick-borne encephalitis virus has extended our view on flavivirus breathing, leading to the identification of a novel mechanism of antibody-mediated infection enhancement and demonstrating breathing intermediates of the envelope protein in the process of membrane fusion. These data are discussed in the context of other flaviviruses and the perspective of a potential role of virus breathing to cope with the requirements of adaptation and replication in evolutionarily very different hosts.
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Affiliation(s)
- Karin Stiasny
- Center for VirologyMedical University of ViennaAustria
| | - Iris Medits
- Center for VirologyMedical University of ViennaAustria
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7
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Lee MF, Wu YS, Poh CL. Molecular Mechanisms of Antiviral Agents against Dengue Virus. Viruses 2023; 15:v15030705. [PMID: 36992414 PMCID: PMC10056858 DOI: 10.3390/v15030705] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/07/2023] [Accepted: 03/07/2023] [Indexed: 03/11/2023] Open
Abstract
Dengue is a major global health threat causing 390 million dengue infections and 25,000 deaths annually. The lack of efficacy of the licensed Dengvaxia vaccine and the absence of a clinically approved antiviral against dengue virus (DENV) drive the urgent demand for the development of novel anti-DENV therapeutics. Various antiviral agents have been developed and investigated for their anti-DENV activities. This review discusses the mechanisms of action employed by various antiviral agents against DENV. The development of host-directed antivirals targeting host receptors and direct-acting antivirals targeting DENV structural and non-structural proteins are reviewed. In addition, the development of antivirals that target different stages during post-infection such as viral replication, viral maturation, and viral assembly are reviewed. Antiviral agents designed based on these molecular mechanisms of action could lead to the discovery and development of novel anti-DENV therapeutics for the treatment of dengue infections. Evaluations of combinations of antiviral drugs with different mechanisms of action could also lead to the development of synergistic drug combinations for the treatment of dengue at any stage of the infection.
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8
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Naresh P, Rajesh Kumar R, Vishwas HN, Rajagopal G, Prabha T, Jubie S. Larvicidal and histopathological efficacy of cinnamic acid analogues: a novel strategy to reduce the dengue vector competence. RSC Adv 2022; 12:9793-9814. [PMID: 35424920 PMCID: PMC8961603 DOI: 10.1039/d1ra09466a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/14/2022] [Indexed: 11/21/2022] Open
Abstract
Background: A novel strategy such as conjugation of amino, Schiff's bases, and thiadiazole moieties to the cinnamic acid nucleus has been adopted in this study to discover new molecules that target the dengue envelope protein (DENVE). Aim: Among the different domains of dengue virus envelope protein (PDB ID 1OKE), we have selected a ligand-binding domain for our structure-based drug design. The designed compounds have also been docked against DENVE protein. Methodology: Based on the in silico results and synthetic feasibility, three different schemes were used to synthesize twenty-three novel cinnamic acid derivatives. Sci-finder ascertained their novelty. The synthesized derivatives were consistent with their assigned spectra. The compounds were further evaluated for their larvicidal activity and histopathological analysis. Multiple linear regression analysis was performed to derive the QSAR model, which was further evaluated internally and externally for the prediction of activity. Results and discussion: Four compounds, namely CA 2, CA 14, ACA 4, and CATD 2, effectively showed larvicidal activity after 24, 48, and 72 h exposure; particularly, compound CA2 showed potent larvicidal activity with LC50 of 82.15 μg ml-1, 65.34 μg ml-1, and 38.68 μg ml-1, respectively, whereas intermittent stages, causes of abscess in the gut, and siphon regions were observed through histopathological studies. Conclusion: Our study identified some novel chemical scaffolds as effective DENVE inhibitors with efficacious anticipated pharmacokinetic profiles, which can be modified further.
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Affiliation(s)
- P Naresh
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research Ooty Tamilnadu India https://www.jssuni.edu.in/
| | - R Rajesh Kumar
- Department of Pharmaceutical Biotechnology, JSS College of Pharmacy, JSS Academy of Higher Education and Research Ooty Tamilnadu India
| | - H N Vishwas
- Department of Pharmacy Practice, JSS College of Pharmacy, JSS Academy of Higher Education and Research Ooty Tamilnadu India
| | - Gopalan Rajagopal
- Postgraduate and Research Department of Zoology, Ayya Nadar Janaki Ammal College Sivakasi Tamilnadu India
| | - T Prabha
- Department of Pharmaceutical Chemistry, Nandha College of Pharmacy, Affiliated to The Tamilnadu Dr MGR Medical University-Chennai Erode Tamilnadu India
| | - S Jubie
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research Ooty Tamilnadu India https://www.jssuni.edu.in/
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9
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Viral Membrane Fusion Proteins and RNA Sorting Mechanisms for the Molecular Delivery by Exosomes. Cells 2021; 10:cells10113043. [PMID: 34831268 PMCID: PMC8622164 DOI: 10.3390/cells10113043] [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: 10/06/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 11/21/2022] Open
Abstract
The advancement of precision medicine critically depends on the robustness and specificity of the carriers used for the targeted delivery of effector molecules in the human body. Numerous nanocarriers have been explored in vivo, to ensure the precise delivery of molecular cargos via tissue-specific targeting, including the endocrine part of the pancreas, thyroid, and adrenal glands. However, even after reaching the target organ, the cargo-carrying vehicle needs to enter the cell and then escape lysosomal destruction. Most artificial nanocarriers suffer from intrinsic limitations that prevent them from completing the specific delivery of the cargo. In this respect, extracellular vesicles (EVs) seem to be the natural tool for payload delivery due to their versatility and low toxicity. However, EV-mediated delivery is not selective and is usually short-ranged. By inserting the viral membrane fusion proteins into exosomes, it is possible to increase the efficiency of membrane recognition and also ease the process of membrane fusion. This review describes the molecular details of the viral-assisted interaction between the target cell and EVs. We also discuss the question of the usability of viral fusion proteins in developing extracellular vesicle-based nanocarriers with a higher efficacy of payload delivery. Finally, this review specifically highlights the role of Gag and RNA binding proteins in RNA sorting into EVs.
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10
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Medits I, Vaney M, Rouvinski A, Rey M, Chamot‐Rooke J, Rey FA, Heinz FX, Stiasny K. Extensive flavivirus E trimer breathing accompanies stem zippering of the post-fusion hairpin. EMBO Rep 2020; 21:e50069. [PMID: 32484292 PMCID: PMC7403712 DOI: 10.15252/embr.202050069] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/23/2022] Open
Abstract
Flaviviruses enter cells by fusion with endosomal membranes through a rearrangement of the envelope protein E, a class II membrane fusion protein, into fusogenic trimers. The rod-like E subunits bend into "hairpins" to bring the fusion loops next to the C-terminal transmembrane (TM) anchors, with the TM-proximal "stem" element zippering the E trimer to force apposition of the membranes. The structure of the complete class II trimeric hairpin is known for phleboviruses but not for flaviviruses, for which the stem is only partially resolved. Here, we performed comparative analyses of E-protein trimers from the tick-borne encephalitis flavivirus with sequential stem truncations. Our thermostability and antibody-binding data suggest that the stem "zipper" ends at a characteristic flavivirus conserved sequence (CS) that cloaks the fusion loops, with the downstream segment not contributing to trimer stability. We further identified a highly dynamic behavior of E trimers C-terminally truncated upstream the CS, which, unlike fully stem-zippered trimers, undergo rapid deuterium exchange at the trimer interface. These results thus identify important "breathing" intermediates in the E-protein-driven membrane fusion process.
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Affiliation(s)
- Iris Medits
- Center for VirologyMedical University of ViennaViennaAustria
| | | | - Alexander Rouvinski
- Unité de Virologie StructuraleInstitut PasteurCNRS UMR 3569 VirologieParisFrance
- Present address:
Department of Microbiology and Molecular GeneticsInstitute for Medical Research Israel‐CanadaThe Kuvin Center for the Study of Infectious and Tropical DiseasesThe Hebrew University of JerusalemJerusalemIsrael
| | - Martial Rey
- Unité de Spectrométrie de Masse pour la BiologieInstitut PasteurCNRS USR 2000ParisFrance
| | - Julia Chamot‐Rooke
- Unité de Spectrométrie de Masse pour la BiologieInstitut PasteurCNRS USR 2000ParisFrance
| | - Felix A Rey
- Unité de Virologie StructuraleInstitut PasteurCNRS UMR 3569 VirologieParisFrance
| | - Franz X Heinz
- Center for VirologyMedical University of ViennaViennaAustria
| | - Karin Stiasny
- Center for VirologyMedical University of ViennaViennaAustria
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11
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Anasir MI, Ramanathan B, Poh CL. Structure-Based Design of Antivirals against Envelope Glycoprotein of Dengue Virus. Viruses 2020; 12:v12040367. [PMID: 32225021 PMCID: PMC7232406 DOI: 10.3390/v12040367] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 02/06/2023] Open
Abstract
Dengue virus (DENV) presents a significant threat to global public health with more than 500,000 hospitalizations and 25,000 deaths annually. Currently, there is no clinically approved antiviral drug to treat DENV infection. The envelope (E) glycoprotein of DENV is a promising target for drug discovery as the E protein is important for viral attachment and fusion. Understanding the structure and function of DENV E protein has led to the exploration of structure-based drug discovery of antiviral compounds and peptides against DENV infections. This review summarizes the structural information of the DENV E protein with regards to DENV attachment and fusion. The information enables the development of antiviral agents through structure-based approaches. In addition, this review compares the potency of antivirals targeting the E protein with the antivirals targeting DENV multifunctional enzymes, repurposed drugs and clinically approved antiviral drugs. None of the current DENV antiviral candidates possess potency similar to the approved antiviral drugs which indicates that more efforts and resources must be invested before an effective DENV drug materializes.
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Affiliation(s)
- Mohd Ishtiaq Anasir
- Center for Virus and Vaccine Research, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia;
| | - Babu Ramanathan
- Department of Biological Sciences, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia;
| | - Chit Laa Poh
- Center for Virus and Vaccine Research, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia;
- Correspondence: ; Tel.: +60-3-7491-8622; Fax: +60-3-5635-8633
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12
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Davis EH, Barrett ADT. Structure-Function of the Yellow Fever Virus Envelope Protein: Analysis of Antibody Epitopes. Viral Immunol 2019; 33:12-21. [PMID: 31682201 DOI: 10.1089/vim.2019.0107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Yellow fever virus (YFV) is the prototype member of the genus Flavivirus, which contains more than 60 positive-sense, single-stranded RNA viruses, many of which are considered public health threats. YF disease is controlled by a live attenuated vaccine, 17D, which was generated empirically through serial passage of the wild-type (WT) strain Asibi in chicken tissue. The vaccine, which has been used for over 80 years, is considered to be one of the safest and most effective live attenuated vaccines. It has been shown that the humoral immune response is essential to a positive disease outcome during infection. As such, the neutralizing antibody response and its correlation to long-term protection are a critical measure of 17D efficacy. The primary target of these antibodies is the envelope (E) protein, which is the major component of the virion. Monoclonal antibodies can distinguish WT strain Asibi and vaccine strain 17D by many different measures, including physical binding, hemagglutination inhibition, neutralization, and passive protection. This makes the WT-vaccine pair ideal candidates to study the structure-function relationship of the E protein in the attenuation and immunogenicity of flaviviruses. In this study, we provide an overview of structure-function of YFV E protein and its involvement in protective immunity.
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Affiliation(s)
- Emily H Davis
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas
| | - Alan D T Barrett
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas
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13
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Niu X, Zhao L, Qu L, Yao Z, Zhang F, Yan Q, Zhang S, Liang R, Chen P, Luo J, Xu W, Lv H, Liu X, Lei H, Yi C, Li P, Wang Q, Wang Y, Yu L, Zhang X, Bryan LA, Davidson E, Doranz JB, Feng L, Pan W, Zhang F, Chen L. Convalescent patient-derived monoclonal antibodies targeting different epitopes of E protein confer protection against Zika virus in a neonatal mouse model. Emerg Microbes Infect 2019; 8:749-759. [PMID: 31130109 PMCID: PMC6542155 DOI: 10.1080/22221751.2019.1614885] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Zika virus (ZIKV) outbreak and its link to microcephaly triggered a public health concern. To examine antibody response in a patient infected with ZIKV, we used single-cell PCR to clone 31 heavy and light chain-paired monoclonal antibodies (mAbs) that bind to ZIKV envelope (E) proteins isolated from memory B cells of a ZIKV-infected patient. Three mAbs (7B3, 1C11, and 6A6) that showed the most potent and broad neutralization activities against the African, Asian, and American strains were selected for further analysis. mAb 7B3 showed an IC50 value of 11.6 ng/mL against the circulating American strain GZ02. Epitope mapping revealed that mAbs 7B3 and 1C11 targeted residue K394 of the lateral ridge (LR) epitope of the EDIII domain, but 7B3 has a broader LR epitope footprint and recognizes residues T335, G337, E370, and N371 as well. mAb 6A6 recognized residues D67, K118, and K251 of the EDII domain. Interestingly, although the patient was seronegative for DENV infection, mAb 1C11, originating from the VH3-23 and VK1-5 germline pair, neutralized both ZIKV and DENV1. Administration of the mAbs 7B3, 1C11, and 6A6 protected neonatal SCID mice infected with a lethal dose of ZIKV. This study provides potential therapeutic antibody candidates and insights into the antibody response after ZIKV infection.
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Affiliation(s)
- Xuefeng Niu
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Lingzhai Zhao
- b Guangzhou 8th People's Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Linbing Qu
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Zhipeng Yao
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China.,d Institute of Physical Science and Information Technology , Anhui University , Hefei , People's Republic of China
| | - Fan Zhang
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China.,d Institute of Physical Science and Information Technology , Anhui University , Hefei , People's Republic of China
| | - Qihong Yan
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China.,e University of Chinese Academy of Science , Beijing , People's Republic of China
| | - Shengnan Zhang
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Renshan Liang
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Peihai Chen
- d Institute of Physical Science and Information Technology , Anhui University , Hefei , People's Republic of China
| | - Jia Luo
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Wei Xu
- b Guangzhou 8th People's Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Huibin Lv
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Xinglong Liu
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Hui Lei
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Changhua Yi
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Pingchao Li
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Qian Wang
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Yang Wang
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Lei Yu
- b Guangzhou 8th People's Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Xiaoyan Zhang
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China.,e University of Chinese Academy of Science , Beijing , People's Republic of China
| | | | | | | | - Liqiang Feng
- c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
| | - Weiqi Pan
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Fuchun Zhang
- b Guangzhou 8th People's Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China
| | - Ling Chen
- a State Key Lab of Respiratory Disease , the First Affiliated Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China.,b Guangzhou 8th People's Hospital of Guangzhou Medical University , Guangzhou , People's Republic of China.,c Guangdong Laboratory of Computational Biomedicine, Chinese Academy of Sciences , Guangzhou Institutes of Biomedicine and Health , Guangzhou , People's Republic of China
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14
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Hu Y, Sun L. Systematic Analysis of Structure Similarity between Zika Virus and Other Flaviviruses. ACS Infect Dis 2019; 5:1070-1080. [PMID: 31038920 DOI: 10.1021/acsinfecdis.9b00047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Zika virus (ZIKV) infection has caused global concern because of its association with fetal microcephaly and serious neurological complications in adults since 2016. Currently, no specific anti-ZIKV therapy is available to control ZIKV infection. During the last couple of years, the intensive investigation of ZIKV structure has provided significant information for structure-based vaccine and drug design. In this review, we summarized the research progress on the structures of ZIKV and its component proteins. We analyzed the structure identity and the differences between ZIKV and other flaviviruses. This information is crucial to guiding structure-based anti-ZIKV inhibitors and vaccine discovery.
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Affiliation(s)
- Yuxia Hu
- The Fifth People’s Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, 131 Dongan Road, Shanghai 20032, China
| | - Lei Sun
- The Fifth People’s Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, 131 Dongan Road, Shanghai 20032, China
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15
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Early Events in Japanese Encephalitis Virus Infection: Viral Entry. Pathogens 2018; 7:pathogens7030068. [PMID: 30104482 PMCID: PMC6161159 DOI: 10.3390/pathogens7030068] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/31/2018] [Accepted: 08/06/2018] [Indexed: 12/15/2022] Open
Abstract
Japanese encephalitis virus (JEV), a mosquito-borne zoonotic flavivirus, is an enveloped positive-strand RNA virus that can cause a spectrum of clinical manifestations, ranging from mild febrile illness to severe neuroinvasive disease. Today, several killed and live vaccines are available in different parts of the globe for use in humans to prevent JEV-induced diseases, yet no antivirals are available to treat JEV-associated diseases. Despite the progress made in vaccine research and development, JEV is still a major public health problem in southern, eastern, and southeastern Asia, as well as northern Oceania, with the potential to become an emerging global pathogen. In viral replication, the entry of JEV into the cell is the first step in a cascade of complex interactions between the virus and target cells that is required for the initiation, dissemination, and maintenance of infection. Because this step determines cell/tissue tropism and pathogenesis, it is a promising target for antiviral therapy. JEV entry is mediated by the viral glycoprotein E, which binds virions to the cell surface (attachment), delivers them to endosomes (endocytosis), and catalyzes the fusion between the viral and endosomal membranes (membrane fusion), followed by the release of the viral genome into the cytoplasm (uncoating). In this multistep process, a collection of host factors are involved. In this review, we summarize the current knowledge on the viral and cellular components involved in JEV entry into host cells, with an emphasis on the initial virus-host cell interactions on the cell surface.
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16
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Qadir A, Riaz M, Saeed M, Shahzad-Ul-Hussan S. Potential targets for therapeutic intervention and structure based vaccine design against Zika virus. Eur J Med Chem 2018; 156:444-460. [PMID: 30015077 DOI: 10.1016/j.ejmech.2018.07.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/28/2018] [Accepted: 07/06/2018] [Indexed: 01/01/2023]
Abstract
Continuously increasing number of reports of Zika virus (ZIKV) infections and associated severe clinical manifestations, including autoimmune abnormalities and neurological disorders such as neonatal microcephaly and Guillain-Barré syndrome have created alarming situation in various countries. To date, no specific antiviral therapy or vaccine is available against ZIKV. This review provides a comprehensive insight into the potential therapeutic targets and describes viral epitopes of broadly neutralizing antibodies (bNAbs) in vaccine design perspective. Interactions between ZIKV envelope glycoprotein E and cellular receptors mediate the viral fusion and entry to the target cell. Blocking these interactions by targeting cellular receptors or viral structural proteins mediating these interactions or viral surface glycans can inhibit viral entry to the cell. Similarly, different non-structural proteins of ZIKV and un-translated regions (UTRs) of its RNA play essential roles in viral replication cycle and potentiate for therapeutic interventions. Structure based vaccine design requires identity and structural description of the epitopes of bNAbs. We have described different conserved bNAb epitopes present in the ZIKV envelope as potential targets for structure based vaccine design. This review also highlights successes, unanswered questions and future perspectives in relation to therapeutic and vaccine development against ZIKV.
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Affiliation(s)
- Amina Qadir
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan
| | - Muhammad Riaz
- Department of Chemistry, University of Azad Jammu & Kashmir, Muzaffarabad, Pakistan
| | - Muhammad Saeed
- Department of Chemistry and Chemical Engineering, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan.
| | - Syed Shahzad-Ul-Hussan
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan.
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17
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Pulkkinen LIA, Butcher SJ, Anastasina M. Tick-Borne Encephalitis Virus: A Structural View. Viruses 2018; 10:v10070350. [PMID: 29958443 PMCID: PMC6071267 DOI: 10.3390/v10070350] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 06/25/2018] [Accepted: 06/27/2018] [Indexed: 12/11/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a growing health concern. It causes a severe disease that can lead to permanent neurological complications or death and the incidence of TBEV infections is constantly rising. Our understanding of TBEV’s structure lags behind that of other flaviviruses, but has advanced recently with the publication of a high-resolution structure of the TBEV virion. The gaps in our knowledge include: aspects of receptor binding, replication and virus assembly. Furthermore, TBEV has mostly been studied in mammalian systems, even though the virus’ interaction with its tick hosts is a central part of its life cycle. Elucidating these aspects of TBEV biology are crucial for the development of TBEV antivirals, as well as the improvement of diagnostics. In this review, we summarise the current structural knowledge on TBEV, bringing attention to the current gaps in our understanding, and propose further research that is needed to truly understand the structural-functional relationship of the virus and its hosts.
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Affiliation(s)
- Lauri I A Pulkkinen
- HiLIFE-Institute of Biotechnology, University of Helsinki, 00790 Helsinki, Finland.
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00790 Helsinki, Finland.
| | - Sarah J Butcher
- HiLIFE-Institute of Biotechnology, University of Helsinki, 00790 Helsinki, Finland.
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00790 Helsinki, Finland.
| | - Maria Anastasina
- HiLIFE-Institute of Biotechnology, University of Helsinki, 00790 Helsinki, Finland.
- Faculty of Biological and Environmental Sciences, University of Helsinki, 00790 Helsinki, Finland.
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18
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Abou-Hamdan A, Belot L, Albertini A, Gaudin Y. Monomeric Intermediates Formed by Vesiculovirus Glycoprotein during Its Low-pH-induced Structural Transition. J Mol Biol 2018; 430:1685-1695. [PMID: 29678555 PMCID: PMC7126088 DOI: 10.1016/j.jmb.2018.04.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/06/2018] [Accepted: 04/10/2018] [Indexed: 01/26/2023]
Abstract
•Vesiculovirus G is the prototype of class III viral fusion glycoproteins. •The structures of both G pre- and post-fusion conformation have been determined. •The structure of monomeric intermediates reveals the pathway of the transition. •A fusion-loop-exposing antiparallel dimer may initiate the fusion process. •Those data challenge the current model proposed for viral membrane fusion.
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Affiliation(s)
- Abbas Abou-Hamdan
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Laura Belot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Aurélie Albertini
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Yves Gaudin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France.
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19
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Cedillo-Barrón L, García-Cordero J, Shrivastava G, Carrillo-Halfon S, León-Juárez M, Bustos Arriaga J, León Valenzuela P, Gutiérrez Castañeda B. The Role of Flaviviral Proteins in the Induction of Innate Immunity. Subcell Biochem 2018; 88:407-442. [PMID: 29900506 DOI: 10.1007/978-981-10-8456-0_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Flaviviruses are positive, single-stranded, enveloped cytoplasmic sense RNA viruses that cause a variety of important diseases worldwide. Among them, Zika virus, West Nile virus, Japanese encephalitis virus, and Dengue virus have the potential to cause severe disease. Extensive studies have been performed to elucidate the structure and replication strategies of flaviviruses, and current studies are aiming to unravel the complex molecular interactions between the virus and host during the very early stages of infection. The outcomes of viral infection and rapid establishment of the antiviral state, depends on viral detection by pathogen recognition receptors and rapid initiation of signalling cascades to induce an effective innate immune response. Extracellular and intracellular pathogen recognition receptors play a crucial role in detecting flavivirus infection and inducing a robust antiviral response. One of the main hallmarks of flaviviral nonstructural proteins is their multiple strategies to antagonise the interferon system. In this chapter, we summarize the molecular characteristics of flaviviral proteins and discuss how viral proteins target different components of the interferon signalling pathway by blocking phosphorylation, enhancing degradation, and downregulating the expression of major components of the Janus kinase/signal transducer and activator of transcription pathway. We also discuss how the interactions of viral proteins with host proteins facilitate viral pathogenesis. Due to the lack of antivirals or prophylactic treatments for many flaviviral infections, it is necessary to fully elucidate how these viruses disrupt cellular processes to influence pathogenesis and disease outcomes.
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Affiliation(s)
- L Cedillo-Barrón
- Departamento de Biomedicina Molecular, CINVESTAV IPN, México, D.F, Mexico.
| | - J García-Cordero
- Departamento de Biomedicina Molecular, CINVESTAV IPN, México, D.F, Mexico
| | - G Shrivastava
- Departamento de Biomedicina Molecular, CINVESTAV IPN, México, D.F, Mexico
| | - S Carrillo-Halfon
- Departamento de Biomedicina Molecular, CINVESTAV IPN, México, D.F, Mexico
| | - M León-Juárez
- Department of Immunobiochemistry, National Institute of Perinatology, México City, Mexico
| | - J Bustos Arriaga
- Unidad de Biomedicina. Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autonoma de México, Edo. de México, Mexico
| | - Pc León Valenzuela
- Departamento de Biomedicina Molecular, CINVESTAV IPN, México, D.F, Mexico
| | - B Gutiérrez Castañeda
- Immunology Department UMF Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autonoma de México, Edo. de México, Mexico
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20
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Subramaniyan V, Venkatachalam R, Srinivasan P, Palani M. In silico prediction of monovalent and chimeric tetravalent vaccines for prevention and treatment of dengue fever. J Biomed Res 2017; 32:222. [PMID: 29497025 PMCID: PMC6265401 DOI: 10.7555/jbr.31.20160109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/27/2017] [Indexed: 11/22/2022] Open
Abstract
Reverse vaccinology method was used to predict the monovalent peptide vaccine candidate to produce antibodies for therapeutic purpose and to predict tetravalent vaccine candidate to act as a common vaccine to cover all the fever dengue virus serotypes. Envelope (E)-proteins of DENV-1-4 serotypes were used for vaccine prediction using NCBI, Uniprot/Swissprot, Swiss-prot viewer, VaxiJen V2.0, TMHMM, BCPREDS, Propred-1, Propred and MHC Pred,. E-proteins of DENV-1-4 serotypes were identified as antigen from which T cell epitopes, through B cell epitopes, were predicted to act as peptide vaccine candidates. Each selected T cell epitope of E-protein was confirmed to act as vaccine and to induce complementary antibody against particular serotype of dengue virus. Chimeric tetravalent vaccine was formed by the conjugation of four vaccines, each from four dengue serotypes to act as a common vaccine candidate for all the four dengue serotypes. It can be justifiably concluded that the monovalent 9-mer T cell epitope for each DENV serotypes can be used to produce specific antibody agaomst dengue virus and a chimeric common tetravalent vaccine candidate to yield a comparative vaccine to cover any of the four dengue virus serotype. This vaccine is expected to act as highly immunogenic against preventing dengue fever.
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Affiliation(s)
- Vijayakumar Subramaniyan
- Computational Phytochemistry Laboratory P.G. and Research Department of Botany and Microbiology, A.V.V.M. Sri Pushpam College (Autonomous), Poondi, Thanjavur district, Tamil Nadu 613503, India
| | - Ramesh Venkatachalam
- Computational Phytochemistry Laboratory P.G. and Research Department of Botany and Microbiology, A.V.V.M. Sri Pushpam College (Autonomous), Poondi, Thanjavur district, Tamil Nadu 613503, India
| | - Prabhu Srinivasan
- Computational Phytochemistry Laboratory P.G. and Research Department of Botany and Microbiology, A.V.V.M. Sri Pushpam College (Autonomous), Poondi, Thanjavur district, Tamil Nadu 613503, India
| | - Manogar Palani
- Computational Phytochemistry Laboratory P.G. and Research Department of Botany and Microbiology, A.V.V.M. Sri Pushpam College (Autonomous), Poondi, Thanjavur district, Tamil Nadu 613503, India
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21
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Haslwanter D, Blaas D, Heinz FX, Stiasny K. A novel mechanism of antibody-mediated enhancement of flavivirus infection. PLoS Pathog 2017; 13:e1006643. [PMID: 28915259 PMCID: PMC5617232 DOI: 10.1371/journal.ppat.1006643] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/27/2017] [Accepted: 09/11/2017] [Indexed: 12/12/2022] Open
Abstract
Antibody-dependent enhancement of viral infection is a well-described phenomenon that is based on the cellular uptake of infectious virus-antibody complexes following their interaction with Fcγ receptors expressed on myeloid cells. Here we describe a novel mechanism of antibody-mediated enhancement of infection by a flavivirus (tick-borne encephalitis virus) in transformed and primary human cells, which is independent of the presence of Fcγ receptors. Using chemical cross-linking and immunoassays, we demonstrate that the monoclonal antibody (mab) A5, recognizing an epitope at the interface of the dimeric envelope protein E, causes dimer dissociation and leads to the exposure of the fusion loop (FL). Under normal conditions of infection, this process is triggered only after virus uptake by the acidic pH in endosomes, resulting in the initiation of membrane fusion through the interaction of the FL with the endosomal membrane. Analysis of virus binding and cellular infection, together with inhibition by the FL-specific mab 4G2, indicated that the FL, exposed after mab A5- induced dimer-dissociation, mediated attachment of the virus to the plasma membrane also at neutral pH, thereby increasing viral infectivity. Since antibody-induced enhancement of binding was not only observed with cells but also with liposomes, it is likely that increased infection was due to FL-lipid interactions and not to interactions with cellular plasma membrane proteins. The novel mechanism of antibody-induced infection enhancement adds a new facet to the complexity of antibody interactions with flaviviruses and may have implications for yet unresolved effects of polyclonal antibody responses on biological properties of these viruses.
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Affiliation(s)
| | - Dieter Blaas
- Max F. Perutz Laboratories, Department for Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Franz X. Heinz
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Karin Stiasny
- Center for Virology, Medical University of Vienna, Vienna, Austria
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22
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Sakuragi M, Suzuki R, Hidari KI, Yamanaka T, Nakano H. Synthesis of p-methoxyphenyl sulfated β-GalNAc derivatives with inhibitory activity against Japanese encephalitis virus. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2016-0921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The N-acetylgalactosamine (GalNAc) residue is one of the units of chondroitin sulfate E (CS-E) which has been reported to have inhibitory activity against Japanese encephalitis virus (JEV). Herein, we describe the synthesis of a series of p-methoxyphenyl β-GalNAc derivatives with a sulfate group at 3-, 4-, and/or 6-positions using an efficient route through a common synthetic intermediate. By measuring the inhibition activity of these compounds that bear different numbers and positions of sulfate groups, the effect of position specificity for interaction with the virus was determined. From these results, GalNAc6S and GalNAc4S6S derivatives inhibited JEV infections well; we suggest the 6-O-sulfate group is necessary for selective recognition by the virus.
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Affiliation(s)
- Miho Sakuragi
- Department of Chemistry , Aichi University of Education , Igaya, Kariya, Aichi 448-8542 , Japan
| | - Ryoko Suzuki
- Department of Chemistry , Aichi University of Education , Igaya, Kariya, Aichi 448-8542 , Japan
| | - Kazuya I.P.J. Hidari
- Junior College Division , University of Aizu, Ikki-machi , Aizuwakamatsu, Fukushima 965-8570 , Japan
| | - Takashi Yamanaka
- Epizootic Research Center, Equine Research Institute, Japan Racing Association , 1400-4 Shiba, Shimotsuke , Tochigi 329-0412 , Japan
| | - Hirofumi Nakano
- Department of Chemistry , Aichi University of Education , Igaya, Kariya, Aichi 448-8542 , Japan
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23
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Sharma N, Murali A, Singh SK, Giri R. Epigallocatechin gallate, an active green tea compound inhibits the Zika virus entry into host cells via binding the envelope protein. Int J Biol Macromol 2017; 104:1046-1054. [PMID: 28666829 DOI: 10.1016/j.ijbiomac.2017.06.105] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 06/25/2017] [Accepted: 06/26/2017] [Indexed: 01/08/2023]
Abstract
Emerging infections of Zika virus (ZIKV) are associated with serious consequences like microcephaly and Guillain-Barré syndrome. It leads to a situation of global health emergency and demand an intensive research investigation to develop safe and effective therapeutics. Various efforts have been made to reduce the pathological pressure of ZIKV, but no effective drug has been introduced against ZIKV infections. A recent study has reported the inhibition of ZIKV entry into the host cells by an active green tea ingredient, Epigallocatechin Gallate (EGCG) in Vero E6cells. The effect of EGCG seems remarkable but lacking the information of the mechanism of action. In this study, we have investigated the binding site (Site1) of EGCG on envelope protein and provided the insights into various interactions of molecule with the binding site using molecular docking studies. Further, using molecular dynamics approaches we proposed the possible associated mechanism of inhibition of ZIKV entry by EGCG molecule. EGCG has found to interact with several residues and providing stability to the protein conformations up to 50ns simulations.
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Affiliation(s)
- Nitin Sharma
- Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India
| | - Aarthy Murali
- Department of Bioinformatics, Computer Aided Drug Design and Molecular Modeling Lab, Alagappa University,Science Block, Karaikudi-630003, Tamilnadu, India
| | - Sanjeev Kumar Singh
- Department of Bioinformatics, Computer Aided Drug Design and Molecular Modeling Lab, Alagappa University,Science Block, Karaikudi-630003, Tamilnadu, India.
| | - Rajanish Giri
- Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, India.
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24
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Yun SI, Lee YM. Zika virus: An emerging flavivirus. J Microbiol 2017; 55:204-219. [PMID: 28243937 DOI: 10.1007/s12275-017-7063-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 02/15/2017] [Indexed: 01/18/2023]
Abstract
Zika virus (ZIKV) is a previously little-known flavivirus closely related to Japanese encephalitis, West Nile, dengue, and yellow fever viruses, all of which are primarily transmitted by blood-sucking mosquitoes. Since its discovery in Uganda in 1947, ZIKV has continued to expand its geographic range, from equatorial Africa and Asia to the Pacific Islands, then further afield to South and Central America and the Caribbean. Currently, ZIKV is actively circulating not only in much of Latin America and its neighbors but also in parts of the Pacific Islands and Southeast Asia. Although ZIKV infection generally causes only mild symptoms in some infected individuals, it is associated with a range of neuroimmunological disorders, including Guillain-Barré syndrome, meningoencephalitis, and myelitis. Recently, maternal ZIKV infection during pregnancy has been linked to neonatal malformations, resulting in various degrees of congenital abnormalities, microcephaly, and even abortion. Despite its emergence as an important public health problem, however, little is known about ZIKV biology, and neither vaccine nor drug is available to control ZIKV infection. This article provides a brief introduction to ZIKV with a major emphasis on its molecular virology, in order to help facilitate the development of diagnostics, therapeutics, and vaccines.
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, 84322-4815, USA
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, 84322-4815, USA. .,Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, 84322-4815, USA.
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25
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Bauve EL, Vernon BC, Ye D, Rogers DM, Siegrist CM, Carson BD, Rempe SB, Zheng A, Kielian M, Shreve AP, Kent MS. Method for measuring the unbinding energy of strongly-bound membrane-associated proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2753-2762. [PMID: 27425029 DOI: 10.1016/j.bbamem.2016.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/23/2016] [Accepted: 07/12/2016] [Indexed: 12/30/2022]
Abstract
We describe a new method to measure the activation energy for unbinding (enthalpy ΔH*u and free energy ΔG*u) of a strongly-bound membrane-associated protein from a lipid membrane. It is based on measuring the rate of release of a liposome-bound protein during centrifugation on a sucrose gradient as a function of time and temperature. The method is used to determine ΔH*u and ΔG*u for the soluble dengue virus envelope protein (sE) strongly bound to 80:20 POPC:POPG liposomes at pH5.5. ΔH*u is determined from the Arrhenius equation whereas ΔG*u is determined by fitting the data to a model based on mean first passage time for escape from a potential well. The binding free energy ΔGb of sE was also measured at the same pH for the initial, predominantly reversible, phase of binding to a 70:30 PC:PG lipid bilayer. The unbinding free energy (20±3kcal/mol, 20% PG) was found to be roughly three times the binding energy per monomer, (7.8±0.3kcal/mol for 30% PG, or est. 7.0kcal/mol for 20% PG). This is consistent with data showing that free sE is a monomer at pH5.5, but assembles into trimers after associating with membranes. This new method to determine unbinding energies should be useful to understand better the complex interactions of integral monotopic proteins and strongly-bound peripheral membrane proteins with lipid membranes.
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Affiliation(s)
| | | | - Dongmei Ye
- Sandia National Laboratories, Albuquerque, NM 87185
| | - David M Rogers
- Department of Chemistry, University of South Florida, 4202 E Fowler Av, Tampa, FL 33620
| | | | | | | | - Aihua Zheng
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
| | - Andrew P Shreve
- Center for Biomedical Engineering and Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM 87131
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Calvert AE, Dixon KL, Piper J, Bennett SL, Thibodeaux BA, Barrett ADT, Roehrig JT, Blair CD. A humanized monoclonal antibody neutralizes yellow fever virus strain 17D-204 in vitro but does not protect a mouse model from disease. Antiviral Res 2016; 131:92-9. [PMID: 27126613 PMCID: PMC4899248 DOI: 10.1016/j.antiviral.2016.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/20/2016] [Accepted: 04/23/2016] [Indexed: 01/29/2023]
Abstract
The yellow fever virus (YFV) vaccine 17D-204 is considered safe and effective, yet rare severe adverse events (SAEs), some resulting in death, have been documented following vaccination. Individuals exhibiting post-vaccinal SAEs are ideal candidates for antiviral monoclonal antibody (MAb) therapy; the time until appearance of clinical signs post-exposure is usually short and patients are quickly hospitalized. We previously developed a murine-human chimeric monoclonal antibody (cMAb), 2C9-cIgG, reactive with both virulent YFV and 17D-204, and demonstrated its ability to prevent and treat YF disease in both AG129 mouse and hamster models of infection. To counteract possible selection of 17D-204 variants that escape neutralization by treatment with a single MAb (2C9-cIgG), we developed a second cMAb, 864-cIgG, for use in combination with 2C9-cIgG in post-vaccinal therapy. MAb 864-cIgG recognizes/neutralizes only YFV 17D-204 vaccine substrain and binds to domain III (DIII) of the viral envelope protein, which is different from the YFV type-specific binding site of 2C9-cIgG in DII. Although it neutralized 17D-204 in vitro, administration of 864-cIgG had no protective capacity in the interferon receptor-deficient AG129 mouse model of 17D-204 infection. The data presented here show that although DIII-specific 864-cIgG neutralizes virus infectivity in vitro, it does not have the ability to abrogate disease in vivo. Therefore, combination of 864-cIgG with 2C9-cIgG for treatment of YF vaccination SAEs does not appear to provide an improvement on 2C9-cIgG therapy alone.
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MESH Headings
- Animals
- Antibodies, Monoclonal, Humanized/immunology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Antibodies, Neutralizing/immunology
- Antibodies, Neutralizing/therapeutic use
- Antibodies, Viral/immunology
- Antibodies, Viral/therapeutic use
- Disease Models, Animal
- Humans
- Immunization, Passive
- Mice
- Neutralization Tests
- Receptors, Interferon/deficiency
- Receptors, Interferon/genetics
- Viral Envelope Proteins/immunology
- Viral Envelope Proteins/metabolism
- Yellow Fever/immunology
- Yellow Fever/prevention & control
- Yellow Fever/therapy
- Yellow Fever Vaccine/adverse effects
- Yellow Fever Vaccine/immunology
- Yellow fever virus/immunology
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Affiliation(s)
- Amanda E Calvert
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Kandice L Dixon
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Joseph Piper
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Susan L Bennett
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Brett A Thibodeaux
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Alan D T Barrett
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas-Medical Branch, Galveston, TX, 77555, USA
| | - John T Roehrig
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Carol D Blair
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA.
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Mir A, Ismatullah H, Rauf S, Niazi UH. Identification of bioflavonoid as fusion inhibitor of dengue virus using molecular docking approach. INFORMATICS IN MEDICINE UNLOCKED 2016. [DOI: 10.1016/j.imu.2016.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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28
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Chaudhury S, Ripoll DR, Wallqvist A. Structure-based pKa prediction provides a thermodynamic basis for the role of histidines in pH-induced conformational transitions in dengue virus. Biochem Biophys Rep 2015; 4:375-385. [PMID: 29124227 PMCID: PMC5669449 DOI: 10.1016/j.bbrep.2015.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 11/21/2022] Open
Abstract
pH-induced conformational changes in dengue virus (DENV) are critical to its ability to infect host cells. The envelope protein heterodimers that make up the viral envelope shift from a dimer to a trimer conformation at low-pH during membrane fusion. Previous studies have suggested that the ionization of histidine residues at low-pH is central to this pH-induced conformational change. We sought out to use molecular modeling with structure-based pKa prediction to provide a quantitative basis for the role of histidines in pH-induced conformational changes and identify which histidine residues were primarily responsible for this transition. We combined existing crystallographic and cryo-electron microscopy data to construct templates of the dimer and trimer conformations for the mature and immature virus. We then generated homology models for the four DENV serotypes and carried out structure-based pKa prediction using Rosetta. Our results showed that the pKa values of a subset of conserved histidines in DENV successfully capture the thermodynamics necessary to drive pH-induced conformational changes during fusion. Here, we identified the structural determinants underlying these pKa values and compare our findings with previous experimental results. Structure-based pKa prediction for histidines in dengue virus was carried out. Conserved histidine residues drive pH-dependent conformation changes. The mature dimer form of the envelop protein is destabilized at low-pH.
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Affiliation(s)
- Sidhartha Chaudhury
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
| | - Daniel R Ripoll
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
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29
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Johnson PTJ, de Roode JC, Fenton A. Why infectious disease research needs community ecology. Science 2015; 349:1259504. [PMID: 26339035 DOI: 10.1126/science.1259504] [Citation(s) in RCA: 256] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Infectious diseases often emerge from interactions among multiple species and across nested levels of biological organization. Threats as diverse as Ebola virus, human malaria, and bat white-nose syndrome illustrate the need for a mechanistic understanding of the ecological interactions underlying emerging infections. We describe how recent advances in community ecology can be adopted to address contemporary challenges in disease research. These analytical tools can identify the factors governing complex assemblages of multiple hosts, parasites, and vectors, and reveal how processes link across scales from individual hosts to regions. They can also determine the drivers of heterogeneities among individuals, species, and regions to aid targeting of control strategies. We provide examples where these principles have enhanced disease management and illustrate how they can be further extended.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
| | | | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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30
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Yun SI, Song BH, Kim JK, Yun GN, Lee EY, Li L, Kuhn RJ, Rossmann MG, Morrey JD, Lee YM. A molecularly cloned, live-attenuated japanese encephalitis vaccine SA14-14-2 virus: a conserved single amino acid in the ij Hairpin of the Viral E glycoprotein determines neurovirulence in mice. PLoS Pathog 2014; 10:e1004290. [PMID: 25077483 PMCID: PMC4117607 DOI: 10.1371/journal.ppat.1004290] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 06/18/2014] [Indexed: 01/12/2023] Open
Abstract
Japanese encephalitis virus (JEV), a mosquito-borne flavivirus that causes fatal neurological disease in humans, is one of the most important emerging pathogens of public health significance. JEV represents the JE serogroup, which also includes West Nile, Murray Valley encephalitis, and St. Louis encephalitis viruses. Within this serogroup, JEV is a vaccine-preventable pathogen, but the molecular basis of its neurovirulence remains unknown. Here, we constructed an infectious cDNA of the most widely used live-attenuated JE vaccine, SA14-14-2, and rescued from the cDNA a molecularly cloned virus, SA14-14-2MCV, which displayed in vitro growth properties and in vivo attenuation phenotypes identical to those of its parent, SA14-14-2. To elucidate the molecular mechanism of neurovirulence, we selected three independent, highly neurovirulent variants (LD50, <1.5 PFU) from SA14-14-2MCV (LD50, >1.5×105 PFU) by serial intracerebral passage in mice. Complete genome sequence comparison revealed a total of eight point mutations, with a common single G1708→A substitution replacing a Gly with Glu at position 244 of the viral E glycoprotein. Using our infectious SA14-14-2 cDNA technology, we showed that this single Gly-to-Glu change at E-244 is sufficient to confer lethal neurovirulence in mice, including rapid development of viral spread and tissue inflammation in the central nervous system. Comprehensive site-directed mutagenesis of E-244, coupled with homology-based structure modeling, demonstrated a novel essential regulatory role in JEV neurovirulence for E-244, within the ij hairpin of the E dimerization domain. In both mouse and human neuronal cells, we further showed that the E-244 mutation altered JEV infectivity in vitro, in direct correlation with the level of neurovirulence in vivo, but had no significant impact on viral RNA replication. Our results provide a crucial step toward developing novel therapeutic and preventive strategies against JEV and possibly other encephalitic flaviviruses.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Western
- Cloning, Molecular
- Encephalitis Virus, Japanese/genetics
- Encephalitis Virus, Japanese/immunology
- Encephalitis, Japanese/genetics
- Encephalitis, Japanese/immunology
- Encephalitis, Japanese/virology
- Female
- Flow Cytometry
- Humans
- Immunoenzyme Techniques
- Japanese Encephalitis Vaccines/genetics
- Japanese Encephalitis Vaccines/immunology
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred ICR
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation/genetics
- Nervous System/virology
- Protein Conformation
- Sequence Homology, Amino Acid
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Viral Envelope Proteins/chemistry
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
- Virulence/genetics
- Virus Replication
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Byung-Hak Song
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Jin-Kyoung Kim
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Gil-Nam Yun
- Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Eun-Young Lee
- Department of Anatomy, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Long Li
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Richard J. Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Michael G. Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - John D. Morrey
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research, College of Agriculture and Applied Sciences, Utah State University, Logan, Utah, United States of America
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31
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Abstract
Enveloped viruses infect host cells by a membrane fusion reaction that takes place at the cell surface or in intracellular compartments following virus uptake. Fusion is mediated by the membrane interactions and conformational changes of specialized virus envelope proteins termed membrane fusion proteins. This article discusses the structures and refolding reactions of specific fusion proteins and the methods for their study and highlights outstanding questions in the field.
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Affiliation(s)
- Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461;
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32
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Abe T, Sando A, Teraoka F, Otsubo T, Morita K, Tokiwa H, Ikeda K, Suzuki T, Hidari KIPJ. Computational design of a sulfoglucuronide derivative fitting into a hydrophobic pocket of dengue virus E protein. Biochem Biophys Res Commun 2014; 449:32-7. [PMID: 24796674 DOI: 10.1016/j.bbrc.2014.04.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/25/2014] [Indexed: 10/25/2022]
Abstract
We performed first-principles calculations based on the ab initio fragment molecular orbital method on dengue virus envelope protein with a hydrophobic ligand, octyl-β-D-glucose to develop an entry inhibitor. As several polar amino acid residues are present at the edge of the pocket, the glucose moiety was chemically modified with hydrophilic groups. Introduction of both sulfated and carboxylated groups on glucose enhanced not only binding affinity to the protein but also inhibition of dengue virus entry. Octyl-2-O-sulfo β-D-glucuronic acid may serve as a molecular probe to study the dengue virus entry process.
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Affiliation(s)
- Tomoko Abe
- Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka-shi, Shizuoka 422-8526, Japan
| | - Ayumi Sando
- Department of Chemistry, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Fumiteru Teraoka
- Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1 Hirokoshingai, Kure-shi, Hiroshima 737-0112, Japan
| | - Tadamune Otsubo
- Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1 Hirokoshingai, Kure-shi, Hiroshima 737-0112, Japan
| | - Kouichi Morita
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Hiroaki Tokiwa
- Department of Chemistry, Faculty of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Kiyoshi Ikeda
- Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1 Hirokoshingai, Kure-shi, Hiroshima 737-0112, Japan.
| | - Takashi Suzuki
- Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka-shi, Shizuoka 422-8526, Japan
| | - Kazuya I P J Hidari
- Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka-shi, Shizuoka 422-8526, Japan.
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33
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Relating structure to evolution in class II viral membrane fusion proteins. Curr Opin Virol 2014; 5:34-41. [PMID: 24525225 PMCID: PMC4028412 DOI: 10.1016/j.coviro.2014.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 01/17/2014] [Indexed: 12/25/2022]
Abstract
Until 2013, class II proteins had only been found in flaviviruses and alphaviruses. A class II fusion protein was recently discovered in the unrelated phlebovirus genus. Within the same family as alphaviruses, rubella virus has a divergent class II fold. Pestiviruses, although they are Flaviviridae, have fusion proteins from a novel class. Viral class II proteins may originate from cellular class II fusion protein ancestors.
Enveloped viruses must fuse their lipid membrane to a cellular membrane to deliver the viral genome into the cytoplasm for replication. Viral envelope proteins catalyze this critical membrane fusion event. They fall into at least three distinct structural classes. Class II fusion proteins have a conserved three-domain architecture and are found in many important viral pathogens. Until 2013, class II proteins had only been found in flaviviruses and alphaviruses. However, in 2013 a class II fusion protein was discovered in the unrelated phlebovirus genus, and two unexpectedly divergent envelope proteins were identified in families that also contain prototypical class II proteins. The structural relationships of newly identified class II proteins, reviewed herein, shift the paradigm for how these proteins evolved.
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34
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Mechanism for maturation-related reorganization of flavivirus glycoproteins. J Struct Biol 2013; 185:27-31. [PMID: 24252771 DOI: 10.1016/j.jsb.2013.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 11/04/2013] [Accepted: 11/08/2013] [Indexed: 01/03/2023]
Abstract
Flaviviruses, such as dengue, West Nile, and yellow fever viruses, assemble as fusion-incompetent particles and subsequently undergo a large reorganization of their glycoprotein envelope resulting in formation of mature infectious virions. Here we used a combination of three-dimensional cryo-electron tomography and two-dimensional image analysis to study pleomorphic maturation intermediates of dengue virus 2. Icosahedral symmetries of immature and mature regions within one particle were mismatched relative to each other. Furthermore, the orientation of the two regions relative to each other differed among particles. Therefore, there cannot be a specific pathway determining the maturation of all particles. Instead, the region with mature structure expands when glycoproteins on its boundary acquire suitable orientation and conformation to allow them to become a stable part of the mature region. This type of maturation is possible because the envelope glycoproteins are anchored to the phospholipid bilayer that is a part of flavivirus virions and are thus restricted to movement on the two-dimensional surface of the particle. Therefore, compounds that limit movement of the glycoproteins within the virus membrane might be used as inhibitors of flavivirus maturation.
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35
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Yun SI, Lee YM. Japanese encephalitis: the virus and vaccines. Hum Vaccin Immunother 2013; 10:263-79. [PMID: 24161909 PMCID: PMC4185882 DOI: 10.4161/hv.26902] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/14/2013] [Accepted: 10/22/2013] [Indexed: 12/11/2022] Open
Abstract
Japanese encephalitis (JE) is an infectious disease of the central nervous system caused by Japanese encephalitis virus (JEV), a zoonotic mosquito-borne flavivirus. JEV is prevalent in much of Asia and the Western Pacific, with over 4 billion people living at risk of infection. In the absence of antiviral intervention, vaccination is the only strategy to develop long-term sustainable protection against JEV infection. Over the past half-century, a mouse brain-derived inactivated vaccine has been used internationally for active immunization. To date, however, JEV is still a clinically important, emerging, and re-emerging human pathogen of global significance. In recent years, production of the mouse brain-derived vaccine has been discontinued, but 3 new cell culture-derived vaccines are available in various parts of the world. Here we review current aspects of JEV biology, summarize the 4 types of JEV vaccine, and discuss the potential of an infectious JEV cDNA technology for future vaccine development.
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Affiliation(s)
- Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research; College of Agriculture and Applied Sciences; Utah State University; Logan, UT USA
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences; Utah Science Technology and Research; College of Agriculture and Applied Sciences; Utah State University; Logan, UT USA
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36
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Fuzo CA, Degrève L. The pH dependence of flavivirus envelope protein structure: insights from molecular dynamics simulations. J Biomol Struct Dyn 2013; 32:1563-74. [DOI: 10.1080/07391102.2013.827132] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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37
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The membrane-proximal "stem" region increases the stability of the flavivirus E protein postfusion trimer and modulates its structure. J Virol 2013; 87:9933-8. [PMID: 23804648 DOI: 10.1128/jvi.01283-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The flavivirus fusion protein E contains a "stem" region which is hypothesized to be crucial for driving fusion. This sequence element connects the ectodomain to the membrane anchor, and its structure in the trimeric postfusion conformation is still poorly defined. Using E trimers of tick-borne encephalitis virus with stem truncations of different lengths, we show that the N-terminal part of the stem increases trimer stability and also modulates the trimer structure outside the stem interaction site.
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38
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Recent advances in DENV receptors. ScientificWorldJournal 2013; 2013:684690. [PMID: 23737723 PMCID: PMC3655683 DOI: 10.1155/2013/684690] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/03/2013] [Indexed: 01/12/2023] Open
Abstract
Dengue is an old disease caused by the mosquito-borne dengue viruses (DENVs), which have four antigenically distinct serotypes (DENV1-4). Infection by any of them can cause dengue fever (DF) and/or a more serious disease, that is, dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). In recent decades, incidence of dengue disease has increased 30-fold, putting a third to half of the world's population living in dengue-endemic areas at high infection risk. However, the pathogenesis of the disease is still poorly understood. The virus binding with its host cell is not only a first and critical step in their replication cycle but also a key factor for the pathogenicity. In recent years, there have been significant advances in understanding interactions of DENVs with their target cells such as dendritic cells (DC), macrophages, endothelial cells, and hepatocytes. Although DENVs reportedly attach to a variety of receptors on these cells, consensus DENV receptors have not been defined. In this review, we summarize receptors for DENVs on different cells identified in recent years.
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39
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Dengue structure differs at the temperatures of its human and mosquito hosts. Proc Natl Acad Sci U S A 2013; 110:6795-9. [PMID: 23569243 DOI: 10.1073/pnas.1304300110] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report on a conformational transition of dengue virus when changing the temperature from that present in its mosquito vectors to that of its human host. Using cryoelectron microscopy, we show that although the virus has a smooth surface, a diameter of ∼500 Å, and little exposed membrane at room temperature, the virions have a bumpy appearance with a diameter of ∼550 Å and some exposed membrane at 37 °C. The bumpy structure at 37 °C was found to be similar to the previously predicted structure of an intermediate between the smooth mature and fusogenic forms. As humans have a body temperature of 37 °C, the bumpy form of the virus would be the form present in humans. Thus, optimal dengue virus vaccines should induce antibodies that preferentially recognize epitopes exposed on the bumpy form of the virus.
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40
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Baquero E, Albertini AA, Vachette P, Lepault J, Bressanelli S, Gaudin Y. Intermediate conformations during viral fusion glycoprotein structural transition. Curr Opin Virol 2013; 3:143-50. [PMID: 23562213 PMCID: PMC7172239 DOI: 10.1016/j.coviro.2013.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/26/2013] [Accepted: 03/13/2013] [Indexed: 11/29/2022]
Abstract
Three classes of fusion glycoproteins have been hitherto identified. Structures of their pre-fusion and post-fusion states have revealed a huge conformational change. Intermediate structures during the structural transition have been recently characterized. Published data are consistent with the existence of a ‘pre-hairpin’ intermediate.
Entry of enveloped viruses into cells requires the fusion of viral and cellular membranes, driven by conformational changes in viral glycoproteins. Three different classes of viral fusion proteins have been hitherto identified based on common structural elements. Crystal structures have provided static pictures of pre-fusion and post-fusion conformations of these proteins and have revealed the dramatic reorganization of the molecules, but the transition pathway remains elusive. In this review, we will focus on recent data aiming to characterize intermediate structures during the conformational change. All these data support the existence of a pre-hairpin intermediate, but its oligomeric status is still a matter of debate.
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Affiliation(s)
- Eduard Baquero
- Centre de Recherche de Gif, Laboratoire de Virologie Moléculaire et Structurale, CNRS (UPR 3296), 91198 Gif sur Yvette Cedex, France
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41
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Carbohydrate-related inhibitors of dengue virus entry. Viruses 2013; 5:605-18. [PMID: 23389466 PMCID: PMC3640517 DOI: 10.3390/v5020605] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 01/12/2023] Open
Abstract
Dengue virus (DENV), which is transmitted by Aedes mosquitoes, causes fever and hemorrhagic disorders in humans. The virus entry process mediated through host receptor molecule(s) is crucial for virus propagation and the pathological progression of dengue disease. Therefore, elucidation of the molecular mechanisms underlying virus entry is essential for an understanding of dengue pathology and for the development of effective new anti-dengue agents. DENV binds to its receptor molecules mediated through a viral envelope (E) protein, followed by incorporation of the virus-receptor complex inside cells. The fusion between incorporated virus particles and host endosome membrane under acidic conditions is mediated through the function of DENV E protein. Carbohydrate molecules, such as sulfated glycosaminoglycans (GAG) and glycosphingolipids, and carbohydrate-recognition proteins, termed lectins, inhibit virus entry. This review focuses on carbohydrate-derived entry inhibitors, and also introduces functionally related compounds with similar inhibitory mechanisms against DENV entry.
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Heinz FX, Stiasny K. Flaviviruses and flavivirus vaccines. Vaccine 2012; 30:4301-6. [PMID: 22682286 DOI: 10.1016/j.vaccine.2011.09.114] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 09/16/2011] [Accepted: 09/23/2011] [Indexed: 12/28/2022]
Abstract
Several human-pathogenic flaviviruses (including yellow fever, dengue, Japanese encephalitis, West Nile and tick-borne encephalitis viruses) have a significant public health impact in different parts of the world and the potential of emerging in previously non-endemic regions. For some viruses, the structure of the most important immunogen, the envelope protein E, has been determined to atomic resolution by X-ray crystallography, and the architecture of virus particles has been resolved by cryo-electron microscopy. Through the combination of structural and immunological investigations, we now have a detailed understanding of the mechanisms of virus neutralization and antibody-dependent enhancement (ADE) of infectivity at a molecular level. The latter phenomenon has been proposed to play an important role in the immunopathology of severe forms of dengue virus infections (hemorrhagic dengue fever and dengue shock syndrome) and is therefore of special relevance in the context of dengue vaccines. Effective human vaccines are in use for the prophylaxis of yellow fever (live attenuated), Japanese encephalitis (live attenuated and inactivated whole virus), and tick-borne encephalitis (inactivated whole virus). Although dengue is the most important flavivirus with respect to global disease incidence, the development and use of vaccines has been hampered so far by the theoretical risk of vaccine-related adverse events such as immune enhancement of infection and the requirement to induce a long-lasting protective immune response against all four dengue serotypes simultaneously. Currently, several kinds of dengue vaccines are in development, but only one of these candidates (a chimeric dengue-yellow fever live attenuated vaccine) has reached the stage of phase 3 clinical trials.
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Affiliation(s)
- Franz X Heinz
- Department of Virology, Medical University of Vienna, Kinderspitalgasse 15, 1095 Vienna, Austria.
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3-O-sulfated glucuronide derivative as a potential anti-dengue virus agent. Biochem Biophys Res Commun 2012; 424:573-8. [DOI: 10.1016/j.bbrc.2012.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 07/02/2012] [Indexed: 11/23/2022]
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Abstract
Dengue virus is an arthropod-borne virus transmitted by Aedes mosquitoes. Dengue virus causes fever and hemorrhagic disorders in humans and non-human primates. Direct interaction of the virus introduced by a mosquito bite with host receptor molecule(s) is crucial for virus propagation and the pathological progression of dengue diseases. Therefore, elucidation of the molecular mechanisms underlying the interaction between dengue virus and its receptor(s) in both humans and mosquitoes is essential for an understanding of dengue pathology. In addition, understanding the molecular mechanism(s) of virus entry is crucial for the development of effective new therapies to treat dengue patients. Binding of dengue virus to its receptor molecules is mediated through a viral envelope glycoprotein, termed E protein. We present a summary and describe the structures, binding properties, and pathological relevance of dengue virus receptor molecules proposed to date. In mammalian cells, there are many candidate molecules that may act as receptors, such as sulfated glycosaminoglycans (GAGs), lectins that recognize carbohydrates, glycosphingolipid (GSL), proteins with chaperone activity, laminin-binding proteins, and other uncharacterized proteins. There are also several lines of evidence for receptor molecules such as GSLs, proteins with chaperone activity, laminin-binding proteins, and other uncharacterized proteins in mosquito cells and organs. This review focuses on several molecules involved in carbohydrate-dependent binding of the virus.
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Affiliation(s)
- Kazuya I P J Hidari
- Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, and Global COE Program for Innovation in Human Health Sciences, 52-1 Yada, Suruga-ku, Shizuoka-shi, Shizuoka 422-8526, Japan
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Abstract
The current model of flavivirus membrane fusion is based on atomic structures of truncated forms of the viral fusion protein E in its dimeric prefusion and trimeric postfusion conformations. These structures lack the two transmembrane domains (TMDs) of E as well as the so-called stem, believed to be involved in an intra- and intermolecular zippering reaction within the E trimer during the fusion process. In order to gain experimental evidence for the functional role of the stem in flavivirus membrane fusion, we performed a mutagenesis study with recombinant subviral particles (RSPs) of tick-borne encephalitis virus, which have fusion properties similar to those of whole infectious virions and are an established model for viral fusion. Mutations were introduced into the stem as well as that part of E predicted to interact with the stem during zippering, and the effect of these mutations was analyzed with respect to fusion peptide interactions with target cells, E protein trimerization, trimer stability, and membrane fusion in an in vitro liposome fusion assay. Our data provide evidence for a molecular interaction between a conserved phenylalanine at the N-terminal end of the stem and a pocket in domain II of E, which appears to be essential for the positioning of the stem in an orientation that allows zippering and the formation of a structure in which the TMDs can interact as required for efficient fusion.
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Bryksa BC, Bhaumik P, Magracheva E, De Moura DC, Kurylowicz M, Zdanov A, Dutcher JR, Wlodawer A, Yada RY. Structure and mechanism of the saposin-like domain of a plant aspartic protease. J Biol Chem 2011; 286:28265-75. [PMID: 21676875 DOI: 10.1074/jbc.m111.252619] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many plant aspartic proteases contain an additional sequence of ~100 amino acids termed the plant-specific insert, which is involved in host defense and vacuolar targeting. Similar to all saposin-like proteins, the plant-specific insert functions via protein-membrane interactions; however, the structural basis for such interactions has not been studied, and the nature of plant-specific insert-mediated membrane disruption has not been characterized. In the present study, the crystal structure of the saposin-like domain of potato aspartic protease was resolved at a resolution of 1.9 Å, revealing an open V-shaped configuration similar to the open structure of human saposin C. Notably, vesicle disruption activity followed Michaelis-Menten-like kinetics, a finding not previously reported for saposin-like proteins including plant-specific inserts. Circular dichroism data suggested that secondary structure was pH-dependent in a fashion similar to influenza A hemagglutinin fusion peptide. Membrane effects characterized by atomic force microscopy and light scattering indicated bilayer solubilization as well as fusogenic activity. Taken together, the present study is the first report to elucidate the membrane interaction mechanism of plant saposin-like domains whereby pH-dependent membrane interactions resulted in bilayer fusogenic activity that probably arose from a viral type pH-dependent helix-kink-helix motif at the plant-specific insert N terminus.
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Affiliation(s)
- Brian C Bryksa
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Butrapet S, Childers T, Moss KJ, Erb SM, Luy BE, Calvert AE, Blair CD, Roehrig JT, Huang CYH. Amino acid changes within the E protein hinge region that affect dengue virus type 2 infectivity and fusion. Virology 2011; 413:118-27. [PMID: 21353281 DOI: 10.1016/j.virol.2011.01.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 12/12/2010] [Accepted: 01/24/2011] [Indexed: 10/18/2022]
Abstract
Fifteen mutant dengue viruses were engineered and used to identify AAs in the molecular hinge of the envelope protein that are critical to viral infection. Substitutions at Q52, A54, or E133 reduced infectivity in mammalian cells and altered the pH threshold of fusion. Mutations at F193, G266, I270, or G281 affected viral replication in mammalian and mosquito cells, but only I270W had reduced fusion activity. T280Y affected the pH threshold for fusion and reduced replication in C6/36 cells. Three different mutations at L135 were lethal in mammalian cells. Among them, L135G abrogated fusion and reduced replication in C6/36 cells, but only slightly reduced the mosquito infection rate. Conversely, L135W replicated well in C6/36 cells, but had the lowest mosquito infection rate. Possible interactions between hinge residues 52 and 277, or among 53, 135, 170, 186, 265, and 276 required for hinge function were discovered by sequence analysis to identify compensatory mutations.
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Affiliation(s)
- Siritorn Butrapet
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
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Martín-Acebes MA, Saiz JC. A West Nile virus mutant with increased resistance to acid-induced inactivation. J Gen Virol 2011; 92:831-40. [PMID: 21228127 DOI: 10.1099/vir.0.027185-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
West Nile virus (WNV) is a mosquito-borne flavivirus responsible for epidemics of febrile illness, meningitis, encephalitis and flaccid paralysis. WNV gains entry into host cells through endocytosis. The acid pH inside endosomes triggers rapid conformational rearrangements of the flavivirus envelope (E) glycoprotein that result in fusion of the endosomal membrane with the virion envelope. Conformational rearrangements of the E glycoprotein can be induced by acid exposure in solution in the absence of target membranes, thus causing a loss of infectivity. Following a genetic approach to study this process, a WNV mutant with increased resistance to acid-induced inactivation was isolated and its complete genome was sequenced. A single amino acid substitution, T70I, in the E glycoprotein was found to be responsible for the increased acid resistance, which was linked to an increase in the sensitivity of infection to the chemical rise of endosomal pH, suggesting that the mutant required a more acid pH inside the endosomes for fusion. No alterations in viral infection kinetics, plaque size or induced mortality rates in mice of the mutant were noted. However, by means of virus competition assays, a reduction in viral fitness under standard culture conditions was observed for the mutant. These results provide new evidence of the adaptive flexibility to environmental factors--pH variation in this case--of WNV populations. Implications of the T70I replacement on the E glycoprotein structure-function relationship are discussed.
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Affiliation(s)
- Miguel A Martín-Acebes
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28040 Madrid, Spain
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Abstract
This chapter discusses the structure and working of viral fusion machinery. The entry of enveloped viruses into cells requires the fusion of viral and cellular membranes, driven by conformational changes in viral glycoproteins. Structural studies have defined three classes of viral membrane fusion proteins. Despite their different structural organizations, all seem to have a common mechanism of action that generates the same lipid organizations during the fusion pathway. The entry of enveloped viruses into host cells requires binding of the virus to one or more receptors present at the cell surface, followed by fusion of the viral envelope with a cellular membrane. These steps are mediated by virally encoded glycoproteins that promote both receptor recognition and membrane fusion. The first crystal structure of a viral fusion protein ectodomain that has been determined is that of influenza virus hemagglutinin (HA) in its prefusion conformation. The structures of viral fusion glycoproteins, of which the conformational change is triggered at low pH, has allowed the identification of amino acid residues that play the role of pH-sensitive molecular switches.
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Kaufmann B, Rossmann MG. Molecular mechanisms involved in the early steps of flavivirus cell entry. Microbes Infect 2010; 13:1-9. [PMID: 20869460 DOI: 10.1016/j.micinf.2010.09.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 08/31/2010] [Accepted: 09/01/2010] [Indexed: 12/31/2022]
Abstract
Flaviviruses enter their host cells by receptor-mediated endocytosis, a well-orchestrated process of receptor recognition, penetration and uncoating. Recent findings on these early steps in the life cycle of flaviviruses are the focus of this review.
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Affiliation(s)
- Bärbel Kaufmann
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA
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