1
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Corliss L, Holliday M, Lennemann NJ. Dual-fluorescent reporter for live-cell imaging of the ER during DENV infection. Front Cell Infect Microbiol 2022; 12:1042735. [PMID: 36389173 PMCID: PMC9640912 DOI: 10.3389/fcimb.2022.1042735] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/11/2022] [Indexed: 08/25/2023] Open
Abstract
Infection by flaviviruses leads to dramatic remodeling of the endoplasmic reticulum (ER). Viral replication occurs within virus-induced vesicular invaginations in the ER membrane. A hallmark of flavivirus infection is expansion of the ER membrane which can be observed at specific time points post infection. However, this process has not been effectively visualized in living cells throughout the course of infection at the single cell resolution. In this study, we developed a plasmid-based reporter system to monitor flavivirus infection and simultaneous virus-induced manipulation of single cells throughout the course of infection in real-time. This system requires viral protease cleavage to release an ER-anchored fluorescent protein infection reporter that is fused to a nuclear localization signal (NLS). This proteolytic cleavage allows for the translocation of the infection reporter signal to the nucleus while an ER-specific fluorescent marker remains localized in the lumen. Thus, the construct allows for the visualization of virus-dependent changes to the ER throughout the course of infection. In this study, we show that our reporter was efficiently cleaved upon the expression of multiple flavivirus proteases, including dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV). We also found that the DENV protease-dependent cleavage of our ER-anchored reporter exhibited more stringent cleavage sequence specificity than what has previously been shown with biochemical assays. Using this system for long term time-lapse imaging of living cells infected with DENV, we observed nuclear translocation of the reporter signal beginning approximately 8 hours post-infection, which continued to increase throughout the time course. Interestingly, we found that increased reporter signal translocation correlated with increased ER signal intensity, suggesting a positive association between DENV infection and ER expansion in a time-dependent manner. Overall, this report demonstrates that the FlavER platform provides a useful tool for monitoring flavivirus infection and simultaneously observing virus-dependent changes to the host cell ER, allowing for study of the temporal nature of virus-host interactions.
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Affiliation(s)
| | | | - Nicholas J. Lennemann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
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2
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Caldwell HS, Pata JD, Ciota AT. The Role of the Flavivirus Replicase in Viral Diversity and Adaptation. Viruses 2022; 14:1076. [PMID: 35632818 PMCID: PMC9143365 DOI: 10.3390/v14051076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 02/04/2023] Open
Abstract
Flaviviruses include several emerging and re-emerging arboviruses which cause millions of infections each year. Although relatively well-studied, much remains unknown regarding the mechanisms and means by which these viruses readily alternate and adapt to different hosts and environments. Here, we review a subset of the different aspects of flaviviral biology which impact host switching and viral fitness. These include the mechanism of replication and structural biology of the NS3 and NS5 proteins, which reproduce the viral genome; rates of mutation resulting from this replication and the role of mutational frequency in viral fitness; and the theory of quasispecies evolution and how it contributes to our understanding of genetic and phenotypic plasticity.
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Affiliation(s)
- Haley S. Caldwell
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
| | - Janice D. Pata
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Alexander T. Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
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3
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Assembly-defective Tembusu virus ectopically expressing capsid protein is an approach for live-attenuated flavivirus vaccine development. NPJ Vaccines 2022; 7:51. [PMID: 35550523 PMCID: PMC9098475 DOI: 10.1038/s41541-022-00468-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 03/17/2022] [Indexed: 11/08/2022] Open
Abstract
Live-attenuated vaccines (LAVs) represent a promising approach for flavivirus vaccine development. In the present study, we demonstrated a method for generating flavivirus LAVs based on breaking spatially and temporally regulated C-prM cleavage to disturb the viral assembly process, using an avian flavivirus (Tembusu virus) as the model. Using reverse genetics technology, we successfully generated two recombinant viruses (CQW1-IRES-mC and CQW1-MINI-mC) with bicistronic genomic RNA in which native capsid genes were deleted and instead expressed in the 3'UTR under the control of an internal ribosome entry site (IRES) or minimum IRES. Both viruses showed a significantly attenuated phenotype in vitro due to impaired viral assembly, and the engineered mutations were genetically stable in vitro within ten passages. Importantly, their virulence was also highly attenuated in ducklings and suckling mice and did not cause any overt clinical symptoms or mortality. In addition, a single dose of immunization with any of these mutant viruses could completely protect ducklings from a lethal challenge, and no viremia was detected after immunization and challenge, even though the viruses induced a relatively moderate immune response in terms of the T-lymphocytes proliferative response and the level of neutralization antibodies compared with that obtained with the wild-type virus. Besides, a recombinant virus ectopically expressing the prM-E protein was also generated in the present study, but this virus was too attenuated with severely decreased proliferation. Our results indicated that the use of a recombinant flavivirus that ectopically expresses structural proteins could be an effective and universal method for flavivirus LAVs development.
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4
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Lücke AC, vom Hemdt A, Wieseler J, Fischer C, Feldmann M, Rothenfusser S, Drexler JF, Kümmerer BM. High-Throughput Platform for Detection of Neutralizing Antibodies Using Flavivirus Reporter Replicon Particles. Viruses 2022; 14:v14020346. [PMID: 35215941 PMCID: PMC8880525 DOI: 10.3390/v14020346] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/01/2022] [Accepted: 02/03/2022] [Indexed: 11/16/2022] Open
Abstract
Flavivirus outbreaks require fast and reliable diagnostics that can be easily adapted to newly emerging and re-emerging flaviviruses. Due to the serological cross-reactivity among flavivirus antibodies, neutralization tests (NT) are considered the gold standard for sero-diagnostics. Here, we first established wild-type single-round infectious virus replicon particles (VRPs) by packaging a yellow fever virus (YFV) replicon expressing Gaussia luciferase (Gluc) with YFV structural proteins in trans using a double subgenomic Sindbis virus (SINV) replicon. The latter expressed the YFV envelope proteins prME via the first SINV subgenomic promoter and the capsid protein via a second subgenomic SINV promoter. VRPs were produced upon co-electroporation of replicon and packaging RNA. Introduction of single restriction enzyme sites in the packaging construct flanking the prME sequence easily allowed to exchange the prME moiety resulting in chimeric VRPs that have the surface proteins of other flaviviruses including dengue virus 1-4, Zika virus, West Nile virus, and tick-borne encephalitis virus. Besides comparing the YF-VRP based NT assay to a YF reporter virus NT assay, we analyzed the neutralization efficiencies of different human anti-flavivirus sera or a monoclonal antibody against all established VRPs. The assays were performed in a 96-well high-throughput format setting with Gluc as readout in comparison to classical plaque reduction NTs indicating that the VRP-based NT assays are suitable for high-throughput analyses of neutralizing flavivirus antibodies.
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Affiliation(s)
- Arlen-Celina Lücke
- Institute of Virology, Medical Faculty, University of Bonn, 53127 Bonn, Germany; (A.-C.L.); (A.v.H.); (J.W.); (M.F.)
| | - Anja vom Hemdt
- Institute of Virology, Medical Faculty, University of Bonn, 53127 Bonn, Germany; (A.-C.L.); (A.v.H.); (J.W.); (M.F.)
| | - Janett Wieseler
- Institute of Virology, Medical Faculty, University of Bonn, 53127 Bonn, Germany; (A.-C.L.); (A.v.H.); (J.W.); (M.F.)
| | - Carlo Fischer
- Institute of Virology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universtät Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; (C.F.); (J.F.D.)
| | - Marie Feldmann
- Institute of Virology, Medical Faculty, University of Bonn, 53127 Bonn, Germany; (A.-C.L.); (A.v.H.); (J.W.); (M.F.)
| | - Simon Rothenfusser
- Division of Clinical Pharmacology, University Hospital, LMU Munich, 80337 Munich, Germany;
- Unit Clinical Pharmacology (EKliP), Helmholtz Center for Environmental Health, 80337 Munich, Germany
| | - Jan Felix Drexler
- Institute of Virology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universtät Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany; (C.F.); (J.F.D.)
- Martinovsky Institute of Medical Parasitology, Tropical and Vector-Borne Diseases, Sechenov University, 119435 Moskow, Russia
- German Center for Infection Research (DZIF), Associated Partner Site Berlin, 10117 Berlin, Germany
| | - Beate Mareike Kümmerer
- Institute of Virology, Medical Faculty, University of Bonn, 53127 Bonn, Germany; (A.-C.L.); (A.v.H.); (J.W.); (M.F.)
- German Center for Infection Research (DZIF), Associated Partner Site Bonn-Cologne, 53127 Bonn, Germany
- Correspondence:
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5
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Alzahrani N, Wu MJ, Sousa CF, Kalinina OV, Welsch C, Yi M. SPCS1-Dependent E2-p7 processing determines HCV Assembly efficiency. PLoS Pathog 2022; 18:e1010310. [PMID: 35130329 PMCID: PMC8853643 DOI: 10.1371/journal.ppat.1010310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 02/17/2022] [Accepted: 01/26/2022] [Indexed: 11/18/2022] Open
Abstract
Recent studies identified signal peptidase complex subunit 1 (SPCS1) as a proviral host factor for Flaviviridae viruses, including HCV. One of the SPCS1’s roles in flavivirus propagation was attributed to its regulation of signal peptidase complex (SPC)-mediated processing of flavivirus polyprotein, especially C-prM junction. However, whether SPCS1 also regulates any SPC-mediated processing sites within HCV polyprotein remains unclear. In this study, we determined that loss of SPCS1 specifically impairs the HCV E2-p7 processing by the SPC. We also determined that efficient separation of E2 and p7, regardless of its dependence on SPC-mediated processing, leads to SPCS1 dispensable for HCV assembly These results suggest that SPCS1 regulates HCV assembly by facilitating the SPC-mediated processing of E2-p7 precursor. Structural modeling suggests that intrinsically delayed processing of the E2-p7 is likely caused by the structural rigidity of p7 N-terminal transmembrane helix-1 (p7/TM1/helix-1), which has mostly maintained membrane-embedded conformations during molecular dynamics (MD) simulations. E2-p7-processing-impairing p7 mutations narrowed the p7/TM1/helix-1 bending angle against the membrane, resulting in closer membrane embedment of the p7/TM1/helix-1 and less access of E2-p7 junction substrate to the catalytic site of the SPC, located well above the membrane in the ER lumen. Based on these results we propose that the key mechanism of action of SPCS1 in HCV assembly is to facilitate the E2-p7 processing by enhancing the E2-p7 junction site presentation to the SPC active site. By providing evidence that SPCS1 facilitates HCV assembly by regulating SPC-mediated cleavage of E2-p7 junction, equivalent to the previously established role of this protein in C-prM junction processing in flavivirus, this study establishes the common role of SPCS1 in Flaviviridae family virus propagation as to exquisitely regulate the SPC-mediated processing of specific, suboptimal target sites.
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Affiliation(s)
- Nabeel Alzahrani
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Ming-Jhan Wu
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Carla F. Sousa
- Drug Bioinformatics Group, HIPS, HZI, Saarbrücken, Germany
| | - Olga V. Kalinina
- Drug Bioinformatics Group, HIPS, HZI, Saarbrücken, Germany
- Medical Faculty, Saarland University, Homburg, Germany
| | - Christoph Welsch
- Department of Internal Medicine 1, Goethe University Hospital, Frankfurt am Main, Germany
| | - MinKyung Yi
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- * E-mail:
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6
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Yang X, Gao GF, Liu WJ. Powassan virus: A tick borne flavivirus infecting humans. BIOSAFETY AND HEALTH 2022. [DOI: 10.1016/j.bsheal.2021.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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7
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Yu X, Shan C, Zhu Y, Ma E, Wang J, Wang P, Shi PY, Cheng G. A mutation-mediated evolutionary adaptation of Zika virus in mosquito and mammalian host. Proc Natl Acad Sci U S A 2021; 118:e2113015118. [PMID: 34620704 PMCID: PMC8545446 DOI: 10.1073/pnas.2113015118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2021] [Indexed: 01/18/2023] Open
Abstract
Zika virus (ZIKV) caused millions of infections during its rapid and expansive spread from Asia to the Americas from 2015 to 2017. Here, we compared the infectivity of ZIKV mutants with individual stable substitutions which emerged throughout the Asian ZIKV lineage and were responsible for the explosive outbreaks in the Americas. A threonine (T) to alanine (A) mutation at the 106th residue of the ZIKV capsid (C) protein facilitated the transmission by its mosquito vector, as well as infection in both human cells and immunodeficient mice. A mechanistic study showed that the T106A substitution rendered the C a preferred substrate for the NS2B-NS3 protease, thereby facilitating the maturation of structural proteins and the formation of infectious viral particles. Over a complete "mosquito-mouse-mosquito" cycle, the ZIKV C-T106A mutant showed a higher prevalence of mosquito infection than did the preepidemic strain, thus promoting ZIKV dissemination. Our results support the contribution of this evolutionary adaptation to the occasional widespread reemergence of ZIKV in nature.
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Affiliation(s)
- Xi Yu
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
- Shenzhen Bay Laboratory, Institute of Infectious Diseases, Shenzhen 518000, China
- Shenzhen Center for Disease Control and Prevention, Institute of Pathogenic Organisms, Shenzhen 518055, China
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Chao Shan
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555
| | - Yibin Zhu
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
- Shenzhen Bay Laboratory, Institute of Infectious Diseases, Shenzhen 518000, China
- Shenzhen Center for Disease Control and Prevention, Institute of Pathogenic Organisms, Shenzhen 518055, China
| | - Enhao Ma
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jinglin Wang
- Yunnan Tropical and Subtropical Animal Viral Disease Laboratory, Yunnan Animal Science and Veterinary Institute, Kunming 650224, China
| | - Penghua Wang
- Department of Immunology, School of Medicine, the University of Connecticut Health Center, Farmington, CT 06030
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555
| | - Gong Cheng
- Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
- Shenzhen Bay Laboratory, Institute of Infectious Diseases, Shenzhen 518000, China
- Shenzhen Center for Disease Control and Prevention, Institute of Pathogenic Organisms, Shenzhen 518055, China
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8
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Ruiz-Jiménez F, Pérez-Olais JH, Raymond C, King BJ, McClure CP, Urbanowicz RA, Ball JK. Challenges on the development of a pseudotyping assay for Zika glycoproteins. J Med Microbiol 2021; 70:001413. [PMID: 34499027 PMCID: PMC8697511 DOI: 10.1099/jmm.0.001413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/15/2021] [Indexed: 11/18/2022] Open
Abstract
Introduction. Zika virus (ZIKV) emerged as a public health concern on the American continent during late 2015. As the number of infected grew so did the concerns about its capability to cause long-term damage especially with the appearance of the congenital Zika syndrome (CZS). Proteins from the TAM family of receptor tyrosine kinases (RTKs) were proposed as the cellular receptors, however, due to the ability of the virus to infect a variety of cell lines different strategies to elucidate the tropism of the virus should be investigated.Hypothesis. Pseudotyping is a powerful tool to interrogate the ability of the glycoprotein (GP) to permit entry of viruses.Aim. We aimed to establish a highly tractable pseudotype model using lenti- and retro-viral backbones to investigate the entry pathway of ZIKV.Methodology. We used different glycoprotein constructs and different lenti- or retro-viral backbones, in a matrix of ratios to investigate production of proteins and functional pseudotypes.Results. Varying the ratio of backbone and glycoprotein plasmids did not yield infectious pseudotypes. Moreover, the supplementation of the ZIKV protease or the substitution of the backbone had no positive impact on the infectivity. We showed production of the proteins in producer cells implying the lack of infectious pseudotypes is due to a lack of successful glycoprotein incorporation, rather than lack of protein production.Conclusion. In line with other reports, we were unable to successfully produce infectious pseudotypes using the variety of methods described. Other strategies may be more suitable in the development of an efficient pseudotype model for ZIKV and other flaviviruses.
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Affiliation(s)
| | | | - Chidinma Raymond
- School of Life Sciences, The University of Nottingham, Nottingham, UK
| | - Barnabas J King
- School of Life Sciences, The University of Nottingham, Nottingham, UK
| | | | - Richard A. Urbanowicz
- School of Life Sciences, The University of Nottingham, Nottingham, UK
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Jonathan K. Ball
- School of Life Sciences, The University of Nottingham, Nottingham, UK
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9
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Kronenberger T, Sá Magalhães Serafim M, Kumar Tonduru A, Gonçalves Maltarollo V, Poso A. Ligand Accessibility Insights to the Dengue Virus NS3-NS2B Protease Assessed by Long-Timescale Molecular Dynamics Simulations. ChemMedChem 2021; 16:2524-2534. [PMID: 33899341 PMCID: PMC8453957 DOI: 10.1002/cmdc.202100246] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Indexed: 11/12/2022]
Abstract
Dengue is a tropical disease caused by the dengue virus (DENV), with an estimate of 300 million new cases every year. Due to the limited vaccine efficiency and absence of effective antiviral treatment, new drug candidates are urgently needed. DENV NS3-NS2B protease complex is essential for viral post-translational processing and maturation, and this enzyme has been extensively studied as a relevant drug target. Crystal structures often underestimate NS3-NS2B flexibility, whereas they can adopt different conformational states depending on the bound substrate. We conducted molecular dynamics simulations (∼30 μs) with a non- and covalently bound inhibitor to understand the conformational changes in the DENV-3 NS3-NS2B complex. Our results show that the open-closing movement of the protease exposes multiple druggable subpockets that can be investigated in later drug discovery efforts.
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Affiliation(s)
- Thales Kronenberger
- Department of Medical Oncology and PneumologyUniversity Hospital of TübingenOtfried-Müller-Strasse 1472076TübingenGermany
- School of PharmacyUniversity of Eastern FinlandKuopio70211Finland
| | - Mateus Sá Magalhães Serafim
- Departamento de MicrobiologiaUniversidade Federal de Minas Gerais (UFMG)Av. Antônio Carlos, 6627PampulhaCEP 31270-901Belo HorizonteBrazil
| | | | - Vinícius Gonçalves Maltarollo
- Departamento de Produtos FarmacêuticosUniversidade Federal de Minas Gerais (UFMG)Av. Antônio Carlos, 6627PampulhaCEP 31270-901Belo HorizonteBrazil
| | - Antti Poso
- Department of Medical Oncology and PneumologyUniversity Hospital of TübingenOtfried-Müller-Strasse 1472076TübingenGermany
- School of PharmacyUniversity of Eastern FinlandKuopio70211Finland
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10
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Xie S, Zhang H, Liang Z, Yang X, Cao R. AXL, an Important Host Factor for DENV and ZIKV Replication. Front Cell Infect Microbiol 2021; 11:575346. [PMID: 33954117 PMCID: PMC8092360 DOI: 10.3389/fcimb.2021.575346] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022] Open
Abstract
Flaviviruses, as critically important pathogens, are still major public health problems all over the world. For instance, the evolution of ZIKV led to large-scale outbreaks in the Yap island in 2007. DENV was considered by the World Health Organization (WHO) as one of the 10 threats to global health in 2019. Enveloped viruses hijack a variety of host factors to complete its replication cycle. Phosphatidylserine (PS) receptor, AXL, is considered to be a candidate receptor for flavivirus invasion. In this review, we discuss the molecular structure of ZIKV and DENV, and how they interact with AXL to successfully invade host cells. A more comprehensive understanding of the molecular mechanisms of flavivirus-AXL interaction will provide crucial insights into the virus infection process and the development of anti-flavivirus therapeutics.
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Affiliation(s)
- Shengda Xie
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Huiru Zhang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Zhenjie Liang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xingmiao Yang
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Ruibing Cao
- Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
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11
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Barnard TR, Abram QH, Lin QF, Wang AB, Sagan SM. Molecular Determinants of Flavivirus Virion Assembly. Trends Biochem Sci 2021; 46:378-390. [PMID: 33423940 DOI: 10.1016/j.tibs.2020.12.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 01/07/2023]
Abstract
Virion assembly is an important step in the life cycle of all viruses. For viruses of the Flavivirus genus, a group of enveloped positive-sense RNA viruses, the assembly step represents one of the least understood processes in the viral life cycle. While assembly is primarily driven by the viral structural proteins, recent studies suggest that several nonstructural proteins also play key roles in coordinating the assembly and packaging of the viral genome. This review focuses on describing recent advances in our understanding of flavivirus virion assembly, including the intermolecular interactions between the viral structural (capsid) and nonstructural proteins (NS2A and NS2B-NS3), host factors, as well as features of the viral genomic RNA required for efficient flavivirus virion assembly.
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Affiliation(s)
- Trisha R Barnard
- Department of Microbiology & Immunology, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Quinn H Abram
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Qi Feng Lin
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Alex B Wang
- Department of Microbiology & Immunology, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Selena M Sagan
- Department of Microbiology & Immunology, McGill University, Montreal, Quebec H3G 1Y6, Canada; Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada.
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12
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Alzahrani N, Wu MJ, Shanmugam S, Yi M. Delayed by Design: Role of Suboptimal Signal Peptidase Processing of Viral Structural Protein Precursors in Flaviviridae Virus Assembly. Viruses 2020; 12:v12101090. [PMID: 32993149 PMCID: PMC7601889 DOI: 10.3390/v12101090] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/04/2020] [Accepted: 09/24/2020] [Indexed: 02/06/2023] Open
Abstract
The Flaviviridae virus family is classified into four different genera, including flavivirus, hepacivirus, pegivirus, and pestivirus, which cause significant morbidity and mortality in humans and other mammals, including ruminants and pigs. These are enveloped, single-stranded RNA viruses sharing a similar genome organization and replication scheme with certain unique features that differentiate them. All viruses in this family express a single polyprotein that encodes structural and nonstructural proteins at the N- and C-terminal regions, respectively. In general, the host signal peptidase cleaves the structural protein junction sites, while virus-encoded proteases process the nonstructural polyprotein region. It is known that signal peptidase processing is a rapid, co-translational event. Interestingly, certain signal peptidase processing site(s) in different Flaviviridae viral structural protein precursors display suboptimal cleavage kinetics. This review focuses on the recent progress regarding the Flaviviridae virus genus-specific mechanisms to downregulate signal peptidase-mediated processing at particular viral polyprotein junction sites and the role of delayed processing at these sites in infectious virus particle assembly.
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Abstract
The flavivirus genus encompasses more than 75 unique viruses, including dengue virus which accounts for almost 390 million global infections annually. Flavivirus infection can result in a myriad of symptoms ranging from mild rash and flu-like symptoms, to severe encephalitis and even hemorrhagic fever. Efforts to combat the impact of these viruses have been hindered due to limited antiviral drug and vaccine development. However, the advancement of knowledge in the structural biology of flaviviruses over the last 25 years has produced unique perspectives for the identification of potential therapeutic targets. With particular emphasis on the assembly and maturation stages of the flavivirus life cycle, it is the goal of this review to comparatively analyze the structural similarities between flaviviruses to provide avenues for new research and innovation.
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Affiliation(s)
- Conrrad M R Nicholls
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States
| | - Madhumati Sevvana
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States
| | - Richard J Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States; Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, IN, United States.
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14
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He Y, Wang M, Chen S, Cheng A. The role of capsid in the flaviviral life cycle and perspectives for vaccine development. Vaccine 2020; 38:6872-6881. [PMID: 32950301 PMCID: PMC7495249 DOI: 10.1016/j.vaccine.2020.08.053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 02/09/2023]
Abstract
The structure and function of flaviviral capsid are very flexible. The capsid gene contains conserved RNA secondary structures. Both steps of assembly and dissociation of nucleocapsid complexes are obscure. Capsid mutant viruses are highly attenuated and immunogenic. ΔC-replicon and single-round infectious particles are promising vaccine approaches.
The arthropod-borne flaviviruses cause a series of diseases in humans and pose a significant threat to global public health. In this review, we aimed to summarize the structure of the capsid protein (CP), its relevant multiple functions in the viral life cycle and innovative vaccines targeting CP. The flaviviral CP is the smallest structural protein and forms a homodimer by antiparallel α-helixes. Its primary function is to package the genomic RNA; however, both steps of assembly and dissociation of nucleocapsid complexes (NCs) have been obscure until now; in fact, flaviviral budding is NC-free, demonstrated by the subviral particles that generally exist in flavivirus infection. In infected cells, CPs associate with lipid droplets, which possibly store CPs prior to packaging. However, the function of nuclear localization of CPs remains unknown. Moreover, introducing deletions into CPs can be used to rationally design safe and effective live-attenuated vaccines or noninfectious replicon vaccines and single-round infectious particles, the latter two representing promising approaches for innovative flaviviral vaccine development.
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Affiliation(s)
- Yu He
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
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15
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Pierson TC, Diamond MS. The continued threat of emerging flaviviruses. Nat Microbiol 2020; 5:796-812. [PMID: 32367055 DOI: 10.1038/s41564-020-0714-0] [Citation(s) in RCA: 483] [Impact Index Per Article: 120.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/27/2020] [Indexed: 12/18/2022]
Abstract
Flaviviruses are vector-borne RNA viruses that can emerge unexpectedly in human populations and cause a spectrum of potentially severe diseases including hepatitis, vascular shock syndrome, encephalitis, acute flaccid paralysis, congenital abnormalities and fetal death. This epidemiological pattern has occurred numerous times during the last 70 years, including epidemics of dengue virus and West Nile virus, and the most recent explosive epidemic of Zika virus in the Americas. Flaviviruses are now globally distributed and infect up to 400 million people annually. Of significant concern, outbreaks of other less well-characterized flaviviruses have been reported in humans and animals in different regions of the world. The potential for these viruses to sustain epidemic transmission among humans is poorly understood. In this Review, we discuss the basic biology of flaviviruses, their infectious cycles, the diseases they cause and underlying host immune responses to infection. We describe flaviviruses that represent an established ongoing threat to global health and those that have recently emerged in new populations to cause significant disease. We also provide examples of lesser-known flaviviruses that circulate in restricted areas of the world but have the potential to emerge more broadly in human populations. Finally, we discuss how an understanding of the epidemiology, biology, structure and immunity of flaviviruses can inform the rapid development of countermeasures to treat or prevent human infections as they emerge.
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Affiliation(s)
- Theodore C Pierson
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, the National Institutes of Health, Bethesda, MD, USA.
| | - Michael S Diamond
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO, USA.
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16
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Diosa-Toro M, Prasanth KR, Bradrick SS, Garcia Blanco MA. Role of RNA-binding proteins during the late stages of Flavivirus replication cycle. Virol J 2020; 17:60. [PMID: 32334603 PMCID: PMC7183730 DOI: 10.1186/s12985-020-01329-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/11/2020] [Indexed: 12/21/2022] Open
Abstract
The genus Flavivirus encompasses several worldwide-distributed arthropod-borne viruses including, dengue virus, Japanese encephalitis virus, West Nile virus, yellow fever virus, Zika virus, and tick-borne encephalitis virus. Infection with these viruses manifest with symptoms ranging from febrile illness to life- threatening hypotensive shock and encephalitis. Therefore, flaviviruses pose a great risk to public health. Currently, preventive measures are falling short to control epidemics and there are no antivirals against any Flavivirus.Flaviviruses carry a single stranded positive-sense RNA genome that plays multiple roles in infected cells: it is translated into viral proteins, used as template for genome replication, it is the precursor of the subgenomic flaviviral RNA and it is assembled into new virions. Furthermore, viral RNA genomes are also packaged into extracellular vesicles, e.g. exosomes, which represent an alternate mode of virus dissemination.Because RNA molecules are at the center of Flavivirus replication cycle, viral and host RNA-binding proteins (RBPs) are critical determinants of infection. Numerous studies have revealed the function of RBPs during Flavivirus infection, particularly at the level of RNA translation and replication. These proteins, however, are also critical participants at the late stages of the replication cycle. Here we revise the function of host RBPs and the viral proteins capsid, NS2A and NS3, during the packaging of viral RNA and the assembly of new virus particles. Furthermore, we go through the evidence pointing towards the importance of host RBPs in mediating cellular RNA export with the idea that the biogenesis of exosomes harboring Flavivirus RNA would follow an analogous pathway.
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Affiliation(s)
- Mayra Diosa-Toro
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, Singapore.
| | - K Reddisiva Prasanth
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Shelton S Bradrick
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
- Global Health, Surveillance & Diagnostics Group, MRIGlobal, Kansas City, MO, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Mariano A Garcia Blanco
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, Singapore.
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
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17
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Ramanathan HN, Zhang S, Douam F, Mar KB, Chang J, Yang PL, Schoggins JW, Ploss A, Lindenbach BD. A Sensitive Yellow Fever Virus Entry Reporter Identifies Valosin-Containing Protein (VCP/p97) as an Essential Host Factor for Flavivirus Uncoating. mBio 2020; 11:e00467-20. [PMID: 32291299 PMCID: PMC7157815 DOI: 10.1128/mbio.00467-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 01/17/2023] Open
Abstract
While the basic mechanisms of flavivirus entry and fusion are understood, little is known about the postfusion events that precede RNA replication, such as nucleocapsid disassembly. We describe here a sensitive, conditionally replication-defective yellow fever virus (YFV) entry reporter, YFVΔSK/Nluc, to quantitively monitor the translation of incoming, virus particle-delivered genomes. We validated that YFVΔSK/Nluc gene expression can be neutralized by YFV-specific antisera and requires known flavivirus entry pathways and cellular factors, including clathrin- and dynamin-mediated endocytosis, endosomal acidification, YFV E glycoprotein-mediated fusion, and cellular LY6E and RPLP1 expression. The initial round of YFV translation was shown to require cellular ubiquitylation, consistent with recent findings that dengue virus capsid protein must be ubiquitylated in order for nucleocapsid uncoating to occur. Importantly, translation of incoming YFV genomes also required valosin-containing protein (VCP)/p97, a cellular ATPase that unfolds and extracts ubiquitylated client proteins from large complexes. RNA transfection and washout experiments showed that VCP/p97 functions at a postfusion, pretranslation step in YFV entry. Finally, VCP/p97 activity was required by other flaviviruses in mammalian cells and by YFV in mosquito cells. Together, these data support a critical role for VCP/p97 in the disassembly of incoming flavivirus nucleocapsids during a postfusion step in virus entry.IMPORTANCE Flaviviruses are an important group of RNA viruses that cause significant human disease. The mechanisms by which flavivirus nucleocapsids are disassembled during virus entry remain unclear. Here, we used a yellow fever virus entry reporter, which expresses a sensitive reporter enzyme but does not replicate, to show that nucleocapsid disassembly requires the cellular protein-disaggregating enzyme valosin-containing protein, also known as p97.
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Affiliation(s)
- Harish N Ramanathan
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, USA
| | - Shuo Zhang
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, USA
| | - Florian Douam
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Katrina B Mar
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jinhong Chang
- Department of Experimental Therapeutics, The Baruch S. Blumberg Institute, Doylestown, Pennsylvania, USA
| | - Priscilla L Yang
- Department of Microbiology and the Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - John W Schoggins
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Alexander Ploss
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Brett D Lindenbach
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, USA
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18
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Sangiambut S, Pethrak C, Anupap C, Ninnabkaew P, Kongsanthia C, Promphet N, Chaiyaloom S, Songjaeng A, Avirutnan P, Puttikhunt C, Kasinrerk W, Sittisombut N, Malasit P. Enhanced production of infectious particles by adaptive modulation of C–prM processing and C–C interaction during propagation of dengue pseudoinfectious virus in stable CprME-expressing cells. J Gen Virol 2020; 101:59-72. [DOI: 10.1099/jgv.0.001345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Sutha Sangiambut
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Chatpong Pethrak
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Chainarong Anupap
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Parichat Ninnabkaew
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Charuphan Kongsanthia
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Natcha Promphet
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Suwipa Chaiyaloom
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Adisak Songjaeng
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Panisadee Avirutnan
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Chunya Puttikhunt
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Watchara Kasinrerk
- Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
- Biomedical Technology Research Center, National Center for Genetic Engineering and Biotechnology, National Sciences and Technology Development Agency at the Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Nopporn Sittisombut
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
| | - Prida Malasit
- Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok 12120, Thailand
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19
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Rana J, Burrone OR. DENV2 Pseudoviral Particles with Unprocessed Capsid Protein Are Assembled and Infectious. Viruses 2019; 12:v12010027. [PMID: 31881703 PMCID: PMC7019998 DOI: 10.3390/v12010027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/06/2019] [Accepted: 12/23/2019] [Indexed: 11/16/2022] Open
Abstract
Proteolytic processing of flavivirus polyprotein is a uniquely controlled process. To date, the sequential cleavage of the capsid anchor sequence at the junction of C-PrM has been considered essential for the production of flaviviruses. In this study, we used two experimental approaches to show the effect of unprocessed capsid on the production and infectivity of dengue virus 2 (DENV2) pseudoviral particles. The results showed that (1) both mature and unprocessed capsids of DENV2 were equally efficient in the viral RNA packaging and also in the assembly of infective particles; (2) DENV2 variants, in which the viral and host mediated cleavage of Ca peptide were independent, produced significantly higher levels of infective particles. Overall, this study demonstrated that unlike other flaviviruses, DENV2 capsid does not require a cleavable Ca sequence, and the sequential cleavage is not an obligatory requirement for the morphogenesis of infective pseudoviral particles.
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Affiliation(s)
- Jyoti Rana
- Correspondence: (J.R.); (O.R.B.); Tel.: +39-040-3757314 (J.R. & O.R.B.)
| | - Oscar R. Burrone
- Correspondence: (J.R.); (O.R.B.); Tel.: +39-040-3757314 (J.R. & O.R.B.)
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20
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Rana J, Slon Campos JL, Poggianella M, Burrone OR. Dengue virus capsid anchor modulates the efficiency of polyprotein processing and assembly of viral particles. J Gen Virol 2019; 100:1663-1673. [DOI: 10.1099/jgv.0.001346] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The assembly and secretion of flaviviruses are part of an elegantly regulated process. During maturation, the viral polyprotein undergoes several co- and post-translational cleavages mediated by both viral and host proteases. Among these, sequential cleavage at the N and C termini of the hydrophobic capsid anchor (Ca) is crucial in deciding the fate of viral infection. Here, using a refined dengue pseudovirus production system, along with cleavage and furin inhibition assays, immunoblotting and secondary structure prediction analysis, we show that Ca plays a key role in the processing efficiency of dengue virus type 2 (DENV2) structural proteins and viral particle assembly. Replacement of the DENV2 Ca with the homologous regions from West nile or Zika viruses or, alternatively, increasing its length, improved cleavage and hence particle assembly. Further, we showed that substitution of the Ca conserved proline residue (P110) to alanine abolishes pseudovirus production, regardless of the Ca sequence length. Besides providing the results of a biochemical analysis of DENV2 structural polyprotein processing, this study also presents a system for efficient production of dengue pseudoviruses.
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Affiliation(s)
- Jyoti Rana
- Present address: Gene and Cell Therapy group, IU School of Medicine, Wells Center of Pediatric Research, IUPUI, Indianapolis, IN 46202, USA
- International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - José Luis Slon Campos
- Present address: Nuffield Department of Medicine, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
- International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - Monica Poggianella
- International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - Oscar R. Burrone
- International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
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21
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Abstract
The flavivirus virion consists of an envelope outer layer, formed by envelope (E) and membrane (M) proteins on a lipid bilayer, and an internal core, formed by capsid (C) protein and genomic RNA. The molecular mechanism of flavivirus assembly is not well understood. Here, we show that Zika virus (ZIKV) NS2A protein recruits genomic RNA, the structural protein prM/E complex, and the NS2B/NS3 protease complex to the virion assembly site and orchestrates virus morphogenesis. Coimmunoprecipitation analysis showed that ZIKV NS2A binds to prM, E, NS2B, and NS3 (but not C, NS4B, or NS5) in a viral RNA-independent manner, whereas prM/E complex does not interact with NS2B/NS3 complex. Remarkably, a single-amino-acid mutation (E103A) of NS2A impairs its binding to prM/E and NS2B/NS3 and abolishes virus production, demonstrating the indispensable role of NS2A/prM/E and NS2A/NS2B/NS3 interactions in virion assembly. In addition, RNA-protein pulldown analysis identified a stem-loop RNA from the 3' untranslated region (UTR) of the viral genome as an "RNA recruitment signal" for ZIKV assembly. The 3' UTR RNA binds to a cytoplasmic loop of NS2A protein. Mutations of two positively charged residues (R96A and R102A) from the cytoplasmic loop reduce NS2A binding to viral RNA, leading to a complete loss of virion assembly. Collectively, our results support a virion assembly model in which NS2A recruits viral NS2B/NS3 protease and structural C-prM-E polyprotein to the virion assembly site; once the C-prM-E polyprotein has been processed, NS2A presents viral RNA to the structural proteins for virion assembly.IMPORTANCE ZIKV is a recently emerged mosquito-borne flavivirus that can cause devastating congenital Zika syndrome in pregnant women and Guillain-Barré syndrome in adults. The molecular mechanism of ZIKV virion assembly is largely unknown. Here, we report that ZIKV NS2A plays a central role in recruiting viral RNA, structural protein prM/E, and viral NS2B/NS3 protease to the virion assembly site and orchestrating virion morphogenesis. One mutation that impairs these interactions does not significantly affect viral RNA replication but selectively abolishes virion assembly, demonstrating the specific role of these interactions in virus morphogenesis. We also show that the 3' UTR of ZIKV RNA may serve as a "recruitment signal" through binding to NS2A to enter the virion assembly site. Following a coordinated cleavage of C-prM-E at the virion assembly site, NS2A may present the viral RNA to C protein for nucleocapsid formation followed by envelopment with prM/E proteins. The results have provided new insights into flavivirus virion assembly.
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22
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Dengue NS2A Protein Orchestrates Virus Assembly. Cell Host Microbe 2019; 26:606-622.e8. [PMID: 31631053 DOI: 10.1016/j.chom.2019.09.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/04/2019] [Accepted: 09/25/2019] [Indexed: 01/12/2023]
Abstract
Dengue virus assembly requires cleavage of viral C-prM-E polyprotein into three structural proteins (capsid, premembrane, and envelope), packaging of viral RNA with C protein into nucleocapsid, and budding of prM and E proteins into virions. The molecular mechanisms underlying these assembly events are unclear. Here, we show that dengue nonstructural protein 2A (NS2A protein) recruits viral RNA, structural proteins, and protease to the site of virion assembly and coordinates nucleocapsid and virus formation. The last 285 nucleotides of viral 3' UTR serve as a "recruiting signal for packaging" that binds to a cytosolic loop of NS2A. This interaction allows NS2A to recruit nascent RNA from the replication complex to the virion assembly site. NS2A also recruits the C-prM-E polyprotein and NS2B-NS3 protease to the virion assembly site by interacting with prM, E, and NS3, leading to coordinated C-prM-E cleavage. Mature C protein assembles onto genomic RNA to form nucleocapsid, followed by prM and E envelopment and virion formation.
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23
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Neufeldt CJ, Cortese M, Acosta EG, Bartenschlager R. Rewiring cellular networks by members of the Flaviviridae family. Nat Rev Microbiol 2019; 16:125-142. [PMID: 29430005 PMCID: PMC7097628 DOI: 10.1038/nrmicro.2017.170] [Citation(s) in RCA: 230] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Members of the Flaviviridae virus family comprise a large group of enveloped viruses with a single-strand RNA genome of positive polarity. Several genera belong to this family, including the Hepacivirus genus, of which hepatitis C virus (HCV) is the prototype member, and the Flavivirus genus, which contains both dengue virus and Zika virus. Viruses of these genera differ in many respects, such as the mode of transmission or the course of infection, which is either predominantly persistent in the case of HCV or acutely self-limiting in the case of flaviviruses. Although the fundamental replication strategy of Flaviviridae members is similar, during the past few years, important differences have been discovered, including the way in which these viruses exploit cellular resources to facilitate viral propagation. These differences might be responsible, at least in part, for the various biological properties of these viruses, thus offering the possibility to learn from comparisons. In this Review, we discuss the current understanding of how Flaviviridae viruses manipulate and usurp cellular pathways in infected cells. Specifically, we focus on comparing strategies employed by flaviviruses with those employed by hepaciviruses, and we discuss the importance of these interactions in the context of viral replication and antiviral therapies.
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Affiliation(s)
- Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Eliana G Acosta
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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24
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Zhang X, Xie X, Zou J, Xia H, Shan C, Chen X, Shi PY. Genetic and biochemical characterizations of Zika virus NS2A protein. Emerg Microbes Infect 2019; 8:585-602. [PMID: 30958095 PMCID: PMC6455252 DOI: 10.1080/22221751.2019.1598291] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Zika virus (ZIKV) can cause devastating congenital Zika syndromes in pregnant women and Guillain-Barre syndrome in adults. Understanding the molecular mechanism of ZIKV replication is essential for antiviral and vaccine development. Here we report the structural and functional characterization of ZIKV NS2A protein. Biochemical structural probing suggests that ZIKV NS2A has a single segment that traverses the ER membrane and six segments that peripherally associate with the ER membrane. Functional analysis has defined distinct NS2A residues essential for viral RNA synthesis or virion assembly. Only the virion assembly-defective mutants, but not the RNA synthesis-defective mutants, could be rescued through trans complementation with a wide-type NS2A protein. These results suggest that the NS2A molecules in virion assembly complex could be recruited in trans, whereas the NS2A molecules in viral replication complex must be recruited in cis. Together with previous results, we propose a flavivirus assembly model where NS2A plays a central role in modulating viral structural and nonstructural proteins as well as genomic RNA during virion assembly.
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Affiliation(s)
- Xianwen Zhang
- a State Key Laboratory of Virology , Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan , People's Republic of China.,b University of Chinese Academy of Sciences , Beijing , People's Republic of China.,c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA
| | - Xuping Xie
- c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA
| | - Jing Zou
- c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA
| | - Hongjie Xia
- c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA
| | - Chao Shan
- c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA
| | - Xinwen Chen
- a State Key Laboratory of Virology , Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan , People's Republic of China.,b University of Chinese Academy of Sciences , Beijing , People's Republic of China.,d Guangzhou Institute of Biomedicine and Health , Chinese Academy of Sciences , Guangzhou , People's Republic of China
| | - Pei-Yong Shi
- c Department of Biochemistry & Molecular Biology , University of Texas Medical Branch , Galveston , TX , USA.,e Institute for Human Infections & Immunity , University of Texas Medical Branch , Galveston , TX , USA.,f Sealy Institute for Vaccine Sciences , University of Texas Medical Branch , Galveston , TX , USA.,g Sealy Center for Structural Biology & Molecular Biophysics , University of Texas Medical Branch , Galveston , TX , USA.,h Department of Pharmacology & Toxicology , University of Texas Medical Branch , Galveston , TX , USA
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25
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Kum DB, Mishra N, Boudewijns R, Gladwyn-Ng I, Alfano C, Ma J, Schmid MA, Marques RE, Schols D, Kaptein S, Nguyen L, Neyts J, Dallmeier K. A yellow fever-Zika chimeric virus vaccine candidate protects against Zika infection and congenital malformations in mice. NPJ Vaccines 2018; 3:56. [PMID: 30564463 PMCID: PMC6292895 DOI: 10.1038/s41541-018-0092-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 11/05/2018] [Indexed: 12/27/2022] Open
Abstract
The recent Zika virus (ZIKV) epidemic in the Americas led to an intense search for therapeutics and vaccines. Here we report the engineering of a chimeric virus vaccine candidate (YF-ZIKprM/E) by replacing the antigenic surface glycoproteins and the capsid anchor of YFV-17D with those of a prototypic Asian lineage ZIKV isolate. By intracellular passaging, a variant with adaptive mutations in the E protein was obtained. Unlike YFV-17D, YF-ZIKprM/E replicates poorly in mosquito cells. Also, YF-ZIKprM/E does not cause disease nor mortality in interferon α/β, and γ receptor KO AG129 mice nor following intracranial inoculation of BALB/c pups. A single dose as low as 1 × 102 PFU results, as early as 7 days post vaccination, in seroconversion to neutralizing antibodies and confers full protection in AG129 mice against stringent challenge with a lethal inoculum (105 LD50) of either homologous or heterologous ZIKV strains. Induction of multi-functional CD4+ and CD8+ T cell responses against ZIKV structural and YFV-17D non-structural proteins indicates that cellular immunity may also contribute to protection. Vaccine immunogenicity and protection was confirmed in other mouse strains, including after temporal blockade of interferon-receptors in wild-type mice to facilitate ZIKV replication. Vaccination of wild-type NMRI dams with YF-ZIKprM/E results in complete protection of foetuses against brain infections and malformations following a stringent intraplacental challenge with an epidemic ZIKV strain. The particular characteristic of YF-ZIKprM/E in terms of efficacy and its marked attenuation in mice warrants further exploration as a vaccine candidate. Zika virus (ZIKV) infection generally results in mild symptoms but can cause serious developmental abnormalities in infants born to ZIKV infected mothers. Kai Dallmeier and colleagues at the KU Leuven in Belgium, engineered a chimeric live-attenuated vaccine (YF-ZIKprM/E) by swapping the glycoprotein from the Yellow Fever vaccine YFV-17D with that of a pre-epidemic ZIKV strain. YF-ZIKprM/E is very well tolerated with no adverse effects even following high dose intracranial infection. Mice highly susceptible to ZIKV infection—including AG129 and type I interferon receptor deficient strains—vaccinated with a single dose of YF-ZIKprM/E are fully protected from lethal ZIKV challenge. Protection can be achieved within 7 days and by low doses of YF-ZIKprM/E, is durable and generally results in sterilizing immunity. YF-ZIKprM/E elicits both neutralizing antibodies and robust cellular immunity. Finally, YF-ZIKprM/E can also prevent vertical transmission of ZIKV and achieve efficient protection of pups from neurological defects following intraplacental challenge.
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Affiliation(s)
- Dieudonné B Kum
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Niraj Mishra
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Robbert Boudewijns
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Ivan Gladwyn-Ng
- 2GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège, Belgium
| | - Christian Alfano
- 2GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège, Belgium
| | - Ji Ma
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Michael A Schmid
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Rafael E Marques
- 3Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo, Brazil
| | - Dominique Schols
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Suzanne Kaptein
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Laurent Nguyen
- 2GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège, Belgium
| | - Johan Neyts
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Kai Dallmeier
- KU Leuven Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
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Molecular Recognition Features in Zika Virus Proteome. J Mol Biol 2018; 430:2372-2388. [DOI: 10.1016/j.jmb.2017.10.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/18/2017] [Accepted: 10/18/2017] [Indexed: 12/23/2022]
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Douam F, Ploss A. Yellow Fever Virus: Knowledge Gaps Impeding the Fight Against an Old Foe. Trends Microbiol 2018; 26:913-928. [PMID: 29933925 DOI: 10.1016/j.tim.2018.05.012] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/07/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022]
Abstract
Yellow fever (YF) was one of the most dangerous infectious diseases of the 18th and 19th centuries, resulting in mass casualties in Africa and the Americas. The etiologic agent is yellow fever virus (YFV), and its live-attenuated form, YFV-17D, remains one of the most potent vaccines ever developed. During the first half of the 20th century, vaccination combined with mosquito control eradicated YFV transmission in urban areas. However, the recent 2016-2018 outbreaks in areas with historically low or no YFV activity have raised serious concerns for an estimated 400-500 million unvaccinated people who now live in at-risk areas. Once a forgotten disease, we highlight here that YF still represents a very real threat to human health and economies. As many gaps remain in our understanding of how YFV interacts with the human host and causes disease, there is an urgent need to address these knowledge gaps and propel YFV research forward.
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Affiliation(s)
- Florian Douam
- Department of Molecular Biology, Princeton University, 110 Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA
| | - Alexander Ploss
- Department of Molecular Biology, Princeton University, 110 Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA.
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28
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Pollett S, Melendrez MC, Maljkovic Berry I, Duchêne S, Salje H, Cummings DAT, Jarman RG. Understanding dengue virus evolution to support epidemic surveillance and counter-measure development. INFECTION GENETICS AND EVOLUTION 2018; 62:279-295. [PMID: 29704626 DOI: 10.1016/j.meegid.2018.04.032] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 04/20/2018] [Accepted: 04/24/2018] [Indexed: 11/30/2022]
Abstract
Dengue virus (DENV) causes a profound burden of morbidity and mortality, and its global burden is rising due to the co-circulation of four divergent DENV serotypes in the ecological context of globalization, travel, climate change, urbanization, and expansion of the geographic range of the Ae.aegypti and Ae.albopictus vectors. Understanding DENV evolution offers valuable opportunities to enhance surveillance and response to DENV epidemics via advances in RNA virus sequencing, bioinformatics, phylogenetic and other computational biology methods. Here we provide a scoping overview of the evolution and molecular epidemiology of DENV and the range of ways that evolutionary analyses can be applied as a public health tool against this arboviral pathogen.
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Affiliation(s)
- S Pollett
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA; Marie Bashir Institute, University of Sydney, NSW, Australia; Institute for Global Health Sciences, University of California at San Francisco, CA, USA.
| | - M C Melendrez
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - I Maljkovic Berry
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - S Duchêne
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Australia
| | - H Salje
- Institut Pasteur, Paris, France; Johns Hopkins School of Public Health, Baltimore, MD, USA
| | - D A T Cummings
- Johns Hopkins School of Public Health, Baltimore, MD, USA; University of Florida, FL, USA
| | - R G Jarman
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
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29
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Barrows NJ, Campos RK, Liao KC, Prasanth KR, Soto-Acosta R, Yeh SC, Schott-Lerner G, Pompon J, Sessions OM, Bradrick SS, Garcia-Blanco MA. Biochemistry and Molecular Biology of Flaviviruses. Chem Rev 2018; 118:4448-4482. [PMID: 29652486 DOI: 10.1021/acs.chemrev.7b00719] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Flaviviruses, such as dengue, Japanese encephalitis, tick-borne encephalitis, West Nile, yellow fever, and Zika viruses, are critically important human pathogens that sicken a staggeringly high number of humans every year. Most of these pathogens are transmitted by mosquitos, and not surprisingly, as the earth warms and human populations grow and move, their geographic reach is increasing. Flaviviruses are simple RNA-protein machines that carry out protein synthesis, genome replication, and virion packaging in close association with cellular lipid membranes. In this review, we examine the molecular biology of flaviviruses touching on the structure and function of viral components and how these interact with host factors. The latter are functionally divided into pro-viral and antiviral factors, both of which, not surprisingly, include many RNA binding proteins. In the interface between the virus and the hosts we highlight the role of a noncoding RNA produced by flaviviruses to impair antiviral host immune responses. Throughout the review, we highlight areas of intense investigation, or a need for it, and potential targets and tools to consider in the important battle against pathogenic flaviviruses.
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Affiliation(s)
- Nicholas J Barrows
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Department of Molecular Genetics and Microbiology , Duke University , Durham , North Carolina 27710 , United States
| | - Rafael K Campos
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Department of Molecular Genetics and Microbiology , Duke University , Durham , North Carolina 27710 , United States
| | - Kuo-Chieh Liao
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - K Reddisiva Prasanth
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Ruben Soto-Acosta
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Shih-Chia Yeh
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - Geraldine Schott-Lerner
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Julien Pompon
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore.,MIVEGEC, IRD, CNRS, Université de Montpellier , Montpellier 34090 , France
| | - October M Sessions
- Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
| | - Shelton S Bradrick
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Mariano A Garcia-Blanco
- Department of Biochemistry and Molecular Biology , University of Texas Medical Branch , Galveston , Texas 77555 , United States.,Programme in Emerging Infectious Diseases , Duke-NUS Medical School , Singapore 169857 , Singapore
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30
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Oral Vaccination with a DNA Vaccine Encoding Capsid Protein of Duck Tembusu Virus Induces Protection Immunity. Viruses 2018; 10:v10040180. [PMID: 29642401 PMCID: PMC5923474 DOI: 10.3390/v10040180] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 04/01/2018] [Accepted: 04/04/2018] [Indexed: 12/26/2022] Open
Abstract
The emergence of duck tembusu virus (DTMUV), a new member of the Flavivirus genus, has caused great economical loss in the poultry industry in China. Since the outbreak and spread of DTMUV is hard to control in a clinical setting, an efficient and low-cost oral delivery DNA vaccine SL7207 (pVAX1-C) based on the capsid protein of DTMUV was developed and evaluated in this study. The antigen capsid protein was expressed from the DNA vaccine SL7207 (pVAX1-C), both in vitro and in vivo. The humoral and cellular immune responses in vivo were observed after oral immunization with the SL7207 (pVAX1-C) DNA vaccine. High titers of the specific antibody against the capsid protein and the neutralizing antibody against the DTMUV virus were both detected after inoculation. The ducks were efficiently protected from lethal DTMUV exposure by the SL7207 (pVAX1-C) vaccine in this experiment. Taken together, we demonstrated that the capsid protein of DTMUV possesses a strong immunogenicity against the DTMUV infection. Moreover, an oral delivery of the DNA vaccine SL7207 (pVAX1-C) utilizing Salmonella SL7207 was an efficient way to protect the ducks against DTMUV infection and provides an economic and fast vaccine delivery strategy for a large scale clinical use.
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31
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The Transactions of NS3 and NS5 in Flaviviral RNA Replication. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1062:147-163. [PMID: 29845531 DOI: 10.1007/978-981-10-8727-1_11] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Dengue virus (DENV) replication occurs in virus-induced vesicles that contain the replication complex (RC) where viral RNA, viral proteins and host proteins participate in RNA-RNA, RNA-protein and protein-protein interactions to ensure viral genome synthesis. However, the details of the multitude of interactions involved in the biogenesis of the infectious virion are not fully understood. In this review, we will focus on the interaction between non-structural (NS) proteins NS3 and NS5, as well as their interactions with viral RNA and briefly also the interaction of NS5 with the host nuclear transport receptor protein importin-α. The multifunctional NS3 protease/helicase and NS5 methyltransferase (MTase)/RNA-dependent RNA polymerase (RdRp) contain all the enzymatic activities required to synthesize the viral RNA genome. The success stories of drug discovery and development with Hepatitis C virus (HCV), a member of the Flaviviridae family, has led to the view that DENV NS3 and NS5 may be attractive antiviral drug targets. However, more than 10 years of intensive research effort by Novatis has revealed that they are not "low hanging fruits" and therefore, the search for potent directly acting antivirals (DAAs) remains a pipeline goal for several medium to large drug discovery enterprises. The effort to discover DAAs for DENV has been boosted by the epidemic outbreak of the closely related flavivirus member - Zika virus (ZIKV). Because the viral RNA replication occurs within a molecular machine that is composed several viral and host proteins, much interest has turned to characterising functionally essential protein-protein interactions in order to identify potential allosteric inhibitor binding sites within the RC.
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32
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Hirano J, Okamoto T, Sugiyama Y, Suzuki T, Kusakabe S, Tokunaga M, Fukuhara T, Sasai M, Tougan T, Matsunaga Y, Yamashita K, Sakai Y, Yamamoto M, Horii T, Standley DM, Moriishi K, Moriya K, Koike K, Matsuura Y. Characterization of SPP inhibitors suppressing propagation of HCV and protozoa. Proc Natl Acad Sci U S A 2017; 114:E10782-E10791. [PMID: 29187532 PMCID: PMC5740650 DOI: 10.1073/pnas.1712484114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Signal peptide peptidase (SPP) is an intramembrane aspartic protease involved in the maturation of the core protein of hepatitis C virus (HCV). The processing of HCV core protein by SPP has been reported to be critical for the propagation and pathogenesis of HCV. Here we examined the inhibitory activity of inhibitors for γ-secretase, another intramembrane cleaving protease, against SPP, and our findings revealed that the dibenzoazepine-type structure in the γ-secretase inhibitors is critical for the inhibition of SPP. The spatial distribution showed that the γ-secretase inhibitor compound YO-01027 with the dibenzoazepine structure exhibits potent inhibiting activity against SPP in vitro and in vivo through the interaction of Val223 in SPP. Treatment with this SPP inhibitor suppressed the maturation of core proteins of all HCV genotypes without the emergence of drug-resistant viruses, in contrast to the treatment with direct-acting antivirals. YO-01027 also efficiently inhibited the propagation of protozoa such as Plasmodium falciparum and Toxoplasma gondii These data suggest that SPP is an ideal target for the development of therapeutics not only against chronic hepatitis C but also against protozoiasis.
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Affiliation(s)
- Junki Hirano
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Toru Okamoto
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan;
| | - Yukari Sugiyama
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Tatsuya Suzuki
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Shinji Kusakabe
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Makoto Tokunaga
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Takasuke Fukuhara
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Miwa Sasai
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Takahiro Tougan
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Yasue Matsunaga
- Planning and Promotion Office for University-Industry Collaboration, Osaka University, Osaka 565-0871, Japan
| | | | - Yusuke Sakai
- Department of Veterinary Pathology, Yamaguchi University, Yamaguchi 753-0841, Japan
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Toshihiro Horii
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Daron M Standley
- Department of Genome Informatics, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Kohji Moriishi
- Department of Microbiology, Faculty of Medicine, University of Yamanashi, Yamanashi 400-8510, Japan
| | - Kyoji Moriya
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8654, Japan
| | - Kazuhiko Koike
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8654, Japan
| | - Yoshiharu Matsuura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan;
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Yokoyama S, Starmer WT. Possible Roles of New Mutations Shared by Asian and American Zika Viruses. Mol Biol Evol 2017; 34:525-534. [PMID: 28087772 PMCID: PMC5400385 DOI: 10.1093/molbev/msw270] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Originating in Africa, the Zika virus (ZIKV) has spread to Asia, Pacific Islands and now to the Americas and beyond. Since the first isolation in 1947, ZIKV strains have been sampled at various times in the last 69 years, but this history has not been reflected in studying the patterns of mutation accumulation in their genomes. Implementing the viral history, we show that the ZIKV ancestor appeared sometime in 1930–1945 and, at that point, its mutation rate was probably less than 0.2 × 10−3/nucleotide site/year and subsequently increased significantly in most of its descendants. Sustaining a high mutation rate of 4 × 10−3/site/year throughout its evolution, the Ancestral Asian strain, which was sampled from a mosquito in Malaysia, accumulated 13 mutations in the 3′-untranslated region of RNA stem-loops prior to 1963, seven of which generate more stable stem-loop structures and are likely to inhibit cellular antiviral activities, including immune and RNA interference (RNAi) pathways. The seven mutations have been maintained in all Asian and American strains and may be responsible for serious medical problems we are facing today and offer testable hypotheses to examine their roles in molecular interactions during brain development.
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34
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The flavivirus capsid protein: Structure, function and perspectives towards drug design. Virus Res 2017; 227:115-123. [DOI: 10.1016/j.virusres.2016.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 09/29/2016] [Accepted: 10/12/2016] [Indexed: 12/12/2022]
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35
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Blazevic J, Rouha H, Bradt V, Heinz FX, Stiasny K. Membrane Anchors of the Structural Flavivirus Proteins and Their Role in Virus Assembly. J Virol 2016; 90:6365-6378. [PMID: 27147734 PMCID: PMC4936158 DOI: 10.1128/jvi.00447-16] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 04/22/2016] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED The structural proteins of flaviviruses carry a unique set of transmembrane domains (TMDs) at their C termini that are derived from the mode of viral polyprotein processing. They function as internal signal and stop-transfer sequences during protein translation, but possible additional roles in protein interactions required during assembly and maturation of viral particles are ill defined. To shed light on the role of TMDs in these processes, we engineered a set of tick-borne encephalitis virus mutants in which these structural elements were replaced in different combinations by the homologous sequences of a distantly related flavivirus (Japanese encephalitis virus). The effects of these modifications were analyzed with respect to protein synthesis, viral particle secretion, specific infectivity, and acidic-pH-induced maturation processes. We provide evidence that interactions involving the double-membrane anchor of the envelope protein E (a unique feature compared to other viral fusion proteins) contribute substantially to particle assembly, stability, and maturation. Disturbances of the inter- and intra-TMD interactions of E resulted in the secretion of a larger proportion of capsidless subviral particles at the expense of whole virions, suggesting a possible role in the still incompletely understood mechanism of capsid integration during virus budding. In contrast, the TMD initially anchoring the C protein to the endoplasmic reticulum membrane does not appear to take part in envelope protein interactions. We also show that E TMDs are involved in the envelope protein rearrangements that are triggered by acidic pH in the trans-Golgi network and represent a hallmark of virus maturation. IMPORTANCE The assembly of flaviviruses occurs in the endoplasmic reticulum and leads to the formation of immature, noninfectious particles composed of an RNA-containing capsid surrounded by a lipid membrane, with the two integrated envelope proteins, prM and E, arranged in an icosahedral lattice. The mechanism by which the capsid is formed and integrated into the budding viral envelope is currently unknown. We provide evidence that the transmembrane domains (TMDs) of E are essential for the formation of capsid-containing particles and that disturbances of these interactions lead to the preferential formation of capsidless subviral particles at the expense of whole virions. E TMD interactions also appear to be essential for the envelope protein rearrangements required for virus maturation and for the generation of infectious virions. Our data thus provide new insights into the biological functions of E TMDs and extend their role during viral polyprotein processing to additional functions in particle assembly and maturation.
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Affiliation(s)
- Janja Blazevic
- Department of Virology, Medical University of Vienna, Vienna, Austria
| | - Harald Rouha
- Department of Virology, Medical University of Vienna, Vienna, Austria
| | - Victoria Bradt
- Department of Virology, Medical University of Vienna, Vienna, Austria
| | - Franz X Heinz
- Department of Virology, Medical University of Vienna, Vienna, Austria
| | - Karin Stiasny
- Department of Virology, Medical University of Vienna, Vienna, Austria
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Chaperone-Assisted Protein Folding Is Critical for Yellow Fever Virus NS3/4A Cleavage and Replication. J Virol 2016; 90:3212-28. [PMID: 26739057 DOI: 10.1128/jvi.03077-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/04/2016] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED DNAJC14, a heat shock protein 40 (Hsp40) cochaperone, assists with Hsp70-mediated protein folding. Overexpressed DNAJC14 is targeted to sites of yellow fever virus (YFV) replication complex (RC) formation, where it interacts with viral nonstructural (NS) proteins and inhibits viral RNA replication. How RCs are assembled and the roles of chaperones in this coordinated process are largely unknown. We hypothesized that chaperones are diverted from their normal cellular protein quality control function to play similar roles during viral infection. Here, we show that DNAJC14 overexpression affects YFV polyprotein processing and alters RC assembly. We monitored YFV NS2A-5 polyprotein processing by the viral NS2B-3 protease in DNAJC14-overexpressing cells. Notably, DNAJC14 mutants that did not inhibit YFV replication had minimal effects on polyprotein processing, while overexpressed wild-type DNAJC14 affected the NS3/4A and NS4A/2K cleavage sites, resulting in altered NS3-to-NS3-4A ratios. This suggests that DNAJC14's folding activity normally modulates NS3/4A/2K cleavage events to liberate appropriate levels of NS3 and NS4A and promote RC formation. We introduced amino acid substitutions at the NS3/4A site to alter the levels of the NS3 and NS4A products and examined their effects on YFV replication. Residues with reduced cleavage efficiency did not support viral RNA replication, and only revertant viruses with a restored wild-type arginine or lysine residue at the NS3/4A site were obtained. We conclude that DNAJC14 inhibition of RC formation upon DNAJC14 overexpression is likely due to chaperone dysregulation and that YFV probably utilizes DNAJC14's cochaperone function to modulate processing at the NS3/4A site as a mechanism ensuring virus replication. IMPORTANCE Flaviviruses are single-stranded RNA viruses that cause a wide range of illnesses. Upon host cell entry, the viral genome is translated on endoplasmic reticulum (ER) membranes to produce a single polyprotein, which is cleaved by host and viral proteases to generate viral proteins required for genome replication and virion production. Several studies suggest a role for molecular chaperones during these processes. While the details of chaperone roles have been elusive, in this report we show that overexpression of the ER-resident cochaperone DNAJC14 affects YFV polyprotein processing at the NS3/4A site. This work reveals that DNAJC14 modulation of NS3/4A site processing is an important mechanism to ensure virus replication. Our work highlights the importance of finely regulating flavivirus polyprotein processing. In addition, it suggests future studies to address similarities and/or differences among flaviviruses and to interrogate the precise mechanisms employed for polyprotein processing, a critical step that can ultimately be targeted for novel drug development.
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Context-Dependent Cleavage of the Capsid Protein by the West Nile Virus Protease Modulates the Efficiency of Virus Assembly. J Virol 2015; 89:8632-42. [PMID: 26063422 DOI: 10.1128/jvi.01253-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/02/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED The molecular mechanisms that define the specificity of flavivirus RNA encapsulation are poorly understood. Virions composed of the structural proteins of one flavivirus and the genomic RNA of a heterologous strain can be assembled and have been developed as live attenuated vaccine candidates for several flaviviruses. In this study, we discovered that not all combinations of flavivirus components are possible. While a West Nile virus (WNV) subgenomic RNA could readily be packaged by structural proteins of the DENV2 strain 16681, production of infectious virions with DENV2 strain New Guinea C (NGC) structural proteins was not possible, despite the very high amino acid identity between these viruses. Mutagenesis studies identified a single residue (position 101) of the DENV capsid (C) protein as the determinant for heterologous virus production. C101 is located at the P1' position of the NS2B/3 protease cleavage site at the carboxy terminus of the C protein. WNV NS2B/3 cleavage of the DENV structural polyprotein was possible when a threonine (Thr101 in strain 16681) but not a serine (Ser101 in strain NGC) occupied the P1' position, a finding not predicted by in vitro protease specificity studies. Critically, both serine and threonine were tolerated at the P1' position of WNV capsid. More extensive mutagenesis revealed the importance of flanking residues within the polyprotein in defining the cleavage specificity of the WNV protease. A more detailed understanding of the context dependence of viral protease specificity may aid the development of new protease inhibitors and provide insight into associated patterns of drug resistance. IMPORTANCE West Nile virus (WNV) and dengue virus (DENV) are mosquito-borne flaviviruses that cause considerable morbidity and mortality in humans. No specific antiflavivirus therapeutics are available for treatment of infection. Proteolytic processing of the flavivirus polyprotein is an essential step in the replication cycle and is an attractive target for antiviral development. The design of protease inhibitors has been informed by insights into the molecular details of the interactions of proteases and their substrates. In this article, studies of the processing of WNV and DENV capsid proteins by the WNV protease identified an unexpected contribution of the sequence surrounding critical residues within the cleavage site on protease specificity. This demonstration of context-dependent protease cleavage has implications for the design of chimeric flaviviruses, new therapeutics, and the interpretation of flavivirus protease substrate specificity studies.
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Roby JA, Setoh YX, Hall RA, Khromykh AA. Post-translational regulation and modifications of flavivirus structural proteins. J Gen Virol 2015; 96:1551-69. [PMID: 25711963 DOI: 10.1099/vir.0.000097] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Flaviviruses are a group of single-stranded, positive-sense RNA viruses that generally circulate between arthropod vectors and susceptible vertebrate hosts, producing significant human and veterinary disease burdens. Intensive research efforts have broadened our scientific understanding of the replication cycles of these viruses and have revealed several elegant and tightly co-ordinated post-translational modifications that regulate the activity of viral proteins. The three structural proteins in particular - capsid (C), pre-membrane (prM) and envelope (E) - are subjected to strict regulatory modifications as they progress from translation through virus particle assembly and egress. The timing of proteolytic cleavage events at the C-prM junction directly influences the degree of genomic RNA packaging into nascent virions. Proteolytic maturation of prM by host furin during Golgi transit facilitates rearrangement of the E proteins at the virion surface, exposing the fusion loop and thus increasing particle infectivity. Specific interactions between the prM and E proteins are also important for particle assembly, as prM acts as a chaperone, facilitating correct conformational folding of E. It is only once prM/E heterodimers form that these proteins can be secreted efficiently. The addition of branched glycans to the prM and E proteins during virion transit also plays a key role in modulating the rate of secretion, pH sensitivity and infectivity of flavivirus particles. The insights gained from research into post-translational regulation of structural proteins are beginning to be applied in the rational design of improved flavivirus vaccine candidates and make attractive targets for the development of novel therapeutics.
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Affiliation(s)
- Justin A Roby
- 1Australian Infectious Diseases Research Centre, The University of Queensland, Australia 2School of Chemistry and Molecular Biosciences, The University of Queensland, Australia
| | - Yin Xiang Setoh
- 1Australian Infectious Diseases Research Centre, The University of Queensland, Australia 2School of Chemistry and Molecular Biosciences, The University of Queensland, Australia
| | - Roy A Hall
- 1Australian Infectious Diseases Research Centre, The University of Queensland, Australia 2School of Chemistry and Molecular Biosciences, The University of Queensland, Australia
| | - Alexander A Khromykh
- 1Australian Infectious Diseases Research Centre, The University of Queensland, Australia 2School of Chemistry and Molecular Biosciences, The University of Queensland, Australia
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Highly efficient production of a dengue pseudoinfectious virus. Vaccine 2014; 32:3854-60. [PMID: 24797700 DOI: 10.1016/j.vaccine.2014.03.091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/01/2014] [Accepted: 03/26/2014] [Indexed: 02/05/2023]
Abstract
Dengue is a major infectious disease that affects people living in tropical and subtropical regions around the world. The causative agents are dengue virus serotype 1, 2, 3, and 4 (DENV1, 2, 3, and 4). Developing a vaccine for dengue is a high priority for public health, but traditional methods have faced numerous obstacles due to the unique immunopathogenesis of dengue virus infection. Here, we report a novel dengue vaccine candidate based on dengue pseudoinfectious virus (PIV) produced by the incorporation of a dengue subgenomic replicon into viral particles in highly efficient packaging cells. The subgenomic replicon was constructed by deleting the capsid protein (C) gene from the dengue viral genome and optimizing the signal peptide sequence of pre-membrane protein (prM) to facilitate the formation of viral particles. Packaging cells were developed for inducible expression of a bi-protein Cpr, where the protein pr is the "pr" segment of viral protein prM that holds the protein C on the endoplasmic reticulum (ER). When the replicon was introduced into the packaging cells, protein C was released from the bi-protein Cpr by a replicon-encoded viral protease. Coordinate expression of viral structural proteins by the replicon and packaging cells led to the incorporation of the replicon into viral particle to produce PIVs. Animal tests showed that the dengue PIV vaccine was highly immunogenic and the immune response protected mice challenged with a hundred-fold LD50 inoculation of dengue virus. The method described here has the potential to be applied to vaccine development for other flaviviruses.
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Gromowski GD, Firestone CY, Hanson CT, Whitehead SS. Japanese encephalitis virus vaccine candidates generated by chimerization with dengue virus type 4. Vaccine 2014; 32:3010-8. [PMID: 24699473 DOI: 10.1016/j.vaccine.2014.03.062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/10/2014] [Accepted: 03/17/2014] [Indexed: 10/25/2022]
Abstract
Japanese encephalitis virus (JEV) is a leading cause of viral encephalitis worldwide and vaccination is one of the most effective ways to prevent disease. A suitable live-attenuated JEV vaccine could be formulated with a live-attenuated tetravalent dengue vaccine for the control of these viruses in endemic areas. Toward this goal, we generated chimeric virus vaccine candidates by replacing the precursor membrane (prM) and envelope (E) protein structural genes of recombinant dengue virus type 4 (rDEN4) or attenuated vaccine candidate rDEN4Δ30 with those of wild-type JEV strain India/78. Mutations were engineered in E, NS3 and NS4B protein genes to improve replication in Vero cells. The chimeric viruses were attenuated in mice and some elicited modest but protective levels of immunity after a single dose. One particular chimeric virus, bearing E protein mutation Q264H, replicated to higher titer in tissue culture and was significantly more immunogenic in mice. The results are compared with live-attenuated JEV vaccine strain SA14-14-2.
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Affiliation(s)
- Gregory D Gromowski
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States.
| | - Cai-Yen Firestone
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Christopher T Hanson
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Stephen S Whitehead
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
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Wang HJ, Li XF, Ye Q, Li SH, Deng YQ, Zhao H, Xu YP, Ma J, Qin ED, Qin CF. Recombinant chimeric Japanese encephalitis virus/tick-borne encephalitis virus is attenuated and protective in mice. Vaccine 2014; 32:949-56. [DOI: 10.1016/j.vaccine.2013.12.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 11/14/2013] [Accepted: 12/18/2013] [Indexed: 12/30/2022]
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A chimeric dengue virus vaccine using Japanese encephalitis virus vaccine strain SA14-14-2 as backbone is immunogenic and protective against either parental virus in mice and nonhuman primates. J Virol 2013; 87:13694-705. [PMID: 24109223 DOI: 10.1128/jvi.00931-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of a safe and efficient dengue vaccine represents a global challenge in public health. Chimeric dengue viruses (DENV) based on an attenuated flavivirus have been well developed as vaccine candidates by using reverse genetics. In this study, based on the full-length infectious cDNA clone of the well-known Japanese encephalitis virus live vaccine strain SA14-14-2 as a backbone, a novel chimeric dengue virus (named ChinDENV) was rationally designed and constructed by replacement with the premembrane and envelope genes of dengue 2 virus. The recovered chimeric virus showed growth and plaque properties similar to those of the parental DENV in mammalian and mosquito cells. ChinDENV was highly attenuated in mice, and no viremia was induced in rhesus monkeys upon subcutaneous inoculation. ChinDENV retained its genetic stability and attenuation phenotype after serial 15 passages in cultured cells. A single immunization with various doses of ChinDENV elicited strong neutralizing antibodies in a dose-dependent manner. When vaccinated monkeys were challenged with wild-type DENV, all animals except one that received the lower dose were protected against the development of viremia. Furthermore, immunization with ChinDENV conferred efficient cross protection against lethal JEV challenge in mice in association with robust cellular immunity induced by the replicating nonstructural proteins. Taken together, the results of this preclinical study well demonstrate the great potential of ChinDENV for further development as a dengue vaccine candidate, and this kind of chimeric flavivirus based on JE vaccine virus represents a powerful tool to deliver foreign antigens.
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Chong MK, Parthasarathy K, Yeo HY, Ng ML. Optimized sequential purification protocol for in vivo site-specific biotinylated full-length dengue virus capsid protein. Protein Eng Des Sel 2013; 26:377-87. [PMID: 23479673 DOI: 10.1093/protein/gzs107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dengue virus (DENV) capsid (C) protein is one of the three structural proteins that form a mature virus. The main challenge impeding the study of this protein is to generate pure non-truncated, full-length C proteins for structural and functional studies. This is mainly due to its small molecular weight, highly positively charged, stability and solubility properties. Here, we report a strategy to construct, express, biotinylate and purify non-truncated, full-length DENV C protein. A 6× His tag and a biotin acceptor peptide (BAP) were cloned at the N-terminus of C protein using overlapping extension-polymerase chain reaction method for site-specific biotinylation. The final construct was inserted into pET28a plasmid and BL-21 (CodonPlus) expression competent cell strain was selected as there are 12% rare codons in the C protein sequence. Strikingly, we found that our recombinant proteins with BAP were biotinylated endogenously with high efficiency in Escherichia coli BL-21 strains. To purify this His-tagged C protein, nickel-nitriloacetic acid affinity chromatography was first carried out under denaturing condition. After stepwise dialysis and concurrent refolding, ion exchange-fast protein liquid chromatography was performed to further separate the residual contaminants. To obtain C protein with high purity, a final round of purification with size exclusion chromatography was carried out and a single peak corresponding to C protein was attained. With this optimized sequential purification protocol, we successfully generated pure biotinylated full-length DENV C protein. The functionality of this purified non-truncated DENV C protein was examined and it was suitable for structural and molecular studies.
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Affiliation(s)
- Mun Keat Chong
- Flavivirology Laboratory, Department of Microbiology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
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The West Nile virus capsid protein blocks apoptosis through a phosphatidylinositol 3-kinase-dependent mechanism. J Virol 2012; 87:872-81. [PMID: 23115297 DOI: 10.1128/jvi.02030-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
West Nile virus (WNV) is a mosquito-transmitted pathogen that can cause serious disease in humans. Our laboratories are focused on understanding how interactions between WNV proteins and host cells contribute to virus replication and pathogenesis. WNV replication is relatively slow, and on the basis of earlier studies, the virus appears to activate survival pathways that delay host cell death during virus replication. The WNV capsid is the first viral protein produced in infected cells; however, its role in virus assembly is not required until after replication of the genomic RNA. Accordingly, from a temporal perspective, it is perfectly suited to block host cell apoptosis during virus replication. In the present study, we provide evidence that the WNV capsid protein blocks apoptosis through a phosphatidylinositol (PI) 3-kinase-dependent pathway. Specifically, expression of this protein in the absence of other viral proteins increases the levels of phosphorylated Akt, a prosurvival kinase that blocks apoptosis through multiple mechanisms. Treatment of cells with the PI 3-kinase inhibitor LY294002 abrogates the protective effects of the WNV capsid protein.
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NS2B/3 proteolysis at the C-prM junction of the tick-borne encephalitis virus polyprotein is highly membrane dependent. Virus Res 2012; 168:48-55. [PMID: 22727684 PMCID: PMC3437442 DOI: 10.1016/j.virusres.2012.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 06/11/2012] [Accepted: 06/11/2012] [Indexed: 11/21/2022]
Abstract
The replication of tick-borne encephalitis virus (TBEV), like that of all flaviviruses, is absolutely dependent on proteolytic processing. Production of the mature proteins C and prM from their common precursor requires the activity of the viral NS2B/3 protease (NS2B/3(pro)) at the C-terminus of protein C and the host signal peptidase I (SPaseI) at the N-terminus of protein prM. Recently, we have shown in cell culture that the cleavage of protein C and the subsequent production of TBEV particles can be made dependent on the activity of the foot-and-mouth disease virus 3C protease, but not on the activity of the HIV-1 protease (HIV1(pro)) (Schrauf et al., 2012). To investigate this failure, we developed an in vitro cleavage assay to assess the two cleavage reactions performed on the C-prM precursor. Accordingly, a recombinant modular NS2B/3(pro), consisting of the protease domain of NS3 linked to the core-domain of cofactor NS2B, was expressed in E. coli and purified to homogeneity. This enzyme could cleave a C-prM protein synthesised in rabbit reticulocyte lysates. However, cleavage was only specific when protein synthesis was performed in the presence of canine pancreatic microsomal membranes and required the prevention of signal peptidase I (SPaseI) activity by lengthening the h-region of the signal peptide. The presence of membranes allowed the concentration of NS2B/3(pro) used to be reduced by 10-20 fold. Substitution of the NS2B/3(pro) cleavage motif in C-prM by a HIV-1(pro) motif inhibited NS2B/3(pro) processing in the presence of microsomal membranes but allowed cleavage by HIV-1(pro) at the C-prM junction. This system shows that processing at the C-terminus of protein C by the TBEV NS2B/3(pro) is highly membrane dependent and will allow the examination of how the membrane topology of protein C affects both SPaseI and NS2B/3(pro) processing.
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Schrauf S, Kurz M, Taucher C, Mandl CW, Skern T. Generation and genetic stability of tick-borne encephalitis virus mutants dependent on processing by the foot-and-mouth disease virus 3C protease. J Gen Virol 2012; 93:504-515. [PMID: 22131310 PMCID: PMC3918513 DOI: 10.1099/vir.0.038398-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mature protein C of tick-borne encephalitis virus (TBEV) is cleaved from the polyprotein precursor by the viral NS2B/3 protease (NS2B/3(pro)). We showed previously that replacement of the NS2B/3(pro) cleavage site at the C terminus of protein C by the foot-and-mouth disease virus (FMDV) 2A StopGo sequence leads to the production of infectious virions. Here, we show that infectious virions can also be produced from a TBEV mutant bearing an inactivated 2A sequence through the expression of the FMDV 3C protease (3C(pro)) either in cis or in trans (from a TBEV replicon). Cleavage at the C terminus of protein C depended on the catalytic activity of 3C(pro) as well as on the presence of an optimized 3C(pro) cleavage site. Passage of the TBEV mutants bearing a 3C(pro) cleavage site either in the absence of 3C(pro) or in the presence of a catalytically inactive 3C(pro) led to the appearance of revertants in which protein C cleavage by NS2B/3(pro) had been regained. In three different revertants, a cleavage site for NS2B/3(pro), namely RR*C, was now present, leading to an elongated protein C. Furthermore, two revertants acquired additional mutations in the C terminus of protein C, eliminating two basic residues. Although these latter mutants showed wild-type levels of early RNA synthesis, their foci were smaller and an accumulation of protein C in the cytoplasm was observed. These findings suggest a role of the positive charge of the C terminus of protein C for budding of the nucleocapsid and further support the notion that TBEV protein C is a multifunctional protein.
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Affiliation(s)
- Sabrina Schrauf
- Institute of Virology, Medical University of Vienna, Kinderspitalgasse 15, A-1095 Vienna, Austria
| | - Martina Kurz
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, A-1030 Vienna, Austria
| | - Christian Taucher
- Institute of Virology, Medical University of Vienna, Kinderspitalgasse 15, A-1095 Vienna, Austria
| | - Christian W. Mandl
- Institute of Virology, Medical University of Vienna, Kinderspitalgasse 15, A-1095 Vienna, Austria
| | - Tim Skern
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, A-1030 Vienna, Austria
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Leardkamolkarn V, Sirigulpanit W, Chotiwan N, Kumkate S, Huang CYH. Development of Dengue type-2 virus replicons expressing GFP reporter gene in study of viral RNA replication. Virus Res 2011; 163:552-62. [PMID: 22197424 DOI: 10.1016/j.virusres.2011.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 11/19/2022]
Abstract
Insertion of green fluorescent protein (GFP) encoding-gene into virus genes has provided a valuable tool for flavivirus research. This study aimed to develop dengue virus (DENV) replicons expressing GFP reporter that would provide a fast in vitro system to analyze functional roles of specific DENV sequences in viral replication. Two classes of recombinant replicon constructs were generated; one was a RNA-launched replicon with a GFP gene directly inserted into a full-length DENV genome (FL-DENV/GFP), and the other consisted of 4 types of DNA-launched DENV subgenomic replicons with GFP replacement at various structural genes (Δ-DENV/GFP). The FL-DENV/GFP resulted in GFP expression in transfected cells with no viable DENV being recovered from the transfection. The Δ-DENV/GFP constructs with partial structural gene deletion (ΔC-, ΔCprM/M-, ΔprM/M-, or ΔE-) expressed bright and long lasting GFP. The GFP expression intensity in living cells correlated well with the level of RNA replication. Various mutations in the 5'noncoding region of DENV-2 previously shown to be important genetic determinants for virus replication and mouse virulence were incorporated into the 5 different replicon constructs. Characterizations of 29 mutants demonstrated that these replicons can provide a useful platform for a quick and powerful in vitro system to analyze genetic determinants of DENV replication. These constructs can also be useful for development of vectors expressing foreign genes for various researches.
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Composition of the sequence downstream of the dengue virus 5' cyclization sequence (dCS) affects viral RNA replication. Virology 2011; 422:346-56. [PMID: 22137186 DOI: 10.1016/j.virol.2011.10.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 08/11/2011] [Accepted: 10/28/2011] [Indexed: 12/31/2022]
Abstract
RNA replication of dengue virus (DENV) requires an RNA-RNA mediated circularization of the viral genome, which includes at least three sets of complementary RNA sequences on both ends of the genome. The 5' and the 3' untranslated regions form several additional RNA elements that are involved in regulation of translation and required for RNA replication. Communication between the genomic termini results in a structural reorganization of the RNA elements, forming a functional RNA panhandle structure. Here we report that the sequence composition downstream of the 5' CS element in the capsid gene, designated as downstream CS (dCS) sequence - but not the capsid protein - also influences the ability of the viral genome to circularize and hence replicate by modulating the topology of the 5' end. These results provide insights for the design of reporter sub-genomic and genomic mosquito-borne flavivirus constructs and contribute to the understanding of viral RNA replication.
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Rumyantsev AA, Giel-Moloney M, Liu Y, Gao QS, Zhang ZX, Catalan J, Frolov I, Almond J, Kleanthous H, Pugachev KV. Characterization of the RepliVax platform for replication-defective flavivirus vaccines. Vaccine 2011; 29:5184-94. [DOI: 10.1016/j.vaccine.2011.05.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/06/2011] [Accepted: 05/11/2011] [Indexed: 02/06/2023]
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50
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Yi Z, Sperzel L, Nürnberger C, Bredenbeek PJ, Lubick KJ, Best SM, Stoyanov CT, Law LMJ, Yuan Z, Rice CM, MacDonald MR. Identification and characterization of the host protein DNAJC14 as a broadly active flavivirus replication modulator. PLoS Pathog 2011; 7:e1001255. [PMID: 21249176 PMCID: PMC3020928 DOI: 10.1371/journal.ppat.1001255] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 12/10/2010] [Indexed: 12/14/2022] Open
Abstract
Viruses in the Flavivirus genus of the Flaviviridae family are arthropod-transmitted and contribute to staggering numbers of human infections and significant deaths annually across the globe. To identify cellular factors with antiviral activity against flaviviruses, we screened a cDNA library using an iterative approach. We identified a mammalian Hsp40 chaperone protein (DNAJC14) that when overexpressed was able to mediate protection from yellow fever virus (YFV)-induced cell death. Further studies revealed that DNAJC14 inhibits YFV at the step of viral RNA replication. Since replication of bovine viral diarrhea virus (BVDV), a member of the related Pestivirus genus, is also known to be modulated by DNAJC14, we tested the effect of this host factor on diverse Flaviviridae family members. Flaviviruses, including the pathogenic Asibi strain of YFV, Kunjin, and tick-borne Langat virus, as well as a Hepacivirus, hepatitis C virus (HCV), all were inhibited by overexpression of DNAJC14. Mutagenesis showed that both the J-domain and the C-terminal domain, which mediates self-interaction, are required for anti-YFV activity. We found that DNAJC14 does not block YFV nor HCV NS2-3 cleavage, and using non-inhibitory mutants demonstrate that DNAJC14 is recruited to YFV replication complexes. Immunofluorescence analysis demonstrated that endogenous DNAJC14 rearranges during infection and is found in replication complexes identified by dsRNA staining. Interestingly, silencing of endogenous DNAJC14 results in impaired YFV replication suggesting a requirement for DNAJC14 in YFV replication complex assembly. Finally, the antiviral activity of overexpressed DNAJC14 occurs in a time- and dose-dependent manner. DNAJC14 overexpression may disrupt the proper stoichiometry resulting in inhibition, which can be overcome upon restoration of the optimal ratios due to the accumulation of viral nonstructural proteins. Our findings, together with previously published work, suggest that the members of the Flaviviridae family have evolved in unique and important ways to interact with this host Hsp40 chaperone molecule.
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Affiliation(s)
- Zhigang Yi
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
- Key Laboratory of Medical Molecular Virology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Lindsey Sperzel
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
| | - Cindy Nürnberger
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
| | - Peter J. Bredenbeek
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Kirk J. Lubick
- Laboratory of Virology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana, United States of America
| | - Sonja M. Best
- Laboratory of Virology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana, United States of America
| | - Cristina T. Stoyanov
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
| | - Lok Man J. Law
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
| | - Zhenghong Yuan
- Key Laboratory of Medical Molecular Virology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Charles M. Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
| | - Margaret R. MacDonald
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, New York, United States of America
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