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Dahmane S, Schexnaydre E, Zhang J, Rosendal E, Chotiwan N, Kumari Singh B, Yau WL, Lundmark R, Barad B, Grotjahn DA, Liese S, Carlson A, Overby A, Carlson LA. Cryo-electron tomography reveals coupled flavivirus replication, budding and maturation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.13.618056. [PMID: 39416041 PMCID: PMC11482891 DOI: 10.1101/2024.10.13.618056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
Flaviviruses replicate their genomes in replication organelles (ROs) formed as bud-like invaginations on the endoplasmic reticulum (ER) membrane, which also functions as the site for virion assembly. While this localization is well established, it is not known to what extent viral membrane remodeling, genome replication, virion assembly, and maturation are coordinated. Here, we imaged tick-borne flavivirus replication in human cells using cryo-electron tomography. We find that the RO membrane bud is shaped by a combination of a curvature-establishing coat and the pressure from intraluminal template RNA. A protein complex at the RO base extends to an adjacent membrane, where immature virions bud. Naturally occurring furin site variants determine whether virions mature in the immediate vicinity of ROs. We further visualize replication in mouse brain tissue by cryo-electron tomography. Taken together, these findings reveal a close spatial coupling of flavivirus genome replication, budding, and maturation.
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Ci Y, Shi L. Compartmentalized replication organelle of flavivirus at the ER and the factors involved. Cell Mol Life Sci 2021; 78:4939-4954. [PMID: 33846827 PMCID: PMC8041242 DOI: 10.1007/s00018-021-03834-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 03/16/2021] [Accepted: 04/01/2021] [Indexed: 12/14/2022]
Abstract
Flaviviruses are positive-sense single-stranded RNA viruses that pose a considerable threat to human health. Flaviviruses replicate in compartmentalized replication organelles derived from the host endoplasmic reticulum (ER). The characteristic architecture of flavivirus replication organelles includes invaginated vesicle packets and convoluted membrane structures. Multiple factors, including both viral proteins and host factors, contribute to the biogenesis of the flavivirus replication organelle. Several viral nonstructural (NS) proteins with membrane activity induce ER rearrangement to build replication compartments, and other NS proteins constitute the replication complexes (RC) in the compartments. Host protein and lipid factors facilitate the formation of replication organelles. The lipid membrane, proteins and viral RNA together form the functional compartmentalized replication organelle, in which the flaviviruses efficiently synthesize viral RNA. Here, we reviewed recent advances in understanding the structure and biogenesis of flavivirus replication organelles, and we further discuss the function of virus NS proteins and related host factors as well as their roles in building the replication organelle.
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Affiliation(s)
- Yali Ci
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China. .,Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
| | - Lei Shi
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China. .,Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
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[Nuclei ultrastructural changes of C6/36 cells infected with virus dengue type 2]. BIOMEDICA 2018; 38:135-143. [PMID: 30184368 DOI: 10.7705/biomedica.v38i0.3997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 04/04/2018] [Indexed: 01/17/2023]
Abstract
INTRODUCTION Dengue virus replication has been considered mainly cytoplasmic, however, studies indicate that some flaviviruses may use the intranuclear pathway as part of the machinery that the virus uses to increase infection capacity in the host cell. This paper describes alterations at nuclear level in the cell infected with dengue, which are likely involved in the virus replication processes. OBJECTIVE This paper addresses the ultrastructural observations of C6/36 cells of the Aedes albopictus mosquito infected with dengue virus type 2. MATERIALS AND METHODS C6/36 cells were infected in culture medium with the serum of a patient positively diagnosed for dengue 2. Subsequently, the cells were incubated for 10 days and the cytopathic effect was assessed. The cells were processed for immunofluorescence assays and transmission electron microscopy. RESULTS The immunofluorescence assays confirmed the presence of viral protein E associated with cellular syncytia in the culture. In the ultrastructural study, the infected cells showed vesicular-tubular structures and dilated cisterns of the endoplasmic reticulum at the cytoplasmic level. Viral particles were found exclusively in cytoplasm localized within the vacuoles. Nuclei of cellular syncytia showed membrane structures arranged in a circular shape and, in some cases, these syncytia displayed lysis; in no case viral particles were observed at the nuclear level. CONCLUSIONS The ultrastructural alterations of nuclei in cells infected with the dengue virus using electron microscopy techniques had not been reported before, as far as we know. It is likely that such modifications are associated with replicative processes at an intranuclear level as an alternate replication mechanism.
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Mosimann ALP, de Siqueira MK, Ceole LF, Nunes Duarte Dos Santos C. A new Aura virus isolate in Brazil shows segment duplication in the variable region of the nsP3 gene. Parasit Vectors 2018; 11:321. [PMID: 29843810 PMCID: PMC5975265 DOI: 10.1186/s13071-018-2907-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 05/20/2018] [Indexed: 12/03/2022] Open
Abstract
Background A new isolate of Aura virus serendipitously discovered as a cell culture contaminant is reported in this manuscript. Aura virus belongs to the family Togaviridae and is classified in the genus Alphavirus. There are only two reports of Aura virus isolation from mosquitoes in the scientific literature, and the existence of a vertebrate host is still unknown. The discovery of this new isolate was based on transmission electron microscopy and nucleic acid amplification through a non-specific RT-PCR amplification protocol followed by sequencing. Results Genetic analysis has shown that the new virus shares a high degree of identity with the previously described isolate (GenBank: AF126284.1). A major difference was observed in the nsP3 gene in which a 234-nucleotide duplication has been identified. Furthermore, a pronounced difference was observed in cell cultures compared to the data available for the previously described isolate. Cell permissiveness and phenotypic characteristics in C6/36, Vero and BHK-21 cells were found to differ from previous reports. This may be due to the genetic differences that have been observed. Conclusions The genetic and biological characteristics of the new Aura virus isolate are suggestive of viral adaptation to the cell substrate. The development of a cDNA clone will lend a perspective and better understanding of these results as well as open avenues for its use as a biotechnological tool, as seen for other alphaviruses. Electronic supplementary material The online version of this article (10.1186/s13071-018-2907-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ana Luiza Pamplona Mosimann
- Laboratory of Molecular Virology, Instituto Carlos Chagas, FIOCRUZ, Rua Prof. Algacyr Munhoz Mader 3775, Cidade Industrial, Curitiba, PR, 81350-010, Brazil
| | - Mirian Krystel de Siqueira
- Laboratory of Molecular Virology, Instituto Carlos Chagas, FIOCRUZ, Rua Prof. Algacyr Munhoz Mader 3775, Cidade Industrial, Curitiba, PR, 81350-010, Brazil.,Present Address: Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, SP, 13083-970, Brazil
| | - Ligia Fernanda Ceole
- Laboratory of Cell Biology, Instituto Carlos Chagas, FIOCRUZ, Rua Prof. Algacyr Munhoz Mader 3775, Cidade Industrial, Curitiba, PR, 81350-010, Brazil
| | - Claudia Nunes Duarte Dos Santos
- Laboratory of Molecular Virology, Instituto Carlos Chagas, FIOCRUZ, Rua Prof. Algacyr Munhoz Mader 3775, Cidade Industrial, Curitiba, PR, 81350-010, Brazil.
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Clark KB, Hsiao HM, Bassit L, Crowe JE, Schinazi RF, Perng GC, Villinger F. Characterization of dengue virus 2 growth in megakaryocyte-erythrocyte progenitor cells. Virology 2016; 493:162-72. [PMID: 27058763 DOI: 10.1016/j.virol.2016.03.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/26/2016] [Accepted: 03/28/2016] [Indexed: 10/22/2022]
Abstract
Megakaryocyte-erythrocyte progenitor (MEP) cells are potential in vivo targets of dengue virus (DENV); the virus has been found associated with megakaryocytes ex vivo and platelets during DENV-induced thrombocytopenia. We report here that DENV serotype 2 (DENV2) propagates well in human nondifferentiated MEP cell lines (Meg01 and K562). In comparison to virus propagated in Vero cells, viruses from MEP cell lines had similar structure and buoyant density. However, differences in MEP-DENV2 stability and composition were suggested by distinct protein patterns in western blot analysis. Also, antibody neutralization of envelope domain I/II on MEP-DENV2 was reduced relative to that on Vero-DENV2. Infectious DENV2 was produced at comparable kinetics and magnitude in MEP and Vero cells. However, fewer virion structures appeared in electron micrographs of MEP cells. We propose that DENV2 infects and produces virus efficiently in megakaryocytes and that megakaryocyte impairment might contribute to dengue disease pathogenesis.
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Affiliation(s)
- Kristina B Clark
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
| | - Hui-Mien Hsiao
- Center for AIDS Research, Department of Pediatrics, Emory University School of Medicine and Veterans Affairs Medical Center, Atlanta, GA, USA
| | - Leda Bassit
- Center for AIDS Research, Department of Pediatrics, Emory University School of Medicine and Veterans Affairs Medical Center, Atlanta, GA, USA
| | - James E Crowe
- Departments of Pediatrics, Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN, USA
| | - Raymond F Schinazi
- Center for AIDS Research, Department of Pediatrics, Emory University School of Medicine and Veterans Affairs Medical Center, Atlanta, GA, USA
| | - Guey Chuen Perng
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Francois Villinger
- Division of Microbiology and Immunology, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA; New Iberia Research Center, University of Louisiana at Lafayette, New Iberia, LA, USA
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Burlaud-Gaillard J, Sellin C, Georgeault S, Uzbekov R, Lebos C, Guillaume JM, Roingeard P. Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles. PLoS One 2014; 9:e93573. [PMID: 24681578 PMCID: PMC3969332 DOI: 10.1371/journal.pone.0093573] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 03/07/2014] [Indexed: 12/29/2022] Open
Abstract
The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.
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Affiliation(s)
- Julien Burlaud-Gaillard
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
| | - Caroline Sellin
- Département Bioprocess, Upstream Platform, Sanofi Pasteur, Marcy l'Etoile, France
| | - Sonia Georgeault
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
| | - Rustem Uzbekov
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
| | - Claude Lebos
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
| | - Jean-Marc Guillaume
- Département Bioprocess, Upstream Platform, Sanofi Pasteur, Marcy l'Etoile, France
| | - Philippe Roingeard
- Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France
- INSERM U966, Université François Rabelais and CHRU de Tours, Tours, France
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Ultrastructural characterization and three-dimensional architecture of replication sites in dengue virus-infected mosquito cells. J Virol 2014; 88:4687-97. [PMID: 24522909 DOI: 10.1128/jvi.00118-14] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED During dengue virus infection of host cells, intracellular membranes are rearranged into distinct subcellular structures such as double-membrane vesicles, convoluted membranes, and tubular structures. Recent electron tomographic studies have provided a detailed three-dimensional architecture of the double-membrane vesicles, representing the sites of dengue virus replication, but temporal and spatial evidence linking membrane morphogenesis with viral RNA synthesis is lacking. Integrating techniques in electron tomography and molecular virology, we defined an early period in virus-infected mosquito cells during which the formation of a virus-modified membrane structure, the double-membrane vesicle, is proportional to the rate of viral RNA synthesis. Convoluted membranes were absent in dengue virus-infected C6/36 cells. Electron tomographic reconstructions elucidated a high-resolution view of the replication complexes inside vesicles and allowed us to identify distinct pathways of particle formation. Hence, our findings extend the structural details of dengue virus replication within mosquito cells and highlight their differences from mammalian cells. IMPORTANCE Dengue virus induces several distinct intracellular membrane structures within the endoplasmic reticulum of mammalian cells. These structures, including double-membrane vesicles and convoluted membranes, are linked, respectively, with viral replication and viral protein processing. However, dengue virus cycles between two disparate animal groups with differing physiologies: mammals and mosquitoes. Using techniques in electron microscopy, we examined the differences between intracellular structures induced by dengue virus in mosquito cells. Additionally, we utilized techniques in molecular virology to temporally link events in virus replication to the formation of these dengue virus-induced membrane structures.
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Acosta EG, Castilla V, Damonte EB. Differential requirements in endocytic trafficking for penetration of dengue virus. PLoS One 2012; 7:e44835. [PMID: 22970315 PMCID: PMC3436767 DOI: 10.1371/journal.pone.0044835] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/13/2012] [Indexed: 11/22/2022] Open
Abstract
The entry of DENV into the host cell appears to be a very complex process which has been started to be studied in detail. In this report, the route of functional intracellular trafficking after endocytic uptake of dengue virus serotype 1 (DENV-1) strain HW, DENV-2 strain NGC and DENV-2 strain 16681 into Vero cells was studied by using a susceptibility to ammonium chloride assay, dominant negative mutants of several members of the family of cellular Rab GTPases that participate in regulation of transport through endosome vesicles and immunofluorescence colocalization. Together, the results presented demonstrate that in spite of the different internalization route among viral serotypes in Vero cells and regardless of the viral strain, DENV particles are first transported to early endosomes in a Rab5-dependent manner. Then a Rab7-dependent pathway guides DENV-2 16681 to late endosomes, whereas a yet unknown sorting event controls the transport of DENV-2 NGC, and most probably DENV-1 HW, to the perinuclear recycling compartments where fusion membrane would take place releasing nucleocapsid into the cytoplasm. Besides the demonstration of a different intracellular trafficking for two DENV-2 strains that shared the initial clathrin-independent internalization route, these studies proved for the first time the involvement of the slow recycling pathway for DENV-2 productive infection.
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Affiliation(s)
- Eliana G. Acosta
- Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Viviana Castilla
- Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Elsa B. Damonte
- Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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A novel coding-region RNA element modulates infectious dengue virus particle production in both mammalian and mosquito cells and regulates viral replication in Aedes aegypti mosquitoes. Virology 2012; 432:511-26. [PMID: 22840606 DOI: 10.1016/j.virol.2012.06.028] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 04/17/2012] [Accepted: 06/21/2012] [Indexed: 12/20/2022]
Abstract
Dengue virus (DENV) is an enveloped flavivirus with a positive-sense RNA genome transmitted by Aedes mosquitoes, causing the most important arthropod-borne viral disease affecting humans. Relatively few cis-acting RNA regulatory elements have been described in the DENV coding-region. Here, by introducing silent mutations into a DENV-2 infectious clone, we identify the conserved capsid-coding region 1 (CCR1), an RNA sequence element that regulates viral replication in mammalian cells and to a greater extent in Ae. albopictus mosquito cells. These defects were confirmed in vivo, resulting in decreased replication in Ae. aegypti mosquito bodies and dissemination to the salivary glands. Furthermore, CCR1 does not regulate translation, RNA synthesis or virion retention but likely modulates assembly, as mutations resulted in the release of non-infectious viral particles from both cell types. Understanding the role of CCR1 could help characterize the poorly-defined stage of assembly in the DENV life cycle and uncover novel anti-viral targets.
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Perera R, Riley C, Isaac G, Hopf-Jannasch AS, Moore RJ, Weitz KW, Pasa-Tolic L, Metz TO, Adamec J, Kuhn RJ. Dengue virus infection perturbs lipid homeostasis in infected mosquito cells. PLoS Pathog 2012; 8:e1002584. [PMID: 22457619 PMCID: PMC3310792 DOI: 10.1371/journal.ppat.1002584] [Citation(s) in RCA: 247] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 01/27/2012] [Indexed: 12/21/2022] Open
Abstract
Dengue virus causes ∼50-100 million infections per year and thus is considered one of the most aggressive arthropod-borne human pathogen worldwide. During its replication, dengue virus induces dramatic alterations in the intracellular membranes of infected cells. This phenomenon is observed both in human and vector-derived cells. Using high-resolution mass spectrometry of mosquito cells, we show that this membrane remodeling is directly linked to a unique lipid repertoire induced by dengue virus infection. Specifically, 15% of the metabolites detected were significantly different between DENV infected and uninfected cells while 85% of the metabolites detected were significantly different in isolated replication complex membranes. Furthermore, we demonstrate that intracellular lipid redistribution induced by the inhibition of fatty acid synthase, the rate-limiting enzyme in lipid biosynthesis, is sufficient for cell survival but is inhibitory to dengue virus replication. Lipids that have the capacity to destabilize and change the curvature of membranes as well as lipids that change the permeability of membranes are enriched in dengue virus infected cells. Several sphingolipids and other bioactive signaling molecules that are involved in controlling membrane fusion, fission, and trafficking as well as molecules that influence cytoskeletal reorganization are also up regulated during dengue infection. These observations shed light on the emerging role of lipids in shaping the membrane and protein environments during viral infections and suggest membrane-organizing principles that may influence virus-induced intracellular membrane architecture.
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Affiliation(s)
- Rushika Perera
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Catherine Riley
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Giorgis Isaac
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Amber S. Hopf-Jannasch
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America
| | - Ronald J. Moore
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Karl W. Weitz
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Ljiljana Pasa-Tolic
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Thomas O. Metz
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Jiri Adamec
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America
| | - Richard J. Kuhn
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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Růžek D, Vancová M, Tesařová M, Ahantarig A, Kopecký J, Grubhoffer L. Morphological changes in human neural cells following tick-borne encephalitis virus infection. J Gen Virol 2009; 90:1649-1658. [DOI: 10.1099/vir.0.010058-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
Tick-borne encephalitis (TBE) is one of the leading and most dangerous human viral neuroinfections in Europe and north-eastern Asia. The clinical manifestations include asymptomatic infections, fevers and debilitating encephalitis that might progress into chronic disease or fatal infection. To understand TBE pathology further in host nervous systems, three human neural cell lines, neuroblastoma, medulloblastoma and glioblastoma, were infected with TBE virus (TBEV). The susceptibility and virus-mediated cytopathic effect, including ultrastructural and apoptotic changes of the cells, were examined. All the neural cell lines tested were susceptible to TBEV infection. Interestingly, the neural cells produced about 100- to 10 000-fold higher virus titres than the conventional cell lines of extraneural origin, indicating the highly susceptible nature of neural cells to TBEV infection. The infection of medulloblastoma and glioblastoma cells was associated with a number of major morphological changes, including proliferation of membranes of the rough endoplasmic reticulum and extensive rearrangement of cytoskeletal structures. The TBEV-infected cells exhibited either necrotic or apoptotic morphological features. We observed ultrastructural apoptotic signs (condensation, margination and fragmentation of chromatin) and other alterations, such as vacuolation of the cytoplasm, dilatation of the endoplasmic reticulum cisternae and shrinkage of cells, accompanied by a high density of the cytoplasm. On the other hand, infected neuroblastoma cells did not exhibit proliferation of membranous structures. The virions were present in both the endoplasmic reticulum and the cytoplasm. Cells were dying preferentially by necrotic mechanisms rather than apoptosis. The neuropathological significance of these observations is discussed.
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Affiliation(s)
- Daniel Růžek
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Martina Tesařová
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Arunee Ahantarig
- Faculty of Science, Mahidol University, 6 Rama Road, Bangkok 10400, Thailand
| | - Jan Kopecký
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic and Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
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12
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Khakpoor A, Panyasrivanit M, Wikan N, Smith DR. A role for autophagolysosomes in dengue virus 3 production in HepG2 cells. J Gen Virol 2009; 90:1093-1103. [PMID: 19264601 DOI: 10.1099/vir.0.007914-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We have recently proposed that amphisomes act as a site for translation and replication of dengue virus (DENV)-2 and that DENV-2 entry and replication are linked through an ongoing association with membranes of an endosomal-autophagosomal lineage. In this report, we present the results of an investigation into the interaction between DENV-3 and the autophagy machinery. Critically, treatment with the lysosomal fusion inhibitor l-asparagine differentiated the interaction of DENV-3 from that of DENV-2. Inhibition of fusion of autophagosomes and amphisomes with lysosomes resulted in decreased DENV-3 production, implying a role for the autophagolysosome in the DENV-3 life cycle. Evidence based upon the co-localization of LC3 and cathepsin D with double stranded RNA and NS1 protein, as assessed by confocal microscopy, support a model in which DENV-3 interacts with both amphisomes and autophagolysosomes. These results demonstrate that the interactions between DENV and the host cell autophagy machinery are complex and may be determined in part by virus-encoded factors.
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Affiliation(s)
- Atefeh Khakpoor
- Molecular Pathology Laboratory, Institute of Molecular Biology and Genetics, Mahidol University, Thailand
| | - Mingkwan Panyasrivanit
- Molecular Pathology Laboratory, Institute of Molecular Biology and Genetics, Mahidol University, Thailand
| | - Nitwara Wikan
- Molecular Pathology Laboratory, Institute of Molecular Biology and Genetics, Mahidol University, Thailand
| | - Duncan R Smith
- Molecular Pathology Laboratory, Institute of Molecular Biology and Genetics, Mahidol University, Thailand
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Kiermayr S, Kofler RM, Mandl CW, Messner P, Heinz FX. Isolation of capsid protein dimers from the tick-borne encephalitis flavivirus and in vitro assembly of capsid-like particles. J Virol 2004; 78:8078-84. [PMID: 15254179 PMCID: PMC446133 DOI: 10.1128/jvi.78.15.8078-8084.2004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flaviviruses have a spherical capsid that is composed of multiple copies of a single capsid protein and, in contrast to the viral envelope, apparently does not have an icosahedral structure. So far, attempts to isolate distinct particulate capsids and soluble forms of the capsid protein from purified virions as well as to assemble capsid-like particles in vitro have been largely unsuccessful. Here we describe the isolation of nucleocapsids from tick-borne encephalitis (TBE) virus and their disintegration into a capsid protein dimer by high-salt treatment. Purified capsid protein dimers could be assembled in vitro into capsid-like particles when combined with in vitro transcribed viral RNA. Particulate structures could also be obtained when single-stranded DNA oligonucleotides were used. These data suggest that the dimeric capsid protein functions as a basic building block in the assembly process of flaviviruses.
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Affiliation(s)
- Stefan Kiermayr
- Institute of Virology, Medical University of Vienna, Vienna, Austria
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Hilgard P, Czaja MJ, Gerken G, Stockert RJ. Proapoptotic function of protein kinase CK2alpha" is mediated by a JNK signaling cascade. Am J Physiol Gastrointest Liver Physiol 2004; 287:G192-201. [PMID: 14962846 DOI: 10.1152/ajpgi.00507.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Protein kinase CK2 (formerly casein kinase II) is a tetrameric enzyme constitutively expressed in all eurakyotic tissues that plays a significant role in the regulation of cell proliferation, malignant transformation, and apoptosis. The catalytic alpha-subunit of the enzyme is known to exist in three isoforms CK2alpha, CK2alpha' and CK2alpha". CK2alpha" is highly expressed in liver compared with other tissues and is required for the normal trafficking of several hepatocellular membrane proteins. Initial studies of dengue virus infection indicated that the CK2alpha"-deficient membrane trafficking mutant cell line (Trf1) was resistant to virus-induced cell death compared with the parental human hepatoma (HuH)-7 hepatoma line. Expression of recombinant CK2alpha" in Trf1 was capable of reverting this resistant phenotype. This study was extended to TNF-alpha in addition to other stimuli of cell death in an attempt to uncover common death pathways that might be modulated by CK2alpha". Evaluation of different pathways involved in death signaling suggest that the regulation of a critical proapoptotic step in HuH-7 cells by CK2alpha" is mediated by a JNK signaling cascade.
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Affiliation(s)
- Philip Hilgard
- Department for Gastroenterology and Hepatology, University-Hospital Essen, 45133 Essen, Germany
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Affiliation(s)
- Brett D Lindenbach
- Center for the Study of Hepatitis C, Laboratory of Virology and Infectious Disease, Rockefeller University, New York, New York 10021, USA
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16
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Ng ML, Chu JH. Interaction of West Nile and Kunjin viruses with cellular components during morphogenesis. Curr Top Microbiol Immunol 2002; 267:353-72. [PMID: 12082997 DOI: 10.1007/978-3-642-59403-8_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- M L Ng
- Department of Microbiology, 5 Science Drive 2, National University of Singapore, 11759 Singapore
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17
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Abstract
Dengue viruses (DEN) cause a broad spectrum of clinical manifestations including potentially life-threatening conditions such as hemorrhagic shock syndrome and less frequently acute hepatitis with liver failure and encephalopathy. In addition, dengue viruses provide a potential model to understand the initiation of hepatocyte infection by the structurally closely related hepatitis C virus (HCV), because this virus at present cannot be grown in cell culture. Although the initial steps of viral infection are a critical determinant of tissue tropism and therefore pathogenesis, little is known about the molecular basis of binding and endocytic trafficking of DEN or of any other flavivirus. Our studies revealed that binding of radiolabeled DEN to the human hepatoma cell line HuH-7 was strictly pH dependent and substantially inhibitable by the glycosaminoglycan heparin. Ligand-blot analysis, performed as a viral overlay assay, showed two heparan sulfate (HS) containing cell-surface binding proteins resolving at 33 and 37 kd. Based on the sensitivity of unprotected virus and the viral binding site on the cell surface to trypsin, viral internalization was quantified as an increase in trypsin protected virus over time. Virus trafficking to the site of degradation was inhibited by pH dissociation of the clathrin coat and dependent on IP(3)-mediated homotypic endosomal fusion. These findings confirm the hypothesis that binding and internalization of DEN by hepatocytes are mediated primarily by HS containing proteoglycans and suggest that flaviviruses traffic the major clathrin-dependent endocytic pathway during infection.
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Affiliation(s)
- P Hilgard
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Ng ML, Yeong FM, Tan SH. Cryosubstitution technique reveals new morphology of flavivirus-induced structures. J Virol Methods 1994; 49:305-14. [PMID: 7868648 DOI: 10.1016/0166-0934(94)90145-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cryotechniques in combination with electron microscopy were used in an attempt to obtain more precise morphological details of flavivirus-induced structures. From conventional chemical fixation procedure, proliferation of endoplasmic reticulum, formation of microtubule paracrystals and clusters of smooth membrane vesicles (with 'thread-like' enclosures) were observed. These induced changes are typical for flavivirus infections. The images obtained from cryosections were disappointing as the structures were not well preserved. On the other hand, cryosubstituted-infected cells gave revealing images of the virus-induced structures. The most obvious difference between the cryosubstituted and chemical fixed processes was on the morphology of the 'thread-like' structure. The 'thread-like' structures instead appeared as dense cores. The morphology of the virus particles was also better defined. The envelope of the virus appeared clearly differentiated from the nucleocapsid. The most important finding was that the cryosubstituted technique was able to preserve the structures of the flavivirus nucleocapsids which so far has not been convincing reported with chemical processing.
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Affiliation(s)
- M L Ng
- Department of Microbiology, Faculty of Medicine, National University of Singapore
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Ng ML, Howe J, Sreenivasan V, Mulders JJ. Flavivirus West Nile (Sarafend) egress at the plasma membrane. Arch Virol 1994; 137:303-13. [PMID: 7944952 DOI: 10.1007/bf01309477] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
West Nile (Sarafend) virus was distinctly observed to bud from the plasma membrane rather than mature intracellularly. This has been observed with transmission electron microscopy. Using conventional scanning electron microscopy, budding at the plasma membrane especially at the filopodia was clearly illustrated. Immunogold labelling against the virus envelope protein was also performed to confirm this mode of exit. The gold particles were observed to be located at the sites where virus budding was seen under the field emission scanning electron microscope.
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Affiliation(s)
- M L Ng
- Department of Microbiology, National University of Singapore
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20
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Ng ML, Hong SS. Flavivirus infection: essential ultrastructural changes and association of Kunjin virus NS3 protein with microtubules. Arch Virol 1989; 106:103-20. [PMID: 2548454 DOI: 10.1007/bf01311042] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Virus-induced vesicles evolved early in the Kunjin virus replication cycle around 9 to 10 h p.i. just before the end of the latent period in infected Vero cells. About 2 h following the appearance of the vesicles, microtubule paracrystals were also formed. These two virus-induced structures seemed interlinked and have essential roles in Kunjin virus replication. A viral protein NS3 was found to be associated with the microtubule component of the cells. When vinblastine sulphate was added to the cells immediately after infection, formation of the paracrystals was delayed by two hours, and the affiliation of NS3 protein was also observed to be rearranged.
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Affiliation(s)
- M L Ng
- Department of Microbiology, National University of Singapore
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21
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Hase T, Summers PL, Eckels KH, Baze WB. An electron and immunoelectron microscopic study of dengue-2 virus infection of cultured mosquito cells: maturation events. Arch Virol 1987; 92:273-91. [PMID: 3813888 DOI: 10.1007/bf01317484] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The maturation process of dengue-2 virus in C6/36 mosquito cells was studied by electron microscopy at 12, 16, 24, 48, and 78 hours postinoculation (p.i.) and by immunoelectron microscopy at 48 and 78 hours p.i. Maturing virions appeared within cytoplasmic vacuoles and on the surface of infected cells from 24 hours p.i. onward in close topographical relationship to the dense particles that occurred concurrently in the cytoplasm. The dense particles measured 25 to 35 nm in diameter; the mature virions measured 50 to 55 nm in diameter, with a dense core measuring 30 to 35 nm in diameter covered by a 10 nm-thick membrane envelope. The morphological observations indicated that the dense particles were dengue nucleocapsids assembled in the cytoplasm and that they apparently budded into the vacuolar lumens and the extracellular space at the vacuolar and plasma membranes, acquiring membrane envelopes and becoming mature virions in the process. The virions that budded into the vacuolar lumens were released extracellularly by exocytosis. In the samples tested with dengue-2 polyclonal antibodies, intense immunostaining occurred at the sites of virus budding on the cell surface; host cell membrane and cytoplasm adjacent to the budding virions stained less intensely. In the samples tested with a dengue-2 monoclonal antibody specific for the envelope glycoprotein, budding virions stained rather exclusively, with no staining occurring in adjacent host membrane or cytoplasm.
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Mosquito Cell Culture. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/b978-0-12-007903-2.50013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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