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de Fabritus L, Nougairède A, Aubry F, Gould EA, de Lamballerie X. Attenuation of tick-borne encephalitis virus using large-scale random codon re-encoding. PLoS Pathog 2015; 11:e1004738. [PMID: 25734338 PMCID: PMC4348424 DOI: 10.1371/journal.ppat.1004738] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/09/2015] [Indexed: 12/20/2022] Open
Abstract
Large-scale codon re-encoding (i.e. introduction of a large number of synonymous mutations) is a novel method of generating attenuated viruses. Here, it was applied to the pathogenic flavivirus, tick-borne encephalitis virus (TBEV) which causes febrile illness and encephalitis in humans in forested regions of Europe and Asia. Using an infectious clone of the Oshima 5–10 strain ("wild-type virus"), a cassette of 1.4kb located in the NS5 coding region, was modified by randomly introducing 273 synonymous mutations ("re-encoded virus"). Whilst the in cellulo replicative fitness of the re-encoded virus was only slightly reduced, the re-encoded virus displayed an attenuated phenotype in a laboratory mouse model of non-lethal encephalitis. Following intra-peritoneal inoculation of either 2.105 or 2.106 TCID50 of virus, the frequency of viraemia, neurovirulence (measured using weight loss and appearance of symptoms) and neuroinvasiveness (detection of virus in the brain) were significantly decreased when compared with the wild-type virus. Mice infected by wild-type or re-encoded viruses produced comparable amounts of neutralising antibodies and results of challenge experiments demonstrated that mice previously infected with the re-encoded virus were protected against subsequent infection by the wild-type virus. This constitutes evidence that a mammalian species can be protected against infection by a virulent wild-type positive-stranded RNA virus following immunisation with a derived randomly re-encoded strain. Our results demonstrate that random codon re-encoding is potentially a simple and effective method of generating live-attenuated vaccine candidates against pathogenic flaviviruses. The arbovirus Tick-borne encephalitis virus (TBEV; genus Flavivirus) is transmitted by ticks of the Ixodes genus. TBEV causes febrile illness and encephalitis in humans in forested regions of Europe and Asia. The incidence of TBE is increasing across Central and Eastern European countries despite the availability of several licensed inactivated vaccines and appropriate vaccination programmes. Large-scale codon re-encoding, a recently developed attenuation method that modifies viral RNA nucleotide composition of large coding regions without alteration of the encoded proteins, has been successfully applied to a variety of RNA viruses. In contrast with previous empirical methods of generating live attenuated vaccines, large-scale codon re-encoding facilitates rapid generation of vaccine candidates using reverse genetics methods, by direct control of the attenuation phenotype. Additional benefits include reduced costs and induction of long-term immunity. Here, we have applied the large-scale codon re-encoding method to the TBEV to demonstrate the principle of developing a live attenuated virus vaccine which protects mice against subsequent infection with the wild type virulent virus. This study therefore illustrates that codon re-encoding is potentially an easily derived and effective method of producing live attenuated vaccine candidates against positive-stranded RNA viruses.
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Affiliation(s)
- Lauriane de Fabritus
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- * E-mail:
| | - Antoine Nougairède
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Fabien Aubry
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
| | - Ernest A Gould
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
| | - Xavier de Lamballerie
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
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Palus M, Bílý T, Elsterová J, Langhansová H, Salát J, Vancová M, Růžek D. Infection and injury of human astrocytes by tick-borne encephalitis virus. J Gen Virol 2014; 95:2411-2426. [PMID: 25000960 DOI: 10.1099/vir.0.068411-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Tick-borne encephalitis (TBE), a disease caused by tick-borne encephalitis virus (TBEV), represents the most important flaviviral neural infection in Europe and north-eastern Asia. In the central nervous system (CNS), neurons are the primary target for TBEV infection; however, infection of non-neuronal CNS cells, such as astrocytes, is not well understood. In this study, we investigated the interaction between TBEV and primary human astrocytes. We report for the first time, to the best of our knowledge, that primary human astrocytes are sensitive to TBEV infection, although the infection did not affect their viability. The infection induced a marked increase in the expression of glial fibrillary acidic protein, a marker of astrocyte activation. In addition, expression of matrix metalloproteinase 9 and several key pro-inflammatory cytokines/chemokines (e.g. tumour necrosis factor α, interferon α, interleukin (IL)-1β, IL-6, IL-8, interferon γ-induced protein 10, macrophage inflammatory protein, but not monocyte chemotactic protein 1) was upregulated. Moreover, we present a detailed description of morphological changes in TBEV-infected cells, as investigated using three-dimensional electron tomography. Several novel ultrastructural changes were observed, including the formation of unique tubule-like structures of 17.9 ±0.15 nm diameter with associated viral particles and/or virus-induced vesicles and located in the rough endoplasmic reticulum of the TBEV-infected cells. This is the first demonstration that TBEV infection activates primary human astrocytes. The infected astrocytes might be a potential source of pro-inflammatory cytokines in the TBEV-infected brain, and might contribute to the TBEV-induced neurotoxicity and blood-brain barrier breakdown that occurs during TBE. The neuropathological significance of our observations is also discussed.
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Affiliation(s)
- Martin Palus
- Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
| | - Tomáš Bílý
- Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Jana Elsterová
- Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Helena Langhansová
- Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Jiří Salát
- Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic
| | - Marie Vancová
- Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Daniel Růžek
- Department of Virology, Veterinary Research Institute, Hudcova 70, CZ-62100 Brno, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.,Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
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Mlera L, Melik W, Bloom ME. The role of viral persistence in flavivirus biology. Pathog Dis 2014; 71:137-63. [PMID: 24737600 PMCID: PMC4154581 DOI: 10.1111/2049-632x.12178] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 12/30/2022] Open
Abstract
In nature, vector borne flaviviruses are persistently cycled between either the tick or mosquito vector and small mammals such as rodents, skunks, and swine. These viruses account for considerable human morbidity and mortality worldwide. Increasing and substantial evidence of viral persistence in humans, which includes the isolation of RNA by RT PCR and infectious virus by culture, continues to be reported. Viral persistence can also be established in vitro in various human, animal, arachnid, and insect cell lines in culture. Although some research has focused on the potential roles of defective virus particles, evasion of the immune response through the manipulation of autophagy and/or apoptosis, the precise mechanism of flavivirus persistence is still not well understood. We propose additional research for further understanding of how viral persistence is established in different systems. Avenues for additional studies include determining whether the multifunctional flavivirus protein NS5 has a role in viral persistence, the development of relevant animal models of viral persistence, and investigating the host responses that allow vector borne flavivirus replication without detrimental effects on infected cells. Such studies might shed more light on the viral–host relationships and could be used to unravel the mechanisms for establishment of persistence. Persistent infections by vector borne flaviviruses are an important, but inadequately studied topic.
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Affiliation(s)
- Luwanika Mlera
- Rocky Mountain Laboratories, Laboratory of Virology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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Yu C, Achazi K, Möller L, Schulzke JD, Niedrig M, Bücker R. Tick-borne encephalitis virus replication, intracellular trafficking, and pathogenicity in human intestinal Caco-2 cell monolayers. PLoS One 2014; 9:e96957. [PMID: 24820351 PMCID: PMC4018392 DOI: 10.1371/journal.pone.0096957] [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: 01/06/2014] [Accepted: 04/13/2014] [Indexed: 12/27/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is one of the most important vector-borne viruses in Europe and Asia. Its transmission mainly occurs by the bite of an infected tick. However, consuming milk products from infected livestock animals caused TBEV cases. To better understand TBEV transmission via the alimentary route, we studied viral infection of human intestinal epithelial cells. Caco-2 cells were used to investigate pathological effects of TBEV infection. TBEV-infected Caco-2 monolayers showed morphological changes including cytoskeleton rearrangements and cytoplasmic vacuolization. Ultrastructural analysis revealed dilatation of the rough endoplasmic reticulum and further enlargement to TBEV containing caverns. Caco-2 monolayers maintained an intact epithelial barrier with stable transepithelial electrical resistance (TER) during early stage of infection. Concomitantly, viruses were detected in the basolateral medium, implying a transcytosis pathway. When Caco-2 cells were pre-treated with inhibitors of cellular pathways of endocytosis TBEV cell entry was efficiently blocked, suggesting that actin filaments (Cytochalasin) and microtubules (Nocodazole) are important for PI3K-dependent (LY294002) virus endocytosis. Moreover, experimental fluid uptake assay showed increased intracellular accumulation of FITC-dextran containing vesicles. Immunofluorescence microscopy revealed co-localization of TBEV with early endosome antigen-1 (EEA1) as well as with sorting nexin-5 (SNX5), pointing to macropinocytosis as trafficking mechanism. In the late phase of infection, further evidence was found for translocation of virus via the paracellular pathway. Five days after infection TER was slightly decreased. Epithelial barrier integrity was impaired due to increased epithelial apoptosis, leading to passive viral translocation. These findings illuminate pathomechanisms in TBEV infection of human intestinal epithelial cells and viral transmission via the alimentary route.
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Affiliation(s)
- Chao Yu
- Centre for Biological Threats and Special Pathogens, ZBS 1: Highly Pathogenic Viruses, Robert Koch Institute, Berlin, Germany
| | - Katharina Achazi
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Lars Möller
- Centre for Biological Threats and Special Pathogens, ZBS 4: Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany
| | - Joerg D. Schulzke
- Department of Gastroenterology, Infectious Diseases and Rheumatology, Division of Nutritional Medicine, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, German
- * E-mail:
| | - Matthias Niedrig
- Centre for Biological Threats and Special Pathogens, ZBS 1: Highly Pathogenic Viruses, Robert Koch Institute, Berlin, Germany
| | - Roland Bücker
- Department of Gastroenterology, Infectious Diseases and Rheumatology, Division of Nutritional Medicine, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, German
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55
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Potokar M, Korva M, Jorgačevski J, Avšič-Županc T, Zorec R. Tick-borne encephalitis virus infects rat astrocytes but does not affect their viability. PLoS One 2014; 9:e86219. [PMID: 24465969 PMCID: PMC3896472 DOI: 10.1371/journal.pone.0086219] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/11/2013] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) causes one of the most dangerous human neuroinfections in Europe and Asia. To infect neurons it must cross the blood-brain-barrier (BBB), and presumably also cells adjacent to the BBB, such as astrocytes, the most abundant glial cell type. However, the knowledge about the viral infection of glial cells is fragmental. Here we studied whether TBEV infects rat astrocytes. Rats belong to an animal group serving as a TBEV amplifying host. We employed high resolution quantitative fluorescence microscopy to investigate cell entry and cytoplasmic mobility of TBEV particles along with the effect on the cell cytoskeleton and cell survival. We report that infection of astrocytes with TBEV increases with time of exposure to TBEV and that with post-infection time TBEV particles gained higher mobility. After several days of infection actin cytoskeleton was affected, but cell survival was unchanged, indicating that rat astrocytes resist TBEV-mediated cell death, as reported for other mammalian cells. Therefore, astrocytes may present an important pool of dormant TBEV infections and a new target for therapeutic intervention.
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Affiliation(s)
- Maja Potokar
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Miša Korva
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tatjana Avšič-Županc
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Robert Zorec
- Celica Biomedical Center, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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56
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Hirano M, Yoshii K, Sakai M, Hasebe R, Ichii O, Kariwa H. Tick-borne flaviviruses alter membrane structure and replicate in dendrites of primary mouse neuronal cultures. J Gen Virol 2014; 95:849-861. [PMID: 24394700 DOI: 10.1099/vir.0.061432-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neurological diseases caused by encephalitic flaviviruses are severe and associated with high levels of mortality. However, detailed mechanisms of viral replication in the brain and features of viral pathogenesis remain poorly understood. We carried out a comparative analysis of replication of neurotropic flaviviruses: West Nile virus, Japanese encephalitis virus and tick-borne encephalitis virus (TBEV), in primary cultures of mouse brain neurons. All the flaviviruses multiplied well in primary neuronal cultures from the hippocampus, cerebral cortex and cerebellum. The distribution of viral-specific antigen in the neurons varied: TBEV infection induced accumulation of viral antigen in the neuronal dendrites to a greater extent than infection with other viruses. Viral structural proteins, non-structural proteins and dsRNA were detected in regions in which viral antigens accumulated in dendrites after TBEV replication. Replication of a TBEV replicon after infection with virus-like particles of TBEV also induced antigen accumulation, indicating that accumulated viral antigen was the result of viral RNA replication. Furthermore, electron microscopy confirmed that TBEV replication induced characteristic ultrastructural membrane alterations in the neurites: newly formed laminal membrane structures containing virion-like structures. This is the first report describing viral replication in and ultrastructural alterations of neuronal dendrites, which may cause neuronal dysfunction. These findings encourage further work aimed at understanding the molecular mechanisms of viral replication in the brain and the pathogenicity of neurotropic flaviviruses.
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Affiliation(s)
- Minato Hirano
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Kentaro Yoshii
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Mizuki Sakai
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Rie Hasebe
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Osamu Ichii
- Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Hiroaki Kariwa
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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58
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Tick-borne encephalitis virus triggers inositol-requiring enzyme 1 (IRE1) and transcription factor 6 (ATF6) pathways of unfolded protein response. Virus Res 2013; 178:471-7. [DOI: 10.1016/j.virusres.2013.10.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 10/15/2013] [Accepted: 10/21/2013] [Indexed: 12/19/2022]
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59
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Kang X, Li Y, Wei J, Zhang Y, Bian C, Wang K, Wu X, Hu Y, Li J, Yang Y. Elevation of matrix metalloproteinase-9 level in cerebrospinal fluid of tick-borne encephalitis patients is associated with IgG extravassation and disease severity. PLoS One 2013; 8:e77427. [PMID: 24223711 PMCID: PMC3815297 DOI: 10.1371/journal.pone.0077427] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/02/2013] [Indexed: 12/17/2022] Open
Abstract
Background Tick-borne encephalitis (TBE), caused by tick-borne encephalitis virus (TBEV), is an infectious disease involving the central nervous system (CNS). The pathogenesis of CNS injury has not been clearly demonstrated. Matrix metalloproteinase-9 (MMP-9) and some cytokines, such as interleukin 6 (IL-6), may play important roles in the disruption of the blood-brain barrier (BBB) and the pathogenesis of TBE. Methods 72 cerebrospinal fluid (CSF) samples were collected from TBE patients in north eastern China. IgG levels in CSF and serum were compared and MMP-9 and IL-6 levels were evaluated by ELISA. The correlation between the elevated MMP-9 levels and IgG extravasation, disease severity, and neuroinflammation was analyzed. Results Increased concentration of MMP-9 was detected in some of the CSF samples, and the elevation was found to be closely related to CSF TBEV IgG extravasation and enhancement of IL-6 expression. Moreover, elevated levels of MMP-9 were found to be correlated with IL-6 enhancement. Four of the 72 patients, the ones who died, presented with high CSF MMP-9 levels. Conclusions In TBE patients, elevated CSF MMP-9 levels were associated with brain inflammatory reaction, disruption of the blood-brain barrier, and disease severity.
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Affiliation(s)
- Xiaoping Kang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yuchang Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jingjing Wei
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yu Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Cai Bian
- Mudanjiang Forest Hospital, Mudanjiang, China
| | - Kun Wang
- Mudanjiang Forest Hospital, Mudanjiang, China
| | - Xiaoyan Wu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yi Hu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jing Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yinhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail:
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Comprehensive assessment of the genetics and virulence of tick-borne encephalitis virus strains isolated from patients with inapparent and clinical forms of the infection in the Russian Far East. Virology 2013; 443:89-98. [DOI: 10.1016/j.virol.2013.04.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 04/15/2013] [Accepted: 04/26/2013] [Indexed: 11/22/2022]
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Dehlinger D, Suer L, Elsheikh M, Peña J, Naraghi-Arani P. Dye free automated cell counting and analysis. Biotechnol Bioeng 2013; 110:838-47. [PMID: 23055412 DOI: 10.1002/bit.24757] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 12/24/2022]
Abstract
We have developed an automated cell counting method that uses images obtained at multiple focal heights to enumerate cells in confluent culture. By taking the derivative of image intensity with respect to focal height using two complementary images, we are able to count high-density monolayers of cells over a large image area. Our method resists errors arising from variability in the focal plane caused by flatness or tilt non-uniformities with a minimal amount of focal plane alignment, allowing the automated collection of images across a large area.
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Affiliation(s)
- Dietrich Dehlinger
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Plekhova NG, Somova LM, Krylova NV, Leonova GN, Lyapun IN, Smirnov IS. Biochemical markers of virus cytopathogenicity in macrophages. APPL BIOCHEM MICRO+ 2012. [DOI: 10.1134/s0003683813010158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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63
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Holtze M, Mickiené A, Atlas A, Lindquist L, Schwieler L. Elevated cerebrospinal fluid kynurenic acid levels in patients with tick-borne encephalitis. J Intern Med 2012; 272:394-401. [PMID: 22443218 DOI: 10.1111/j.1365-2796.2012.02539.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Kynurenic acid (KYNA) is a neuroactive metabolite of tryptophan that is thought to regulate cognitive functions. Previous studies have shown that levels of KYNA increase during virus infection and that this metabolite interacts with the immune system. OBJECTIVE The aim of the study was to investigate whether patients with tick-borne encephalitis (TBE), a viral infectious disease associated with long-term cognitive impairment, have increased levels of KYNA in the cerebrospinal fluid (CSF). METHODS CSF KYNA was analysed using high-performance liquid chromatography in 108 patients with TBE and 52 age-matched controls. Patients were classified according to the severity of TBE: mild (47%), moderate (44%) or severe (9%). RESULTS Concentrations of CSF KYNA were considerably higher in patients with TBE (5.3 nmol L(-1) ) than in control subjects (0.99 nmol L(-1) ). KYNA concentration in the CSF varied greatly amongst individuals with TBE and increased (P < 0.05) with the severity of disease. CONCLUSIONS This is the first study to demonstrate increased levels of CSF KYNA in patients with TBE. The importance of brain KYNA in both immune modulation and neurotransmission raises the possibility that abnormal levels of the compound in TBE might play a part in the pathophysiology of the disease. A detailed knowledge of endogenous brain KYNA during the course of CNS infection might yield further insights into the neuroimmunological role of the compound and may also provide new pharmacological approaches for the treatment of cognitive symptoms.
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Affiliation(s)
- M Holtze
- Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden
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64
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Frey S, Mossbrugger I, Altantuul D, Battsetseg J, Davaadorj R, Tserennorov D, Buyanjargal T, Otgonbaatar D, Zöller L, Speck S, Wölfel R, Dobler G, Essbauer S. Isolation, preliminary characterization, and full-genome analyses of tick-borne encephalitis virus from Mongolia. Virus Genes 2012; 45:413-25. [PMID: 22847274 DOI: 10.1007/s11262-012-0795-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 07/20/2012] [Indexed: 10/28/2022]
Abstract
Tick-borne encephalitis virus (TBEV) causes one of the most important inflammatory diseases of the central nervous system, namely severe encephalitis in Europe and Asia. Since the 1980s tick-borne encephalitis is known in Mongolia with increasing numbers of human cases reported during the last years. So far, however, data on TBEV strains are still sparse. We herein report the isolation of a TBEV strain from Ixodes persulcatus ticks collected in Mongolia in 2010. Phylogenetic analysis of the E-gene classified this isolate as Siberian subtype of TBEV. The Mongolian TBEV strain showed differences in virus titers, plaque sizes, and growth properties in two human neuronal cell-lines. In addition, the 10,242 nucleotide long open-reading frame and the corresponding polyprotein sequence were revealed. The isolate grouped in the genetic subclade of the Siberian subtype. The strain Zausaev (AF527415) and Vasilchenko (AF069066) had 97 and 94 % identity on the nucleotide level. In summary, we herein describe first detailed data regarding TBEV from Mongolia. Further investigations of TBEV in Mongolia and adjacent areas are needed to understand the intricate dispersal of this virus.
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Affiliation(s)
- Stefan Frey
- Department of Virology & Rickettsiology, Bundeswehr Institute of Microbiology, Neuherbergstraße 11, Munich, Germany
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65
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Sips GJ, Wilschut J, Smit JM. Neuroinvasive flavivirus infections. Rev Med Virol 2011; 22:69-87. [PMID: 22086854 DOI: 10.1002/rmv.712] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/05/2011] [Accepted: 08/09/2011] [Indexed: 12/16/2022]
Abstract
Flaviviruses, including Dengue, West Nile, Japanese encephalitis, and Tick-borne encephalitis virus, are major emerging human pathogens, affecting millions of individuals worldwide. Many clinically important flaviviruses elicit CNS diseases in infected hosts, including traditional "hemorrhagic" viruses, such as Dengue. This review focuses on the epidemiology, symptomatology, neuropathology, and, specifically, neuropathogenesis of flavivirus-induced human CNS disease. A detailed insight into specific factors priming towards neuroinvasive disease is of clear clinical significance, as well as importance to the development of antiviral therapies and identification of key mechanisms involved in the (re)emergence of specific flaviviruses, including potentially novel or previously unrecognized ones, as neuroinvasive pathogens.
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Affiliation(s)
- Gregorius J Sips
- Department of Medical Microbiology, Molecular Virology Section, University Medical Center Groningen, University of Groningen, The Netherlands
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66
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Jakubova R, Mickova A, Buzgo M, Rampichova M, Prosecka E, Tvrdik D, Amler E. Immobilization of thrombocytes on PCL nanofibres enhances chondrocyte proliferation in vitro. Cell Prolif 2011; 44:183-91. [PMID: 21401760 DOI: 10.1111/j.1365-2184.2011.00737.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVES The aim of this study was to develop functionalized nanofibres as a simple delivery system for growth factors (GFs) and make nanofibre cell-seeded scaffold implants a one-step intervention. MATERIALS AND METHODS We have functionalized polycaprolactone (PCL) nanofibres with thrombocytes adherent on them. Immobilized, these thrombocytes attached to nanofibre scaffolds were used as a nanoscale delivery system for native (autologous) proliferation and differentiation factors, in vitro. Pig chondrocytes were seeded on the thrombocyte-coated scaffolds and levels of proliferation and differentiation of these cells were compared with those seeded on non-coated scaffolds. RESULTS Immobilized thrombocytes on PCL nanofibres effectively enhanced chondrocyte proliferation due to time-dependent degradation of thrombocytes and release of their GFs. CONCLUSIONS These simply functionalized scaffolds present new possibilities for nanofibre applications, as smart cell scaffolds equipped with a GF delivery tool.
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Affiliation(s)
- R Jakubova
- Institute of Biophysics, 2nd Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
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67
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Süss J. Tick-borne encephalitis 2010: Epidemiology, risk areas, and virus strains in Europe and Asia—An overview. Ticks Tick Borne Dis 2011; 2:2-15. [DOI: 10.1016/j.ttbdis.2010.10.007] [Citation(s) in RCA: 236] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 10/26/2010] [Accepted: 10/27/2010] [Indexed: 12/13/2022]
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68
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Abstract
Omsk haemorrhagic fever is an acute viral disease prevalent in some regions of western Siberia in Russia. The symptoms of this disease include fever, headache, nausea, severe muscle pain, cough, and moderately severe haemorrhagic manifestations. A third of patients develop pneumonia, nephrosis, meningitis, or a combination of these complications. The only treatments available are for control of symptoms. No specific vaccine has been developed, although the vaccine against tick-borne encephalitis might provide a degree of protection against Omsk haemorrhagic fever virus. The virus is transmitted mainly by Dermacentor reticulatus ticks, but people are mainly infected after contact with infected muskrats (Ondatra zibethicus). Muskrats are very sensitive to Omsk haemorrhagic fever virus. The introduction of this species to Siberia in the 1930s probably led to viral emergence in this area, which had previously seemed free from the disease. Omsk haemorrhagic fever is, therefore, an example of a human disease that emerged owing to human-mediated disturbance of an ecological niche. We review the biological properties of the virus, and the epidemiological and clinical characteristics of Omsk haemorrhagic fever.
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Affiliation(s)
- Daniel Růžek
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic.
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69
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Růžek D, Dobler G, Donoso Mantke O. Tick-borne encephalitis: pathogenesis and clinical implications. Travel Med Infect Dis 2010; 8:223-32. [PMID: 20970725 DOI: 10.1016/j.tmaid.2010.06.004] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 06/07/2010] [Accepted: 06/28/2010] [Indexed: 12/13/2022]
Abstract
Tick-borne encephalitis (TBE) is an important and severe neurological illness occurring in large areas of Europe and northern Asia. Only a small proportion of those infected develop clinical symptoms. The symptomatic cases are, however, characterized with fevers and debilitating encephalitis that might progress into chronic disease or fatal infections. This review summarizes data on clinical presentation, pathogenesis and pathology of TBE in humans, and of experimental TBE in animal models with the purpose to explain why is TBE such a severe disease clinically.
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Affiliation(s)
- Daniel Růžek
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005 České Budějovice, Czech Republic.
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70
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Tick-borne encephalitis virus and the immune response of the mammalian host. Travel Med Infect Dis 2010; 8:213-22. [DOI: 10.1016/j.tmaid.2010.05.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 05/25/2010] [Indexed: 01/01/2023]
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71
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Wigerius M, Melik W, Elväng A, Johansson M. Rac1 and Scribble are targets for the arrest of neurite outgrowth by TBE virus NS5. Mol Cell Neurosci 2010; 44:260-71. [PMID: 20363326 DOI: 10.1016/j.mcn.2010.03.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 03/09/2010] [Accepted: 03/29/2010] [Indexed: 01/09/2023] Open
Abstract
Tick-borne encephalitis virus (TBEV) causes extensive CNS disease in humans known as TBE, however, relatively little is known of the molecular mechanisms for its progress. Here, we now show that TBEV produces defects in neuronal development of PC12 cells through a function of the viral NS5 protein. The methyltransferase domain of NS5 is critical and sufficient for restriction of nerve growth factor induced neurite outgrowth. This effect is reversed by expression of NS5 mutants unable to bind Scribble and unexpectedly, in Scribble depleted cells with binding-competent NS5. Furthermore, we also demonstrate that the Rho GTPase Rac1 and the guanine nucleotide-exchange factor, betaPIX are outcompeted by NS5 for binding to Scribble, linking to effects on neurite outgrowth by TBEV. Together, these findings provide the first experimental evidence that Rac1 and betaPIX are indirect targets of NS5 acting through the multifunctional polarity protein Scribble to oppose neuronal differentiation. In conclusion, our results offer a potential mechanism by which TBEV alters neuronal circuitry and opens new avenues for therapeutic interventions.
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Affiliation(s)
- Michael Wigerius
- School of Life Sciences, Södertörn University, SE-141 89 Huddinge, Sweden
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