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Kwasnik M, Rola J, Rozek W. Tick-Borne Encephalitis-Review of the Current Status. J Clin Med 2023; 12:6603. [PMID: 37892741 PMCID: PMC10607749 DOI: 10.3390/jcm12206603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 09/01/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The tick-borne encephalitis virus (TBEV) is the arboviral etiological agent of tick-borne encephalitis (TBE), considered to be one of the most important tick-borne viral diseases in Europe and Asia. In recent years, an increase in the incidence of TBE as well as an increasing geographical range of the disease have been noted. Despite the COVID-19 pandemic and the imposition of restrictions that it necessitated, the incidence of TBE is rising in more than half of the European countries analyzed in recent studies. The virus is transmitted between ticks, animals, and humans. It seems that ticks and small mammals play a role in maintaining TBEV in nature. The disease can also affect dogs, horses, cattle, and small ruminants. Humans are incidental hosts, infected through the bite of an infected tick or by the alimentary route, through the consumption of unpasteurized milk or milk products from TBEV-infected animals. TBEV infections in humans may be asymptomatic, but the symptoms can range from mild flu-like to severe neurological. In Europe, cases of TBE are reported every year. While there is currently no effective treatment for TBE, immunization and protection against tick bites are critical in preventing this disease.
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Affiliation(s)
- Malgorzata Kwasnik
- Department of Virology, National Veterinary Research Institute, Al. Partyzantow 57, 24-100 Pulawy, Poland; (J.R.); (W.R.)
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2
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Binderup A, Galli A, Fossat N, Fernandez-Antunez C, Mikkelsen LS, Rivera-Rangel LR, Scheel TKH, Fahnøe U, Bukh J, Ramirez S. Differential activity of nucleotide analogs against tick-borne encephalitis and yellow fever viruses in human cell lines. Virology 2023; 585:179-185. [PMID: 37356253 DOI: 10.1016/j.virol.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/25/2023] [Accepted: 06/05/2023] [Indexed: 06/27/2023]
Abstract
With no approved antiviral therapies, the continuous emergence and re-emergence of tick-borne encephalitis virus (TBEV) and yellow fever virus (YFV) is a rising concern. We performed head-to-head comparisons of the antiviral activity of available nucleos(t)ide analogs (nucs) using relevant human cell lines. Eight existing nucs inhibited TBEV and/or YFV with differential activity between cell lines and viruses. Remdesivir, uprifosbuvir and sofosbuvir were the most potent drugs against TBEV and YFV in liver cells, but they had reduced activity in neural cells, whereas galidesivir retained uniform activity across cell lines and viruses. Ribavirin, valopicitabine, molnupiravir and GS-6620 exhibited only moderate antiviral activity. We found antiviral activity for drugs previously reported as inactive, demonstrating the importance of using human cell lines and comparative experimental assays when screening the activity of nucs. The relatively high antiviral activity of remdesivir, sofosbuvir and uprifosbuvir against TBEV and YFV merits further investigation in clinical studies.
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Affiliation(s)
- Alekxander Binderup
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andrea Galli
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolas Fossat
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carlota Fernandez-Antunez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lotte S Mikkelsen
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lizandro René Rivera-Rangel
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Troels K H Scheel
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrik Fahnøe
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Santseharay Ramirez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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3
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Sherwood AV, Rivera-Rangel LR, Ryberg LA, Larsen HS, Anker KM, Costa R, Vågbø CB, Jakljevič E, Pham LV, Fernandez-Antunez C, Indrisiunaite G, Podolska-Charlery A, Grothen JER, Langvad NW, Fossat N, Offersgaard A, Al-Chaer A, Nielsen L, Kuśnierczyk A, Sølund C, Weis N, Gottwein JM, Holmbeck K, Bottaro S, Ramirez S, Bukh J, Scheel TKH, Vinther J. Hepatitis C virus RNA is 5'-capped with flavin adenine dinucleotide. Nature 2023:10.1038/s41586-023-06301-3. [PMID: 37407817 DOI: 10.1038/s41586-023-06301-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 06/08/2023] [Indexed: 07/07/2023]
Abstract
RNA viruses have evolved elaborate strategies to protect their genomes, including 5' capping. However, until now no RNA 5' cap has been identified for hepatitis C virus1,2 (HCV), which causes chronic infection, liver cirrhosis and cancer3. Here we demonstrate that the cellular metabolite flavin adenine dinucleotide (FAD) is used as a non-canonical initiating nucleotide by the viral RNA-dependent RNA polymerase, resulting in a 5'-FAD cap on the HCV RNA. The HCV FAD-capping frequency is around 75%, which is the highest observed for any RNA metabolite cap across all kingdoms of life4-8. FAD capping is conserved among HCV isolates for the replication-intermediate negative strand and partially for the positive strand. It is also observed in vivo on HCV RNA isolated from patient samples and from the liver and serum of a human liver chimeric mouse model. Furthermore, we show that 5'-FAD capping protects RNA from RIG-I mediated innate immune recognition but does not stabilize the HCV RNA. These results establish capping with cellular metabolites as a novel viral RNA-capping strategy, which could be used by other viruses and affect anti-viral treatment outcomes and persistence of infection.
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Affiliation(s)
- Anna V Sherwood
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Lizandro R Rivera-Rangel
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Line A Ryberg
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Helena S Larsen
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Klara M Anker
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Rui Costa
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Cathrine B Vågbø
- Proteomics and Modomics Experimental Core (PROMEC), Norwegian University of Science and Technology and the Central Norway Regional Health Authority, Trondheim, Norway
| | - Eva Jakljevič
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Long V Pham
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Carlota Fernandez-Antunez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Gabriele Indrisiunaite
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Agnieszka Podolska-Charlery
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Julius E R Grothen
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Nicklas W Langvad
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Nicolas Fossat
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Anna Offersgaard
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Amal Al-Chaer
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Louise Nielsen
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Anna Kuśnierczyk
- Proteomics and Modomics Experimental Core (PROMEC), Norwegian University of Science and Technology and the Central Norway Regional Health Authority, Trondheim, Norway
| | - Christina Sølund
- Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen N, Denmark
| | - Nina Weis
- Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen N, Denmark
| | - Judith M Gottwein
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Kenn Holmbeck
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Sandro Bottaro
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Santseharay Ramirez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark.
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark.
| | - Troels K H Scheel
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark.
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark.
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA.
| | - Jeppe Vinther
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen N, Denmark.
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Trozzi G, Adjadj NR, Vervaeke M, Matthijs S, Sohier C, De Regge N. Comparison of Serological Methods for Tick-Borne Encephalitis Virus-Specific Antibody Detection in Wild Boar and Sheep: Impact of the Screening Approach on the Estimated Seroprevalence. Viruses 2023; 15:v15020459. [PMID: 36851673 PMCID: PMC9958861 DOI: 10.3390/v15020459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/10/2023] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a flavivirus transmitted by ticks. Serological screenings in animals are performed to estimate the prevalence and distribution of TBEV. Most screenings consist of a primary screening by ELISA, followed by confirmation of positive samples by plaque reduction neutralization tests (PRNTs). In this study, 406 wild boar sera were tested with 2 regularly used commercial ELISAs for flavivirus screening in animals (Immunozym FSME (TBEV) IgG All Species (Progen) and ID Screen West Nile Competition (Innovative Diagnostics)) and PRNTs for TBEV and USUTU virus. The results showed that the Immunozym and IDScreen ELISAs had low relative sensitivities of 23% and 20%, respectively, compared to the PRNT results. The relative specificities were 88% and 84% due to cross reactions with USUTU virus-specific antibodies. The minimal TBEV prevalence in our sample set was 8.6% when determined by PRNT. When the screening approach of ELISA testing followed by PRNT confirmation was applied, a TBEV seroprevalence of only 2.0% and 1.7% was found. The suboptimal performance of the ELISAs was confirmed by testing sera collected from experimentally TBEV-infected sheep. While the PRNT detected TBEV specific antibodies in 94% of samples collected between 7 and 18 days post-infection, the ELISAs classified only 50% and 31% of the samples as positive. Both routinely used ELISAs for TBEV antibody screening in animal sera were shown to have a low sensitivity, potentially leading to an underestimation of the true prevalence, and furthermore cross-react with other flavivirus antibodies.
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Affiliation(s)
- Gabrielle Trozzi
- Unit of Exotic and Vector-Borne Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium
- Correspondence:
| | - Nadjah Radia Adjadj
- Unit of Exotic and Vector-Borne Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium
| | | | - Severine Matthijs
- Viral Reemerging, Enzootic and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium
| | - Charlotte Sohier
- Unit of Exotic and Vector-Borne Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium
| | - Nick De Regge
- Unit of Exotic and Vector-Borne Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium
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Holliday M, Corliss L, Lennemann NJ. Construction and Rescue of a DNA-Launched DENV2 Infectious Clone. Viruses 2023; 15:275. [PMID: 36851490 PMCID: PMC9959642 DOI: 10.3390/v15020275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/15/2022] [Accepted: 01/13/2023] [Indexed: 01/20/2023] Open
Abstract
Flaviviruses represent a large group of globally significant, insect-borne pathogens. For many of these viruses, there is a lack of antivirals and vaccines. Thus, there is a need to continue the development of tools to further advance our efforts to combat these pathogens, including reverse genetics techniques. Traditionally, reverse genetics methods for flaviviruses rely on producing infectious RNA from in vitro transcription reactions followed by electroporation or transfection into permissive cell lines. However, the production of Zika virus has been successful from CMV promoter-driven expression plasmids, which provides cost and time advantages. In this report, we describe the design and construction of a DNA-launched infectious clone for dengue virus (DENV) serotype 2 strain 16681. An artificial intron was introduced in the nonstructural protein 1 segment of the viral genome to promote stability in bacteria. We found that rescued viruses maintained the ability to form plaques and replicate efficiently in commonly used cell lines. Thus, we present a rapid and cost-effective method for producing DENV2 strain 16681 from plasmid DNA. This construct will be a useful platform for the continued development of anti-DENV therapeutics and vaccines.
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Affiliation(s)
| | | | - Nicholas J. Lennemann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Activation of Early Proinflammatory Responses by TBEV NS1 Varies between the Strains of Various Subtypes. Int J Mol Sci 2023; 24:ijms24021011. [PMID: 36674524 PMCID: PMC9863113 DOI: 10.3390/ijms24021011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 12/29/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
Tick-borne encephalitis (TBE) is an emerging zoonosis that may cause long-term neurological sequelae or even death. Thus, there is a growing interest in understanding the factors of TBE pathogenesis. Viral genetic determinants may greatly affect the severity and consequences of TBE. In this study, nonstructural protein 1 (NS1) of the tick-borne encephalitis virus (TBEV) was tested as such a determinant. NS1s of three strains with similar neuroinvasiveness belonging to the European, Siberian and Far-Eastern subtypes of TBEV were studied. Transfection of mouse cells with plasmids encoding NS1 of the three TBEV subtypes led to different levels of NS1 protein accumulation in and secretion from the cells. NS1s of TBEV were able to trigger cytokine production either in isolated mouse splenocytes or in mice after delivery of NS1 encoding plasmids. The profile and dynamics of TNF-α, IL-6, IL-10 and IFN-γ differed between the strains. These results demonstrated the involvement of TBEV NS1 in triggering an immune response and indicated the diversity of NS1 as one of the genetic factors of TBEV pathogenicity.
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7
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Reverse genetics in virology: A double edged sword. BIOSAFETY AND HEALTH 2022. [DOI: 10.1016/j.bsheal.2022.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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T-Cell Immunoglobulin and Mucin Domain 1 (TIM-1) Is a Functional Entry Factor for Tick-Borne Encephalitis Virus. mBio 2022; 13:e0286021. [PMID: 35073759 PMCID: PMC8787471 DOI: 10.1128/mbio.02860-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is the causative agent of a potentially fatal neurological infection affecting humans. The host factors required for viral entry have yet to be described. Here, we found that T-cell immunoglobulin and mucin domain 1 (TIM-1) acted as the cellular entry factor for TBEV. Using a virus overlay protein binding assay, TIM-1 was identified as a virion-interacting protein. Cells that were relatively resistant to TBEV infection became highly susceptible to infection when TIM-1 was ectopically expressed. TIM-1 knockout and viral RNA bypass assays showed that TIM-1 functioned in the entry phase of TBEV infection. TIM-1 mediated TBEV uptake and was cointernalized with virus particles into the cell. Antibodies for TIM-1, soluble TIM-1, or TIM-1 knockdown significantly inhibited TBEV infection in permissive cells. Furthermore, in TIM-1 knockout mice, TIM-1 deficiency markedly lowered viral burden and reduced mortality and morbidity, highlighting the functional relevance of TIM-1 in vivo. With TIM-1, we have identified a key host factor for TBEV entry and a potential target for antiviral intervention. IMPORTANCE TBEV is a tick-transmitted flavivirus that causes serious diseases in the human central nervous system in Eurasia. The host determinants required for viral entry remain poorly understood. Here, we found that TIM-1 is a cellular entry factor for TBEV. Antibodies directed at TIM-1 or soluble TIM-1 treatment decreased virus infection in cell cultures. TIM-1 was cointernalized with virus particles into cells. TIM-1 deficiency significantly lowered viral burden and attenuated pathogenesis in the murine TBEV infection model. The demonstration of TIM-1 as a cellular entry factor for TBEV will improve understanding of virus infection and provide a target for antiviral development.
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Lindenbach BD. Reinventing positive-strand RNA virus reverse genetics. Adv Virus Res 2022; 112:1-29. [PMID: 35840179 PMCID: PMC9273853 DOI: 10.1016/bs.aivir.2022.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Reverse genetics is the prospective analysis of how genotype determines phenotype. In a typical experiment, a researcher alters a viral genome, then observes the phenotypic outcome. Among RNA viruses, this approach was first applied to positive-strand RNA viruses in the mid-1970s and over nearly 50 years has become a powerful and widely used approach for dissecting the mechanisms of viral replication and pathogenesis. During this time the global health importance of two virus groups, flaviviruses (genus Flavivirus, family Flaviviridae) and betacoronaviruses (genus Betacoronavirus, subfamily Orthocoronavirinae, family Coronaviridae), have dramatically increased, yet these viruses have genomes that are technically challenging to manipulate. As a result, several new techniques have been developed to overcome these challenges. Here I briefly review key historical aspects of positive-strand RNA virus reverse genetics, describe some recent reverse genetic innovations, particularly as applied to flaviviruses and coronaviruses, and discuss their benefits and limitations within the larger context of rigorous genetic analysis.
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An Absolutely Conserved Tryptophan in the Stem of the Envelope Protein E of Flaviviruses Is Essential for the Formation of Stable Particles. Viruses 2021; 13:v13091727. [PMID: 34578308 PMCID: PMC8473212 DOI: 10.3390/v13091727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022] Open
Abstract
The major envelope protein E of flaviviruses contains an ectodomain that is connected to the transmembrane domain by the so-called “stem” region. In mature flavivirus particles, the stem is composed of two or three mostly amphipathic α-helices and a conserved sequence element (CS) with an undefined role in the viral life cycle. A tryptophan is the only residue within this region which is not only conserved in all vector-borne flaviviruses, but also in the group with no known vector. We investigated the importance of this residue in different stages of the viral life cycle by a mutagenesis-based approach using tick-borne encephalitis virus (TBEV). Replacing W421 by alanine or histidine strongly reduced the release of infectious virions and their thermostability, whereas fusion-related entry functions and virus maturation were still intact. Serial passaging of the mutants led to the emergence of a same-site compensatory mutation to leucine that largely restored these properties of the wildtype. The conserved tryptophan in CS (or another big hydrophobic amino acid at the same position) is thus essential for the assembly and infectivity of flaviviruses by being part of a network required for conferring stability to infectious particles.
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Recovery of a Far-Eastern Strain of Tick-Borne Encephalitis Virus with a Full-Length Infectious cDNA Clone. Virol Sin 2021; 36:1375-1386. [PMID: 34191223 DOI: 10.1007/s12250-021-00396-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a pathogenic virus known to cause central nervous system (CNS) diseases in humans, and has become an increasing public health threat nowadays. The rates of TBEV infection in the endemic countries are increasing. However, there is no effective antiviral against the disease. This underscores the urgent need for tools to study the emergence and pathogenesis of TBEV and to accelerate the development of vaccines and antivirals. In this study, we reported an infectious cDNA clone of TBEV that was isolated in China (the WH2012 strain). A beta-globin intron was inserted in the coding region of nonstructural protein 1 (NS1) gene to improve the stability of viral genome in bacteria. In mammalian cells, the inserted intron was excised and spliced precisely, which did not lead to the generation of inserted mutants. High titers of infectious progeny viruses were generated after the transfection of the infectious clone. The cDNA-derived TBEV replicated efficiently, and caused typical cytopathic effect (CPE) and plaques in BHK-21 cells. In addition, the CPE and growth curve of cDNA-derived virus were similar to that of its parental isolate in cells. Together, we have constructed the first infectious TBEV cDNA clone in China, and the clone can be used to investigate the genetic determinants of TBEV virulence and disease pathogenesis, and to develop countermeasures against the virus.
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12
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Tuchynskaya K, Volok V, Illarionova V, Okhezin E, Polienko A, Belova O, Rogova A, Chernokhaeva L, Karganova G. Experimental Assessment of Possible Factors Associated with Tick-Borne Encephalitis Vaccine Failure. Microorganisms 2021; 9:1172. [PMID: 34072340 PMCID: PMC8229799 DOI: 10.3390/microorganisms9061172] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 12/30/2022] Open
Abstract
Currently the only effective measure against tick-borne encephalitis (TBE) is vaccination. Despite the high efficacy of approved vaccines against TBE, rare cases of vaccine failures are well documented. Both host- and virus-related factors can account for such failures. In this work, we studied the influence of mouse strain and sex and the effects of cyclophosphamide-induced immunosuppression on the efficacy of an inactivated TBE vaccine. We also investigated how an increased proportion of non-infectious particles in the challenge TBE virus would affect the protectivity of the vaccine. The vaccine efficacy was assessed by mortality, morbidity, levels of viral RNA in the brain of surviving mice, and neutralizing antibody (NAb) titers against the vaccine strain and the challenge virus. Two-dose vaccination protected most animals against TBE symptoms and death, and protectivity depended on strain and sex of mice. Immunosuppression decreased the vaccine efficacy in a dose-dependent manner and changed the vaccine-induced NAb spectrum. The vaccination protected mice against TBE virus neuroinvasion and persistence. However, viral RNA was detected in the brain of some asymptomatic animals at 21 and 42 dpi. Challenge with TBE virus enriched with non-infectious particles led to lower NAb titers in vaccinated mice after the challenge but did not affect the protective efficacy.
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Affiliation(s)
- Ksenia Tuchynskaya
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
| | - Viktor Volok
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
- Department of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Victoria Illarionova
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
- Department of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Egor Okhezin
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
- Department of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alexandra Polienko
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
| | - Oxana Belova
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
| | - Anastasia Rogova
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
| | - Liubov Chernokhaeva
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
| | - Galina Karganova
- FSBSI “Chumakov FSC R&D IBP RAS”, 108819 Moscow, Russia; (K.T.); (V.V.); (V.I.); (E.O.); (A.P.); (O.B.); (A.R.); (L.C.)
- Department of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
- Institute of Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
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13
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Immunity to TBEV Related Flaviviruses with Reduced Pathogenicity Protects Mice from Disease but Not from TBEV Entry into the CNS. Vaccines (Basel) 2021; 9:vaccines9030196. [PMID: 33652698 PMCID: PMC7996866 DOI: 10.3390/vaccines9030196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a leading cause of vector-borne viral encephalitis with expanding endemic regions across Europe. In this study we tested in mice the efficacy of preinfection with a closely related low-virulent flavivirus, Langat virus (LGTV strain TP21), or a naturally avirulent TBEV strain (TBEV-280) in providing protection against lethal infection with the highly virulent TBEV strain (referred to as TBEV-Hypr). We show that prior infection with TP21 or TBEV-280 is efficient in protecting mice from lethal TBEV-Hypr challenge. Histopathological analysis of brains from nonimmunized mice revealed neuronal TBEV infection and necrosis. Neuroinflammation, gliosis, and neuronal necrosis was however also observed in some of the TP21 and TBEV-280 preinfected mice although at reduced frequency as compared to the nonimmunized TBEV-Hypr infected mice. qPCR detected the presence of viral RNA in the CNS of both TP21 and TBEV-280 immunized mice after TBEV-Hypr challenge, but significantly reduced compared to mock-immunized mice. Our results indicate that although TBEV-Hypr infection is effectively controlled in the periphery upon immunization with low-virulent LGTV or naturally avirulent TBEV 280, it may still enter the CNS of these animals. These findings contribute to our understanding of causes for vaccine failure in individuals vaccinated with TBE vaccines.
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Baker C, Shi PY. Construction of Stable Reporter Flaviviruses and Their Applications. Viruses 2020; 12:v12101082. [PMID: 32992987 PMCID: PMC7599567 DOI: 10.3390/v12101082] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/28/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Flaviviruses are significant human pathogens that cause frequent emerging and reemerging epidemics around the world. Better molecular tools for studying, diagnosing, and treating these diseases are needed. Reporter viruses represent potent tools to fill this gap but have been hindered by genetic instability. Recent advances have overcome these hurdles, opening the way for increased use of stable reporter flaviviruses to diagnose infections, screen and study antiviral compounds, and serve as potential vaccine vectors.
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Affiliation(s)
- Coleman Baker
- Microbiology and Immunology Department, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Pei-Yong Shi
- Biochemistry and Molecular Biology Department, University of Texas Medical Branch, Galveston, TX 77555, USA
- Institute for Human Infections & Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
- Institute for Translational Science, University of Texas Medical Branch, Galveston, TX 77555, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA
- Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
- Correspondence:
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15
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Ott D, Ulrich K, Ginsbach P, Öhme R, Bock-Hensley O, Falk U, Teinert M, Lenhard T. Tick-borne encephalitis virus (TBEV) prevalence in field-collected ticks (Ixodes ricinus) and phylogenetic, structural and virulence analysis in a TBE high-risk endemic area in southwestern Germany. Parasit Vectors 2020; 13:303. [PMID: 32527288 PMCID: PMC7291635 DOI: 10.1186/s13071-020-04146-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 05/23/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Tick-borne encephalitis (TBE) is the most common viral CNS infection with incidences much higher than all other virus infections together in many risk areas of central and eastern Europe. The Odenwald Hill region (OWH) in southwestern Germany is classified as a TBE risk region and frequent case numbers but also more severe infections have been reported within the past decade. The objective of the present study was to survey the prevalence of tick-borne encephalitis virus (TBEV) in Ixodes ricinus and to associate TBEV genetic findings with TBE infections in the OWH. METHODS Ticks were collected by the flagging methods supported by a crowdsourcing project implementing the interested public as collectors to cover completely and collect randomly a 3532 km2 area of the OWH TBE risk region. Prevalence of TBEV in I. ricinus was analysed by reversed transcription quantitative real-time PCR. Phylogeographic analysis was performed to classify OWH TBEV isolates within a European network of known TBEV strains. Mutational sequence analysis including 3D modelling of envelope protein pE was performed and based on a clinical database, a spatial association of TBE case frequency and severity was undertaken. RESULTS Using the crowd sourcing approach we could analyse a total of 17,893 ticks. The prevalence of TBEV in I. ricinus in the OWH varied, depending on analysed districts from 0.12% to 0% (mean 0.04%). Calculated minimum infection rate (MIR) was one decimal power higher. All TBEV isolates belonged to the European subtype. Sequence analysis revealed a discontinuous segregation pattern of OWH isolates with two putative different lineages and a spatial association of two isolates with increased TBE case numbers as well as exceptional severe to fatal infection courses. CONCLUSIONS TBEV prevalence within the OWH risk regions is comparatively low which is probably due to our methodological approach and may more likely reflect prevalence of natural TBEV foci. As for other European regions, TBEV genetics show a discontinuous phylogeny indicating among others an association with bird migration. Mutations within the pE gene are associated with more frequent, severe and fatal TBE infections in the OWH risk region.
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Affiliation(s)
- Daniela Ott
- Neuroinfectious Diseases Group, Department of Neurology, University Hospital Heidelberg, University of Heidelberg, Im Neuenheimer Feld 350, 69120 Heidelberg, Germany
| | - Kristina Ulrich
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA Scotland, UK
| | | | - Rainer Öhme
- Molecular Biology Laboratory, Landesgesundheitsamt Stuttgart, Nordbahnhofstraße 135, 70191 Stuttgart, Germany
| | - Oswinde Bock-Hensley
- Gesundheitsamt Rhein-Neckarkreis, Kurfürsten-Anlage 38-40, 69115 Heidelberg, Germany
| | - Ulrich Falk
- Gesundheitsamt Odenwaldkreis, Michelstädter Str. 12, 64711 Erbach, Germany
| | - Martina Teinert
- Gesundheitsamt Neckar-Odenwaldkreis, Neckarelzer Str. 7, 74821 Mosbach, Germany
| | - Thorsten Lenhard
- Neuroinfectious Diseases Group, Department of Neurology, University Hospital Heidelberg, University of Heidelberg, Im Neuenheimer Feld 350, 69120 Heidelberg, Germany
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16
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Nyataya J, Maraka M, Lemtudo A, Masakhwe C, Mutai B, Njaanake K, Estambale BB, Nyakoe N, Siangla J, Waitumbi JN. Serological Evidence of Yersiniosis, Tick-Borne Encephalitis, West Nile, Hepatitis E, Crimean-Congo Hemorrhagic Fever, Lyme Borreliosis, and Brucellosis in Febrile Patients Presenting at Diverse Hospitals in Kenya. Vector Borne Zoonotic Dis 2020; 20:348-357. [PMID: 31928511 DOI: 10.1089/vbz.2019.2484] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Data on pathogen prevalence is crucial for informing exposure and disease risk. We evaluated serological evidence of tick-borne encephalitis (TBE), West Nile (WN), Hepatitis E virus (HEV), Crimean-Congo Hemorrhagic Fever (CCHF), Yersiniosis, Lyme Disease (LD), and brucellosis in 1033 patients presenting with acute febrile illness at 9 health care facilities from diverse ecological zones of Kenya: arid and semiarid (Garissa District Hospital, Lodwar District Hospital, Marigat District Hospital, Gilgil District Hospital), Lake Victoria basin (Kisumu District Hospital, Alupe District Hospital, Kombewa Sub-County Hospital), Kisii highland (Kisii District Hospital), and coastal (Malindi District Hospital). Epidemiological information of the patients such as geography, age, gender, and keeping animals were analyzed as potential risk factors. Of the 1033 samples, 619 (59.9%) were seropositive to at least one pathogen by IgM (current exposure), IgG/IgM (recent exposure), and IgG (past exposure). Collective seroprevalence for current, recent, and past to the pathogens was 9.4%, 5.1%, and 21.1% for LD; 3.6%, 0.5%, and 12.4% for WN; 0.9%, 0.5%, and 16.9% for HEV; 5.8%, 1.3%, and 3.9% for brucellosis; 5.7%, 0.2%, and 2.3% for yersiniosis; 1.7%, 0%, and 6.2% for TBE; and 0.4%, 0%, and 1.9% for CCHF. Brucellosis risk was higher in patients recruited at Garissa District Hospital (odds ratio [OR] = 3.41), HEV (OR = 2.45) and CCHF (OR = 5.46) in Lodwar District Hospital, LD in Alupe District Hospital (OR = 5.73), Kombewa Sub-district hospital (OR = 8.17), and Malindi District hospital (OR = 3.3). Exposure to LD was highest in the younger age group, whereas yersiniosis did not vary with age. Age was a significant risk for WN, brucellosis, CCHF, TBE, and HEV and in those aged >14 years there was an increased risk to WN (OR = 2.30, p < 0.0001), brucellosis (OR = 1.84, p = 0.005), CCHF (OR = 4.35, p = 0.001), TBE (OR = 2.78, p < 0.0001), and HEV (OR = 1.94, p = 0.0001). We conclude that LD is pervasive and constitutes a significant health burden to the study population, whereas yersiniosis and CCHF are not significant threats. Going forward, community-based studies will be needed to capture the true seroprevalence rates and the associated risk factors.
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Affiliation(s)
- Josphat Nyataya
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - Moureen Maraka
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - Allan Lemtudo
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - Clement Masakhwe
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - Beth Mutai
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - Kariuki Njaanake
- Department of Medical Microbiology, College of Health Sciences, University of Nairobi, Nairobi, Kenya
| | - Benson B Estambale
- Division of Research, Innovation and Outreach, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Nancy Nyakoe
- Department of Biochemistry, Cell and Molecular Biology, West African Center for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Joram Siangla
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
| | - John Njenga Waitumbi
- Medical Research Directorate-Africa/Kenya Medical Research Institute, Basic Science Laboratory, Kisumu, Kenya
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17
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Tkachev SE, Babkin IV, Chicherina GS, Kozlova IV, Verkhozina MM, Demina TV, Lisak OV, Doroshchenko EK, Dzhioev YP, Suntsova OV, Belokopytova PS, Tikunov AY, Savinova YS, Paramonov AI, Glupov VV, Zlobin VI, Tikunova NV. Genetic diversity and geographical distribution of the Siberian subtype of the tick-borne encephalitis virus. Ticks Tick Borne Dis 2019; 11:101327. [PMID: 31767494 DOI: 10.1016/j.ttbdis.2019.101327] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/21/2019] [Accepted: 11/06/2019] [Indexed: 11/16/2022]
Abstract
The tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is currently subdivided into three main subtypes-the European (TBEV-Eu), the Far-Eastern (TBEV-FE), and the Siberian (TBEV-Sib). The TBEV-Sib is the most common subtype and found in all regions where TBEV was detected, except for Central and Western Europe. Currently, four genetic lineages have been described within TBEV-Sib. In this study, detailed analysis of TBEV-Sib genetic diversity, geographic distribution, phylogeography and divergence time of different TBEV-Sib genetic lineages based on E gene fragments, complete genome sequences, and all currently available data in the GenBank database was performed. As a result, a novel Bosnia lineage within the TBEV-Sib was identified. It was demonstrated that the Zausaev lineage is the most widely distributed among the TBEV-Sib lineages, and was detected in all studied regions except the Far East. The Vasilchenko lineage was found from Western Siberia to the Far East. The Baltic lineage is presented from Europe to Western Siberia. The Obskaya lineage was found only in Western Siberia. TBEV strains from a newly described Bosnia lineage were detected in Bosnia, the Crimean peninsula, Kyrgyzstan and Kazakhstan. The greatest divergence of the TBEV-Sib genetic variants was observed in Western Siberia. Within the TBEV-Sib, the Obskaya lineage diverged from the common ancestor the earliest, after that the Bosnia lineage was separated, then the Baltic lineage, and the Zausaev and Vasilchenko lineages diverged most recently.
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Affiliation(s)
- S E Tkachev
- Institute of Chemical Biology and Fundamental Medicine of the SB RAS, Acad. Lavrentyev's pr., 8, Novosibirsk, 630090, Russia.
| | - I V Babkin
- Institute of Chemical Biology and Fundamental Medicine of the SB RAS, Acad. Lavrentyev's pr., 8, Novosibirsk, 630090, Russia
| | - G S Chicherina
- Institute of Systematics and Ecology of Animals SB RAS, Frunze str., 11, Novosibirsk, 630091, Russia
| | - I V Kozlova
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - M M Verkhozina
- Center for Hygiene and Epidemiology in the Irkutsk Region, Trilisser Str., 51, Irkutsk, 664047, Russia
| | - T V Demina
- Irkutsk State Agrarian University by A.A. Ezhevsky, Molodezhny Settlement, Irkutsk District, Irkutsk, 664038, Russia
| | - O V Lisak
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - E K Doroshchenko
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - Yu P Dzhioev
- Research Institute of Biomedical Technology of Irkutsk State Medical University, Krasnogo Vosstaniya Str., 1/3, Irkutsk, 664003, Russia
| | - O V Suntsova
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - P S Belokopytova
- Institute of Chemical Biology and Fundamental Medicine of the SB RAS, Acad. Lavrentyev's pr., 8, Novosibirsk, 630090, Russia
| | - A Yu Tikunov
- Institute of Chemical Biology and Fundamental Medicine of the SB RAS, Acad. Lavrentyev's pr., 8, Novosibirsk, 630090, Russia
| | - Yu S Savinova
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - A I Paramonov
- Scientific Centre for Family Health and Human Reproduction Problems, Timiryazev Str., 16, Irkutsk, 664003, Russia
| | - V V Glupov
- Institute of Systematics and Ecology of Animals SB RAS, Frunze str., 11, Novosibirsk, 630091, Russia
| | - V I Zlobin
- Research Institute of Biomedical Technology of Irkutsk State Medical University, Krasnogo Vosstaniya Str., 1/3, Irkutsk, 664003, Russia
| | - N V Tikunova
- Institute of Chemical Biology and Fundamental Medicine of the SB RAS, Acad. Lavrentyev's pr., 8, Novosibirsk, 630090, Russia.
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18
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Selinger M, Tykalová H, Štěrba J, Věchtová P, Vavrušková Z, Lieskovská J, Kohl A, Schnettler E, Grubhoffer L. Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin. PLoS Negl Trop Dis 2019; 13:e0007745. [PMID: 31560682 PMCID: PMC6785130 DOI: 10.1371/journal.pntd.0007745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 10/09/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off. Tick-borne encephalitis virus (TBEV) is a causative agent of a severe human neuroinfection that threatens Europe and Asia. Little is known about the interaction of this neurotropic virus with neural cells, even though this may be important to better understand why or how TBEV can cause high pathogenicity in humans, especially following neural cell infection. Here, we showed that TBEV induced host translational shut-off in cells of neural origin. In addition, TBEV interfered also with the expression of host ribosomal RNAs. Interestingly, the transcriptional shut-off was documented for rRNA species transcribed by RNA polymerase I (18S rRNA, 28S rRNA and their precursor 45-47S pre-rRNA), but not for RNA polymerase III rRNA transcripts (5S rRNA). Artificial inhibition of host translation using cycloheximide resulted in the decrease of all rRNA species. Based on these data, TBEV seems to specifically target transcription of RNA polymerase I. These new findings further increase our understanding of TBEV interactions with a key target cell type.
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Affiliation(s)
- Martin Selinger
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Hana Tykalová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Ján Štěrba
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Pavlína Věchtová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Zuzana Vavrušková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
| | - Jaroslava Lieskovská
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Esther Schnettler
- Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, Hamburg, Germany
- German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel-Riems, Hamburg, Germany
- * E-mail: (ES); (LG)
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská, České Budějovice, Czech Republic
- * E-mail: (ES); (LG)
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19
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Velay A, Paz M, Cesbron M, Gantner P, Solis M, Soulier E, Argemi X, Martinot M, Hansmann Y, Fafi-Kremer S. Tick-borne encephalitis virus: molecular determinants of neuropathogenesis of an emerging pathogen. Crit Rev Microbiol 2019; 45:472-493. [PMID: 31267816 DOI: 10.1080/1040841x.2019.1629872] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tick-borne encephalitis virus (TBEV) is a zoonotic agent causing severe encephalitis. The transmission cycle involves the virus, the Ixodes tick vector, and a vertebrate reservoir, such as small mammals (rodents, or shrews). Humans are accidentally involved in this transmission cycle. Tick-borne encephalitis (TBE) has been a growing public health problem in Europe and Asia over the past 30 years. The mechanisms involved in the development of TBE are very complex and likely multifactorial, involving both host and viral factors. The purpose of this review is to provide an overview of the current literature on TBE neuropathogenesis in the human host and to demonstrate the emergence of common themes in the molecular pathogenesis of TBE in humans. We discuss and review data on experimental study models and on both viral (molecular genetics of TBEV) and host (immune response, and genetic background) factors involved in TBE neuropathogenesis in the context of human infection.
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Affiliation(s)
- Aurélie Velay
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France.,INSERM, IRM UMR_S 1109 , Strasbourg , France
| | - Magali Paz
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France
| | - Marlène Cesbron
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France
| | - Pierre Gantner
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France.,INSERM, IRM UMR_S 1109 , Strasbourg , France
| | - Morgane Solis
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France.,INSERM, IRM UMR_S 1109 , Strasbourg , France
| | | | - Xavier Argemi
- Service des maladies infectieuses et tropicales, Hôpitaux Universitaires de Strasbourg , Strasbourg , France
| | - Martin Martinot
- Service de Médecine Interne et de Rhumatologie, Hôpitaux Civils de Colmar , Colmar , France
| | - Yves Hansmann
- Service des maladies infectieuses et tropicales, Hôpitaux Universitaires de Strasbourg , Strasbourg , France
| | - Samira Fafi-Kremer
- Virology Laboratory, University Hospital of Strasbourg , Strasbourg , France.,INSERM, IRM UMR_S 1109 , Strasbourg , France
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20
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Abstract
Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus within the family Flaviviridae, causes fatal encephalitis with severe sequelae in humans. TBEV is
prevalent over a wide area of the Eurasian continent including Europe, Russia, Far-Eastern Asia, and Japan. While it was previously thought that TBEV was not endemic in Japan, the first
confirmed case of serologically diagnosed TBE was reported in 1993 in the southern area of Hokkaido Prefecture, Japan. In addition, TBEV has been isolated from dogs, wild rodents and ticks
in the area. Our epizootiological survey indicated that endemic foci of TBEV were maintained in Hokkaido and other areas of Honshu. TBEV can be divided into three subtypes based on
phylogenetic analyses. The Japanese isolates were classified as the Far Eastern subtype, which causes severe neural disorders with a higher mortality rate up to 30%. However, how viral
replication and pathogenicity contribute to the neurological manifestations remains unclear. Recent studies have revealed distinctive mechanisms of TBEV pathogenicity and viral genetic
factors associated with virulence. This review discusses the recent findings regarding the epidemiology and pathogenesis of TBEV.
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Affiliation(s)
- Kentaro Yoshii
- Laboratory of Public Health, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
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21
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Chen Y, Liu T, Zhang Z, Chen M, Rong L, Ma L, Yu B, Wu D, Zhang P, Zhu X, Huang X, Zhang H, Li YP. Novel genetically stable infectious clone for a Zika virus clinical isolate and identification of RNA elements essential for virus production. Virus Res 2018; 257:14-24. [PMID: 30144463 DOI: 10.1016/j.virusres.2018.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/18/2018] [Accepted: 08/20/2018] [Indexed: 01/19/2023]
Abstract
Zika virus (ZIKV) is an Aedes mosquitoes-transmitted flavivirus, and its infection may cause severe neurological diseases. A genetically stable infectious clone is essential for ZIKV research, however the toxicity and instability of the viral cDNA in bacteria potentially due to its bacterial promoter activity are major challenges. Here, we constructed a full-length cDNA clone for isolate ZG01 by introducing non-coding changes T1865C/A1868G to reduce the bacterial promoter activity. Wild-type and recombinant ZG01 were highly attenuated in Vero cells, thus we serially passaged wild-type ZG01 through neonatal mice and Vero cells to generate high-titer virus, from which four mutations (4m, C2178T/G2913A/T4991C/T10561C) were identified. Addition of 4m greatly enhanced the infectivity, as ZG01_4m released ZIKV of 107.0-107.5 plaque-forming unit (PFU)/ml in infected Vero and A549 cells. ZG01_4m resembled the infectivity of high-titer ZG01 in vitro and in vivo. Notably, ZG01_4m plasmid was genetically stable after multiple rounds of transformation-purification in bacteria. Using ZG01_4m, we identified a potential RNA-RNA interaction between 5'UTR and 3'UTR and demonstrated that the nucleotides involved were essential for ZIKV production. The genetically stable ZG01 cDNA clone provides a reliable tool for the study of this important virus, and the strategy used here is feasible for the development of reverse genetics systems for other ZIKV isolates and related flaviviruses.
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Affiliation(s)
- Yiyi Chen
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Ting Liu
- Department of Immunology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Zhenzhen Zhang
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Mingxiao Chen
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Liang Rong
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Ling Ma
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Bolan Yu
- Key Lab for Major Obstetric Diseases of Guangdong Province, Guangzhou Medical University, Guangzhou 510150, China
| | - De Wu
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China
| | - Ping Zhang
- Department of Immunology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Xun Zhu
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Xi Huang
- The Fifth Affiliated Hospital of Sun Yat-sen University, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Hui Zhang
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China
| | - Yi-Ping Li
- Institute of Human Virology, Zhongshan School of Medicine, and Key Laboratory of Tropical Disease Control of Ministry of Education, Sun Yat-Sen University, Guangzhou 510080, China; Program in Pathobiology, The Fifth Affiliated Hospital and Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.
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Haslwanter D, Blaas D, Heinz FX, Stiasny K. A novel mechanism of antibody-mediated enhancement of flavivirus infection. PLoS Pathog 2017; 13:e1006643. [PMID: 28915259 PMCID: PMC5617232 DOI: 10.1371/journal.ppat.1006643] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/27/2017] [Accepted: 09/11/2017] [Indexed: 12/12/2022] Open
Abstract
Antibody-dependent enhancement of viral infection is a well-described phenomenon that is based on the cellular uptake of infectious virus-antibody complexes following their interaction with Fcγ receptors expressed on myeloid cells. Here we describe a novel mechanism of antibody-mediated enhancement of infection by a flavivirus (tick-borne encephalitis virus) in transformed and primary human cells, which is independent of the presence of Fcγ receptors. Using chemical cross-linking and immunoassays, we demonstrate that the monoclonal antibody (mab) A5, recognizing an epitope at the interface of the dimeric envelope protein E, causes dimer dissociation and leads to the exposure of the fusion loop (FL). Under normal conditions of infection, this process is triggered only after virus uptake by the acidic pH in endosomes, resulting in the initiation of membrane fusion through the interaction of the FL with the endosomal membrane. Analysis of virus binding and cellular infection, together with inhibition by the FL-specific mab 4G2, indicated that the FL, exposed after mab A5- induced dimer-dissociation, mediated attachment of the virus to the plasma membrane also at neutral pH, thereby increasing viral infectivity. Since antibody-induced enhancement of binding was not only observed with cells but also with liposomes, it is likely that increased infection was due to FL-lipid interactions and not to interactions with cellular plasma membrane proteins. The novel mechanism of antibody-induced infection enhancement adds a new facet to the complexity of antibody interactions with flaviviruses and may have implications for yet unresolved effects of polyclonal antibody responses on biological properties of these viruses.
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Affiliation(s)
| | - Dieter Blaas
- Max F. Perutz Laboratories, Department for Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Franz X. Heinz
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Karin Stiasny
- Center for Virology, Medical University of Vienna, Vienna, Austria
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Taba P, Schmutzhard E, Forsberg P, Lutsar I, Ljøstad U, Mygland Å, Levchenko I, Strle F, Steiner I. EAN consensus review on prevention, diagnosis and management of tick‐borne encephalitis. Eur J Neurol 2017; 24:1214-e61. [DOI: 10.1111/ene.13356] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 06/01/2017] [Indexed: 12/30/2022]
Affiliation(s)
- P. Taba
- Department of Neurology and Neurosurgery University of Tartu Tartu Estonia
| | - E. Schmutzhard
- Department of Neurology Medical University Innsbruck Innsbruck Austria
| | - P. Forsberg
- Department of Clinical and Experimental Medicine and Department of Infectious Diseases Linköping University Linköping Sweden
| | - I. Lutsar
- Department of Microbiology University of Tartu Tartu Estonia
| | - U. Ljøstad
- Department of Neurology Sørlandet Hospital Kristiansand Norway
- Department of Clinical Medicine University of Bergen Bergen Norway
| | - Å. Mygland
- Department of Neurology Sørlandet Hospital Kristiansand Norway
- Department of Clinical Medicine University of Bergen Bergen Norway
| | - I. Levchenko
- Institute of Neurology Psychiatry and Narcology of the National Academy of Medical Sciences of Ukraine Kharkiv Ukraine
| | - F. Strle
- Department of Infectious Diseases University Medical Centre Ljubljana Ljubljana Slovenia
| | - I. Steiner
- Department of Neurology Rabin Medical Center Petach Tikva Israel
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24
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Complete Genome Sequence of a Low-Virulence Tick-Borne Encephalitis Virus Strain. GENOME ANNOUNCEMENTS 2016; 4:4/5/e01145-16. [PMID: 27795275 PMCID: PMC5073262 DOI: 10.1128/genomea.01145-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here the complete genome sequence (GenBank accession no. KX268728) of tick-borne encephalitis strain HB171/11, isolated from an Ixodes ricinus tick from a natural focus where human neurological disease is rare. The strain shows unique characteristics in neuroinvasiveness and neurovirulence.
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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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26
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Shan C, Xie X, Muruato AE, Rossi SL, Roundy CM, Azar SR, Yang Y, Tesh RB, Bourne N, Barrett AD, Vasilakis N, Weaver SC, Shi PY. An Infectious cDNA Clone of Zika Virus to Study Viral Virulence, Mosquito Transmission, and Antiviral Inhibitors. Cell Host Microbe 2016; 19:891-900. [PMID: 27198478 PMCID: PMC5206987 DOI: 10.1016/j.chom.2016.05.004] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 11/17/2022]
Abstract
The Asian lineage of Zika virus (ZIKV) has recently caused epidemics and severe disease. Unraveling the mechanisms causing increased viral transmissibility and disease severity requires experimental systems. We report an infectious cDNA clone of ZIKV that was generated using a clinical isolate of the Asian lineage. The cDNA clone-derived RNA is infectious in cells, generating recombinant ZIKV. The recombinant virus is virulent in established ZIKV mouse models, leading to neurological signs relevant to human disease. Additionally, recombinant ZIKV is infectious for Aedes aegypti and thus provides a means to examine virus transmission. The infectious cDNA clone was further used to generate a luciferase ZIKV that exhibited sensitivity to a panflavivirus inhibitor, highlighting its potential utility for antiviral screening. This ZIKV reverse genetic system, together with mouse and mosquito infection models, may help identify viral determinants of human virulence and mosquito transmission as well as inform vaccine and therapeutic strategies.
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Affiliation(s)
- Chao Shan
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Xuping Xie
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Antonio E Muruato
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Shannan L Rossi
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Christopher M Roundy
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Sasha R Azar
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Science, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Yujiao Yang
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Robert B Tesh
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Nigel Bourne
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pediatrics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Alan D Barrett
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Nikos Vasilakis
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Scott C Weaver
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Translational Science, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Pei-Yong Shi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
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Pavitrakar DV, Ayachit VM, Mundhra S, Bondre VP. Development and characterization of reverse genetics system for the Indian West Nile virus lineage 1 strain 68856. J Virol Methods 2015; 226:31-9. [DOI: 10.1016/j.jviromet.2015.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/09/2015] [Accepted: 09/15/2015] [Indexed: 12/14/2022]
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Detection of Langat virus by TaqMan real-time one-step qRT-PCR method. Sci Rep 2015; 5:14007. [PMID: 26360297 PMCID: PMC4566139 DOI: 10.1038/srep14007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/13/2015] [Indexed: 11/08/2022] Open
Abstract
Langat virus (LGTV), one of the members of the tick-borne encephalitis virus (TBEV) complex, was firstly isolated from Ixodes granulatus ticks in Malaysia. However, the prevalence of LGTV in ticks in the region remains unknown. Surveillance for LGTV is therefore important and thus a tool for specific detection of LGTV is needed. In the present study, we developed a real-time quantitative reverse-transcription-polymerase chain reaction (qRT-PCR) for rapid detection of LGTV. Our findings showed that the developed qRT-PCR could detect LGTV at a titre as low as 0.1 FFU/ml. The detection limit of the qRT-PCR assay at 95% probability was 0.28 FFU/ml as determined by probit analysis (p ≤ 0.05). Besides, the designed primers and probe did not amplify ORF of the E genes for some closely related and more pathogenic viruses including TBEV, Louping ill virus, Omsk hemorrhagic fever virus (OHFV), Alkhurma virus (ALKV), Kyasanur Forest Disease virus (KFDV) and Powassan virus (POWV) which showed the acceptable specificity of the developed assay. The sensitivity of the developed method also has been confirmed by determining the LGTV in infected tick cell line as well as LGTV- spiked tick tissues.
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Flavivirus reverse genetic systems, construction techniques and applications: a historical perspective. Antiviral Res 2014; 114:67-85. [PMID: 25512228 PMCID: PMC7173292 DOI: 10.1016/j.antiviral.2014.12.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/26/2014] [Accepted: 12/03/2014] [Indexed: 12/20/2022]
Abstract
The study of flaviviruses, which cause some of the most important emerging tropical and sub-tropical human arbovirus diseases, has greatly benefited from the use of reverse genetic systems since its first development for yellow fever virus in 1989. Reverse genetics technology has completely revolutionized the study of these viruses, making it possible to manipulate their genomes and evaluate the direct effects of these changes on their biology and pathogenesis. The most commonly used reverse genetics system is the infectious clone technology. Whilst flavivirus infectious clones provide a powerful tool, their construction as full-length cDNA molecules in bacterial vectors can be problematic, laborious and time consuming, because they are often unstable, contain unwanted induced substitutions and may be toxic for bacteria due to viral protein expression. The incredible technological advances that have been made during the past 30years, such as the use of PCR or new sequencing methods, have allowed the development of new approaches to improve preexisting systems or elaborate new strategies that overcome these problems. This review summarizes the evolution and major technical breakthroughs in the development of flavivirus reverse genetics technologies and their application to the further understanding and control of these viruses and their diseases.
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30
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Pu SY, Wu RH, Tsai MH, Yang CC, Chang CM, Yueh A. A novel approach to propagate flavivirus infectious cDNA clones in bacteria by introducing tandem repeat sequences upstream of virus genome. J Gen Virol 2014; 95:1493-1503. [DOI: 10.1099/vir.0.064915-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Despite tremendous efforts to improve the methodology for constructing flavivirus infectious cDNAs, the manipulation of flavivirus cDNAs remains a difficult task in bacteria. Here, we successfully propagated DNA-launched type 2 dengue virus (DENV2) and Japanese encephalitis virus (JEV) infectious cDNAs by introducing seven repeats of the tetracycline-response element (7×TRE) and a minimal cytomegalovirus (CMVmin) promoter upstream of the viral genome. Insertion of the 7×TRE-CMVmin sequence upstream of the DENV2 or JEV genome decreased the cryptic E. coli promoter (ECP) activity of the viral genome in bacteria, as measured using fusion constructs containing DENV2 or JEV segments and the reporter gene Renilla luciferase in an empty vector. The growth kinetics of recombinant viruses derived from DNA-launched DENV2 and JEV infectious cDNAs were similar to those of parental viruses. Similarly, RNA-launched DENV2 infectious cDNAs were generated by inserting 7×TRE-CMVmin, five repeats of the GAL4 upstream activating sequence, or five repeats of BamHI linkers upstream of the DENV2 genome. All three tandem repeat sequences decreased the ECP activity of the DENV2 genome in bacteria. Notably, 7×TRE-CMVmin stabilized RNA-launched JEV infectious cDNAs and reduced the ECP activity of the JEV genome in bacteria. The growth kinetics of recombinant viruses derived from RNA-launched DENV2 and JEV infectious cDNAs displayed patterns similar to those of the parental viruses. These results support a novel methodology for constructing flavivirus infectious cDNAs, which will facilitate research in virology, viral pathogenesis and vaccine development of flaviviruses and other RNA viruses.
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Affiliation(s)
- Szu-Yuan Pu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
| | - Ren-Huang Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
| | - Ming-Han Tsai
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
| | - Chi-Chen Yang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
| | - Chung-Ming Chang
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
| | - Andrew Yueh
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, R.O.C
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan, R.O.C
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RNA virus reverse genetics and vaccine design. Viruses 2014; 6:2531-50. [PMID: 24967693 PMCID: PMC4113782 DOI: 10.3390/v6072531] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/18/2014] [Accepted: 06/19/2014] [Indexed: 12/22/2022] Open
Abstract
RNA viruses are capable of rapid spread and severe or potentially lethal disease in both animals and humans. The development of reverse genetics systems for manipulation and study of RNA virus genomes has provided platforms for designing and optimizing viral mutants for vaccine development. Here, we review the impact of RNA virus reverse genetics systems on past and current efforts to design effective and safe viral therapeutics and vaccines.
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Sakai M, Yoshii K, Sunden Y, Yokozawa K, Hirano M, Kariwa H. Variable region of the 3' UTR is a critical virulence factor in the Far-Eastern subtype of tick-borne encephalitis virus in a mouse model. J Gen Virol 2014; 95:823-835. [PMID: 24394696 DOI: 10.1099/vir.0.060046-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a major arbovirus that causes thousands of cases of severe neurological illness in humans annually. However, virulence factors and pathological mechanisms of TBEV remain largely unknown. To identify the virulence factors, we constructed chimeric viruses between two TBEV strains of the Far-Eastern subtype, Sofjin-HO (highly pathogenic) and Oshima 5-10 (low pathogenic). The replacement of the coding region for the structural and non-structural proteins from Sofjin into Oshima showed a partial increase of the viral pathogenicity in a mouse model. Oshima-based chimeric viruses with the variable region of the 3' UTR of Sofjin, which had a deletion of 207 nt, killed 100 % of mice and showed almost the same virulence as Sofjin. Replacement of the variable region of the 3' UTR from Sofjin into Oshima did not increase viral multiplication in cultured cells and a mouse model at the early phase of viral entry into the brain. At the terminal phase of viral infection in mice, the virus titre of the Oshima-based chimeric virus with the variable region of the 3' UTR of Sofjin reached a level identical to that of Sofjin and showed a similar histopathological change in the brain tissue. This is the first report to show that the variable region of the 3' UTR is a critical virulence factor in mice. These findings encourage further study to understand the mechanisms of the pathogenicity of TBEV, and to develop preventative and therapeutic strategies for tick-borne encephalitis.
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Affiliation(s)
- Mizuki Sakai
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Kentaro Yoshii
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Yuji Sunden
- Laboratory of Comparative Pathology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Kana Yokozawa
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Minato Hirano
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Hiroaki Kariwa
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
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34
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Three-dimensional architecture of tick-borne encephalitis virus replication sites and trafficking of the replicated RNA. J Virol 2013; 87:6469-81. [PMID: 23552408 DOI: 10.1128/jvi.03456-12] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Flavivirus replication is accompanied by the rearrangement of cellular membranes that may facilitate viral genome replication and protect viral components from host cell responses. The topological organization of viral replication sites and the fate of replicated viral RNA are not fully understood. We exploited electron microscopy to map the organization of tick-borne encephalitis virus (TBEV) replication compartments in infected cells and in cells transfected with a replicon. Under both conditions, 80-nm vesicles were seen within the lumen of the endoplasmic reticulum (ER) that in infected cells also contained virions. By electron tomography, the vesicles appeared as invaginations of the ER membrane, displaying a pore that could enable release of newly synthesized viral RNA into the cytoplasm. To track the fate of TBEV RNA, we took advantage of our recently developed method of viral RNA fluorescent tagging for live-cell imaging combined with bleaching techniques. TBEV RNA was found outside virus-induced vesicles either associated to ER membranes or free to move within a defined area of juxtaposed ER cisternae. From our results, we propose a biologically relevant model of the possible topological organization of flavivirus replication compartments composed of replication vesicles and a confined extravesicular space where replicated viral RNA is retained. Hence, TBEV modifies the ER membrane architecture to provide a protected environment for viral replication and for the maintenance of newly replicated RNA available for subsequent steps of the virus life cycle.
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Abstract
Zoonoses are infections in humans transmitted by animal pathogens or animal infections transmitted to humans. Viruses are the main etiological agents of emerging or re-emerging zoonoses. This chapter will discuss the most relevant foodborne and waterborne viral zoonotic infections along with their specific etiological agent, the issue of global and local infections, climate change, clinical manifestations and epidemiology and possible control and prevention measures.
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36
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[Reverse genetics system for flaviviruses]. Uirusu 2013; 63:13-22. [PMID: 24769573 DOI: 10.2222/jsv.63.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Flaviviruses such as Japanese encephalitis virus, West Nile virus, yellow fever virus, dengue virus, and tick-borne encephalitis virus belong to a family Flaviviridae. These viruses are transmitted to vertebrates by infected mosquitoes or ticks, producing diseases, which have a serious impact on global public health. Reverse genetics is a powerful tool for studying the viruses. Although infectious full-length clones have been obtained for multiple flaviviruses, their early-stage development had the difficulty because of the instability problem of the viral cDNA in E. coli. Several strategies have been developed to circumvent the problem of infectious clone instability. The current knowledge accumulated on reverse genetics system of flaviviruses and its application are summarized in this review.
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A novel bacterium-free method for generation of flavivirus infectious DNA by circular polymerase extension reaction allows accurate recapitulation of viral heterogeneity. J Virol 2012; 87:2367-72. [PMID: 23236063 DOI: 10.1128/jvi.03162-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A novel bacterium-free approach for rapid assembly of flavivirus infectious cDNAs using circular polymerase extension reaction was applied to generate infectious cDNA for the virulent New South Wales isolate of the Kunjin strain of West Nile virus (KUNV) that recently emerged in Australia. Recovered virus recapitulated the genetic heterogeneity present in the original isolate. The approach was utilized to generate viral mutants with designed phenotypic properties and to identify E protein glycosylation as one of the virulence determinants.
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38
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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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Lommano E, Burri C, Maeder G, Guerne M, Bastic V, Patalas E, Gern L. Prevalence and genotyping of tick-borne encephalitis virus in questing Ixodes ricinus ticks in a new endemic area in western Switzerland. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:156-164. [PMID: 22308784 DOI: 10.1603/me11044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE) and causes neurological disease in humans in Eurasia. TBEV is transmitted by ticks of the genus Ixodes. Currently 10,000-12,000 clinical cases are reported annually in approximately 30 TBE endemic countries. Since 1990 the epidemiology of TBE is characterized by a global increase of clinical cases and an expansion of risk areas. Similar trends are also observed in Switzerland but few studies confirmed the emergence of new TBE foci by detecting viral RNA in field-collected ticks. In this study, free-living Ixodes ricinus (L.) ticks from one nonendemic and three new TBE endemic regions located in the Western part of Switzerland were screened during four consecutive years (2007-2010) for the presence of TBEV. A total of 9,868 I. ricinus ticks (6,665 nymphs and 3,203 adults) were examined in pools for TBEV by real-time reverse transcription polymerase chain reaction. Our results confirmed the presence of viral RNA in 0.1% (6/6120) of questing ticks collected in one new endemic region. Among TBE endemic sites, the minimal infection rate per 100 ticks tested ranged from 0.21 (1/477) to 0.95 (1/105). Four positive samples were sequenced and phylogenetic analysis of the NS5 gene showed that all TBEV nucleotide sequences belonged to the European subtype and were split into two distinct lineages originating probably independently from two distinct foci located North-East and East of the study region.
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Affiliation(s)
- E Lommano
- Institute of Biology, Laboratory of Eco-Epidemiology of Parasites, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland
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40
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Takano A, Yoshii K, Omori-Urabe Y, Yokozawa K, Kariwa H, Takashima I. Construction of a replicon and an infectious cDNA clone of the Sofjin strain of the Far-Eastern subtype of tick-borne encephalitis virus. Arch Virol 2011; 156:1931-41. [PMID: 21785855 DOI: 10.1007/s00705-011-1066-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 07/01/2011] [Indexed: 11/27/2022]
Abstract
Tick-borne encephalitis virus (TBEV) causes severe encephalitis in humans. The Sofjin-HO strain is the prototype strain of the TBEV Far-Eastern subtype and is highly pathogenic in a mouse model. In this study, we constructed replicons and infectious cDNA clones of the Sofjin-HO strain. The replication of the replicon RNA was confirmed, and infectious viruses were recovered from the infectious cDNA clone. The recombinant viruses showed similar virulence characteristics to those of the parental virus. While characterizing the replicon and infectious cDNA, several amino acid differences derived from cell culture adaptations were analysed. The amino acids differences at E position 496 and NS4A position 58 were found to affect viral replication. The Gly- or Ala-to-Glu substitution at E position 122 was shown to increase neuroinvasiveness in mice. These replicons and infectious cDNA clones are useful in revealing the viral molecular determinants involved in the replication and pathogenicity of TBEV.
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MESH Headings
- Animals
- Cell Line
- Cricetinae
- DNA, Complementary/genetics
- DNA, Complementary/metabolism
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Encephalitis Viruses, Tick-Borne/classification
- Encephalitis Viruses, Tick-Borne/genetics
- Encephalitis Viruses, Tick-Borne/pathogenicity
- Encephalitis Viruses, Tick-Borne/physiology
- Encephalitis, Tick-Borne/virology
- Female
- Humans
- Mice
- Mice, Inbred C57BL
- Replicon
- Virulence
- Virus Replication
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Affiliation(s)
- Ayako Takano
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan
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41
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Mutational analysis of three predicted 5'-proximal stem-loop structures in the genome of tick-borne encephalitis virus indicates different roles in RNA replication and translation. Virology 2011; 417:79-86. [PMID: 21645915 DOI: 10.1016/j.virol.2011.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 04/07/2011] [Accepted: 05/14/2011] [Indexed: 11/24/2022]
Abstract
Flavivirus gene expression is modulated by RNA secondary structure elements at the terminal ends of the viral RNA molecule. For tick-borne encephalitis virus (TBEV), four stem-loop (SL) elements have been predicted in the first 180 nucleotides of the viral genome: 5'-SL1, 5'-SL2, 5'-SL3 and 5'-SL4. The last three of these appear to be unique to tick-borne flaviviruses. Here, we report their characterization by mutagenesis in a TBEV luciferase reporter system. By manipulating their thermodynamic properties, we found that an optimal stability of the 5'-SL2 is required for efficient RNA replication. 5'-SL3 formation is also important for viral RNA replication, but although it contains the viral start codon, its formation is dispensable for RNA translation. 5'-SL4 appears to facilitate both RNA translation and replication. Our data suggest that maintenance of the balanced thermodynamic stability of these SL elements is important for temporal regulation of its different functions.
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42
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The unique transmembrane hairpin of flavivirus fusion protein E is essential for membrane fusion. J Virol 2011; 85:4377-85. [PMID: 21325407 DOI: 10.1128/jvi.02458-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The fusion of enveloped viruses with cellular membranes is mediated by proteins that are anchored in the lipid bilayer of the virus and capable of triggered conformational changes necessary for driving fusion. The flavivirus envelope protein E is the only known viral fusion protein with a double membrane anchor, consisting of two antiparallel transmembrane helices (TM1 and TM2). TM1 functions as a stop-transfer sequence and TM2 as an internal signal sequence for the first nonstructural protein during polyprotein processing. The possible role of this peculiar C-terminal helical hairpin in membrane fusion has not been investigated so far. We addressed this question by studying TM mutants of tick-borne encephalitis virus (TBEV) recombinant subviral particles (RSPs), an established model system for flavivirus membrane fusion. The engineered mutations included the deletion of TM2, the replacement of both TM domains (TMDs) by those of the related Japanese encephalitis virus (JEV), and the use of chimeric TBEV-JEV membrane anchors. Using these mutant RSPs, we provide evidence that TM2 is not just a remnant of polyprotein processing but, together with TM1, plays an active role in fusion. None of the TM mutations, including the deletion of TM2, affected early steps of the fusion process, but TM interactions apparently contribute to the stability of the postfusion E trimer and the completion of the merger of the membranes. Our data provide evidence for both intratrimer and intertrimer interactions mediated by the TMDs of E and thus extend the existing models of flavivirus membrane fusion.
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43
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Successful propagation of flavivirus infectious cDNAs by a novel method to reduce the cryptic bacterial promoter activity of virus genomes. J Virol 2011; 85:2927-41. [PMID: 21228244 DOI: 10.1128/jvi.01986-10] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reverse genetics is a powerful tool to study single-stranded RNA viruses. Despite tremendous efforts having been made to improve the methodology for constructing flavivirus cDNAs, the cause of toxicity of flavivirus cDNAs in bacteria remains unknown. Here we performed mutational analysis studies to identify Escherichia coli promoter (ECP) sequences within nucleotides (nt) 1 to 3000 of the dengue virus type 2 (DENV2) and Japanese encephalitis virus (JEV) genomes. Eight and four active ECPs were demonstrated within nt 1 to 3000 of the DENV2 and JEV genomes, respectively, using fusion constructs containing DENV2 or JEV segments and empty vector reporter gene Renilla luciferase. Full-length DENV2 and JEV cDNAs were obtained by inserting mutations reducing their ECP activity in bacteria without altering amino acid sequences. A severe cytopathic effect occurred when BHK21 cells were transfected with in vitro-transcribed RNAs from either a DENV2 cDNA clone with multiple silent mutations within the prM-E-NS1 region of dengue genome or a JEV cDNA clone with an A-to-C mutation at nt 90 of the JEV genome. The virions derived from the DENV2 or JEV cDNA clone exhibited infectivities similar to those of their parental viruses in C6/36 and BHK21 cells. A cis-acting element essential for virus replication was revealed by introducing silent mutations into the central portion (nt 160 to 243) of the core gene of DENV2 infectious cDNA or a subgenomic DENV2 replicon clone. This novel strategy of constructing DENV2 and JEV infectious clones could be applied to other flaviviruses or pathogenic RNA viruses to facilitate research in virology, viral pathogenesis, and vaccine development.
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44
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Yoshii K, Igarashi M, Ito K, Kariwa H, Holbrook MR, Takashima I. Construction of an infectious cDNA clone for Omsk hemorrhagic fever virus, and characterization of mutations in NS2A and NS5. Virus Res 2011; 155:61-8. [DOI: 10.1016/j.virusres.2010.08.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 08/26/2010] [Accepted: 08/26/2010] [Indexed: 10/19/2022]
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45
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Rouha H, Thurner C, Mandl CW. Functional microRNA generated from a cytoplasmic RNA virus. Nucleic Acids Res 2010; 38:8328-37. [PMID: 20705652 PMCID: PMC3001059 DOI: 10.1093/nar/gkq681] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
MicroRNAs (miRNAs) are a class of small, non-coding RNAs that play a pivotal role in the regulation of posttranscriptional gene expression in a wide range of eukaryotic organisms. Although DNA viruses have been shown to encode miRNAs and exploit the cellular RNA silencing machinery as a convenient way to regulate viral and host gene expression, it is generally believed that this pathway is not available to RNA viruses that replicate in the cytoplasm of the cell because miRNA biogenesis is initiated in the nucleus. In fact, among the >200 viral miRNAs that have been experimentally verified so far, none is derived from an RNA virus. Here, we show that a cytoplasmic RNA virus can indeed encode and produce a functional miRNA. We introduced a heterologous miRNA-precursor stem-loop sequence element into the RNA genome of the flavivirus tick-borne encephalitis virus, and this led to the production of a functional miRNA during viral infection without impairing viral RNA replication. These findings demonstrate that miRNA biogenesis can be used by cytoplasmic RNA viruses to produce regulatory molecules for the modulation of the transcriptome.
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Affiliation(s)
- Harald Rouha
- Department of Virology, Medical University of Vienna, Vienna, Austria
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46
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Orlinger KK, Holzer GW, Schwaiger J, Mayrhofer J, Schmid K, Kistner O, Noel Barrett P, Falkner FG. An inactivated West Nile Virus vaccine derived from a chemically synthesized cDNA system. Vaccine 2010; 28:3318-24. [PMID: 20211218 PMCID: PMC7115638 DOI: 10.1016/j.vaccine.2010.02.092] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/17/2010] [Accepted: 02/19/2010] [Indexed: 01/29/2023]
Abstract
A cDNA comprising the complete genome of West Nile Virus (WNV) was generated by chemical synthesis using published sequence data, independent of any preformed viral components. The synthetic WNV, produced by transfection of in vitro transcribed RNA into cell culture, exhibited undistinguishable biological properties compared to the corresponding animal-derived wild-type virus. No differences were found concerning viral growth in mammalian and insect cell lines and concerning expression of viral proteins in cells. There were also no significant differences in virulence in mice following intranasal challenge. After immunizations of mice with experimental vaccines derived from the synthetic and wild-type viruses, protection from lethal challenge was achieved with similar amounts of antigen. Both vaccine preparations also induced comparable levels of neutralizing antibodies in mice. In addition, the synthetic approach turned out to be very accurate, since the rescued WNV genome contained no undesired mutations. Thus, the first flavivirus based on chemical gene synthesis was indistinguishable from the parent virus. This demonstrates that virus isolates from animal sources are dispensable to derive seed viruses for vaccine production or research.
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Affiliation(s)
- Klaus K Orlinger
- Baxter Bioscience, Biomedical Research Center, Uferstrasse 15, A-2304 Orth/Donau, Austria
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47
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A trans-complementing recombination trap demonstrates a low propensity of flaviviruses for intermolecular recombination. J Virol 2010; 84:599-611. [PMID: 19864381 DOI: 10.1128/jvi.01063-09] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Intermolecular recombination between the genomes of closely related RNA viruses can result in the emergence of novel strains with altered pathogenic potential and antigenicity. Although recombination between flavivirus genomes has never been demonstrated experimentally, the potential risk of generating undesirable recombinants has nevertheless been a matter of concern and controversy with respect to the development of live flavivirus vaccines. As an experimental system for investigating the ability of flavivirus genomes to recombine, we developed a "recombination trap," which was designed to allow the products of rare recombination events to be selected and amplified. To do this, we established reciprocal packaging systems consisting of pairs of self-replicating subgenomic RNAs (replicons) derived from tick-borne encephalitis virus (TBEV), West Nile virus (WNV), and Japanese encephalitis virus (JEV) that could complement each other in trans and thus be propagated together in cell culture over multiple passages. Any infectious viruses with intact, full-length genomes that were generated by recombination of the two replicons would be selected and enriched by end point dilution passage, as was demonstrated in a spiking experiment in which a small amount of wild-type virus was mixed with the packaged replicons. Using the recombination trap and the JEV system, we detected two aberrant recombination events, both of which yielded unnatural genomes containing duplications. Infectious clones of both of these genomes yielded viruses with impaired growth properties. Despite the fact that the replicon pairs shared approximately 600 nucleotides of identical sequence where a precise homologous crossover event would have yielded a wild-type genome, this was not observed in any of these systems, and the TBEV and WNV systems did not yield any viable recombinant genomes at all. Our results show that intergenomic recombination can occur in the structural region of flaviviruses but that its frequency appears to be very low and that therefore it probably does not represent a major risk in the use of live, attenuated flavivirus vaccines.
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48
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Extension of flavivirus protein C differentially affects early RNA synthesis and growth in mammalian and arthropod host cells. J Virol 2009; 83:11201-10. [PMID: 19692461 DOI: 10.1128/jvi.01025-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The translation of flaviviral RNA genomes yields a single polyprotein that is processed into the mature proteins by viral and host cell proteases. Mature capsid protein C is freed from the polyprotein by the viral NS2B/3 protease, cleaving in the C-terminal region of protein C in front of the signal sequence for prM. Protein C has been shown to be involved in viral assembly and RNA packaging. To examine further the role of protein C and its production by proteolysis, we replaced the NS2B/3 capsid cleavage site in tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) by the 2A protein of foot-and-mouth disease virus (TBEV-2A and WNV-2A). This obviated the need for NS2B/3 processing at the C terminus of mature protein C while simultaneously producing a 19-amino-acid extension on protein C. Infectious virions were generated with both viruses; the phenotype depended on the host cell. TBEV-2A replicated well in BHK-21 cells but was essentially incapable of replication in tick cells. In contrast, WNV-2A replicated well in mosquito cells but showed a small-plaque phenotype in Vero cells, with frequent production of larger plaques. Sequencing of viral RNA from the larger plaques showed substitutions in the signal sequence for prM, presumably improving coordinated protein processing at the C-prM junction. Furthermore, both TBEV-2A and WNV-2A were also defective in unpackaging and/or early RNA synthesis. Together, these results indicate a role for flavivirus protein C in both viral assembly and RNA replication, possibly by interacting with host cell factors required to set up the cell for RNA replication.
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Mansfield KL, Johnson N, Phipps LP, Stephenson JR, Fooks AR, Solomon T. Tick-borne encephalitis virus - a review of an emerging zoonosis. J Gen Virol 2009; 90:1781-1794. [PMID: 19420159 DOI: 10.1099/vir.0.011437-0] [Citation(s) in RCA: 310] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
During the last 30 years, there has been a continued increase in human cases of tick-borne encephalitis (TBE) in Europe, a disease caused by tick-borne encephalitis virus (TBEV). TBEV is endemic in an area ranging from northern China and Japan, through far-eastern Russia to Europe, and is maintained in cycles involving Ixodid ticks (Ixodes ricinus and Ixodes persulcatus) and wild vertebrate hosts. The virus causes a potentially fatal neurological infection, with thousands of cases reported annually throughout Europe. TBE has a significant mortality rate depending upon the strain of virus or may cause long-term neurological/neuropsychiatric sequelae in people affected. In this review, we comprehensively reviewed TBEV, its epidemiology and pathogenesis, the clinical manifestations of TBE, along with vaccination and prevention. We also discuss the factors which may have influenced an apparent increase in the number of reported human cases each year, despite the availability of effective vaccines.
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Affiliation(s)
- K L Mansfield
- Rabies and Wildlife Zoonoses Group, Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey, UK
| | - N Johnson
- Rabies and Wildlife Zoonoses Group, Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey, UK
| | - L P Phipps
- Rabies and Wildlife Zoonoses Group, Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey, UK
| | | | - A R Fooks
- Rabies and Wildlife Zoonoses Group, Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey, UK
| | - T Solomon
- Brain Infections Group, Divisions of Neurological Science and Medical Microbiology, University of Liverpool, Liverpool, UK
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Helices alpha2 and alpha3 of West Nile virus capsid protein are dispensable for assembly of infectious virions. J Virol 2009; 83:5581-91. [PMID: 19297470 DOI: 10.1128/jvi.02653-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The internal hydrophobic sequence within the flaviviral capsid protein (protein C) plays an important role in the assembly of infectious virions. Here, this sequence was analyzed in a West Nile virus lineage I isolate (crow V76/1). An infectious cDNA clone was constructed and used to introduce deletions into the internal hydrophobic domain which comprises helix alpha2 and part of the loop intervening helices alpha2 and alpha3. In total, nine capsid deletion mutants (4 to 14 amino acids long) were constructed and tested for virus viability. Some of the short deletions did not significantly affect growth in cell culture, whereas larger deletions removing almost the entire hydrophobic region significantly impaired viral growth. Efficient growth of the majority of mutants could, however, be restored by the acquisition of second-site mutations. In most cases, these resuscitating mutations were point mutations within protein C changing individual amino acids into more hydrophobic residues, reminiscent of what had been observed previously for another flavivirus, tick-borne encephalitis virus. However, we also identified viable spontaneous pseudorevertants with more than one-third of the capsid protein removed, i.e., 36 or 37 of a total of 105 residues, including all of helix alpha3 and a hydrophilic segment connecting alpha3 and alpha4. These large deletions are predicted to induce formation of large, predominantly hydrophobic fusion helices which may substitute for the loss of the internal hydrophobic domain, underlining the unrivaled structural and functional flexibility of protein C.
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