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Lang D, Chitimia-Dobler L, Bestehorn-Willmann M, Lindau A, Drehmann M, Stroppel G, Hengge H, Mackenstedt U, Kaier K, Dobler G, Borde J. The Emergence and Dynamics of Tick-Borne Encephalitis Virus in a New Endemic Region in Southern Germany. Microorganisms 2022; 10:2125. [PMID: 36363717 PMCID: PMC9693875 DOI: 10.3390/microorganisms10112125] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 06/11/2024] Open
Abstract
Tick-borne encephalitis (TBE) is the most important viral tick-borne infection in Europe and Asia. It is emerging in new areas. The mechanisms of emergence are fairly unknown or speculative. In the Ravensburg district in southern Germany, TBE emerged, mainly over the last five years. Here, we analyzed the underlying epidemiology in humans. The resulting identified natural foci of the causal TBE virus (TBEV) were genetically characterized. We sampled 13 potential infection sites at these foci and detected TBEV in ticks (Ixodes ricinus) at eight sites. Phylogenetic analysis spurred the introduction of at least four distinct TBEV lineages of the European subtype into the Ravensburg district over the last few years. In two instances, a continuous spread of these virus strains over up to 10 km was observed.
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Affiliation(s)
- Daniel Lang
- National Reference Laboratory for TBEV, Bundeswehr Institute for Microbiology, 80937 Munich, Germany
| | - Lidia Chitimia-Dobler
- National Reference Laboratory for TBEV, Bundeswehr Institute for Microbiology, 80937 Munich, Germany
| | - Malena Bestehorn-Willmann
- National Reference Laboratory for TBEV, Bundeswehr Institute for Microbiology, 80937 Munich, Germany
| | - Alexander Lindau
- Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Marco Drehmann
- Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Gabriele Stroppel
- Public Health Office, District Ravensburg, 88212 Ravensburg, Germany
| | - Helga Hengge
- Public Health Office, District Ravensburg, 88212 Ravensburg, Germany
| | - Ute Mackenstedt
- Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Klaus Kaier
- Institute of Medical Biometry and Statistics (IMBI), University Medical Center Freiburg im Breisgau, 79106 Freiburg im Breisgau, Germany
| | - Gerhard Dobler
- National Reference Laboratory for TBEV, Bundeswehr Institute for Microbiology, 80937 Munich, Germany
- Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Johannes Borde
- Praxis Prof. Borde & Kollegen, Gesundheitszentrum Oberkirch, 77704 Oberkirch, Germany
- Division of Infectious Diseases, Department of Internal Medicine, University Medical Center Freiburg im Breisgau, 79106 Freiburg im Breisgau, Germany
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Magouras I, Schoster A, Fouché N, Gerber V, Groschup MH, Ziegler U, Fricker R, Griot C, Vögtlin A. Neurological disease suspected to be caused by tick-borne encephalitis virus infection in 6 horses in Switzerland. J Vet Intern Med 2022; 36:2254-2262. [PMID: 36093849 DOI: 10.1111/jvim.16533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Reports on acute tick-borne encephalitis virus (TBEV) infections with signs of neurologic disease in horses are limited. OBJECTIVES To describe the epidemiological, clinical, and laboratory findings of suspected acute TBEV infections in 6 horses. ANIMALS Six horses originating from TBEV endemic regions of Switzerland were presented to equine hospitals with acute onset of neurologic disease between 2011 and 2019. METHODS Retrospective case series. Horses with acute onset of signs of neurologic disease that were subjected to clinical and microbiological examinations to rule out infectious diseases affecting the central nervous system. RESULTS All horses exhibited acute signs of neurologic disease including ataxia and proprioceptive deficits. Horses tested positive for TBEV using virus neutralization test and samples were further tested for TBEV-specific IgM. The presence of TBEV-specific IgM antibodies was confirmed in 5 horses (cases 1-5, Laboratory Unit [LU] values ranging from 30 to 56). One horse (case no. 6) with an LU value just below the test threshold (LU = 22.3) was also included under the hypothesis that the horse was transitioning from acute to chronic infection. All horses originated from areas where humans with confirmed tick-borne encephalitis reported to have been bitten by ticks. CONCLUSIONS AND CLINICAL IMPORTANCE Acute TBEV infection should be a differential diagnosis in horses with signs of neurologic disease and originating from TBEV endemic areas. The establishment of harmonized diagnostic criteria would help to overcome the diagnostic challenges associated with TBEV and other Flavivirus infections in horses.
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Affiliation(s)
- Ioannis Magouras
- Veterinary Public Health Institute, Department of Clinical Research and Veterinary Public Health, University of Bern, Bern, Switzerland.,Centre for Applied One Health Research and Policy Advice, Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong, China
| | - Angelika Schoster
- Clinic for Equine Internal Medicine, Equine Department, University of Zurich, Zurich, Switzerland
| | - Nathalie Fouché
- Swiss Institute of Equine Medicine, University of Bern, Bern, Switzerland
| | - Vinzenz Gerber
- Swiss Institute of Equine Medicine, University of Bern, Bern, Switzerland
| | - Martin H Groschup
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Ute Ziegler
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Raffael Fricker
- Institute for Virology and Immunology IVI, Department of Infectious Diseases and Pathobiology, University of Bern, Mittelhäusern and Bern, Switzerland
| | - Christian Griot
- Institute for Virology and Immunology IVI, Department of Infectious Diseases and Pathobiology, University of Bern, Mittelhäusern and Bern, Switzerland
| | - Andrea Vögtlin
- Institute for Virology and Immunology IVI, Department of Infectious Diseases and Pathobiology, University of Bern, Mittelhäusern and Bern, Switzerland
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3
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Smura T, Tonteri E, Jääskeläinen A, von Troil G, Kuivanen S, Huitu O, Kareinen L, Uusitalo J, Uusitalo R, Hannila-Handelberg T, Voutilainen L, Nikkari S, Sironen T, Sane J, Castrén J, Vapalahti O. Recent establishment of tick-borne encephalitis foci with distinct viral lineages in the Helsinki area, Finland. Emerg Microbes Infect 2019; 8:675-683. [PMID: 31084456 PMCID: PMC6522972 DOI: 10.1080/22221751.2019.1612279] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Number of tick-borne encephalitis (TBE) cases has increased and new foci have emerged in Finland during the last decade. We evaluated risk for locally acquired TBE in the capital region inhabited by 1.2 million people. We screened ticks and small mammals from probable places of TBE virus (TBEV) transmission and places without reported circulation. The TBEV positive samples were sequenced and subjected to phylogenetic analysis. Within the study period 2007–2017, there was a clear increase of both all TBE cases and locally acquired cases in the Helsinki area. The surveillance of ticks and small mammals for TBEV confirmed four distinct TBEV foci in the Helsinki area. All detected TBEV strains were of the European subtype. TBEV genome sequences indicated that distinct TBEV lineages circulate in each focus. Molecular clock analysis suggested that the virus lineages were introduced to these foci decades ago. In conclusion, TBE has emerged in the mainland of Helsinki area during the last decade, with at least four distinct virus lineages independently introduced into the region previously. Although the overall annual TBE incidence is below the threshold for recommending general vaccinations, the situation requires further surveillance to detect and prevent possible further emergence of local TBE clusters.
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Affiliation(s)
- Teemu Smura
- a Department of Virology , University of Helsinki , Helsinki , Finland.,b Division of Clinical Microbiology , Helsinki University Hospital Laboratory Services (HUSLAB) , Helsinki , Finland
| | - Elina Tonteri
- c Centers for Military Medicine and Biothreat Preparedness , Helsinki , Finland
| | - Anu Jääskeläinen
- b Division of Clinical Microbiology , Helsinki University Hospital Laboratory Services (HUSLAB) , Helsinki , Finland
| | | | - Suvi Kuivanen
- a Department of Virology , University of Helsinki , Helsinki , Finland
| | - Otso Huitu
- e Natural Resources Institute Finland (Luke) , Helsinki , Finland
| | - Lauri Kareinen
- a Department of Virology , University of Helsinki , Helsinki , Finland
| | - Joni Uusitalo
- a Department of Virology , University of Helsinki , Helsinki , Finland
| | - Ruut Uusitalo
- a Department of Virology , University of Helsinki , Helsinki , Finland.,f Department of Geosciences and Geography , University of Helsinki , Helsinki , Finland.,g Department of Veterinary Biosciences , University of Helsinki , Helsinki , Finland
| | | | - Liina Voutilainen
- c Centers for Military Medicine and Biothreat Preparedness , Helsinki , Finland
| | - Simo Nikkari
- c Centers for Military Medicine and Biothreat Preparedness , Helsinki , Finland
| | - Tarja Sironen
- a Department of Virology , University of Helsinki , Helsinki , Finland
| | - Jussi Sane
- h Department of Health Security, Infectious Disease Control and Vaccinations Unit , National Institute for Health and Welfare , Helsinki , Finland
| | | | - Olli Vapalahti
- a Department of Virology , University of Helsinki , Helsinki , Finland.,b Division of Clinical Microbiology , Helsinki University Hospital Laboratory Services (HUSLAB) , Helsinki , Finland.,g Department of Veterinary Biosciences , University of Helsinki , Helsinki , Finland
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4
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Casati Pagani S, Frigerio Malossa S, Klaus C, Hoffmann D, Beretta O, Bomio-Pacciorini N, Lazzaro M, Merlani G, Ackermann R, Beuret C. First detection of TBE virus in ticks and sero-reactivity in goats in a non-endemic region in the southern part of Switzerland (Canton of Ticino). Ticks Tick Borne Dis 2019; 10:868-874. [PMID: 31047827 DOI: 10.1016/j.ttbdis.2019.04.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/28/2019] [Accepted: 04/10/2019] [Indexed: 10/27/2022]
Abstract
In Switzerland, tick-borne encephalitis (TBE) is a notifiable human disease with an average of 210 cases per year in the last 10 years (2008-2017). A national surveillance conducted in 2009 reported a prevalence of 0.46% for tick-borne encephalitis virus (TBEV) detected in ticks, which is in accordance with the prevalences found in Europe from 0.1%-5%. The Canton of Ticino in the southern part of Switzerland, geographically separated from the rest of the national territory by the Alps, is considered a non-endemic region, as no autochthonous clinical cases and no TBEV presence in ticks have ever been reported. In order to understand the epidemiological situation in Ticino, we conducted a large study investigating the TBEV presence in field-collected Ixodes ricinus ticks and in goat and human sera. Goats and sheep were considered as sentinel hosts showing persistence of antibodies also after 28 months in the absence of symptoms; this longevity supports the data validity to characterize an area with the TBEV status. The goat sera collection was composed of a total of 662 samples from 37 flocks. The total seroprevalence was 14.6%. 39 (40%) of the 97 SNT-positive samples showed an antibody titer ≥ 1:120 which indicates recent infection and consequently the probable presence of active foci among the pastures frequented by the goats belonging to 10 flocks. In total, 51 owners participated in the study and all were TBEV antibody-free. A total of 12'052 I. ricinus ticks (nymphs and adults) were collected and 1'371 pools were tested using quantitative real-time RT-PCR. Only one positive pool was reported with a prevalence of 0.35%. Metagenomic analysis revealed that the TBEV strain isolated from the ticks collected in Ticino is closely related to 2 strains coming from the Canton of Valais (99.1% and 98.7% identity, respectively), a neighbouring region of the Canton of Ticino. These two Cantons are close together but separated by high mountains (Alps) and we hypothesize that infected ticks were transported by wild animals from Valais into the Valle Maggia in Ticino where we found positive ticks. In conclusion, our data show for the first time the presence of TBEV in ticks and the related sero-reactivity in goats, confirming the presence of TBEV in the environment of the Canton of Ticino. Further surveillance studies will have to be conducted to follow the persistence of TBEV in this region.
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Affiliation(s)
- Simona Casati Pagani
- Dipartimento della sanità e della socialità, Ufficio del medico cantonale, Via Dogana 16, 6500, Bellinzona, Switzerland.
| | - Simona Frigerio Malossa
- EOC - Dipartimento di medicina di laboratorio, Servizio di microbiologia (SMIC), Via Mirasole 22a, 6500, Bellinzona, Switzerland
| | - Christine Klaus
- Friedrich-Loeffler-Institut, Institute of Bacterial Infections and Zoonoses, Naumburger Str. 96a, 07743, Jena, Germany
| | - Donata Hoffmann
- Friedrich-Loeffler-Institut, Institute of Diagnostic Virology, Südufer 10, 17493, Greifswald-Insel Riems, Germany
| | - Ottavio Beretta
- Dipartimento della sanità e della socialità, Ufficio del medico cantonale, Via Dogana 16, 6500, Bellinzona, Switzerland
| | - Nicola Bomio-Pacciorini
- Dipartimento del territorio, Ufficio forestale 4° circondario, Via Antonio Ciseri 13, 6600, Locarno, Switzerland
| | - Mario Lazzaro
- Dipartimento della sanità e della socialità, Ufficio del medico cantonale, Via Dogana 16, 6500, Bellinzona, Switzerland
| | - Giorgio Merlani
- Dipartimento della sanità e della socialità, Ufficio del medico cantonale, Via Dogana 16, 6500, Bellinzona, Switzerland
| | - Rahel Ackermann
- National Reference Centre for Tick-Transmitted Diseases (NRZK), Labor Spiez, Ausstrasse, 3700, Spiez, Switzerland
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5
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Saksida A, Jakopin N, Jelovšek M, Knap N, Fajs L, Lusa L, Lotrič-Furlan S, Bogovič P, Arnež M, Strle F, Avšič-Županc T. Virus RNA Load in Patients with Tick-Borne Encephalitis, Slovenia. Emerg Infect Dis 2019; 24:1315-1323. [PMID: 29912706 PMCID: PMC6038823 DOI: 10.3201/eid2407.180059] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We determined levels of tick-borne encephalitis (TBE) virus (TBEV) RNA in serum samples obtained from 80 patients during the initial phase of TBE in Slovenia. For most samples, levels were within the range of 3-6 log10 copies RNA/mL. Levels were higher in female patients than in male patients, but we found no association between virus load and several laboratory and clinical parameters, including severity of TBE. However, a weak humoral immune response was associated with a more severe disease course, suggesting that inefficient clearance of virus results in a more serious illness. To determine whether a certain genetic lineage of TBEV had a higher virulence potential, we obtained 56 partial envelope protein gene sequences by directly sequencing reverse transcription PCR products from clinical samples of patients. This method provided a large set of patient-derived TBEV sequences. We observed no association between phylogenetic clades and virus load or disease severity.
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6
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Lenz N, Engler O, Grandgirard D, Leib SL, Ackermann-Gäumann R. Evaluation of antivirals against tick-borne encephalitis virus in organotypic brain slices of rat cerebellum. PLoS One 2018; 13:e0205294. [PMID: 30300398 PMCID: PMC6177190 DOI: 10.1371/journal.pone.0205294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/21/2018] [Indexed: 12/30/2022] Open
Abstract
Neurotropic tick borne encephalitis virus (TBEV) causes life-threatening disease, and accounts for most cases of tick-transmitted viral infections in Central and Eastern Europe and Russia. No specific treatment for TBEV infections exists, and vaccination is recommended for people at risk. So far, various nucleoside analogues have been investigated in vitro as potential candidates for treatment of TBEV infections. However, in vitro experiments with more complex cell culture systems, such as organotypic culture slices which model the sophisticated architecture of the target tissue are lacking. Using TBEV as a model, we investigated the suitability of rat organotypic cerebellum slices (OCS) to study the effectiveness of nucleoside analogues with a well-known anti-TBEV activity. In these OCS, 50 μM of the nucleoside analogues 2’-C-methyladenosine (2’-CMA) and especially 7-deaza-2’-C-methyladenosine (7-deaza-2’-CMA) exhibited strong inhibitory effects on TBEV replication, reducing viral titers to an average of 103-fold and TBEV RNA content 60-90-fold. In contrast, the influence of 2’-C-methylcytidine (2’-CMC) on TBEV replication was very weak, reducing virus titers by 10-fold and TBEV RNA content by 3-fold. In agreement with other studies, there was no noticeable difference in TBEV titers between OCS treated with 50 μM of Ribavirin and the DMSO treated controls. All tested nucleoside analogues exhibited excellent cytotoxicity profiles at concentrations of 50 μM. Our findings in OCS were highly comparable to data obtained in cell line culture systems. Therefore, OCS represent an ideal in vitro approach to study antivirals against TBEV and possibly other neurotropic viruses.
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Affiliation(s)
- Nicole Lenz
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Biology Division, Spiez Laboratory, Swiss Federal Office for Civil Protection, Spiez, Switzerland
| | - Olivier Engler
- Biology Division, Spiez Laboratory, Swiss Federal Office for Civil Protection, Spiez, Switzerland
| | - Denis Grandgirard
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Stephen L. Leib
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- * E-mail:
| | - Rahel Ackermann-Gäumann
- Biology Division, Spiez Laboratory, Swiss Federal Office for Civil Protection, Spiez, Switzerland
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7
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Ignatieva EV, Igoshin AV, Yudin NS. A database of human genes and a gene network involved in response to tick-borne encephalitis virus infection. BMC Evol Biol 2017; 17:259. [PMID: 29297316 PMCID: PMC5751789 DOI: 10.1186/s12862-017-1107-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
BACKGROUND Tick-borne encephalitis is caused by the neurotropic, positive-sense RNA virus, tick-borne encephalitis virus (TBEV). TBEV infection can lead to a variety of clinical manifestations ranging from slight fever to severe neurological illness. Very little is known about genetic factors predisposing to severe forms of disease caused by TBEV. The aims of the study were to compile a catalog of human genes involved in response to TBEV infection and to rank genes from the catalog based on the number of neighbors in the network of pairwise interactions involving these genes and TBEV RNA or proteins. RESULTS Based on manual review and curation of scientific publications a catalog comprising 140 human genes involved in response to TBEV infection was developed. To provide access to data on all genes, the TBEVhostDB web resource ( http://icg.nsc.ru/TBEVHostDB/ ) was created. We reconstructed a network formed by pairwise interactions between TBEV virion itself, viral RNA and viral proteins and 140 genes/proteins from TBEVHostDB. Genes were ranked according to the number of interactions in the network. Two genes/proteins (CCR5 and IFNAR1) that had maximal number of interactions were revealed. It was found that the subnetworks formed by CCR5 and IFNAR1 and their neighbors were a fragments of two key pathways functioning during the course of tick-borne encephalitis: (1) the attenuation of interferon-I signaling pathway by the TBEV NS5 protein that targeted peptidase D; (2) proinflammation and tissue damage pathway triggered by chemokine receptor CCR5 interacting with CD4, CCL3, CCL4, CCL2. Among nine genes associated with severe forms of TBEV infection, three genes/proteins (CCR5, IL10, ARID1B) were found to have protein-protein interactions within the network, and two genes/proteins (IFNL3 and the IL10, that was just mentioned) were up- or down-regulated in response to TBEV infection. Based on this finding, potential mechanisms for participation of CCR5, IL10, ARID1B, and IFNL3 in the host response to TBEV infection were suggested. CONCLUSIONS A database comprising 140 human genes involved in response to TBEV infection was compiled and the TBEVHostDB web resource, providing access to all genes was created. This is the first effort of integrating and unifying data on genetic factors that may predispose to severe forms of diseases caused by TBEV. The TBEVHostDB could potentially be used for assessment of risk factors for severe forms of tick-borne encephalitis and for the design of personalized pharmacological strategies for the treatment of TBEV infection.
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Affiliation(s)
- Elena V Ignatieva
- Laboratory of Evolutionary Bioinformatics and Theoretical Genetics, The Federal Research Center Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Center for Brain Neurobiology and Neurogenetics, The Federal Research Center Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Novosibirsk State University, Novosibirsk, 630090, Russia.
| | - Alexander V Igoshin
- Laboratory of Infectious Disease Genomics, The Federal Research Center Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Nikolay S Yudin
- Laboratory of Infectious Disease Genomics, The Federal Research Center Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
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Goats as sentinel hosts for the detection of tick-borne encephalitis risk areas in the Canton of Valais, Switzerland. BMC Vet Res 2017; 13:217. [PMID: 28693561 PMCID: PMC5504567 DOI: 10.1186/s12917-017-1136-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/29/2017] [Indexed: 12/27/2022] Open
Abstract
Background Tick-borne encephalitis (TBE) is an important tick-borne disease in Europe. Detection of the TBE virus (TBEV) in local populations of Ixodes ricinus ticks is the most reliable proof that a given area is at risk for TBE, but this approach is time-consuming and expensive. A cheaper and simpler approach is to use immunology-based methods to screen vertebrate hosts for TBEV-specific antibodies and subsequently test the tick populations at locations with seropositive animals. Results The purpose of the present study was to use goats as sentinel animals to identify new risk areas for TBE in the canton of Valais in Switzerland. A total of 4114 individual goat sera were screened for TBEV-specific antibodies using immunological methods. According to our ELISA assay, 175 goat sera reacted strongly with TBEV antigen, resulting in a seroprevalence rate of 4.3%. The serum neutralization test confirmed that 70 of the 173 ELISA-positive sera had neutralizing antibodies against TBEV. Most of the 26 seropositive goat flocks were detected in the known risk areas in the canton of Valais, with some spread into the connecting valley of Saas and to the east of the town of Brig. One seropositive site was 60 km to the west of the known TBEV-endemic area. At two of the three locations where goats were seropositive, the local tick populations also tested positive for TBEV. Conclusion The combined approach of screening vertebrate hosts for TBEV-specific antibodies followed by testing the local tick population for TBEV allowed us to detect two new TBEV foci in the canton of Valais. The present study showed that goats are useful sentinel animals for the detection of new TBEV risk areas. Electronic supplementary material The online version of this article (doi:10.1186/s12917-017-1136-y) contains supplementary material, which is available to authorized users.
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9
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Yurchenko OO, Dubina DO, Vynograd NO, Gonzalez JP. Partial Characterization of Tick-Borne Encephalitis Virus Isolates from Ticks of Southern Ukraine. Vector Borne Zoonotic Dis 2017; 17:550-557. [PMID: 28654319 PMCID: PMC5564047 DOI: 10.1089/vbz.2016.2094] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Tick-borne encephalitis (TBE) is the most common tick-borne viral infection in Eurasia; thousands of human cases are annually reported from several European countries. Several tick species are vectors of the tick-borne encephalitis virus (TBEV), while TBE appears to be spreading from the Eurasian continent westward to Europe. Fifteen study sites were chosen from five territories of southern Ukraine, including Odessa, Mykolaiv, Kherson Oblast, the Autonomous Republic of Crimea, and Sevastopol. Tick collection was performed in spring season of three consecutive years (1988–1990) using either flagging technique or direct collection of specimens feeding on cattle. A total of 15,243 tick imagoes and nymphs were collected from nine species, including Dermacentor marginatus, D. reticulatus, Haemaphysalis parva, H. punctata, Hyalomma marginatum, Ixodes ricinus, Rhipicephalus bursa, R. rossicus, and R. sanguineus, pooled in 282 monospecific samples. Supernatant of grinded pool was used for inoculation to suckling mice for virus isolation. Eight TBEV isolates were identified from ticks among six study sites. Ticks showed a minimum infection rate from 0.11% to 0.81%. Phylogenetic analysis of the envelope (E) protein gene of seven isolates, assigned all to the European subtype (TBEV-Eu) showing a maximum identity of 97.17% to the “Pan” TBEV-Eu reference strain. Compared to 104 TBEV-Eu isolates they clustered within the same clade as the Pan reference strain and distinguished from other TBEV-Eu isolates. Amino acid sequence analysis of the South Ukrainian TBEV-Eu isolates revealed the presence of four amino acid substitutions 67 (N), 266 (R), 306 (V), and 407 (R), in the ectodomains II and III and in the stem-anchor region of the E protein gene. This study confirmed TBEV-Eu subtype distribution in the southern region of Ukraine, which eventually overlaps with TBEV-FE (Far Eastern subtype) and TBEV-Sib (Siberian subtype) domains, showing the heterogeneity of TBEV circulating in Ukraine.
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Affiliation(s)
- Oksana O Yurchenko
- 1 State Body "I.I. Mechnikov Ukranian Anti-Plague Research Institute of the Ministry of Health of Ukraine ," Odessa, Ukraine
| | - Dmytro O Dubina
- 1 State Body "I.I. Mechnikov Ukranian Anti-Plague Research Institute of the Ministry of Health of Ukraine ," Odessa, Ukraine
| | | | - Jean-Paul Gonzalez
- 3 Health for Development , Paris, France .,4 Center of Excellence for Emerging Zoonotic Animal Diseases, Kansas State University , Manhattan, Kansas
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10
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Althouse BM, Hanley KA. The tortoise or the hare? Impacts of within-host dynamics on transmission success of arthropod-borne viruses. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0299. [PMID: 26150665 DOI: 10.1098/rstb.2014.0299] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Arthropod-borne viruses (arboviruses) are maintained in a cycle of alternating transmission between vertebrate hosts and arthropod vectors. Arboviruses possess RNA genomes capable of rapid diversification and adaptation, and the between-host trade-offs inherent to host alternation impose well-documented constraints on arbovirus evolution. Here, we investigate the less well-studied within-host trade-offs that shape arbovirus replication dynamics and transmission. Arboviruses generally establish lifelong infection in vectors but transient infection of variable magnitude (i.e. peak virus concentration) and duration in vertebrate hosts. In the majority of experimental infections of vertebrate hosts, both the magnitude and duration of arbovirus replication depended upon the dose of virus administered, with increasing dose resulting in greater magnitude but shorter duration of viraemia. This pattern suggests that the vertebrate immune response imposes a trade-off between the height and breadth of the virus replication curve. To investigate the impact of this trade-off on transmission, we used a simple modelling approach to contrast the effect of 'tortoise' (low magnitude, long duration viraemia) and 'hare' (high magnitude, short duration viraemia) arbovirus replication strategies on transmission. This model revealed that, counter to previous theory, arboviruses that adopt a tortoise strategy have higher rates of persistence in both host and vector populations.
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Affiliation(s)
- Benjamin M Althouse
- Santa Fe Institute, Santa Fe, NM 87501, USA Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA Institute for Disease Modeling, Bellevue, WA 98005, USA
| | - Kathryn A Hanley
- Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA
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Muto M, Bazartseren B, Tsevel B, Dashzevge E, Yoshii K, Kariwa H. Isolation and characterization of tick-borne encephalitis virus from Ixodes persulcatus in Mongolia in 2012. Ticks Tick Borne Dis 2015; 6:623-9. [PMID: 26025267 DOI: 10.1016/j.ttbdis.2015.05.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/16/2015] [Accepted: 05/09/2015] [Indexed: 10/23/2022]
Abstract
Tick-borne encephalitis virus (TBEV) is a zoonotic virus belonging to the genus Flavivirus, in the family Flaviviridae. The virus, which is endemic in Europe and northern parts of Asia, causes severe encephalitis. Tick-borne encephalitis (TBE) has been reported in Mongolia since the 1980s, but details about the biological characteristics of the endemic virus are lacking. In this study, 680 ticks (Ixodes persulcatus) were collected in Selenge aimag, northern Mongolia, in 2012. Nine Mongolian TBEV strains were isolated from tick homogenates. A sequence analysis of the envelope protein gene revealed that all isolates belonged to the Siberian subtype of TBEV. Two strains showed similar growth properties in cultured cells, but their virulence in mice differed. Whole genome sequencing revealed only thirteen amino acid differences between these Mongolian TBEV strains. Our results suggest that these naturally occurring amino acid mutations affected the pathogenicity of Mongolian TBEV. Our results may be an important platform for monitoring TBEV to evaluate the epidemiological risk in TBE endemic areas of Mongolia.
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Affiliation(s)
- Memi Muto
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
| | - Boldbaatar Bazartseren
- Laboratory of Virology, Institute of Veterinary Medicine, Mongolian State University of Agriculture, Zaisan, Ulaanbaatar 17024, Mongolia
| | - Bazartseren Tsevel
- Laboratory of Virology, Institute of Veterinary Medicine, Mongolian State University of Agriculture, Zaisan, Ulaanbaatar 17024, Mongolia
| | - Erdenechimeg Dashzevge
- Laboratory of Virology, Institute of Veterinary Medicine, Mongolian State University of Agriculture, Zaisan, Ulaanbaatar 17024, Mongolia
| | - Kentaro Yoshii
- 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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12
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Rieille N, Bressanelli S, Freire CCM, Arcioni S, Gern L, Péter O, Voordouw MJ. Prevalence and phylogenetic analysis of tick-borne encephalitis virus (TBEV) in field-collected ticks (Ixodes ricinus) in southern Switzerland. Parasit Vectors 2014; 7:443. [PMID: 25245773 PMCID: PMC4261884 DOI: 10.1186/1756-3305-7-443] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/13/2014] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Tick-borne encephalitis is the most common tick-borne viral infection in Europe with 3,000 human cases reported each year. In Western Europe, the castor bean tick, Ixodes ricinus, is the principal vector of the tick-borne encephalitis virus (TBEV). TBEV appears to be spreading geographically and was recently detected for the first time in Canton Valais in the southern part of Switzerland. The purpose of the present study was to survey the I. ricinus tick populations of Canton Valais for TBEV. METHODS We collected a total of 19,331 I. ricinus ticks at 45 different sites in Canton Valais between 2010 and 2013. Ticks were processed in pools and tested for TBEV using reverse transcription quantitative PCR. The NS5 gene and the envelope gene of the TBEV isolates were partially sequenced for phylogenetic analysis. RESULTS TBEV was detected in tick populations at six of the 45 sites. These six sites were all located in a 33 km transect along the Rhône River. TBEV was detected in two sites for three of the four years of the study showing the temporal persistence of the pathogen. Prevalence of TBEV in the six positive sites ranged from 0.16% to 11.11%. Phylogenetic analysis found that all TBEV isolates from Canton Valais belonged to the European subtype. Genetic analysis found two distinct lineages of TBEV suggesting that Canton Valais experienced two independent colonization events. CONCLUSIONS TBEV appears to be well established at certain locations in Canton Valais.
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Affiliation(s)
- Nadia Rieille
- />Central Institute of Valais Hospitals, Infectious diseases, Av Grand Champsec 86, Sion, Switzerland
- />Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Stéphane Bressanelli
- />Laboratoire de Virologie Moléculaire et Structurale, CNRS UPR3296, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette cedex, France
| | - Caio C M Freire
- />Inter-institutional Grad Program on Bioinformatics, University of Sao Paulo, Matao Street 1010, Sao Paulo, Brazil
| | - Séverine Arcioni
- />Central Institute of Valais Hospitals, Genetics, Av Grand Champsec 86, Sion, Switzerland
| | - Lise Gern
- />Laboratory of Eco-Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Olivier Péter
- />Central Institute of Valais Hospitals, Infectious diseases, Av Grand Champsec 86, Sion, Switzerland
| | - Maarten J Voordouw
- />Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
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13
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Kovalev SY, Mukhacheva TA. Clusterons as a tool for monitoring populations of tick-borne encephalitis virus. J Med Virol 2013; 86:283-9. [PMID: 24037877 DOI: 10.1002/jmv.23732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2013] [Indexed: 11/10/2022]
Abstract
Tick-borne encephalitis (TBE) is a natural focal viral neuroinfection that is widespread in the temperate zone of Eurasia. Knowledge of the genetic structure of tick-borne encephalitis virus (TBEV) populations is important for understanding, not only the origin and evolution of the virus, but also the formation and maintenance of natural foci. A new approach to the differentiation of TBEV strains within subtype, with clusterons as the basis of analysis, has recently been proposed. In the present study, the genetic structure of TBEV-Sib populations has been investigated based on 387 strains isolated in the Middle Urals (Sverdlovsk region). Fourteen of the 18 currently known TBEV-Sib clusterons were identified. They belong to the Asian and Eastern European (Baltic) groups. It was shown that each TBE foci could be characterized by a unique clusteron profile. Three clusterons that emerged within the last 50 years have been identified which implies an active evolutionary process in the TBEV-Sib populations. The greatest diversity of clusterons was observed in the south of the Middle Urals along the Trans-Siberian Way. Such a pattern could reflect the history of colonization of the area and is closely related to the roads passing from Siberia to the European part of Russia through the Urals. In this article, the principles of continuous monitoring in the regional and local TBE foci are proposed, based on the quantitative and qualitative analysis of TBEV-Sib clusteron profiles.
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Affiliation(s)
- Sergey Y Kovalev
- Laboratory of Molecular Genetics, Department of Biology, Ural Federal University, Yekaterinburg, Russia
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14
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Amicizia D, Domnich A, Panatto D, Lai PL, Cristina ML, Avio U, Gasparini R. Epidemiology of tick-borne encephalitis (TBE) in Europe and its prevention by available vaccines. Hum Vaccin Immunother 2013; 9:1163-71. [PMID: 23377671 PMCID: PMC3899155 DOI: 10.4161/hv.23802] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/21/2013] [Accepted: 01/28/2013] [Indexed: 12/30/2022] Open
Abstract
Tick-borne Encephalitis (TBE), which is caused by a Flavivirus, is the most common tick-transmitted disease in Central and Eastern Europe and Russia. Today, TBE is endemic in 27 European countries, and has become an international public health problem. The epidemiology of TBE is changing owing to various factors, such as improvements in diagnosis and case reporting, increased recreational activities in areas populated by ticks, and changes in climatic conditions affecting tick habitats. Vaccination remains the most effective protective measure against TBE for people living in risk zones, occupationally exposed subjects and travelers to endemic areas. The vaccines currently in use are FSME-Immun(®), Encepur(®), EnceVir(®) and TBE vaccine Moscow(®). The numerous studies performed on the efficacy and safety of these vaccines have shown a high level of immunogenicity and an excellent safety profile. Several studies have also shown a high level of cross-protection among strains belonging to different subtypes. In the present paper we attempted to describe the continuously changing epidemiology of TBE in European States and to overview clinical development of available vaccines paying particular attention on cross-protection elicited by the vaccines.
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Affiliation(s)
- Daniela Amicizia
- Department of Health Sciences; University of Genoa; Genoa, Italy
| | | | | | - Piero Luigi Lai
- Department of Health Sciences; University of Genoa; Genoa, Italy
| | | | - Ulderico Avio
- Business Unit Manager Vaccines; Baxter S.p.A.; Rome, Italy
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15
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Fajs L, Durmiši E, Knap N, Strle F, Avšič-Županc T. Phylogeographic characterization of tick-borne encephalitis virus from patients, rodents and ticks in Slovenia. PLoS One 2012. [PMID: 23185257 PMCID: PMC3502456 DOI: 10.1371/journal.pone.0048420] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is the most important arboviral agent causing infections of the central nervous system in central Europe. Previous studies have shown that TBEV exhibits pronounced genetic variability, which is often correlated to the geographical origin of TBEV. Genetic variability of TBEV has previously been studied predominantly in rodents and ticks, while information about the variability in patients is scarce. In order to understand the molecular relationships of TBEV between natural hosts, vectors and humans, as well as correlation between phylogenetic and geographical clustering, sequences of TBEV E and NS5 protein genes, were obtained by direct sequencing of RT-PCR products from TBE-confirmed patients as well as from rodents and ticks collected from TBE-endemic regions in Slovenia. A total of 27 partial E protein gene sequences representing 15 human, 4 rodent and 8 tick samples and 30 partial NS5 protein gene sequences representing 17 human, 5 rodent and 8 tick samples were obtained. The complete genome sequence of TBEV strain Ljubljana I was simultaneously obtained. Phylogenetic analysis of the E and NS5 protein gene sequences revealed a high degree of TBEV variability in patients, ticks and rodents. Furthermore, an evident correlation between geographical and phylogenetic clustering was shown that was independent of the TBEV host. Moreover, we show the presence of a possible recombination event in the TBEV genome obtained from a patient sample, which was supported with multiple recombination event detection methods. This is the first study that simultaneously analyzed the genetic relationships of directly sequenced TBEV samples from patients, ticks and rodents and provides the largest set of patient-derived TBEV sequences up to date. In addition, we have confirmed the geographical clustering of TBEV sequences in Slovenia and have provided evidence of a possible recombination event in the TBEV genome, obtained from a patient.
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Affiliation(s)
- Luka Fajs
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Emina Durmiši
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Nataša Knap
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Franc Strle
- Department of Infectious Diseases, University Medical Center Ljubljana, Ljubljana, Slovenia
| | - Tatjana Avšič-Županc
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- * E-mail:
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