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.

• Publikační typ
• časopisecké články MeSH

• Publikační typ
• abstrakt z konference MeSH

Tick-borne encephalitis (TBE) is one of the most common zoonotic diseases in Europe transmitted by Ixodidae vectors. While small mammals such as bank voles and ticks constitute the main reservoirs for virus transmission, large sylvatic species act as a food source for ticks. Cervids such as roe deer and red deer are considered sentinel species for TBE in natural foci. In addition, an increase of the population size and density of large wild mammals in an area corresponds to an increase in the tick burden and may potentially increase the prevalence of TBE virus (TBEV) in ticks and tick hosts and further exposure risk in humans. Humans are considered accidental hosts. The prevalence of TBE relies on interactions between host, vector and environment. The present study examines the exposure of the largest European herbivore, the European bison (Bison bonasus) to TBEV infection. Assessed using the IMMUNOZYM FSME ELISA (PROGEN), the overall TBEV seroprevalence was 62.7% in the 335 European bison that were studied. ELISA results were confirmed by the gold-standard virus neutralization test (VNT) with 98.7% sensitivity and thus giving a true prevalence of 63.5%. TBEV seroprevalence was significantly correlated to the origin, age group, sex, population type (free living/captive) and sanitary status (healthy/selectively eliminated/found dead/killed in accident) of the European bison in the univariable analysis. The highest seroprevalences were observed in the three largest north-eastern wild populations (Białowieska, Borecka and Knyszyńska forests), which corresponded with the highest incidence of human cases reported in the country. The risk of TBEV seropositivity increased with age and was higher in female and free-ranging European bison. Additionally, to the epidemiological investigation, the continuous detection of TBEV antibodies was studied by repetitive testing of animals over the course of 34 months. Two of six seropositive animals remained seropositive throughout the study. The presence of antibodies was followed throughout the study in seropositive European bison and for at least a year in animals that seroconverted during the observation period.

• MeSH
• bizon * MeSH
• incidence MeSH
• klíšťová encefalitida epidemiologie   veterinární   virologie   MeSH
• prevalence MeSH
• séroepidemiologické studie MeSH
• viry klíšťové encefalitidy izolace a purifikace   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Polsko MeSH

Cíl práce: Virus západonilské horečky (WNV) je významný celosvětově rozšířený flavivirus přenášený komáry. Ve střední Evropě se virus dlouhodobě sporadicky vyskytuje, ale v letech 2008 a 2009 se masivně rozšířil po celém Maďarsku. Cílem práce bylo zjistit aktuální výskyt infekce WNV u koní v České republice (ČR). Materiál a metody: Celkem bylo v letech 2011–2013 vyšetřeno 2 349 sér dospělých zdravých nevakcinovaných koní z území celé ČR. K vyšetření byl použit komerčně vyráběný kompetitivní imunoenzymatický test (cELISA), pozitivně reagující vzorky byly konfirmovány virus-neutralizačním testem (VNT) s WNV a virem klíšťové encefalitidy (TBEV). Výsledky: Imunoenzymatický test byl pozitivní u 11,5 % vzorků (271 pozitivních/2349 vyšetřených). Konfirmačním vyšetřením VNT byly prokázány protilátky proti WNV u 16 vzorků. Jedenáct z nich reagovalo pozitivně pouze s WNV v titrech 8 až 1024, ve VNT s virem TBEV byly negativní. Souběžná WNV a TBEV séropozitivita byla zjištěna u třech vzorků. Titry protilátek proti WNV byly ale vždy nižší nebo shodné s titry proti TBEV. Pravděpodobně se uplatnila křížová reaktivita flavivirů, ale u vzorků s obdobným titrem WNV a TBEV nelze vyloučit ani souběžnou infekci oběma patogeny. Dva koně reagovali ve VNT s WNV v hraničním titru 4. U séropozitivních koní byl ověřován jejich původ a přesuny. Pět sérologicky WNV pozitivních/TBEV negativních koní (0,2 %) pocházelo z pěti krajů ČR (Jihočeský, Karlovarský, Středočeský, Jihomoravský, Moravskoslezský), přičemž do zahraničí nebyla tato zvířata nikdy přemisťována. Čtyři z nich nebyli přemísťováni ani po ČR a hospodářství majitele neopustili. Dalších šest WNV pozitivních/TBEV negativních koní bylo do ČR dovezeno ze severní Ameriky nebo střední a západní Evropy, nelze jednoznačně určit, zda se v těchto případech jedná o importovanou nebo autochtonní infekci. Závěr: Výsledky studie potvrzují, že výskyt protilátek proti WNV u koní v ČR je sporadický. Bylo prokázáno, že virus cirkuluje v různých částech České republiky, nejen na jižní Moravě.

Study aim: The West Nile virus (WNV) is an important mosquito-borne flavivirus occurring around the world. Occasionally found in Central Europe, the virus spread massively through whole Hungary between 2008 and 2009. The aim of our study was to determine the recent prevalence of the WNV infection in horses in the Czech Republic. Material and methods: Overall, 2349 serum samples, collected from healthy unvaccinated adult horses in the Czech Republic between 2011 and 2013, were tested. A commercially available competitive ELISA kit (cELISA) was used for this purpose and positive samples were confirmed by virus neutralisation tests using WNV and tick-borne encephalitis virus (TBEV). Results: Altogether 271 of 2348 samples (11.5%) were positive by cELISA. Confirmatory VNT revealed 16 WNV positive samples, 11 of which had titres from 8 to 1024; VNTs with TBEV were negative. Three samples had antibodies against both viruses and the WNV antibody titres were less than or equal to the TBEV antibody titres. A cross reactivity of flaviviruses might have had an impact on the results, but in samples with similar WNV and TBEV titres, co-infection with both pathogens cannot be ruled out either. VNT antibody titres in two horses were inconclusive (cut-off titre 4). The place of birth and transfers (if any) were checked for each WNV seropositive horse. Five WNV positive/TBEV negative samples (0.2 %) came from five administrative regions (South Bohemian, Karlovy Vary, Central Bohemian, South Moravian, and Moravian-Silesian) and the respective animals were never moved to a foreign country. Four of these horses never left the farm. Other six WNV positive/TBEV negative horses were imported to the Czech Republic from North America or Central and West Europe and therefore, it is not possible to tell unambiguously whether their infection is autochthonous or imported. Conclusion: The results of the present study confirm that WNV antibodies occur sporadically in horses in the Czech Republic. WNV was found to circulate in different parts of the Czech Republic and not only in the South of Moravia.

• MeSH
• ELISA MeSH
• imunoenzymatické techniky MeSH
• koně * MeSH
• nemoci koní diagnóza   krev   MeSH
• sérum MeSH
• statistika jako téma MeSH
• západonilská horečka * diagnóza   veterinární   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH

Cieľ: Cieľom tejto séroepidemiologickej štúdie bolo zistiť súčasnú prevalenciu protilátok proti Borrelia burgdorferi sensu lato (B. burgdorferi s. l.) a proti vírusu kliešťovej encefalitídy (TBEV) v populácii východného Slovenska a vyhodnotiť rizikové faktory spojené so séropozitivitou. Metódy: Vzorky séra s vyplnenými dotazníkmi, ktoré sa použili na analýzu rizikových faktorov, sme získali od 275 osôb (zdravé osoby s možnou pracovnou expozíciou kliešťom a častými voľnočasovými aktivitami v prírode a pacienti s rôznymi diagnózami). Vyšetrovaný súbor tvorilo 108 (39,3 %) mužov a 167 (60,7 %) žien. Séra sa testovali ELISA testom a immunoblotovým testom (IB). Počas analýzy sme pomocou logistickej regresie interpretovali asociáciu medzi vybranými premennými. Výsledky: Skríningový ELISA test na B. burgdorferi s. l. odhalil 18,2 % pozitívnych vzoriek na anti-B. burgdorferi s. l. IgG a immunoblot, ktorý sa vykonal pre pozitívne a hraničné vzorky IgG, bol pozitívny v 15,3 %. Pozitívne protilátky triedy IgM sa našli u 9,1 % skúmanej populácie. Zistili sme 0,4 % séropozitivitu IgG a 1,1 % pozitívnych protilátok IgM proti TBEV. Naše výsledky tiež potvrdili, že nasledujúce rizikové faktory, ako je bydlisko, časté vonkajšie aktivity a vlastníctvo zvierat sú významne spojené s vyššou prevalenciou špecifických protilátok. Záver: Výsledky vyššej séroprevalencie v sledovanom súbore potvrdzujú možnosť infekcie B. burgdorferi s. l. a TBEV u respondentov vystavených kontaktu s kliešťami.

Objective: The aim of this seroepidemiological study was to determine the current prevalence of antibodies against Borrelia burgdorferi sensu lato (B. burgdorferi s. l.) and tick-borne encephalitis virus (TBEV) among the population of Eastern Slovakia and to evaluate risk factors associated with seropositivity. Methods: Serum samples with completed questionnaires used for the risk factor analysis were obtained from 275 persons (healthy persons with possible working exposure to tick and outdoor activities and patients from different clinical departments). The set of respondents consisted of 108 (39.3%) men and 167 (60.7%) women. Sera were tested with ELISA and immunoblot assay (IB). During the analysis, we used logistic regression to interpret the influence between selected variables. Results: The B. burgdorferi screening ELISA test revealed 18.2% positive samples for anti-B. burgdorferi s. l. IgG. The immunoblot, which was performed for the positive and borderline IgG samples, was positive in 15.3%. Positive antibodies of the IgM class were found in 9.1% of the population under study. We detected 0.4% seropositivity of IgG and 1.1% of positive IgM antibodies against tick-borne encephalitis virus. Our results also confirmed that the following risk factors, such as residence, frequent outdoor activities, and pet ownership are significantly associated with the prevalence of specific antibodies. Conclusion: The results of seroprevalence obtained in the present study confirm the possibility of infection with B. burgdorferi and TBEV among respondents exposed to contact with ticks.

The flavivirus, tick-borne encephalitis virus (TBEV) is transmitted by Ixodes spp. ticks and may cause severe and potentially lethal neurological tick-borne encephalitis (TBE) in humans. Studying TBEV requires the use of secondary methodologies to detect the virus in infected cells. To overcome this problem, we rationally designed and constructed a recombinant reporter TBEV that stably expressed the mCherry reporter protein. The resulting TBEV reporter virus (named mCherry-TBEV) and wild-type parental TBEV exhibited similar growth kinetics in cultured cells; however, the mCherry-TBEV virus produced smaller plaques. The magnitude of mCherry expression correlated well with progeny virus production but remained stable over <4 passages in cell culture. Using well-characterized antiviral compounds known to inhibit TBEV, 2'-C-methyladenosine and 2'-deoxy-2'-β-hydroxy-4'-azidocytidine (RO-9187), we demonstrated that mCherry-TBEV is suitable for high-throughput screening of antiviral drugs. Serum samples from a TBEV-vaccinated human and a TBEV-infected dog were used to evaluate the mCherry-based neutralization test. Collectively, recombinant mCherry-TBEV reporter virus described here provides a powerful tool to facilitate the identification of potential antiviral agents, and to measure levels of neutralizing antibodies in human and animal sera.

• MeSH
• antivirové látky izolace a purifikace   MeSH
• buněčné linie MeSH
• klíšťová encefalitida imunologie   virologie   MeSH
• křečci praví MeSH
• ledviny cytologie   MeSH
• lidé MeSH
• luminescentní proteiny genetika   MeSH
• neutralizační testy * MeSH
• neutralizující protilátky krev   MeSH
• protilátky virové krev   MeSH
• rychlé screeningové testy metody   MeSH
• viry klíšťové encefalitidy genetika   růst a vývoj   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Tick-borne encephalitis virus (TBEV), the causative agent of tick-borne encephalitis (TBE), is a medically important flavivirus endemic to the European-Asian continent. Although more than 12,000 clinical cases are reported annually worldwide, there is no anti-TBEV therapy available to treat patients with TBE. Porphyrins are macrocyclic molecules consisting of a planar tetrapyrrolic ring that can coordinate a metal cation. In this study, we investigated the cytotoxicity and anti-TBEV activity of a large series of alkyl- or (het)aryl-substituted porphyrins, metalloporphyrins, and chlorins and characterized their molecular interactions with the viral envelope in detail. Our structure-activity relationship study showed that the tetrapyrrole ring is an essential structural element for anti-TBEV activity, but that the presence of different structurally distinct side chains with different lengths, charges, and rigidity or metal cation coordination can significantly alter the antiviral potency of porphyrin scaffolds. Porphyrins were demonstrated to interact with the TBEV lipid membrane and envelope protein E, disrupt the TBEV envelope and inhibit the TBEV entry/fusion machinery. The crucial mechanism of the anti-TBEV activity of porphyrins is based on photosensitization and the formation of highly reactive singlet oxygen. In addition to blocking viral entry and fusion, porphyrins were also observed to interact with RNA oligonucleotides derived from TBEV genomic RNA, indicating that these compounds could target multiple viral/cellular structures. Furthermore, immunization of mice with porphyrin-inactivated TBEV resulted in the formation of TBEV-neutralizing antibodies and protected the mice from TBEV infection. Porphyrins can thus be used to inactivate TBEV while retaining the immunogenic properties of the virus and could be useful for producing new inactivated TBEV vaccines.

• MeSH
• antivirové látky farmakologie   terapeutické užití   MeSH
• internalizace viru MeSH
• kationty terapeutické užití   MeSH
• klíšťová encefalitida * MeSH
• lidé MeSH
• myši MeSH
• porfyriny * farmakologie   terapeutické užití   MeSH
• protilátky virové terapeutické užití   MeSH
• RNA MeSH
• virový obal MeSH
• viry klíšťové encefalitidy * genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Tick-borne encephalitis (TBE) is a potentially lethal neuroinfection in humans, caused by TBE virus (TBEV). Currently, there are no approved therapeutic agents to treat TBE. Previously, it was suggested that application of high dose intravenous immunoglobulin (IVIG) may pose potentially successful treatment for severe cases of TBE. In this study, we determined the titers of TBEV-neutralizing antibodies in two IVIG lots originating from the same manufacturer, and tested their ability to treat a lethal TBEV-infection in a mouse model. Using an in vitro assay, more than 100-fold difference in TBEV-neutralizing capacity was demonstrated between the two individual IVIG lots. High TBEV-neutralizing activity of IVIG containing TBEV-specific antibody was confirmed in two different human neural cell lines, but IVIG without TBEV-specific antibodies had no or little effect on virus titers in the culture. In TBEV-infected mice, 90% of protection was achieved when the mice were treated with IVIG containing higher titers of TBEV-specific antibodies, whereas no immunotherapeutic effect was seen when mice were treated with IVIG without TBEV-specific antibodies. No antibody-dependent enhancement of TBEV infectivity induced by cross-reactive antibodies or by virus-specific antibodies at neutralizing or sub-neutralizing levels was observed either in cell culture or in TBEV-infected mice treated with any of the IVIG preparations. The results indicate that IVIG lots with high TBEV antibody titers might represent a post-exposure prophylaxis or first-line effective therapy of patients with a severe form of TBE.

• MeSH
• glioblastom virologie   MeSH
• intravenózní imunoglobuliny aplikace a dávkování   MeSH
• klíšťová encefalitida terapie   MeSH
• lidé MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• neuroblastom virologie   MeSH
• viry klíšťové encefalitidy účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Tick-borne encephalitis (TBE) is an illness caused by tick-borne encephalitis virus (TBEV) infection which is often limited to a febrile illness, but may lead to very aggressive downstream neurological manifestations. The disease is prevalent in forested areas of Europe and northeastern Asia, and is typically caused by infection involving one of three TBEV subtypes, namely the European (TBEV-Eu), the Siberian (TBEV-Sib), or the Far Eastern (TBEV-FE) subtypes. In addition to the three main TBEV subtypes, two other subtypes; i.e., the Baikalian (TBEV-Bkl) and the Himalayan subtype (TBEV-Him), have been described recently. In Europe, TBEV-Eu infection usually results in only mild TBE associated with a mortality rate of <2%. TBEV-Sib infection also results in a generally mild TBE associated with a non-paralytic febrile form of encephalitis, although there is a tendency towards persistent TBE caused by chronic viral infection. TBE-FE infection is considered to induce the most severe forms of TBE. Importantly though, viral subtype is not the sole determinant of TBE severity; both mild and severe cases of TBE are in fact associated with infection by any of the subtypes. In keeping with this observation, the overall TBE mortality rate in Russia is ∼2%, in spite of the fact that TBEV-Sib and TBEV-FE subtypes appear to be inducers of more severe TBE than TBEV-Eu. On the other hand, TBEV-Sib and TBEV-FE subtype infections in Russia are associated with essentially unique forms of TBE rarely seen elsewhere if at all, such as the hemorrhagic and chronic (progressive) forms of the disease. For post-exposure prophylaxis and TBE treatment in Russia and Kazakhstan, a specific anti-TBEV immunoglobulin is currently used with well-documented efficacy, but the use of specific TBEV immunoglobulins has been discontinued in Europe due to concerns regarding antibody-enhanced disease in naïve individuals. Therefore, new treatments are essential. This review summarizes available data on the pathogenesis and clinical features of TBE, plus different vaccine preparations available in Europe and Russia. In addition, new treatment possibilities, including small molecule drugs and experimental immunotherapies are reviewed. The authors caution that their descriptions of approved or experimental therapies should not be considered to be recommendations for patient care.

• MeSH
• antivirové látky terapeutické užití   MeSH
• fylogeneze MeSH
• klíšťata virologie   MeSH
• klíšťová encefalitida farmakoterapie   imunologie   prevence a kontrola   MeSH
• lidé MeSH
• myši MeSH
• virové vakcíny imunologie   MeSH
• viry klíšťové encefalitidy imunologie   patogenita   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Geografické názvy
• Evropa MeSH
• Rusko MeSH

Tick-borne encephalitis virus (TBEV) is divided into three subtypes: European (TBEV-Eu), Siberian (TBEV-Sib), and Far Eastern (TBEV-FE) subtypes. The geographical range of TBEV-Eu dominates in Europe, but this subtype is present focally across the whole non-tropical forested Eurasian belt, through Russia to South Korea. However, the TBEV-Eu strains isolated outside Europe remain poorly characterized. In this study, full-genome sequences of eight TBEV-Eu isolates were determined. These strains were isolated from Ixodes persulcatus ticks, long-tailed ground squirrel (Spermophilus undulatus), and human blood in the natural foci of Western and Eastern Siberia, Russia. A phylogenetic analysis of all available TBEV-Eu genomic sequences revealed that strains from Siberia were closely related to other strains from Europe and South Korea. The closest relation was identified between the Siberian strains and strains from Zmeinogorsk (Western Siberia, Russia) and strain Absettarov (Karelia, Russia), and were most divergent from strains from the Czech Republic and Norway. TBEV-Eu strains isolated in Eastern Siberia were more closely related phylogenetically to strains from South Korea, but strains from Western Siberia grouped together with the strains from Europe, suggesting two genetic TBEV-Eu lineages present in Siberia.

• MeSH
• fylogeneze MeSH
• genom virový * MeSH
• klíště virologie   MeSH
• lidé MeSH
• Sciuridae virologie   MeSH
• sekvenční analýza RNA MeSH
• viry klíšťové encefalitidy genetika   izolace a purifikace   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Sibiř MeSH