Tick-borne encephalitis virus in wild rodents in winter, Finland, 2008-2009.
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ABSTRACT:
SUBMITTER: Tonteri E
PROVIDER: S-EPMC3204619 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Tick-borne encephalitis virus (TBEV) is a zoonotic agent causing severe encephalitis in humans. A recent epizootiological survey indicated that endemic foci of TBEV have been maintained in the southern part of Hokkaido until recently. In this study, we sought to isolate TBEV from wild rodents in the area. One virus, designated Oshima 08-As, was isolated from an Apodemus speciosus captured in Hokuto in 2008. Oshima 08-As was classified as the Far Eastern subtype of TBEV and formed a cluster with the other strains isolated in Hokkaido from 1995 to 1996. Thirty-six nucleotide differences resulted in 12 amino acid changes between Oshima 08-As and Oshima 5-10 isolated in 1995. Oshima 08-As caused high mortality and morbidity in a mouse model compared with Oshima 5-10. Although similar transient viral multiplication in the spleen was observed in the mice infected with Oshima 08-As and Oshima 5-10, greater viral multiplication with an inflammatory response was noted in the brains of mice infected with Oshima 08-As than those infected with Oshima 5-10. These data indicate that a few naturally occurring mutations affect the pathogenicity of the Oshima strains endemic in the southern part of Hokkaido.
| S-EPMC3669602 | biostudies-literature
Project description:IntroductionTick-borne encephalitis virus (TBEV) causes one of the most important flavivirus infections of the central nervous system, affecting humans in Europe and Asia. It is mainly transmitted by the bite of an infected tick and circulates among them and their vertebrate hosts. Until now, TBE risk analysis in Germany has been based on the incidence of human cases. Because of an increasing vaccination rate, this approach might be misleading, especially in regions of low virus circulation.MethodTo test the suitability of rodents as a surrogate marker for virus spread, laboratory-bred Microtus arvalis voles were experimentally infected with TBEV and analyzed over a period of 100 days by real-time (RT)-quantitative polymerase chain reaction. Further, the prevalence of TBEV in rodents trapped in Brandenburg, a rural federal state in northeastern Germany with autochthonous TBE cases, was determined and compared with that in rodents from German TBE risk areas as well as TBE nonrisk areas.ResultsIn experimentally infected M. arvalis voles, TBEV was detectable in different organs for at least 3 months and in blood for 1 month. Ten percent of all rodents investigated were positive for TBEV. However, in TBE risk areas, the infection rate was higher compared with that of areas with only single human cases or of nonrisk areas. TBEV was detected in six rodent species: Apodemus agrarius, Apodemus flavicollis, Apodemus sylvaticus, Microtus agrestis, Microtus arvalis, and Myodes glareolus. M. glareolus showed a high infection rate in all areas investigated.Discussion and conclusionThe infection experiments proved that TBEV can be reliably detected in infected M. arvalis voles. These voles developed a persistent TBE infection without clinical symptoms. Further, the study showed that rodents, especially M. glareolus, are promising sentinels particularly in areas of low TBEV circulation.
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Project description:Tick-borne encephalitis virus Raw sequence reads
| PRJNA1174237 | ENA
Project description:Tick-borne encephalitis virus Genome sequencing and assembly
| PRJNA953225 | ENA
Project description:Tick-borne encephalitis virus Genome sequencing and assembly
| PRJNA587877 | ENA
Project description:In most locations except for Russia, tick-borne encephalitis is mainly caused by the European virus subtype. In 2015, fatal infections caused by European and Siberian tick-borne encephalitis virus subtypes in the same Ixodes ricinus tick focus in Finland raised concern over further spread of the Siberian subtype among widespread tick species.
| S-EPMC5938788 | biostudies-literature
Project description: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.
| S-EPMC3502456 | biostudies-literature
Project description:In Croatia, several rodent- and vector-borne agents are endemic and of medical importance. In this study, we investigated hantaviruses and, for the first time, tick-borne encephalitis virus (TBEV) and Rickettsia spp. in small wild rodents from two different sites (mountainous and lowland region) in Croatia. In total, 194 transudate and tissue samples from 170 rodents (A. flavicollis, n=115; A. agrarius, n=2; Myodes glareolus, n=53) were tested for antibodies by indirect immunofluorescence assays (IIFT) and for nucleic acids by conventional (hantaviruses) and real-time RT-/PCRs (TBEV and Rickettsia spp.). A total of 25.5% (24/94) of the rodents from the mountainous area revealed specific antibodies against hantaviruses. In all, 21.3% (20/94) of the samples from the mountainous area and 29.0% (9/31) from the lowland area yielded positive results for either Puumala virus (PUUV) or Dobrava-Belgrade virus (DOBV) using a conventional RT-PCR. All processed samples (n=194) were negative for TBEV by IIFT or real-time RT-PCR. Serological evidence of rickettsial infection was detected in 4.3% (4/94) rodents from the mountainous region. Another 3.2% (3/94) rodents were positive for Rickettsia spp. by real-time PCR. None of the rodents (n=76) from the lowland area were positive for Rickettsia spp. by real-time PCR. Dual infection of PUUV and Rickettsia spp. was found in one M. glareolus from the mountainous area by RT-PCR and real-time PCR, respectively. To our knowledge, this is the first detection of Rickettsia spp. in small rodents from Croatia. Phylogenetic analyses of S- and M-segment sequences obtained from the two study sites revealed well-supported subgroups in Croatian PUUV and DOBV. Although somewhat limited, our data showed occurrence and prevalence of PUUV, DOBV, and rickettsiae in Croatia. Further studies are warranted to confirm these data and to determine the Rickettsia species present in rodents in these areas.
| S-EPMC4098074 | biostudies-literature
Project description: Not available
| S-EPMC3903456 | biostudies-literature
Project description:Tick-borne encephalitis virus (TBEV) is a leading cause of human neuroinfections in Europe and Northeast Asia. There are no antiviral therapies for treating TBEV infection. A series of nucleoside analogues was tested for the ability to inhibit the replication of TBEV in porcine kidney cells and human neuroblastoma cells. The interactions of three nucleoside analogues with viral polymerase were simulated using advanced computational methods. The nucleoside analogues 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA), 2'-C-methyladenosine (2'-CMA), and 2'-C-methylcytidine (2'-CMC) inhibited TBEV replication. These compounds showed dose-dependent inhibition of TBEV-induced cytopathic effects, TBEV replication (50% effective concentrations [EC50]of 5.1 ± 0.4 μM for 7-deaza-2'-CMA, 7.1 ± 1.2 μM for 2'-CMA, and 14.2 ± 1.9 μM for 2'-CMC) and viral antigen production. Notably, 2'-CMC was relatively cytotoxic to porcine kidney cells (50% cytotoxic concentration [CC50] of ∼50 μM). The anti-TBEV effect of 2'-CMA in cell culture diminished gradually after day 3 posttreatment. 7-Deaza-2'-CMA showed no detectable cellular toxicity (CC50 > 50 μM), and the antiviral effect in culture was stable for >6 days posttreatment. Computational molecular analyses revealed that compared to the other two compounds, 7-deaza-2'-CMA formed a large cluster near the active site of the TBEV polymerase. High antiviral activity and low cytotoxicity suggest that 7-deaza-2'-CMA is a promising candidate for further investigation as a potential therapeutic agent in treating TBEV infection.
| S-EPMC4538560 | biostudies-literature