Browsing by Subject "TBEV"

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  • von Troil, Gabriel (Helsingin yliopisto, 2020)
    Antalet smittfall av fästingburet encefalitvirus (TBEV) har ökat och nya riskområden för TBEV har identifierats årligen i Finland under det senaste årtiondet. Som resultat av ökat intresse hos lokala invånare att utreda över nyintroducerade TBEV riskområden initierades detta projekt år 2016 i samarbete med Helsingfors universitets virologiska avdelning och det privatägda företaget Skärgårdsdoktorn Ab, att samla fästingar från Drumsö och senare testa dessa på TBEV (RNA). Senare kom projektet också att innefatta Esbo. Materialet samlades under åren 2016 - 2017 och bestod av fästingar samlade lokalt både direkt från naturen, samt fästingar som låtits hämtas in utav privatpersoner till utgivna lokalisationer. Det slutliga materialet bestod av 754st fästingar varav 666st härstammade från Esbo och 88st härstammade från Drumsö i Helsingfors. Laboratorieanalyserna gjordes i Helsingfors universitets virologiska avdelnings utrymmen. Utav enstaka fästingar isolerades RNA och DNA lösning i separata provrör i en manuell laboratorieprocess, och senare genomgick dessa lösningar automatiserade TBEV (RNA) respektive Borrelia Burgdorferi tester. Denna rapport behandlar endast TBEV testerna och deras resultat. I de slutliga TBEV testerna hittades 7st TBEV RNA positiva fästingar, av vilka alla härstammade från 3 olika regioner i Esbo; Esbogård, Tomtekulla och Larsvik. Av dessa områden var Larsvik det ända varifrån det inte tidigare rapporterats några TBEV smittor. Resultaten i denna studie är i linje med tidigare kända uppgifter över TBEV demografi i den finska huvudstadsregionen och antyder för potentialen även till ytterligare spridning till övriga lokalisationer inom detta område.
  • Pulkkinen, Lauri I. A.; Barrass, Sarah; Domanska, Ausra; Overby, Anna K.; Anastasina, Maria; Butcher, Sarah J. (2022)
    Tick-borne encephalitis virus (TBEV) is a pathogenic, enveloped, positive-stranded RNA virus in the family Flaviviridae. Structural studies of flavivirus virions have primarily focused on mosquito-borne species, with only one cryo-electron microscopy (cryo-EM) structure of a tick-borne species published. Here, we present a 3.3 angstrom cryo-EM structure of the TBEV virion of the Kuutsalo-14 isolate, confirming the overall organisation of the virus. We observe conformational switching of the peripheral and transmembrane helices of M protein, which can explain the quasi-equivalent packing of the viral proteins and highlights their importance in stabilising membrane protein arrangement in the virion. The residues responsible for M protein interactions are highly conserved in TBEV but not in the structurally studied Hypr strain, nor in mosquito-borne flaviviruses. These interactions may compensate for the lower number of hydrogen bonds between E proteins in TBEV compared to the mosquito-borne flaviviruses. The structure reveals two lipids bound in the E protein which are important for virus assembly. The lipid pockets are comparable to those recently described in mosquito-borne Zika, Spondweni, Dengue, and Usutu viruses. Our results thus advance the understanding of tick-borne flavivirus architecture and virion-stabilising interactions.
  • Pulkkinen, Lauri I. A.; Butcher, Sarah J.; Anastasina, Maria (2018)
    Tick-borne encephalitis virus (TBEV) is a growing health concern. It causes a severe disease that can lead to permanent neurological complications or death and the incidence of TBEV infections is constantly rising. Our understanding of TBEV's structure lags behind that of other flaviviruses, but has advanced recently with the publication of a high-resolution structure of the TBEV virion. The gaps in our knowledge include: aspects of receptor binding, replication and virus assembly. Furthermore, TBEV has mostly been studied in mammalian systems, even though the virus' interaction with its tick hosts is a central part of its life cycle. Elucidating these aspects of TBEV biology are crucial for the development of TBEV antivirals, as well as the improvement of diagnostics. In this review, we summarise the current structural knowledge on TBEV, bringing attention to the current gaps in our understanding, and propose further research that is needed to truly understand the structural-functional relationship of the virus and its hosts.
  • Jääskeläinen, Anne J.; Korhonen, Essi M.; Huhtamo, Eili; Lappalainen, Maija; Vapalahti, Olli; Kallio-Kokko, Hannimari (2019)
    The laboratory confirmation of Zika virus (ZIKV) infection, and the differential diagnosis from other flavivirus infections such as dengue virus (DENV), often requires the use of several diagnostic test types. Cross-reactions and secondary infections complicate the serological diagnosis and specific viral RNA detection assays are often needed for confirming the diagnosis. The aim of this study was to validate serological and molecular methods for diagnosing ZIKV infection. This included the evaluation of a ZIKV RT-qPCR assay for diagnostics that was previously set up for research use and to compare the ZIKV, DENV and TBEV EIA methods. External and in-house controls and pre-characterized sample panels were tested, and also automated and manual nucleic acid extraction methods were compared. A total of ten Finnish traveler patients were diagnosed with acute ZIKV infection during 2015-2017 including one suspected dual DENV and ZIKV infection. These samples along with panels of DENV and tick-bome encephalitis virus (TBEV) infections were used to test the cross-reactive properties of ZIKV, DENV and TBEV IgM assays. Additionally, the diagnosed acute ZIKV patient samples were tested using commercially available diagnostic DENV NS1 antigen assay and a ZIKV NS1 antigen assay intended for research use. The ZIKV RT-qPCR assay was demonstrated to be both specific and sensitive (one genome per reaction) and suitable for routine diagnostic use utilizing automated nucleic acid extraction. Of the tested IgM tests the NS1 antigen-based ZIKV IgM (Euroimmun) assay performed with least cross -reactivity with a specificity of 97.4%. The DENV IgM assay (Focus Diagnostics) had specificity of only 86.1%. The results are in line with previous studies and additionally highlight that also acute TBEV patients may give a false positive test result in DENV and ZIKV IgM assays.