Tick-Borne Encephalitis Virus Isolates Features from Natural Foci of Pribaikalie (Eastern Siberia, Russia)

Tick-borne encephalitis virus (TBEV) exists in natural foci, which are areas where TBEV is circulating among its vectors (ticks of different species and genera) and reservoir hosts (usually rodents and small mammals). Based on phylogenetic studies, four TBEV subtypes (Far-Eastern, Siberian, European, Baikalian) and two putative subtypes (Himalayan and “178-79” group) are known. Within each subtype, some genetic lineages are described. The European subtype (TBEV-EU) (formerly known also as the “Western subtype”) of TBEV is prevalent in Europe, but it was also isolated in Western and Eastern Siberia in Russia and South Korea. The Far-Eastern subtype (TBEV-FE) was preferably found in the territory of the far-eastern part of Eurasia, but some strains were isolated in other regions of Eurasia. The Siberian (TBEV-SIB) subtype is the most common and has been found in almost all TBEV habitat areas. The Baikalian subtype is prevalent around Lake Baikal and was isolated several times from ticks and rodents. In addition to the four TBEV subtypes, one single isolate of TBEV (178-79) and two genetic sequences (Himalayan) supposed to be new TBEV subtypes were described in Eastern Siberia and China. The data on TBEV seroprevalence in humans and animals can serve as an indication for the presence or absence of TBEV in studied area.

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THE FIRST TICK-BORNE ENCEPHALITIS VIRUS ISOLATES FROM NORWAY

Acta Pathologica Microbiologica Scandinavica Section B Microbiology ◽

10.1111/j.1699-0463.1978.tb00040.x ◽

2009 ◽

Vol 86B (1-6) ◽

pp. 253-256 ◽

Cited By ~ 1

Author(s):

T. Traavik ◽

R. Mehl ◽

R. Wiger

Keyword(s):

Encephalitis Virus ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus ◽

Virus Isolates

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IMMUNE INTERLAYER TO TICK-BORNE ENCEPHALITIS VIRUS IN HUMAN POPULATION OF TRANSBAIKALIA AS AN INDICATOR OF NATURAL FOCI ACTIVITY

Russian Journal of Infection and Immunity ◽

10.15789/2220-7619-2018-3-335-340 ◽

2018 ◽

Vol 8 (3) ◽

pp. 335-340

Author(s):

A. O. Turanov ◽

A. Y. Nikitin ◽

E. I. Andaev

Keyword(s):

Human Population ◽

Steppe Zone ◽

Encephalitis Virus ◽

Forest Steppe ◽

Mountain Tundra ◽

Tick Borne Encephalitis ◽

Taiga Forest ◽

Natural Foci ◽

Tick Borne Encephalitis Virus ◽

Mountain Taiga

Studying of immune interlayer value to tick-borne encephalitis virus in human population of the Transbaikalia Territory resulted from natural immunization of the healthy population in 31 Municipal areas in 2011–2016 is presented. Human selections were formed proportionally to the population size in the concrete human settlement among persons of the various age and professional groups living at this territory not less than 10 years and unvaccinated against tick-borne encephalitis virus. Total 4367 blood sera were investigated. Laboratory testing for antibodies of G class to tick-borne encephalitis virus in blood sera of the human population was performed by immune-enzyme analysis using a set of reagents “VektoVKE-IgG” of Joint-Stock Company “Vektor-Best” (Novosibirsk city). The monitoring data indicated the presence of natural immunity to tick-borne encephalitis virus in the human population. Mean annual level of immune interlayer in Municipal areas varied from 3.1 to 52.7% (in Transbaikalian Territory — 13.1±0.51%). High level (from 20 to 52.7%) was characteristic for mountain-taiga-forest-steppe zone (Krasnochikoisky — 23.8±3.36%; Uletovsky — 52.4±4.48%; Gazimuro-Zavodsky — 29.4±4.94% districts) and mountain-tundra-taiga zone (Tungokochensky district — 20.0±3.58%). In steppe zone the level of immune interlayer was lower and observed in districts with elements of south-taiga larch and pine forests. It was established that levels of the immune interlayer in human population living in mountain-taiga-foreststeppe and mountain-tundra-taiga zones authentically higher than in steppe area — t = 3.8; Р < 0.001 and t = 2.27; Р < 0.05, respectively. Distinctions in the value of the immune interlayer between mountain-tundra-taiga and mountain-taigaforest-steppe zones were non-authentic: t = 0.1; P > 0.05. Active circulation of tick-borne encephalitis virus was accompanied by authentic (Р < 0.01) increase of the interlayer in persons with the virus antibodies in 2014–2016 (15.8±0.69%) in comparison with 2011–2013 (9.7±0.78%). Also it was noted in all landscape zones: in steppe zone the increase was to 42.8% (P > 0.05); in mountain-taiga-forest-steppe — to 61.3% (P > 0.05); in mountain-tundra-taiga — to 150.0% (Р < 0.01). It was not possible to reveal correlation between the recourse for medical aid and the value of immune interlayer in the population formed as a result of latent immunization. Results of the population immunity studying essentially expand our knowledge about the condition of the natural foci and dynamics of development of the epidemic processes in it, and can be used at planning of the preventive actions.

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Comparative analysis of genomes of tick-borne encephalitis virus strains isolated from mosquitoes and ticks

Voprosy Virusologii ◽

10.18821/0507-4088-2017-62-1-30-35 ◽

2017 ◽

Vol 62 (1) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. M. Pukhovskaya ◽

O. V. Morozova ◽

N. B. Belozerova ◽

S. V. Bakhmetyeva ◽

N. P. Vysochina ◽

...

Keyword(s):

Vaccine Strain ◽

Far East ◽

Encephalitis Virus ◽

Ixodes Persulcatus ◽

Aedes Vexans ◽

Tick Borne Encephalitis ◽

Tbev Strain ◽

Natural Foci ◽

Tick Borne Encephalitis Virus ◽

Far Eastern

The tick-borne encephalitis virus (TBEV) strain Lazo MP36 was isolated from the pool of mosquitoes Aedes vexans collected in Lazo region of Khabarovsk territory in August 2014. Phylogenetic analysis of the strain Lazo MP36 complete genome (GenBank accession number KT001073) revealed its correspondence to the TBEV Far Eastern subtype and differences from the following strains: 1) from ticks Ixodes persulcatus P. Schulze, 1930 [vaccine strain 205 (JX498939) and strains Khekhtzir 1230 (KF880805), Chichagovka (KP844724), Birobidzhan 1354 (KF880805) isolated in 2012-2013]; 2) from mosquitoes [strain Malyshevo (KJ744034) isolated in 1978 from Aedes vexans nipponii in Khabarovsk territory; strain Sakhalin 6-11 isolated from the pool of mosquitoes in 2011 (KF826916)]; 3) from human brain [vaccine strain Sofjin (JN229223), Glubinnoe/2004(DQ862460). Kavalerovo (DQ862460), Svetlogorie (DQ862460)]. The fusion peptide necessary for flavivirus entry to cells of the three TBEV strains isolated from mosquitoes (Lazo MP36, Malyshevo and Sakhalin 6-11) has the canonical structure 98-DRGWGNHCGLFGKGSI-113 for the tick-borne flaviviruses. Amino acid transition H104G typical for the mosquito-borne flaviviruses was not found. Structures of 5’- and 3’-untranslated (UTR) regions of the TBEV strains from mosquitoes were 85-98% homologous to the TBEV strains of all subtypes without recombination with mosquito-borne flaviviruses found in the Far East of Russia. Secondary structures of 5’- and 3'-UTR as well as cyclization sequences (CS) of types a and B are highly homologous for all TBEV isolates independently of the biological hosts and vectors. similarity of the genomes of the TBEV isolates from mosquitoes, ticks and patients as well as pathogenicity of the isolates for new-borne laboratory mice and tissue cultures might suggest a possible role of mosquitoes in the TBEV circulation in natural foci as an accidental or additional virus carrier.

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TBE in Belarus

Tick-borne encephalitis - The Book ◽

10.33442/26613980_12b2-3 ◽

2020 ◽

Keyword(s):

Encephalitis Virus ◽

Central European ◽

Tick Borne Encephalitis ◽

Natural Foci ◽

Risk Areas ◽

Tick Borne Encephalitis Virus ◽

European Subtype

Almost the entire territory of Belarus is believed to be endemic for tick-borne encephalitis virus (TBEV), with the Central European subtype, also known as TBEV-EU (Figure 1). In all, 96 counties (i.e., 71.5% of all administrative districts) are considered to be risk areas for tick-borne encephalitis (TBE). The most intensive natural foci have been found in the western part of the country (Brest and Grodno Area), and infections in these areas account for an average of 40% each of the total number of reported cases

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Tick-Borne Encephalitis Virus Habitats in North East Germany: Reemergence of TBEV in Ticks after 15 Years of Inactivity

BioMed Research International ◽

10.1155/2014/308371 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 11

Author(s):

Silvius Frimmel ◽

Anja Krienke ◽

Diana Riebold ◽

Micha Loebermann ◽

Martina Littmann ◽

...

Keyword(s):

Human Case ◽

Encephalitis Virus ◽

Federal State ◽

Natural Focus ◽

North East ◽

Tick Borne Encephalitis ◽

Close Relationship ◽

Natural Foci ◽

Tick Borne Encephalitis Virus ◽

Migrating Birds

The incidence of tick-borne encephalitis has risen in Europe since 1990 and the tick-borne encephalitis virus (TBEV) has been documented to be spreading into regions where it was not previously endemic. In Mecklenburg-West Pomerania, a federal state in Northern Germany, TBEV was not detectable in over 16,000 collected ticks between 1992 and 2004. Until 2004, the last human case of TBE in the region was reported in 1985. Following the occurrence of three autochthonous human cases of TBE after 2004, however, we collected ticks from the areas in which the infections were contracted. To increase the chance of detecting TBEV-RNA, some of the ticks were fed on mice. Using nested RT-PCR, we were able to confirm the presence of TBEV in ticks for the first time after 15 years. A phylogenetic analysis revealed a close relationship between the sequences we obtained and a TBEV sequence from Mecklenburg-East Pomerania published in 1992 and pointed to the reemergence of a natural focus of TBEV after years of low activity. Our results imply that natural foci of TBEV may either persist at low levels of activity for years or reemerge through the agency of migrating birds.

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