scholarly journals Biological properties and phylogenetic relationships of tick-borne encephalitis virus (Flaviviridae, Flavivirus) isolates of siberian subtype isolated in the south of East siberia in modern period

2021 ◽  
Vol 66 (4) ◽  
pp. 310-321
Author(s):  
O. V. Mel’nikova ◽  
R. V. Adel’shin ◽  
K. V. Lopatovskaya ◽  
Yu. T. Trushina ◽  
N. V. Yakovchits ◽  
...  
Keyword(s):  
Phylogenetic Relationships ◽  
Biological Properties ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Enzyme Linked Immunosorbent Assay ◽  
East Siberia ◽  
Tick Borne Encephalitis ◽  
Natural Foci ◽  
Tick Borne Encephalitis Virus ◽  
Siberian Subtype

Introduction. Tick-borne encephalitis virus (TBEV) is medically most important representative of the same-name serogroup of genus Flavivirus (Flaviviridae). In the view of various researchers there are 3 to 5 TBEV subtypes, of them siberian being the most prevalent. The aim of the work is to compare the biological properties and to reveal phylogenetic relationships of large group of modern (2006–2019) TBEV isolates of siberian subtype from natural foci in southern East Siberia.Material and methods. Ixodid ticks (Ixodidae) and small mammals (Mammalia) from tick-borne encephalitis (TBE) natural foci in Irkutsk Region, Republic of Buryatia and Republic of Tuva, as well as specimens from TBE patients, were examined for TBEV markers using enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). Virus was isolated from suspensions with positive result, and its pathogenicity for white mice (Mus) (WM) was studied by different inoculation ways. Analysis of the nucleotide sequences of E gene was performed for isolates at 1st passage. Phylogenetic tree was constructed using MEGA X program.Results. The phylogenetic analysis has shown that TBEV of siberian subtype that circulates in natural foci of the studied territory belong to two genetic lines. These lines are «Vasilchenko» and «Zausaev» with a strong predominance of the first. The differences in biological properties between the two groups of strains have been demonstrated. Most of the strains from both groups showed high virulence for WM both after intracerebral and subcutaneous inoculation. Only four strains demonstrated the reduced ability to overcome the blood-brain barrier. However, the analysis of the E protein coding sequences revealed evident correlation between phylogenetic clustering and geographical origin of isolates, but not with TBE host or pathogenicity for WM.Conclusion. Further search for TBE genome regions associated with pathogenicity require the analysis of complete genome sequences of representative group of strains with different biological properties.

scholarly journals CHARACTERISTICS OF THE BAIKAL SUBTYPE OF TICK-BORNE ENCEPHALITIS VIRUS CIRCULATING IN EASTERN SIBERIA

2018 ◽  
Vol 3 (4) ◽  
pp. 53-60 ◽  
Author(s):  
I. V. Kozlova ◽  
T. V. Demina ◽  
S. E. Tkachev ◽  
E. K. Doroshchenko ◽  
O. V. Lisak ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Evolutionary History ◽  
Baikal Region ◽  
Biological Properties ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Eastern Siberia ◽  
Tick Borne Encephalitis ◽  
Human Pathology ◽  
Tick Borne Encephalitis Virus

Background. During the study of the genetic variability of the tick-borne encephalitis virus (TBEV) in Eastern Siberia, a group of 22  strains with a unique genetic structure significantly different from all  known TBEV subtypes was identified. This TBEV variant was  tentatively called “group 886”. Therefore, for this original TBEV  variant it was necessary to study the genetic, biological properties of the “group 886” strains, clarify its TBEV taxonomic status, its range, evolutionary history, etc.Aim. The generalization of the currently available data on genetic and biological properties of TBEV “886” group.Materials and methods. The genetic structure of “group 886” strains was studied by the complex of molecular-genetic methods (MHNA, sequencing of fragments or the complete genome).Results. It was shown that “group 886” strains form a separate cluster on phylogenetic tree, and the level of genetic differences  from other genotypes is more than 12 %. It was defined that this  TBEV variant has its own area (Irkutsk region, Republic of Buryatia,  Trans-Baikal region, Northern Mongolia). Its ecological connection  with all links of the transmissive chain (ixodid ticks, small mammals,  human), participation in human pathology, stability and duration of  circulation in the Baikal region, individual evolutionary history  were proved. Some phenotypic characteristics of the “group 886” strains were considered.Conclusion. The presented data testify to the validity of the “886 group” isolation as an independent genetic type. Taking into account  the geographical distribution of this TBEV genotype, we propose to assign it the name “Baikal genotype/subtype”.

scholarly journals Analysis of Multiple Risk Factors for Seronegative Rate of Anti-Tick-Borne Encephalitis Virus Immunization in Human Serum

Medicina ◽  
2020 ◽  
Vol 56 (5) ◽  
pp. 244
Author(s):  
Marta Janik ◽  
Sylwia Płaczkowska ◽  
Mieczysław Woźniak ◽  
Iwona Bil-Lula
Keyword(s):  
Risk Factors ◽  
Booster Vaccination ◽  
Vaccination Schedule ◽  
High Risk Group ◽  
Encephalitis Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Booster Immunization ◽  
Tick Borne Encephalitis ◽  
Waning Immunity ◽  
Tick Borne Encephalitis Virus

Background and objectives: Tick-borne encephalitis virus (TBEV) infections have been the cause of threatening outbreaks for many years. Apart from several physical and chemical methods to prevent tick bites, active vaccination of people highly exposed to infection is still the most important strategy of prevention. However, in some subjects, the lack of or low response to TBEV antigens is observed. The aim of the current study was to assess the prevalence of seronegative rate for anti-TBEV antibodies and the risk factors for waning immunity. Materials and Methods: 2315 at least primary vaccinated subjects from the high risk group for TBEV infections participated in this study. A commercial enzyme-linked immunosorbent assay (ELISA) test was used for the assessment of anti-TBEV IgG serum level. Results: Data showed that 86.2% of subjects who underwent vaccination were positive for anti-TBEV antibodies within 5 years. As much as 13.8% of subjects that underwent primary or primary and booster vaccination were barely protected after vaccination. Women and subjects under 60 years underwent more effective protection but sex and older age was not a risk factor for being a subject of waning immunity. A logistic regression showed that both a longer time since the vaccination and a lower number of booster doses constantly increased the chance of lost anti-TBEV antibodies. Conclusions: This study demonstrates that the vaccination schedule should be reevaluated. The extension of the interval of booster immunization is risky and all subjects should be surrounded by care consisting of more frequent monitoring of serum antibodies by personalized schedule to adjust the frequency of subsequent doses of booster vaccination.

Tick-Borne Encephalitis Virus Diversity in Ixodid Ticks and Small Mammals in South-Western Siberia, Russia

2016 ◽  
Vol 16 (8) ◽  
pp. 541-549 ◽  
Author(s):  
Valentina N. Bakhvalova ◽  
Galina S. Chicherina ◽  
Olga F. Potapova ◽  
Victor V. Panov ◽  
Victor V. Glupov ◽  
...  
Keyword(s):  
Small Mammals ◽  
Western Siberia ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Virus Diversity ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

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

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.

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

2017 ◽  
Vol 62 (1) ◽  
pp. 30-35 ◽  
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.

Properties of the tick-borne encephalitis virus population during persistent infection of ixodid ticks and tick cell lines

2017 ◽  
Vol 8 (6) ◽  
pp. 895-906 ◽  
Author(s):  
Oxana A. Belova ◽  
Alexander G. Litov ◽  
Ivan S. Kholodilov ◽  
Liubov I. Kozlovskaya ◽  
Lesley Bell-Sakyi ◽  
...  
Keyword(s):  
Cell Lines ◽  
Persistent Infection ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Virus Population ◽  
Tick Cell ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

TBE in Belarus

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

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

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
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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