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 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.

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

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

scholarly journals CHARACTERISTICS OF THE FAR EASTERN POPULATION OF TICK-BORNE ENCEPHALITIS VIRUS AND SOLVING ISSUES OF SPECIFIC PREVENTION

2018 ◽  
Vol 3 (4) ◽  
pp. 42-46
Author(s):  
G. N. Leonova
Keyword(s):  
Virulent Strain ◽  
Biological Properties ◽  
Encephalitis Virus ◽  
Viral Population ◽  
Full Genome Sequencing ◽  
Genetic Characteristics ◽  
Specific Antibodies ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus ◽  
Far Eastern

The subdivision of the viral population into subtypes and clusters based on the molecular genetic characteristics of the tick-borne  encephalitis virus (TBEV) strains predetermines not only the  differences in the biological properties of these strains, but also their different responses to specific antibodies in persons vaccinated against TBE.The aim of the present study is to show the differences in biological properties on the model of two strains of Far Eastern TBEV subtype  belonging to different clusters and to substantiate the need for a  personalized approach to the vaccine prophylaxis of tick-borne encephalitis.Results. Two strains of TBEV were used in the studies. On the basis of full genome sequencing the Dal’negorsk strain (FJ402886,  GenBank) is referred to the typical representative of Sofjin-like, and  Primorye-437 (JQ825162, GenBank) – to Oshima-like TBEV strains  of the Far Eastern subtype.The experiment shows the levels of  specific antibodies capable of neutralizing virulence strains of tick- borne encephalitis virus. Low antibody titers (1:100 and 1:400) can  neutralize only a low dose of a non-virulent strain of tick-borne  encephalitis virus. Reliable protection against the disease of people infected with virulent strains of the TBEV can provide only a  high level of specific antibodies.Conclusion. If the level of specific antibodies of IgG is 1:400 or lower, the vaccination course should be continued, at a titer of  antibodies above 1:400, revaccination can be postponed subject to  annual monitoring of specific immunity parameters in the pre-epidemic TBE season.

Analysis of laboratory methods for monitoring of tick-borne encephalitis natural foci

2021 ◽  
pp. 26-32
Author(s):  
Olga Vitalievna Melnikova ◽  
Yuliya Nikolaevna Trushina ◽  
Renat Viktorovich Adelshin ◽  
Nikolay Vasilievich Yakovchits ◽  
Evgeniy Ivanovich Andaev ◽  
...  
Keyword(s):  
Baikal Region ◽  
Ixodid Ticks ◽  
Ixodes Persulcatus ◽  
Isolation And Identification ◽  
Tick Borne Encephalitis ◽  
Natural Foci ◽  
Group 2 ◽  
Tick Borne Encephalitis Virus ◽  
Tbev Infection ◽  
Group 1

Introduction. Ixodid ticks simultaneously are hosts and vectors of tick-borne encephalitis virus (TBEV), presenting a high risk to humans. Monitoring of the vectors part of TBEV population is usually held by means of express analysis methods (ELISA and PCR), but only isolation and identification of infectious virus is reliable evidence of TBEV circulation in the natural foci. Objectives — to demonstrate the TBEV infection rates of Ixodid ticks from natural TBE foci of Baikal Region, based on comprehensive study, including ELISA, PCR and isolation of virus on laboratory mice (LM) model. Methods. Questing adult Ixodid ticks (n = 20 111, mainly — Ixodes persulcatus Schulze, 1930), were collected in TBE natural foci of Baikal Region during 2013–2020. The suspension on saline solution was prepared from the each tick and analyzed by ELISA first. The samples with positive ELISA results were verified in PCR-RT. Furthermore, randomly selected samples with negative ELISA results were analyzed by PCR. Suspensions with positive ELISA and PCR results have been inoculated to suckling LM intracerebrally. Results. The samples with positive PCR results have been divided into two groups: group 1 — all suspensions with positive ELISA results, group 2 — randomly selected samples with negative ELISA results. The positive PCR results in group 1 made up 70.5 % with average Ct rate 24.9. The positive PCR results in group 2 have been obtained in 2.2 % of cases with average Ct rate 30.7. The isolation on LM model was more successful in group 1 (25.8 vs 13.0 %; р < 0.01; df = 69). Conclusion. ELISA is more useful for study of large amounts of ticks during monitoring of natural TBE foci, offering insight into the epidemically important vectors rate. To get the more full assessment of the ticks’ infection rate one must use ELISA and PCR simultaneously, and sum the results into general rate. For high strains isolation results the LM should be inoculated with the suspensions, which had shown positive both ELISA and PCR results.

Tick-borne encephalitis virus in Eastern Siberia: complete genome characteristics

2012 ◽  
Vol 157 (11) ◽  
pp. 2253-2255 ◽  
Author(s):  
Nina V. Kulakova ◽  
Evgenii I. Andaev ◽  
Sergei I. Belikov
Keyword(s):  
Complete Genome ◽  
Encephalitis Virus ◽  
Eastern Siberia ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

scholarly journals Tick-borne encephalitis virus – a review of an emerging zoonosis

2009 ◽  
Vol 90 (8) ◽  
pp. 1781-1794 ◽  
Author(s):  
K. L. Mansfield ◽  
N. Johnson ◽  
L. P. Phipps ◽  
J. R. Stephenson ◽  
A. R. Fooks ◽  
...  
Keyword(s):  
Clinical Manifestations ◽  
Northern China ◽  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Ixodes Persulcatus ◽  
Tick Borne Encephalitis ◽  
Far Eastern Russia ◽  
Tick Borne Encephalitis Virus ◽  
Far Eastern

During the last 30 years, there has been a continued increase in human cases of tick-borne encephalitis (TBE) in Europe, a disease caused by tick-borne encephalitis virus (TBEV). TBEV is endemic in an area ranging from northern China and Japan, through far-eastern Russia to Europe, and is maintained in cycles involving Ixodid ticks (Ixodes ricinus and Ixodes persulcatus) and wild vertebrate hosts. The virus causes a potentially fatal neurological infection, with thousands of cases reported annually throughout Europe. TBE has a significant mortality rate depending upon the strain of virus or may cause long-term neurological/neuropsychiatric sequelae in people affected. In this review, we comprehensively reviewed TBEV, its epidemiology and pathogenesis, the clinical manifestations of TBE, along with vaccination and prevention. We also discuss the factors which may have influenced an apparent increase in the number of reported human cases each year, despite the availability of effective vaccines.

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