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.

scholarly journals Comparative analysis of the tick-borne encephalitis virus (TBEV) infection of unfed adult ixodid ticks Ixodes pavlovsky Pomerantsev 1946 and Ixodes persulcatus Schulze in the area of sympatria of their natural habitats

2015 ◽  
Vol 20 (1) ◽  
pp. 20-26
Author(s):  
G. S Chicherina ◽  
O. V Morozova ◽  
V. V Panov ◽  
V. N Romanenko ◽  
S. A Bakhvalov ◽  
...  
Keyword(s):  
Encephalitis Virus ◽  
Ixodid Ticks ◽  
Ixodes Persulcatus ◽  
Anthropogenic Pressure ◽  
Laboratory Mice ◽  
Natural Habitats ◽  
Tick Borne Encephalitis ◽  
Ixodes Pavlovskyi ◽  
Tick Borne Encephalitis Virus ◽  
Tbev Infection

With the use of the ELISA method to detect an antigen, reverse transcription with quantitative real-time PCR with subtype-specific fluorescent probes, phylogenetic analysis of E and NS1 gene nucleotide sequences, bioassays with suckling mice, hemagglutination and neuroinvasiveness tests there was made a comparison of the tick-borne encephalitis virus (TBEV) infection of ixodid ticks Ixodes persulcatus P.Schulze and Ixodes pavlovskyi Pomerantsev 1946 in the area of sympatria of their natural habitats in the Novosibirsk region during growth period of their populations with the replacement ofprevailing species of monodominant type of the ixodid population structure. The ratio of 2 tick species didn’t depend on biotopes ofpine or birch forest but rather on the distance from the Novosibirsk Scientific Center: the lower anthropogenic pressure the smaller I.pavlovskyi proportion. The TBEV rate (including both pathogenic and apathogenic for laboratory mice virus), spectra of the TBEV3 main genetic types, neurovirulence and hemagglutination activity were similarfor both I.persulcatus and I.pavlovskyi. However, the proportion ofpathogenic for laboratory mice virus and the TBEV Far Eastern subtype, as well as viral loads of Siberian and European types for the TBEV from I.pavlovskyi were significantly higher than those from I.persulcatus.

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.

Analysis of effectivity of the tickborne encephalitis virus detection methods in ixodid ticks

2021 ◽  
Vol 66 (4) ◽  
pp. 237-241
Author(s):  
O. V. Mel’nikova ◽  
Yu. N. Trushina ◽  
R. V. Adel’shin ◽  
E. I. Andaev ◽  
G. N. Leonova
Keyword(s):  
Virus Detection ◽  
Viral Disease ◽  
Ixodid Ticks ◽  
Detection Methods ◽  
Tbe Virus ◽  
Natural Foci ◽  
Complex Picture ◽  
Group 2 ◽  
Express Methods ◽  
Group 1

Tick-borne encephalitis (TBE) is transmissible viral disease widely common in temperate zone of Eurasia. ELISA and PCR are used for express identification of the vector’s infection, but the results of the two methods often do not agree. Aim of the work is comparative analysis for TBE virus of Ixodid ticks from nature using complex of methods, including ELISA, PCR, and isolation of the virus in laboratory mice. 18608 Ixodid ticks were collected during 2013-2019 in TBE natural foci of the Baikal Region. The ticks suspensions were examined individually, using ELISA (n=17610) and PCR (n=2999). Suckling mice were inoculated with the suspensions positive in the both tests. The TBEV antigen was found in 1.2 % of ticks in average. All ticks positive in ELISA were examined in PCR (Group 1). Randomly selected part of negative-ELISA samples were examined in PCR too (Group 2). The PCR results were positive in 68.9±3.13 % of the Group 1, with average Ct index 24.6±0.38. Positive results of PCR in Group 2 accounted for just 2.7±0.31 % with average Ct index 31.0±0.70. The average Ct margin of the Groups 1 and 2 is statistically significant (p < 0.001; df = 118). Isolation of strains was significantly more successful in Group 1 (21.7±2.77 %), than in Group 2 (8.2±5.26 %; p < 0.05; df = 50). ELISA is more useful for examining large amounts of ticks. To get a more complex picture about epidemically dangerous part of the vectors in TBE natural foci, the results of the two express-methods is better to sum. The isolation of the virus is useful to carry out of the samples positive in ELISA and PCR concurrently.

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.

scholarly journals Tick-borne encephalitis virus isolates from natural foci of the Irkutsk region: clarification of the genotype landscape

2016 ◽  
Vol 61 (5) ◽  
pp. 229-234 ◽  
Author(s):  
O. V. Mel’Nikova ◽  
R. V. Adel’Shin ◽  
V. M. Korzun ◽  
Yu. N. Trushina ◽  
E. I. Andaev
Keyword(s):  
Small Mammals ◽  
Encephalitis Virus ◽  
Ixodes Persulcatus ◽  
Tick Borne Encephalitis ◽  
Irkutsk Region ◽  
High Virulence ◽  
Natural Foci ◽  
Tick Borne Encephalitis Virus ◽  
Relationship Of ◽  
Far Eastern

The Irkutsk region is the unique territory where all known subtypes of tick-borne encephalitis virus (TBEV) circulate. In the last years, the phenomenon of changes in TBEV subtypes (substitution of the Far-Eastern subtype by the Siberian one) was noted in some regions of the Russian Federation. The results of individual investigation of 11522 Ixodes persulcatus ticks and brain specimens from 81 small mammals collected in natural foci of the Irkutsk region during 2006-2014 are presented in the article. More than 60 TBEV strains have been isolated and studied by virological methods; E gene fragments (1193 b.p.) of 68 isolates have been typed. The majority of the strains (irrespective of subtype) were of high virulence for laboratory mice (LM) in case of both intracerebral and subcutaneous inoculation of virus. All isolates from warm-blooded small mammals and humans were of high virulence for LM, but placed in the same clusters of the phylogenetic tree with ticks collected in the same area. Tick-borne strains of different virulence also did not form separate clusters on the tree. Phylogenetic analysis showed that modern TBEV genotypic landscape of the studied territory is changing toward absolute predominance of the Siberian subtype (94.1%). This subtype is represented by two groups with prototype strains “Zausaev” and “Vasilchenko”. The “Vasilchenko” group of strains is spread on the whole territory under study; the strains of “Zausaev” group were isolated previously in the Irkutsk suburbs. The European subtype of TBEV circulates in natural foci of Pribaikalie permanently (at least 5% of the random sampling); the strains are of high virulence for LM. The Far-Eastern TBEV subtype was not found within the group of isolates collected in 20062014. The phylogenetic relationship of the strains under study had a higher correlation with the place of isolation than with the year or source.

scholarly journals Ixodid ticks in Southern part of Eastern Siberia and Mongolia and their spontaneous infectiveness by infectious agents

2006 ◽  
Vol 5 ◽  
pp. 137-143
Author(s):  
G. A. Danchinova ◽  
M. A. Khasnatinov ◽  
V. I. Zlobin ◽  
I. V. Kozlova ◽  
M. M. Verkhozina ◽  
...  
Keyword(s):  
Ixodid Ticks ◽  
Ixodes Persulcatus ◽  
Eastern Siberia ◽  
Borrelia Garinii ◽  
Genetic Characteristics ◽  
Tick Borne Encephalitis ◽  
Vector Borne ◽  
Tick Borne Encephalitis Virus ◽  
Rickettsia Sibirica

The goal of the study is to reveal the species of Ixodid ticks in Eastern Siberia and Mongolia, having epidemiological value and pathogens that transmit to humans via their bites. The tasks is to determine ecologo-epidemiologial characteristics of the main vectors and genetic characteristics of the agents of tick-borne infections. Characterization of the materials. There are materials of the study of more than 200 000 Ixodid ticks of 4 species and their rate of infection by different pathogens with zooparasitological, epidemiological, virological, microbiological, molecular-biological standard and modified to the goals and tasks of the study. Most abundance and dangerous species is Ixodes persulcatus P.Sch. ticks, that is widespread in region investigated. The agents of known vector-borne infections in Eastern Siberia and Mongolia are tick-borne encephalitis virus, Borrelia garinii, Borrelia afze- lii, Rickettsia sibirica, R. sp. DnS14 group.

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 Roe deer as sentinels for endemicity of tick-borne encephalitis virus

1995 ◽  
Vol 115 (2) ◽  
pp. 355-365 ◽  
Author(s):  
H.-J. Gerth ◽  
D. Grimshandl ◽  
B. Stage ◽  
G. Döller ◽  
C. Kunz
Keyword(s):  
Roe Deer ◽  
Neutralization Test ◽  
Haemagglutination Inhibition ◽  
Capreolus Capreolus ◽  
Encephalitis Virus ◽  
Antibody Prevalence ◽  
Tick Borne Encephalitis ◽  
Natural Foci ◽  
Tick Borne Encephalitis Virus ◽  
Tbev Infection

SummaryThe suitability of serological surveys of roe deer (Capreolus capreolus) in determining the spread of tick-borne encephalitis virus (TBEV) was tested in a south German area with a low risk of TBEV infection to humans. Sera obtained from 192 hunted roe were screened by an haemagglutination–inhibition test (HAI) and in an ELISA developed in our laboratory. Those found positive were tested in a neutralization test (NT). Fifty (26·0%) sera reacted positive by ELISA and 43 (86·0%) of these were confirmed by HAI or NT. Forty-seven (24·5%) samples were positive by HAI, 44 (93·6%) of which were also positive in NT or ELISA. Only insignificant increase of the antibody prevalence with age (P = 0·17 for HAI antibodies) suggests that most infections occur at an early age in scattered natural foci. The antibody prevalence in females was lower than in males (OR = 0·63; P = 0·02 for HAI antibodies). In determining the distribution of seropositive roe we increased the sample size to 235 sera. No antibodies were detected in 56 (23·8%) sera collected in the eastern third of the county. The areas of high antibody prevalence in roe match those in which humans have been infected. We conclude that serosurveys of roe deer are useful in marking out areas in which humans face the risk of infection, provided that an adequate number of sera, preferably from males, is available.

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”.

Chapter 11: General epidemiology of TBE

2020 ◽  
Keyword(s):  
Eastern Siberia ◽  
Genetic Lineages ◽  
Phylogenetic Studies ◽  
Tick Borne Encephalitis ◽  
Natural Foci ◽  
Genetic Sequences ◽  
Tick Borne Encephalitis Virus ◽  
Almost All ◽  
Far Eastern ◽  
Reservoir Hosts

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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