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Background. Infections transmitted to humans by the bites of ixodid ticks remain an urgent public health problem. In this work we explored the natural foci of tickborne infections located in the valley of the Chikoy River, which is a part of the buffer zone of the Baikal natural territory.The aim. To characterize the modern diversity and prevalence of tick-borne pathogens in the ecosystems of the valley of the Chikoy River (Trans-Baikal Territory, Russian Federation).Materials and methods. Thirteen sampling sites were located in typical biotopes throughout the Chikoy valley. In total 48 adult Ixodes persulcatus ticks, 1 female Haemaphysalis concinna tick and 38 specimens of small mammals were studied. All samples were tested for infection with seven tick-borne pathogens using multiplex real-time PCR.Results. No pathogens were detected in the H. concinna specimen. No R. sibirica and R. heilongjiangensis were detected both in ticks and in rodents. Among I. persulcatus, tick-borne encephalitis virus (TBEV), and the prevalence of Borrelia burgdorferi s. l. comprised 39.5 %, A. phagocytophilum – 16.7 %, B. miyamotoi – 8.3 % and Ehrlichia sp. – 2.1 %. Among infected ticks 6.2 % were co-infected with B. burgdorferi s. l. and A. phagocytophilum. Four rodent hosts of ticks and infections were identified: Myodes rufocanus (44.7 %), Apodemus peninsulae (39 %), Microtus oeconomus (13.2 %) and M. rutilus (2.6 %). Mean prevalence of B. burgdorferi s. l. in rodents comprised 39.5 %, B. miyamotoi – 28.9 %, Ehrlichia sp. – 21.1 % and A. phagocytophilum – 18.4 %. TBEV was detected in 5.3 % of rodents.Conclusion. At least five tick-borne pathogens circulate in the Chikoi River valley, i. e. TBEV, B. burgdorferi sensu lato, A. phagocytophilum, B. miyamotoi and Ehrlichia sp. The wide spread of I. persulcatus and abundance of competent rodent hosts of infections and ticks indicates that natural foci of tick-borne diseases are widely distributed in the Chikoi River valley.

Background. Aptamers are small single-stranded DNA or RNA molecules that have an affinity for a specific target molecule. The main method of aptamers construction is the technology of systematic evolution of ligands with exponential enrichment (SELEX). However, the exact approach depends on the nature of target molecules, and is selected and optimized by each researcher independently. The article describes the technique of production of aptamers to the tick-borne encephalitis virus (TBEV) using membrane ultrafiltration with a molecular weight cut-off of 100 kDa. As a result, the pool of aptamers with observable affinity for TBEV is successfully selected and enriched.The aim. To develop the technique suitable for selection of specific DNA aptamers to a live, crude TBEV suspension directly in cell culture supernatant.Materials and methods. The selection of aptamers was carried out using a modified SELEX DNA aptamer technology in combination with semipermeable membrane ultrafiltration using Vivaspin 6 (Sartorius, Germany) concentrators of molecular weight cut-off of 100 kDa. Enrichment of a specific pool of aptamers was performed using real time polymerase chain reaction. Aptamers were sequenced with automated Sanger sequencing method. The direct virucidal effect of the aptamers was determined by the decrease in the titer of the infectious virus after incubation with the aptamer.Results. The pool of aptamers to TBEV was selected and enriched. This aptamer pool expressed affinity both to the infectious TBEV and to the TBEV antigen. Sixteen aptamers were sequenced from this pool and four of them were synthesized and tested for antiviral activity against TBEV. No antiviral activity was observed.Conclusions. The technique developed that can be successfully used to select aptamers to a live virus culture for the viruses comparable in size to TBEV or larger.

Background. Smell disorder is a recognized clinical symptom of COVID-19 infection. The problem of the loss of sense of smell in the structure of COVID-19 pathogenesis during pregnancy remains unresolved. The aim of the study. To determine the sense of smell and taste in pregnant women with COVID-19, as well as to evaluate the relationship between the sense of smell and the number of SARS-CoV-2 genome equivalents in the nasopharyngeal secretion. Material and methods. In the case-control study, 121 pregnant women participated: 40 of them were infected with COVID-19; 81 were not infected with COVID-19 earlier and at the time of the study. The survey was conducted in July 2021. Sense of smell was assessed using the Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test, which includes olfactory threshold determination and odor identification assessment. Taste was measured according to the O. Massarelli method. Viral load was calculated using a standardized method for determining the numberof SARS-CoV-2 RNA copies in 1 ml of nasopharyngeal secretion. Results. The incidence of olfactory disorders (moderate / severe and anosmia) in pregnant women with COVID-19 is 62.5 % compared to 22.23 % among pregnant women who have never had COVID-19 (p = 0.002). No significant taste disorders were identified. The threshold value for the manifestation of olfactory disorders was 17794 RNA copies of the SARS-CoV-2 virus, which corresponds to the 37th threshold cycle (Ct). Conclusion. During pregnancy in the acute phase of COVID-19, sense of smell is significantly impaired, but not sense of taste. Decreased sense of smell is associated with SARS-CoV-2 viral load.

Background. In spring and summer, the population of the Baikal region regularly comes into contact with the pathogens transmitted through the bites of ixodid ticks. In the Center for Diagnosis and Prevention of Tick-Borne Infections (Irkutsk, Russian Federation), we annually detect anaplasmas of the Anaplasma phagocytophilum species, as well as Ehrlichia chaffeensis/E. muris in both ixodid ticks and blood samples from people who have been bitten by ticks. At the same time, there are no data in open sources on the incidence of human granulocytic anaplasmosis and human monocytic ehrlichiosis in the Baikal region. Currently, there is very little information on the studies of intensity of the immune response to anaplasmas and ehrlichia in people living in the surveyed area, although this information is critical for assessing the frequency of contacts and the risk of infection of people in a territory endemic for tick-borne infections. The aim. To update information on the presence and prevalence of specific immunoglobulins M and G to A. phagocytophilum and Ehrlichia sp. among the population of the Irkutsk Region affected by tick bites. Materials and methods. In total, 204 samples of blood serum from the residents of the Irkutsk Region who were registered to be bitten by ticks were analyzed for the presence of IgM and IgG to human monocytic ehrlichiosis and human granulocytic anaplasmosis agents. Results. IgG to A. phagocytophilum were found in 9 samples, IgG to E. chaffeensis/E. muris – in 1 sample; no IgM to both pathogens were found in any sample. Conclusions. The results obtained indicate regular infection of the population with anaplasmas and ehrlichia which is a testifies to the existence of active natural foci of human monocytic ehrlichiosis and human granulocytic anaplasmosis in the Baikal region. To clarify the real epidemic role of these infections, a detailed study of the immune status is required both among healthy individuals and among patients with symptoms of an infectious disease.

Background. The tick-borne encephalitis virus (TBEV) is one of the most dangerous and epidemiologically significant vector-borne pathogens. There is a need for effective antiviral agents for the treatment and prevention of this infection. Previously we found that the mycelium of Inonotus rheades grown on birch wood contains water-soluble substances with strong virulicidal properties against TBEV. It is necessary to check whether the mycelium of I. rheades can synthesize virulicidal substances from wood of other species.The aim: to study the antiviral properties of extracts of I. rheades mycelium grown on coniferous wood, both in the presence and in the absence of blue light during cultivation.Materials and methods. The mycelium of I. rheades was grown on birch, pine, and fir wood. The direct virulicidal effect of the extract was evaluated by the decrease in the titer of the infectious virus incubated in the presence of the extract. The ability of the extract to inhibit the reproduction of the virus in infected cells was studied by the calculation of 50 % effective concentration (EC50). The toxicity of extracts for cells was evaluated based on the calculation of 50 % cytotoxic concentration.Results. Mycelium extracts grown on conifers under blue light do not cause a statistically significant decrease in the concentration of infectious TBEV (p = 0.2563). However, the BP10 extract (pine, blue light) inhibits TBEV reproduction in infected cells (EC50 = 0.28 ± 0.06 mg/mL). Toxicity for SPEV cell culture is low. In the extracts of conifers grown in the dark, no antiviral effect was found at all.Conclusions. The component composition and mechanism of the antiviral action of I. rheades extracts are determined by the species of the wood substrate. The most promising sources of new drugs in relation to TBEV appear to be extracts of I. rheades mycelium grown on birch and pine.

Background. The viral load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the new coronavirus infection, is becoming increasingly important in clinical and epidemiological contexts. Despite this, there are significant complexities in the implementation of viral load quantitative measurement into clinical practice due to the limited approaches to its assessment.The aim of this work was to develop an approach for SARS-CoV-2 viral load analysis by the value of sample threshold cycles (Ct) relative to the Ct of the internal control sample obtained in routine PCR diagnostics of the COVID-19, and to use this approach for quantitative monitoring of viral load in patients with first positive SARS-CoV-2 test from the Irkutsk region.Materials and methods. Using regression models based on the least squares method, an approach to determine the number of copies of SARS-CoV-2 RNA in 1 ml of nasopharyngeal secretion was developed. The viral load of SARS-CoV-2 was assessed in nasopharyngeal and pharyngeal samples obtained from 1370 patients from Irkutsk and Angarsk with primary diagnosed positive PCR result in the period from July 1 to November 10, 2020.Results. A tenfold increase in the average monthly viral load among patients in September-October 2020 was revealed. We assume that the change in the epidemiological pattern of the spread of the new coronavirus infection during this period is associated with an increase in the number of contacts in the population due to the school year beginning. Higher viral loads are observed in populations at risk for COVID-19 – among healthcare workers and adults/elderly patients. Conclusion. The development of a standardized quantification of SARS-CoV-2 viral load in the nasopharyngeal samples can be a predictive clinical marker and a reliable tool for improving COVID-19 surveillance using the proposed approach to assess average viral load in a local population.

Background. Tick-borne encephalitis virus is dangerous and widespread pathogen that is transmitted to humans through the bites of hard ticks. Wild fungi, such as xylotrophic basidiomycetes, are widely used in traditional medicine to treat the infectious diseases and are promising natural sources of new antiviral agents. It was previously shown that aqueous extracts from the mycelium of the Inonotus rheades (Pers.) P. Karst. (1882) fungus exhibit significant antiviral activity against tick-borne encephalitis virus, however, the mechanisms of this activity remain unclear.Aim. To analyze the relationship between the virucidal properties of I. rheades extract and the substrate on which the cultivation was carried out.Materials and methods. The mycelium was grown either in a standard liquid medium with wort or on wooden disks from birch. Extracts of water-soluble polysaccharides were prepared from both mycelium samples. The concentration of infectious tick-borne encephalitis virus was determined using the method of titration of plaque-forming components (PFU). Approximately 30 000 PFU of tick-borne encephalitis virus was mixed with an equal volume of corresponding I. rheades extract at concentration of 8 mg/mL and incubated for 30 min at 37 °C. Afterwards, the residual infectivity of tick-borne encephalitis virus was determined using the identical virus sample incubated with sterile water as a reference.Results. It was found that treatment of tick-borne encephalitis virus with extracts from I. rheades mycelium resulted in inhibition of the infectivity of the virus in the cell culture. However, the same strain of I. rheades, grown on medium with wort, did not exhibit antiviral properties.Conclusions. Virucidal substances are likely to be not the main metabolites of the mycelium of I. rheades, but are rather metabolized wood polysaccharides. Further research is needed to more accurately identify the active ingredients and assess their antiviral activity.

Background. Tick-borne encephalitis virus (TBEV) in nature exists due to the constant circulation between vertebrate animals and tick viruses. To study the characteristics of reproduction of TBEV in the cells of vertebrate hosts of various species, it is necessary to simulate infection in the cell lines of both natural and accidental hosts of TBEV.Aim. To study the possibility of reproduction of TBEV in the cell line of the kidney of Siberian bat Myotis sibiricus (Kastschenko, 1905) – an accidental host of the virus.Materials and methods. The cell line of Siberian bat M. sibiricus was established by serial passages of primary culture of kidney cells. The SPEV line porcine kidney cells were used as reference. Cells were infected with a strain of TBEV of the Siberian subtype 92M and both cells and cell culture fluids were sampled every 2 hours during first 24 hours post infection. In addition, the samples were collected daily up to 5 days post infection. Evaluation of the amount of intracellular RNA of TBEV of positive polarity (+RNA) was performed using quantitative real-time PCR. The concentration of infectious TBEV was evaluated using the method of titration TBEV on plaque forming units.Results. The continuous cell line, designated as MdbK, was established from the kidney cell suspension of M. sibiricus and was used for experiments after 20 serial passages. MdbK cells were able to support the replication of TBEV RNA and production of infectious virus was also possible. The concentration of intracellular RNA had reached 9.1 lg copies/μl by day 3 post infection, whereas highest titer of infectious TBEV in cell culture fluid had comprised 5,5 PFU/ml and was detected by day 4. The concentration of intracellular RNA and the virus infectivity in MdbK cell line was significantly lower than in convenient SPEV line porcine kidney cell.Conclusions. The results suggest the low fitness of TBEV to the intracellular environment of an accidental host.

Background. The specific detection of genomic/template +RNA and replicative –RNA of tick-born encephalitis virus (TBEV) is necessary to study the mechanisms of viral replication in the cells of reservoir and accidental hosts. However, the current approaches of quantitative reverse transcription – polymerase chain reaction (qRT-PCR) are rather focused on the detection of total viral RNA load in the sample. Thus, the significant optimization is necessary both for RT-PCR and for RNA copy number standard preparation.Aims. To develop the set of standard samples of synthetic +RNA of TBEV and to optimize qRT-PCR for quantification of genomic +RNA of the virus.Materials and methods. Fragment of the genomic +RNA of TBEV was synthesized using pTZ57R-T\A plasmid vector with embedded T7 promoter and T7 RNA polymerase. The DNA contamination was removed using RNase-free DNase I treatment followed by additional RNA purification step. Reverse transcription was performed using specific antisense primer 11154R 5`- AGCGGGTGTTTTTCCG-3` and qPCR detection was used according to the modified procedure of M. Schwaiger and P. Cassinotti (2003).Results. As a result of the amplification of standard samples, the concentration of positive polarity ТBEV RNA, carried out in five independent repetitions on different days, the correlation coefficient R2 between the quantification cycle and the concentration of the standard sample was 0.99, and the efficiency of PCR was 100 %. The coefficient of variation in assessing the inter-test accuracy of determination averaged 2.8 %.Conclusions. Optimized qRT-PCR procedure and set of +RNA standards allow to determine the concentration of genomic +RNA of TBEV in routine laboratory practice.

Introduction. Annually, there are several patients attended the Center for Diagnosis and Prevention of Tick-borne Infections in Irkutsk after bites of ticks that happened outside the Pribaikalye region or abroad. In such cases, the attacking ticks do not belong to convenient species that are usual for Eastern Siberia. Consequently, the spectrum of pathogenic microorganisms transmitted by these ticks may significantly differ from those that are detected by usual laboratory tests. Thus, both physicians and laboratory personnel may have difficulties in proper detection and identification of pathogens as well as in diagnosing and treating of such patients.The purpose of the study was the analysis of potential risks of human infection with the pathogens that are common in foreign countries outside the Russian Federation.Material and methods. The article uses information from electronic databases created by the authors during 2007-2017.Results and discussion. During 11 years of observations, 52 tick bites were registered in 20 countries, with 48 of them in the Eastern Hemisphere (92.3 %), three (5.8 %) in the United States and one (1.9 %) in the Republic of Cuba. The results indicate a real danger of infection by tick-borne pathogens of people traveling as the tourists and with business purposes to the countries of Europe, Asia and America. Conclusion. It is necessary to improve the existing algorithm for diagnosis, prevention and treatment for people bitten by ixodid ticks outside the Russian Federation, taking into account the possibility of infection by inconvenient imported infections.

The Republic of Cuba is a popular destination for Russian tourists and about 30-50 thousands of Russian citizens visit Cuba annually. However, the recreational activity is often associated with the risk of Ixodid ticks bites and infection with tick-borne pathogens. According to published literature, the fauna of the hard tick in Cuba is represented by nine species including Ixodes capromydis, Amblyomma albopictum, A. cajennense, A. dissimile, A. quadricavum, A. torrei, Dermacentor nitens, Rhipicephalus sanguineus and R. (Boophilus) microplus. Five of these species, i.e. A. cajennense, A. dissimile, D. nitens, R. sanguineus and R. (Boophilus) microplus, were reported as human parasites. Ticks are spread over the most part of the island territory. Several tick-borne pathogens should be considered as a potential threat for the bitten humans in Cuba, including Borrelia burgdorferi sensu lato, Rickettsia sp., Anaplasma sp., Ehrlichia sp., Coxiella sp., thogotovirus and Crimean-Congo hemorrhagic fever virus. Implications for the epidemiology of tick-borne infections in the Russian Federation are discussed.

Background. Early detection of tick-borne pathogens in blood samples of infected people prevents the disease before clinical manifestations using antibiotic and immunoglobulin treatment. As far as tick-borne diseases are associated with significant activation of innate immune response, the changes in the cytokine profile soon after a tick bite could be used as an indicator of early tick-borne infection. Aims. The goal of this study was to characterize the production of cytokines during first 2-4 days after a tick bite in asymptomatic people infected with tick-borne pathogens. Materials and methods. The infection of tick-borne encephalitis virus, B. burgdorferi sensu lato, A. phagocytophilum and E. chaffeensis / E. muris was detected in blood of bitten humans using appropriate commercial real time RT-PCR and ELISA assays. Concentration of 14 cytokines in plasma of 89 infected and 45 non-infected people was established using quantitative ELISA kits. Results. Between 2nd and 4th days after tick bite, the prevalence and concentration of certain cytokines in blood of infected people significantly differed from those of the control group. Bacterial pathogens exhibited very similar patterns of cytokine profiles with induction of IL-1a, IL-8 и IFN-a and suppression of SOD, IL-1Ra и IL-17A. For virus infection the increased concentrations of IL-1 a, IL-8, IL-10, IL-17A, IFN-y and SOD were detected. The only suppressed cytokine was IL-1Ra receptor antagonist. Conclusions. The results suggest that evaluation of innate immune response between 2nd and 4th days after the tick bite could be a useful tool for evaluation of the risk of tick-borne disease for the humans bitten by ticks.

Tick-borne encephalitis (TBE) is a widely known viral disease that is transmitted through the bites of ixodid ticks. In severe cases, it leads to disability or death of the patient. The causative agent of the TBE is the tick-borne encephalitis virus (TBEV), which belongs to the Flaviviridae family. Despite the great importance of TBE in human pathology, currently the only way to prevent and treat this disease is a donor immunoglobulin, which has a number of significant disadvantages. In this paper, we analyzed modern literature on the detection of antiviral properties of herbal preparations and assessed the possibility of using them to search for new drugs against TBE. In general, the published works can be divided into two areas of research - the study of whole plant extracts and the study of the biological activity of the purified extract components. The most informative results can be obtained under certain conditions; for example, the study of both water extracts of plants and extracts with organic solvents, fractionation of the initial preparations with the detected antiviral activity followed by the concentration of the target substance; identification of an antiviral agent to obtain standardized drugs and preclinical testing in laboratory animals and cell cultures. This approach made it possible to identify three substances - hebulinic acid, panicalagin and baikalein - possessing inhibitory activity against Dengue flavivirus. The article discusses the possibility of using these substances against TBEV and the optimal algorithm for searching for antiviral agents in plant preparations.

Background. Hantavirus infections are one of the most important zoonotic diseases in the Russian Federation. However, the pathogenicity of Hantaviruses circulating in Siberia is still unknown. The aim of the study was to assess the incidence of Hantavirus infection in patients with fever of unknown origin from Irkutsk region and adjacent territories. Materials and methods. Serum samples collected in 2016 from individuals with symptoms of health deterioration were screened by ELISA to investigate possible Hantavirus infection, in addition to tick-borne infections. Depending on date of tick bite specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to tick-borne encephalitis, borreliosis and Hantavirus were tested by ELISA or screened by PCR for tick-borne encephalitis, borreliosis, human granulocytic anaplasmosis and monocytic erlychiosis RNA/DNA. Results. Out of 92 serum samples, 6.5 % were positive for hantavirus-specific antibodies, which is at least twice higher than the seroprevalence among healthy people in the Irkutsk region. IgM and IgM+IgG antibodies were found in 5.4 % of cases, while IgG antibodies - in 1.1 % of cases. The clinical symptoms among sero-positive patients were fever, skin lesion, fatigue syndrome, headache and lymphadenitis. IgM antibodies to borreliosis were found in two hantavirus sero-positive cases. Lung tissues from small mammals captured in 2016 were screened by ELISA for the presence of Hantavirus antigen. Hantaviral antigen was detected in 6.3 % of 48 samples. Conclusions. Thus, present and previous studies demonstrate existence of natural foci of Hantavirus infections in addition to tick-born infections in the territory of the Irkutsk region.

Ixodid ticks are the vectors of many pathogens including tick-borne encephalitis virus and the Lyme disease agent Borrelia burgdorferi sensu lato. In Pribaikalye, Ixodes persulcatus, Dermacentor nuttalli, D. silvarum and Haemaphysalis concinna are regarded as main vectors of the diseases. Recently, significant changes in world tick fauna have been reported and this affects the spread of tick-borne pathogens. We studied the current species diversity, population structure and the number of attacks of hard ticks (Acari:Ixodidae) on humans in Irkutsk region and nearby territories during the season 2015. Long-term trends of changes in attack rate were analyzed as well. In total, 4268 individual ticks were identified and analyzed during the season 2015. The majority (86 %) of victims was bitten by I. persulcatus; 13.55 % of attacks on humans were caused by D. nuttalli and D. silvarum; whereas H. concinna was documented only in 2 cases (~0.05 %). No non-endemic or invasive tick species were documented in 2015. The seasonal activity and the age/gender structure of tick population that bite human hosts were described as well. The comparison of the results of 2015 with previously reported datasets on tick bite ratesfrom 1992-2001 andfrom 2007-2014 indicates that, after the burst of tick bites in 1992-2001, there are no significant increase of attack rate since 2007. Possible implications to human health and epidemiology of tick-borne infections are discussed.

Tick borne encephalitis (TBE) is a dangerous neurological disease that is transmitted to humans through the bite of Ixodid ticks. The disease exhibits an estimated 16 000 cases recorded annually over 30 European and Asian countries. The agent of TBE is the tick borne encephalitis virus (TBEV), belonging to the family Flaviviridae, genus Flavivirus. In spite the significant impact of TBE on human health, there is a serious lack of specific treatment against this disease. The only specific drug available is the human anti-TBEV immunoglobulin from vaccinated blood donors. The drug is produced and used in Russia only, both to prevent and to cure the TBE. In this work, we evaluated the ability of TBEV-specific DNA-aptamers and extracts of traditional medicine plants to neutralize the TBEV Selection of aptamers was performed using SELEX approach. Extracts of the seeds of Momordica cochinchinensis and Terminalia chebula were produced by boiling the ground seeds in water, clarified by centrifugation and filtration steps and filter sterilized. The SELEX had produced two aptamers - My13 and My38. Neither of two was capable to neutralize TBEV in vitro. The ability to shield the antibody binding sites on the surface of TBEV virions was also absent. The extract of M. cochinchinensis exhibited no neutralizing activity as well. Surprisingly, the T. chebula extract completely neutralized the TBEV after 30 min of incubation at 37 °C. The possible explanations and further development of the project are discussed.

The urgent detection of tick-borne pathogens in attached ticks or in human blood followed by the prophylaxis of infection with specific immunoglobulin and/or antibiotics is one of the most reliable measures to prevent human disease. The aim of this work was to evaluate the usability of real-time PCR (RT-PCR) assay in early detection of tick-borne infections. Using commercial RT-PCR assay (Amplisens, Russia) we studied 361 Ixodes persulcatus ticks, 33 Dermacentor sp. ticks and 448 samples of human blood delivered by people attacked by ticks in Irkutsk region during 2013-2014for presence of DNA/RNA of tick-borne encephalitis virus (TBEV), Borrelia burgdorferi sensu lato (B.b.s.l.), Anaplsma phagocytophilum and Ehrlichia chaffeensis/E. muris. The ELISA assay and direct microscopy were used to validate the detection of TBEV and B.b.s.l. respectively. The highest prevalence of tick-borne infections was observed for I. persulcatus ticks - 6,9; 23,8; 6,9; and 11,9 % for TBEV, B.b.s.l., A. phagocytophillum and E. chaffeensis/E. muris respectively. The Dermacentor sp. ticks were less frequently infected with abovementioned pathogens - 3,0; 6,1; 3,0 and 9,1 % respectively. The prevalence of infection in blood samples was lowest and comprised 2,5; 4,2; 2,2 and 4,5 % respectively. Mixed infections were documented in 6,5 % of ticks and 0,7 % of human blood samples. The testing of blood samples in ELISA and testing of ticks in ELISA and direct microscopy corresponded to the results, obtained by RT-PCR. Thus, RT-PCR is valuable and reliable approach for urgent detection and prophylaxis of tick-borne infections.

For the first time the current situation with tick-borne infections in recreational places of the Republic of Buryatia is evaluated. According to the data of the Center for diagnostic and prophylaxis of tick-borne infections (Irkutsk) collected in 2007 - 2014 the tick-borne encephalitis, Lyme disease, monocytic ehrlichiosis and granulocytic anaplasmosis are widely spread in most popular recreational places of south coast of the Baikal Lake and Tunka valley.

Influenza A virus (IAV) is a worldwide pathogen of humans and animals. In nature IAV is associated with aquatic birds. The regular survey of natural populations of aquatic birds is important to describe the diversity of IAV, evaluate pathogenic potential of circulating strains for human and domestic animals and reveal possible routes of virus spread during seasonal migrations of wild birds. In this paper the results of annual ecological and viroiogicai survey among wild birds of Eastern Siberia performed between 2005 and 2012 are presented. The cloacal swabs and tissue samples from 901 wild birds were analyzed for presence of IAV using virus isolation in chicken embryos and/or PCR assay. The subtype of IAV was established using haemaggiutintion inhibition assay and genome sequencing. Seventeen subtypes of IAV were discovered including H1N1, H5N1, HswNl, H0N1, H1N4, HlNlsw, H2N2, H3N2, H3N5, H3N6, H3N8, H4N6, H7N1, H7N8, H10N7, H13N6, H13N8. Highest prevalence of infection was detected among wild ducks Anas crecca (18.3 %), A. platyrhynchos (13.8 %) and herring gull Larus argentatus (6.5 %). The most diverse virus population was revealed in Irkutsk Region among L. argentatus that hosted subtypes H3, H6N1 and H9. In the Republic of Tuva and Krasnoyarsk territory H3N8, H5N1 and H7 subtypes were detected. The wild birds from Republic of Khakassia were shown to hostH4 subtype, whereas in Republic of Buryatia subtypes H3 and H4 were detected in wild ducks and herring gulls. Possible routes of IAV spread and epidemiological implications are discussed.

The grand-scale laboratory investigation on finding influenza type A virus in wild and synanthropic birds on vast territories of Eastern Siberia was conducted for the first time. Alongside with the ornithological investigations, we also conducted collection of over 17,000 samples of laboratory investigations of 165 bird species. In the south of Central Siberia in 2006-2011, the antibodies to antihemagglutination were found in 484 samples, 179 out of which were from synanthropic birds. During the investigation of PCR of RNA avian influenza 167 samples were isolated, 17 (10,2 %) out of which were from synanthropic species. In 2014, antibodies were isolated from 30 species, RNA avian influenza were isolated from 26 species of the following bird orders: Podicipediformes - 3/1 (in hemagglutination-inhibition reaction/polymerase chain reaction) of species, Ciconiiformes - 0/1, Anseriformes - 12/10, Gruiformes - 1/1, Charadriiformes - 7/4, Passeriformes - 6/8. In the following years the participation in epizootic process of new species/ subspecies were increased. The maximum virus carriage (40.2 %) and birds infection takes place during the period from July 15 till August 28, which is characterized mainly by the presence of a large number of multipleaged young-of-the-year water fowls on the ponds and riparian vegetation. In the process of work, there was compiled not only the list of species/subspecies of avian influenza virus carriers and vectors, but also revealed their connection with wintering areas and the main location of the recombinant subtypes of highly pathogenic virus H5N1. The cases of virus spreading and its influence on the birds of various ecologic groups were described.

Complex analysis of the data on epidemiology and clinical picture of the tick-borne borrelioses in the territory of the Trans-Baikal Region over the last decade since 2003 to 2012 has demonstrated that there is a distinct upward tendency as concerns its morbidity rates. Spotted have been the potentially hazardous, as regards the infection, areas. Highest incidence rates are registered between May-July among adult men, and erythema form of the disease prevails. Based on the results of molecular-genetic investigation of Ixodidae ticks, for the first time ever in the territory of the Dul’durginsk Region identified has been circulation of Borrelia garinii , and B. afzelii , pathogenic for humans bacterial species of Borrelia genus.

The article describes the results of recognaissance surveys of blood serums of humans in Baikal area for hantavirus antibodies and of tissue specimens (lungs) of small mammal for hantavirus antigens. This investigation demonstrated that Baikal area inhabitants contact such dangerous pathogens as hantaviruses. It's proved by the presence of hantavirus antibodies in human serum samples. IgG or IgM antibodies to hantaviruses were found in 3,7 % of 379 tested serum samples. IgM were found in 1,6 % of cases, IgG - in 2,1 % of cases. 2 patients with IgG and IgM with suspected traces of hantavirus infection had complaints to hyperthermia (up to 40,5 °C) and wasting. Blood serums with positive results of hantavirus antibodies were found in residents of Irkutsk region. Hantavirus antigens weren't found in researched lung samples of mouse-like rodent and insectivores from Angarsk, Irkutsk, Zalari and Ust-Kut districts of Irkutsk region and Tunkinsky district of Republic of Buryatia.

Hokkaido hantavirus (HOKV) identified originally in the grey red-backed vole (Myodes rufocanus) in Hokkaido, Japan. Subsequent studies showed different genetic lineages of HOKV in Sakhalin, Buryatia and Far Eastern regions of Russia and in China. Tissuesfrom 68 arvicolid rodents, captured in regions south and west of Baikal Lake, were initially tested for hantaviral antigen by ELISA, and tissues from antigen-positive rodents were analyzed for hantavirus RNA by RT-PCr. Taxonomic identification of host species was based on phylogenetic analysis of partial cytochrome b gene sequences. Hantavirus Land S-segment sequences were detected in two antigen-positive M. rufocanus, from the Tunka region of Buryatia Republic (south side) and the Olhon region of Irkutsk Oblast (west side). Sequence analysis showed that the newfound hantavirus strains, designated Baikal and Siberia, represented genetic variants of HOKV Previously unknown genetic variant designated Siberia was identified in M. rufocanus captured in Olhon region. Second genetic variant from Tunka region, designated Baikal, was closely related to previously described hantavirus strain from the same region. Alignment and comparison of the nucleotide and amino acid sequences showed intra-strain differences of 18,4 % and 5,3 % for the L segment and 17,4 % and 3,5 % for the S segment, respectively. Sequence divergence from geographically distant HOKV strains were 17,4-21,5 % and 3,9-6,8 % for the L segment and 15,2-17,0 % and 3,3-4,0 % for the S segment, respectively. Phylogenetic analysis, based on a 346-nucleotide region of the L segment, revealed four lineages represented by previously reported variants from Japan and Sakhalin (strains Kitahiyama128L/2008, Tobetsu35L/2010 and Sakhalin99L/1998), Shkotovo in Far-Eastern Russia (strain Khekhtsir37L/2002) and the new variants from Baikal Lake. Analysis of the N protein, coding by the S segment, identified specific amino acid signatures for YJRV of Lys5, Arg26, Val/Ile68, Val/Ala9 He262, Pro283. Conclusions: HOKV is widespread across the geographic range of its arvicolid rodent reservoir host.

The information about more than 17 thousand cases of public inquiries to the Center of Diagnostics and prevention of tick-borne infections of Scientific Center of Problems Family and Human Reproduction Problems because of bites of ticks at the territory of Irkutsk Region during the last six years (2007-2012) is analyzed in the article. All age groups undergo to the bites of ticks. Over the half of the people asking for help have the policy of voluntary health insurance of "Anti tick" kind. The percentage of people vaccinated against the tick borne encephalitis is a little bit over than 8 % what proves the low level of the sanitary education and neglect to the human health in the region. Every year the cases of tick's bites and findings of tick-borne encephalitis virus antigen in blood serum of bitten people in the northern areas of Irkutsk region are revealed. Every year in average 90 examples of blood serum had tick-borne encephalitis virus antigen that means 3 % of bitten people have pre-clinical infection of tick-borne encephalitis. Patients with positive result of tick-borne encephalitis virus antigen (543 patients) had the necessary consultation and preventive treatment with specific immunoglobulin according to the instruction of application. Diseases of tick-borne encephalitis among the patients had the preventive treatment in time were not marked.

There are 3 subtypes of tick-borne encephalitis virus (TBEV) distinguished, at present time: European (EU), Siberian (SIB) and Far Eastern (FE). The former one is associated with Ixodes ricinus tick, whereas the latter two - with I. persulcatus. The circulation of TBEV in nature is mediated by the non-viraemic transmission, between infected and. uninfected ticks co-feeding on the same hosts and. it was shown that transmission rate of «Hypr» strain (EU subtype) is much higher than rate of «Vasilchenko» strain (SIB subtype) - 60 and 5 % respectively. To reveal the viral determinants of transmission efficacy, we constructed the series of recombinant viruses with gradually exchanged genes coding structural (str) and. non-structural (ns) viral proteins. The recombinant virus Hypr[str]Vs[ns] achieved the rate of non-viraemic transmission of 70 %. The introduction of separate structural genes of Hypr into Vs infectious clone has enhanced the transmission efficacy as well, though not to such extent as entire structural region but up to 33 % only. Thus, it was shown that efficacy of non-viraemic transmission of TBEV depends from properties of viral structural proteins mainly.

The results of the research of Selenga river basin as territory of highest risk of human infection with diseases with natural focality in Buryatia and Mongolia are present in this paper. Both in Buryatia and. in Mongolia the highest incidence rate for tick-borne encephalitis is associated with districts situated in the basin of Selenga river - Pribaykalskyi district and Selenge aimag respectively. All tick-borne infections and. every vector tick species detected in Buryatia and. Mongolia so far are present on the territories of these two districts. The epidemiological processes in the natural foci of these territories are shown to be very similar in spite of national and administrative borders.

For the first time the results of the study of 1399 blood serum, samples from people bitten by Ixodid ticks in Predbaykalye region (East Siberia, Russia) and asking for medical care in the Center for prophylaxis of tick-borne diseases of Scientific Center of Family Health. Problems and. Human Reproduction. SB RAMS. The study showed, high, (up to 99,93 %) efficacy of early antibiotic course in preventing the Lyme disease in bitten people

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.

The results of differential express diagnostic of tick-borne encephalitis and Lyme borreliosis agents in ticks, removed from pa- tients are present in this article (1995—2004). The entire complex of serolological and genetical methods were used. The specific prophylaxis based on the results of diagnostic had shown to be very effective for both infections. The first data about human ehrli- chiosis and anaplasmosis in Irkutsk region had been obtained. The improvement of diagnostic and prophylactic procedures are pro- posed.

To determine the reservoir animals and vector ticks for Anaplasma phagocytophilum in Far East Asia, which causes human granulocytic anaplasmosis, we analyzed tissue samples from deer and boars in Japan rodents in Taiwan and. Ixodes persulcatus in Russia by PCR-targeted. to 16S rDNA. Anaplasma species including Anaplasma bovis and. Anaplasma centrale-infected wild deer and boars were detected. The detection rates for A. phagocytophilum, A. bovis and. A. centrale in deer were 15,6 %, 21,9 % and. 37,5 %, respectively. These infection rates in wild boar were 3,6 %, 17,9 % and. 3,6 %, respectively. Wild rodents captured in Taiwan were positive for A. phagocytophilum. and. A. bovis. Prevalence rate of A. phagocytophilum. on I. persulcatus ticks in Irkutsk and. in Khabarovsk were 6,3 % and. 11,3 %, respectively. The 16SrDNA sequences detected from Russian ticks were identical to those of A. phagocytophilum. detected, in US and. Europe, and. from tick Ixodes ovatus and. Ixodes persulcatus in Japan. However the sequence detected from deer and boars in Japan were identical to sequences previously detected from deer and cattle in Japan, and. showed. less similarity (98,6 %) with typical A. phagocytophilum.. Sequences detected from wild rodents collected in Taiwan showed higher similarity (99,7 %) with typical A. phagocytophilum but formed the branch from those of A. phagocytophilum. detected in US and Europe. The finding suggests that the A. phagocytophilum-related sequence detected from deer and boars in Japan, and. wild rodents in Taiwan were different from those of typical A. phagocytophilum. found in Ixodid ticks.

The California encephalitis serogroup virus, Batai virus and Geta virus were isolated as result of investigation of distribution of arboviruses in Pribaikalye. The results of the study of influenza A virus in birds in Pribaikalye are presented as well.

In June, 2008, in the Irkutsk suburban zone, a man was beaten by a tick of an unknown in this area species. According to its morphological characteristics this tick was classified as Amblyomma americanum L., 1758 species, which is the endemic one in the North, Central, and South America. In this respect, the discovery of the unknown previously in this region and in the Russian Federation species of the ixodic tick is not only of a great scientific importance, but presents specific practical interest, as the ticks of this species are the carriers of a wide range of infectious diseases. Probable scenarios of importation of the new species of ticks in the territory of the Russian Federation are under discussion now and the risks, related to this problem, are being assessed.

Here we present the results of the analysis of mt16S ribosomal RNA gene of two species of ticks from Irkutsk region - Dermacentor nuttalli and D. silvarum.. The ticks from are closely related to each other with 99-100 % identity of nucleotide sequence of mt16S rRNA gene. The phylogenetic analysis has shown that both species are closely related and. formed the separate clade together with specimens of D. nuttalli and. D. silvarum. from China.

During 1999-2011 we conducted the collaborative research in Northern, Central and Eastern Mongolia. Several tick-borne infections were revealed in ticks and. human patients. Most important of them are tick-borne encephalitis, Lyme disease, tick-borne rickettsiosis, human granulocytic anaplasmosis and. babesiosis. The importance, risk of infection and. spread of tick-borne diseases in Mongolia are discussed in the paper.