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The aim of this study was to evaluate the risk of tick-borne infections in humans. The prevalence of 4 tick-borne pathogens was studied in the population of Ixodid ticks attacking human hosts in Irkutsk city and neighbouring territories from 2007 to 2017. Methods and Results: In total, 46,357 tick specimens detached from bitten people were analyzed. The antigen of tick-borne encephalitis virus (TBEV) was detected in each tick individually by ELISA assay using a commercial kit for the envelope protein E of TBEV. Total RNA and DNA were extracted from ticks using a RiboPrep kit. Reverse transcription was performed using a Reverta-L kit and RNA\DNA of TBEV; B. burgdorferi sensu lato, A. phagocytophylum and Ehrlichia muris\E. chaffeensis were detected using a real-time multiplex PCR kit. In total, during 8 years of observations, I. persulcatus caused approximately 86% of bites, Dermacentor sp. 13.95 %, and H. concinna 0.05 %. The most prevalent tick-borne pathogen in I. persulcatus ticks was Lyme disease agent B. burgdorferi sensu lato, which was detected in 12±6.5% of specimens annually. A. phagocytophilum and Ehrlichia sp. were detected in 7.8±2.7% and 4.6±1.5% of specimens, respectively. TBEV was present in 1±0.7% of I. persulcatus. Conclusion: I. persulcatus remains the most important vector of tick-borne diseases to humans in Eastern Siberia. D. nuttalli and D. silvarum are much less aggressive to humans and are less infected with major tick-borne pathogens. H. concinna does not play any significant role as a disease vector. However, a rigorous analysis of TBEV spread in the Dermacentor sp. population is necessary.

Hard ticks are the vectors of many pathogens including tick-borne encephalitis virus and the Lyme disease agent Borrelia burgdorferi sensu lato. In Eastern Siberia, Ixodes persulcatus, Dermacentor nuttalli, Dermacentor silvarum and Haemaphysalis concinna are regarded as aggressive to humans. 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 prevalence of tick-borne pathogens of hard ticks (Acari: Ixodidae) that attacked humans in Eastern Siberia (Irkutsk region, Russia). In total, 31,892 individual ticks were identified and analysed during the years 2007-2014. The majority (85.4%) of victims was bitten by I. persulcatus, 14.55% of attacks on humans were caused by D. nuttalli and D. silvarum, whereas H. concinna was documented only in 15 cases (0.05%). The seasonal activity and the age/gender structure of the tick population were studied as well. Among all the studied ticks, three unconventional species, i.e. Rhipicephalus sanguineus, Dermacentor reticulatus and Amblyomma americanum, were identified. Analysis of tick bite histories indicates at least three events of invasion of non-endemic ticks into the ecosystems of northern Eurasia with harsh continental climates. Invading ticks are able to reach the adult life stage and are aggressive to the local human population. Phylogenetic analysis of mt 16S rRNA gene fragments suggests multiple independent routes of tick migration to Eastern Siberia. Possible implications to human health and epidemiology of tick-borne infections are discussed.

Dermacentor nuttalli is an epidemiologically important tick in Palearctic Asia which transmits several infectious diseases including tularemia, North Asian tick-borne rickettsiosis, Lyme disease and tick-borne encephalitis. The genetic specificity and phylogeny of D. nuttalli from four geographic localities in Eastern Siberia were characterized using the mitochondrial (mt) 16S ribosomal RNA (rRNA) gene and internal transcribed spacer 2 (ITS2). Low genetic diversity was observed in the populations of ticks distributed from South Siberia to North China. From 11 detected mt 16S haplotypes, one was found in all populations, whereas the others were restricted to specific localities. These results suggested that the genetic structure of D. nuttalli represents integrated populations with no geographic isolation across the distribution area. The phylogenetic reconstructions inferred from the mt 16S rRNA gene and ITS2 were in agreement and showed a distinct D. nuttalli clade within a monophyletic Eurasian lineage of Dermacentor sp.

ISSN 16076729, Doklady Biochemistry an d Biophysics, 2013, Vol. 448, pp. 1–3. © Pleiades Publishing, Ltd., 2012.Original Russian Text © I.G. Kondratov, M.A. Khasnatinov, U.V. Potapova, V.V. Potapov, S.A. Levitskii, G.N. Leonova, E.V. Pavlenko, I.S. Solovarov, N.N. Denikina, N.V. Kulakova,S.I. Belikov, 2013, published in Doklady Akademii Nauk, 2013, Vol. 448, No. 1, pp. 000–000.

Over 50 million humans live in areas of potential exposure to tick-borne encephalitis virus (TBEV). The disease exhibits an estimated 16,000 cases recorded annually over 30 European and Asian countries. Conventionally, TBEV transmission to Ixodes spp. ticks occurs whilst feeding on viraemic animals. However, an alternative mechanism of non-viraemic transmission (NVT) between infected and uninfected ticks co-feeding on the same transmission-competent host, has also been demonstrated. Here, using laboratory-bred I. ricinus ticks, we demonstrate low and high efficiency NVT for TBEV strains Vasilchenko (Vs) and Hypr, respectively. These virus strains share high sequence similarity but are classified as two TBEV subtypes. The Vs strain is a Siberian subtype, naturally associated with I. persulcatus ticks whilst the Hypr strain is a European subtype, transmitted by I. ricinus ticks. In mammalian cell culture (porcine kidney cell line PS), Vs and Hypr induce low and high cytopathic effects (cpe), respectively. Using reverse genetics, we engineered a range of viable Vs/Hypr chimaeric strains, with substituted genes. No significant differences in replication rate were detected between wild-type and chimaeric viruses in cell culture. However, the chimaeric strain Vs[Hypr str] (Hypr structural and Vs non-structural genomic regions) demonstrated high efficiency NVT in I. ricinus whereas the counterpart Hypr[Vs str] was not transmitted by NVT, indicating that the virion structural proteins largely determine TBEV NVT transmission efficiency between ticks. In contrast, in cell culture, the extent of cpe was largely determined by the non-structural region of the TBEV genome. Chimaeras with Hypr non-structural genes were more cytotoxic for PS cells when compared with Vs genome-based chimaeras.

The alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally very widespread, infecting a large variety of terrestrial animals, insects and even fish, and circulate both in the sylvatic and urban/peri-urban environment, causing considerable human morbidity and mortality. Nevertheless, despite their obvious importance as pathogens, there are currently no effective antiviral drugs with which to treat humans or animals infected by any of these viruses. The EU-supported project VIZIER (Comparative Structural Genomics of Viral Enzymes Involved in Replication, FP6 Project: 2004-511960) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the alphaviruses [Coutard, B., Gorbalenya, A.E., Snijder, E.J., Leontovich, A.M., Poupon, A., De Lamballerie, X., Charrel, R., Gould, E.A., Gunther, S., Norder, H., Klempa, B., Bourhy, H., Rohayemj, J., L'hermite, E., Nordlund, P., Stuart, D.I., Owens, R.J., Grimes, J.M., Tuckerm, PA., Bolognesi, M., Mattevi, A., Coll, M., Jones, TA., Aqvist, J., Unger, T., Hilgenfeld, R., Bricogne, G., Neyts, J., La Colla, P., Puerstinger, G., Gonzalez, J.P., Leroy, E., Cambillau, C., Romette, J.L., Canard, B., 2008. The VIZIER project: preparedness against pathogenic RNA viruses. Antiviral Res. 78, 37-46]. This review highlights some of the major features of alphaviruses that have been investigated during recent years. After describing their classification, epidemiology and evolutionary history and the expanding geographic distribution of Chikungunya virus, we review progress in understanding the structure and function of alphavirus replicative enzymes achieved under the VIZIER programme and the development of new disease control strategies. (C) 2009 Elsevier B.V. All rights reserved.

Tick-borne encephalitis virus (TBEV) causes human epidemics across Eurasia. Clinical manifestations range from inapparent infections and fevers to fatal encephalitis but the factors that determine disease severity are currently undefined. TBEV is characteristically a hemagglutinating (HA) virus; the ability to agglutinate erythrocytes tentatively reflects virion receptor/fusion activity. However, for the past few years many atypical HA-deficient strains have been isolated from patients and also from the natural European host tick, Ixodes persulcatus. By analysing the sequences of HA-deficient strains we have identified 3 unique amino acid substitutions (D67G, E122G or D277A) in the envelope protein, each of which increases the net charge and hydrophobicity of the virion surface. Therefore, we genetically engineered virus mutants each containing one of these 3 substitutions; they all exhibited HA-deficiency. Unexpectedly, each genetically modified non-HA virus demonstrated increased TBEV reproduction in feeding Ixodes ricinus, not the recognised tick host for these strains. Moreover, virus transmission efficiency between infected and uninfected ticks co-feeding on mice was also intensified by each substitution. Retrospectively, the mutation D67G was identified in viruses isolated from patients with encephalitis. We propose that the emergence of atypical Siberian HA-deficient TBEV strains in Europe is linked to their molecular adaptation to local ticks. This process appears to be driven by the selection of single mutations that change the virion surface thus enhancing receptor/fusion function essential for TBEV entry into the unfamiliar tick species. As the consequence of this adaptive mutagenesis, some of these mutations also appear to enhance the ability of TBEV to cross the human blood-brain barrier, a likely explanation for fatal encephalitis. Future research will reveal if these emerging Siberian TBEV strains continue to disperse westwards across Europe by adaptation to the indigenous tick species and if they are associated with severe forms of TBE.

To generate the most diverse phylogenetic dataset for the flaviviruses to date, we determined the genomic sequences and phylogenetic relationships of 14 flaviviruses, of which 10 are primarily associated with Culex spp. mosquitoes. We analyze these data, in conjunction with a comprehensive collection of flavivirus genomes, to characterize flavivirus evolutionary and biogeographic history in unprecedented detail and breadth. Based on the presumed introduction of yellow fever virus into the Americas via the transatlantic slave trade, we extrapolated a timescale for a relevant subset of flaviviruses whose evolutionary history, shows that different Culex-spp. associated flaviviruses have been introduced from the Old World to the New World on at least five separate occasions, with 2 different sets of factors likely to have contributed to the dispersal of the different viruses. We also discuss the significance of programmed ribosomal frameshifting in a central region of the polyprotein open reading frame in some mosquito-associated flaviviruses. ispartof: PLoS One vol:10 issue:2 ispartof: location:United States status: published

Objective : Our aim was to evaluate the child and adolescent population immunity to influenza A viruses (IAV) and influenza B virus (IBV). Methods : The concentration and specificity of antiviral antibodies was evaluated by hemagglutination inhibition assay (HAI) that was performed using commercial HAI diagnostic kits. Results : The serum samples of 254 clinically healthy children and adolescents were examined in this study. 245 participants had the antibodies to IAV, 199 — to IAV and IBV, and only 4 children aged between 1 and 4 years and a 12-year-old boy had no immunity to IAV or IBV. The number of children with specific immunity increased in elder groups by 43% (from 81 to 116) for N 0 N 1 and H 3 N 2 subtypes and by 110% (from 38 to 80) for H 1 N 1 subtype of IAV. In children younger than 4 years the titer of specific antibodies against the H 1 N 1 pdm09 was 1:210 and against the H 3 N 2 — 1:270, whereas in adolescents of 10–14 years these figures were by 1.6 and 2.4 times lower (1:130 and 1:120) respectively. Antibodies to the subtypes H 2 N 2 and H 5 N 1 were not detected. Conclusion : The results indicate that 98.4% of child and adolescent population in interepidemic influenza season are immune to the various IAV (H 3 N 2 , H 1 N 1 , H 0 N 1 ) as well as to the IBV. More than half of children and adolescents (57.4%) are immune to H 1 N 1 pdm09 subtype of IAV. The strength of immune response to the recent pathogens (H 3 N 2 и H 1 N 1 pdm09) is higher in infants than in teenagers.

Background The herb formulation Deva-5 is used in traditional medicine to treat acute infectious diseases. Deva-5 is composed of five herbs: Gentiana decumbens L., Momordica cochinchinensis L., Hypecoum erectum L., Polygonum bistorta L., and Terminalia chebula Retz. Deva-5 and its five components were investigated for in vitro antiviral activity against avian influenza A virus subtype H3N8. Methods The water extracts of the herbal parts of G. decumbens, H. erectum and P. bistorta, the seeds of T. chebula and M. cochinchinensis and Deva-5 were prepared by boiling and clarified by low-speed centrifugation and filtration. To assess the antiviral properties, avian influenza virus isolate A/Teal/Tunka/7/2010(H3N8) was incubated at 37°C for 30 min in the presence and absence of the extracts of five plants and DEVA-5 in various concentrations. Subsequently, the concentration of infectious virus in each sample was determined by plaque assays. Neutralisation indexes and 90% plaque reduction concentrations were estimated for each extract, and the significance of the data was evaluated using statistical methods. Results The extracts of G. decumbens, H. erectum, P. bistorta and Deva-5 demonstrated no significant toxicity at concentrations up to 2%, whereas extracts of T. chebula and M. cochinchinensis were well-tolerated by Madin-Darby canine kidney cells at concentrations up to 1%. The extracts of H. erectum, M. cochinchinensis and T. chebula reduced the titre of A/Teal/Tunka/7/2010 (H3N8) by approximately five-fold (p ≤ 0.05). The other three extracts did not significantly reduce the infectivity of the virus. The plaque reduction neutralisation tests revealed that none of the extracts tested were able to inhibit formation of plaques by 90%. However, three extracts, H. erectum, T. chebula and M. cochinchinensis, were able to inhibit formation of plaques by more than 50% at low dilutions from 1:3 to 1:14. The T. chebula extract had a concentration-dependent inhibitory effect. Conclusions For the first time, the consistent direct antiviral action of the extracts of H. erectum, T. chebula and M. cochinchinensis was detected. These extracts significantly reduced the infectivity of influenza A virus H3N8 in vitro when used at high concentrations (0.5–1%). However, Deva-5 itself and the remainder of its components did not exhibit significant antiviral action. The results suggest that H. erectum, T. chebula and M. cochinchinensis plants contain substances with direct antiviral activity and could be promising sources of new antiviral drugs.