BackgroundThe 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.MethodsThe 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.ResultsThe 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.ConclusionsFor 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.

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.

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 2 nd and 4 th 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-1α, IL-8 и IFN-α and suppression of SOD, IL-1Ra и IL-17A. For virus infection the increased concentrations of IL-1α, IL-8, IL-10, IL-17A, IFN-γ and SOD were detected. The only suppressed cytokine was IL-1Ra receptor antagonist. Conclusions. The results suggest that evaluation of innate immune response between 2 nd and 4 th 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.

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