This review presents the analysis of the literature data on the mechanisms of ZIKV pathogenesis using biomodels (sensitive cell cultures and animals). Human and animal cell cultures have shown that this virus effectively infects primary endometrial stromal cells, embryonic stem cells, cortical and motor neurons, astrocytes, peripheral neurons and neural crest cells of the embryo. Cultures of prostate, testis and kidney cells showed a high level of ZIKV load without cytopathic disorders which implies their participation in the persistence of the pathogen. A productive infection of ZIKV on cell cultures derived from non-human primate, pig, rabbit, hamster and chicken suggests that these animal species may be important reservoirs and/or potential laboratory models. Monkeys of the species Macaca mulatta (macaque rhesus) have the disease caused by ZIKV similar to that in humans. Therefore these animals are a suitable model for studying the pathogenesis of a congenital infection as well as for preclinical evaluation of vaccines and antiviral drugs during pregnancy. Mice, domestic pigs and humanized chicken embryos can be used as surrogate models for studying ZIKV pathogenesis. Recently, attenuated ZIKV has become the object of research in a new area of medical virology – in oncolytic virotherapy against glioblastoma.

In 2017 the International Committee on Taxonomy of Viruses (ICTY) established and approved a new order Bunyavirales that unite evolutionary related viruses whose genome is represented by a segmented linear single-stranded RNA of negative or ambisense polarity. Currently, the order Bunyavirales includes 10 families that infect vertebrate animals, invertebrates (arthropods), and plants. At least 41 zoonotic bunyaviruses, including pathogenic for human, were isolated on the territory of Northern Eurasia. This review presents the data on the composition of the families belonging to the order Bunyavirales and a list of zoonotic bunyaviruses, isolated in Northern Eurasia, indicating their modern taxonomy. Most of them are arboviruses, associated with different species of mosquitoes or ticks.

Among the viruses transmitted by Chiroptera, filoviruses, lissaviruses, henipaviruses, and coronaviruses pose the major threat to humans. The featured review is devoted to the analysis of the results of studies on the role of African Chiropterans in the circulation sustenance of the viruses. Chronology of investigations on the search of natural reservoir of Filoviruses and the evidence of Chiroptera participation in their circulation are described in the paper. Presented are summarized data on the involvement of chiropterans in the circulation of lissaviruses on the African continent. Given is the information concerning the role of African species of Chiroptera in the circulation of henipaviruses - dangerous for humans viruses of Paramyxoviridae family, associated with chiropterans of South-Eastern Asia. Considered is the possibility of SARS and MERS-like coronaviruses circulation in the populations of certain species of African Chiroptera. Engagement of the Chiroptera from Guinean Republic in maintenance of circulation of the mentioned above viruses in potential natural foci in the territory of the country and possibility of occurrence of dangerous human infection outbreaks is also assessed. The necessity for further investigation of the role of Chiroptera as carriers of the stated viruses to clarify the current epidemiological and epizootiological situation on the viral pathogens in the Republic of Guinea is substantiated.

Objective of the study was to describe the organization of epidemiological surveillance over internal risks associated with the intensification of natural-focal diseases in the Republic of Tatarstan, analysis of the measures taken to prevent natural focal diseases during the preparation and holding of the FIFA World Cup-2018. Materials and methods. The data from surveys and forecasts as regards the numbers of small mouse-like rodents as carriers and arthropod vectors of natural-focal diseases, epizootic and epidemiological situation reports in the Republic of Tatarstan and information on infectious and parasitic disease morbidity rates in the Republic of Tatarstan, presented by the Center of Hygiene and Epidemiology in the Republic of Tatarstan over 2015-2018 were utilized for analysis. Results and conclusions. The natural conditions of the Republic of Tatarstan are favorable for the circulation of pathogens of natural-focal diseases, which carriers are mammals (primarily small rodents) and birds, and vectors - blood-sucking arthropods: Ixodidae ticks, mosquitoes. The results of circulation monitoring of natural focal infection pathogens in the ambient environment made it possible to conclude that during the FIFA World Cup-2018, the epidemic risk of occurrence of natural-focal diseases would remain high. Considering the existing and forecasted internal risks, priorities were identified in the organization of preventive measures aimed at minimizing epidemiological risks in relation to natural-focal infections during the preparation and holding of the FIFA World Cup 2018. The chosen preventive strategy made it possible to prevent the infection with natural-focal infectious diseases among the population and ensure a stable epidemiological situation during the FIFA World Cup-2018.

Current international and major part of national documents, regulating experiments on laboratory animals, is set out in Bioethics Convention 3”R”. Presently this 3”R” principle is still relevant and commonly accepted global standard. Objective of the study was to verify the compliance of the staff at the institute with the ethical principles of biological safety when handling laboratory animals infected with pathogenic biological agents (PBA) of the I-II groups, performing diagnostic, experimental, and manufacturing activities. Results and discussion. Carried out analysis of ethical principle implementation, when working with biomodels infected with pathogenic biological agents of the I-II groups, performing scientific and manufacturing activities shows that operational procedures comply with the requirements of biological safety and regulations of ethical code, as well as international standards for humane treatment to animals in biomedical investigations. Conclusions. The work with laboratory animals infected with PBA of the I-II groups at the premises of RusRAPI “Microbe” meets the requirements of biological safety and norms of ethical code. Experiments on animals are aimed at obtainment of new scientific knowledge, preservation and improvement of human health, and also monitoring of natural foci of particularly dangerous infections following the rules of 3“R” bioethical concept.

Abstract. Objective of the study was the development of a method for the detection and quantitative analysis (realtime RT-PCR) to identify genetic markers of Lassa virus - LASV-Fl. Materials and methods. We utilized all the available in the GenBank database (https://www.ncbi.nlm.nih.gov/genbank/) Lassa virus sequences that have been aligned to identify conservative sites applying the BioEdit 7.2.5 software package (IbisBiosciences, USA). To test the developed PCR kit, the control panel of Lassa virus RNA and pseudo-viral particles, 27 viral strains belonging to different fami­lies, as well as 37 serum samples from patients with feverish diseases selected in medical institutions of the Republic of Guinea in 2016-2018 and 55 samples of organ suspensions from multi-spiked mice were used. Results and discussion. The analytical sensitivity of the method varied from 10³ copies/ml to 10⁵ copies/ml and had 96.4 % diagnostic sensitivity, while the analytical and diagnostic specificity was 100 %. It is shown that the developed technique can be successfully introduced into practice for the detection of Lassa virus in the Republic of Guinea, using various types of material from small mammals, including whole blood and organ suspensions of M. natalensis, as well as samples of human blood sera collected 3-7 days after the onset of the disease. It is also suggested that this method can be used for strains of Lassa virus, common not only in Guinea but also in other endemic areas, but this fact must be confirmed in further studies.

It is known that territories of nature plague foci are non-equal by the degree of epizootic situation tension. There are locations (sectors of primary regions) where plague has not been registered or has been registered rarely during all the time of surveillance. In this connection, it is necessary to reestablish the borders of plague focus territory for excluding the sectors without plague manifestations or the areas where plague occurs periodically. However, mathematically reliable criteria to substantiate such decisions are currently unknown to the authors. Objective was to propose evidence-based criteria for the exclusion of certain areas from plague focus territory using probabilistic approach. Material and methods. Surveillance data on Central-Caucasian natural plague focus for the period of 28 years (1987-2013) were used. For each sector of primary zoning in the focus a multiplicity of surveillances and multiplicity of plague epizooty reports was calculated. Some nonparametric techniques (Spearman correlation, quantile analysis) and concepts of probability theory were used for statistical processing. Results and discussion. By the example of Central-Caucasian high-mountain natural plague focus, the method for probability calculation for manifestations of epizooties in the sectors of plague focus is put forward. The evidence-based criteria for the exclusion of certain areas from plague focus territory using probabilistic approach are proposed. Algorithm for excluding the sectors of primary zoning from the surveillance scheme taking into account different levels of significance is presented. The ranking of the focus by the probability of epizooty detection in a sector and probability of surveillance can be utilized alongside the index of frequency of epizooties when planning epizootiological survey of the focal territory.

Objective of the study was to analyze the basic quality parameters of the produced live plague vaccine and stability of the preparation during the storage process. Materials and methods. Specifications for batch series of the live plague vaccine on the basis of Yersinia pestis EV NIIEG, manufactured between 2012 and 2017, in compliance with the regulations of the normative documentation were assessed. The parameters under investigation were: viability, thermal resistance, absence of extraneous substances and fungi, weight loss in the process of drying, immunogenicity. Results and conclusions. Comparative analysis of the vaccine viability (quantity of live microbe cells) in the batches manufactured over the past 6 years was carried out. All the studied vaccine series have the appropriate indicators stated in the Specification to the Pharmacopeia Monograph and master formula which testifies to the stability of manufacturing line and basic live plague vaccine quality parameters throughout the whole term of storage. It is outlined that the production of the vaccine, corresponding to the requirements of the normative regulations, depends upon the strict adherence to the rules by the personnel, usage of high-grade stock and materials, validation of equipment and technological processes of manufacturing.

Objective - risk-oriented assessment of current epidemiological situation on Crimean hemorrhagic fever (CHF) in the Astrakhan Region. Materials and methods. Documents and reports of the Astrakhan Plague Control Station, Rospotrebnadzor Administration in the Astrakhan Region, and A.M. Nichogi Regional Infectious Clinical Hospital were utilized for the study. Key method of investigation was epidemiological analysis of morbidity rates among the population of the Astrakhan Region over the period of 2000-2016. The subject of the epidemiological analysis - 125 case histories. Results and conclusions. As a result of retrospective epidemiological analysis basic risk categories as regards Crimean hemorrhagic fever infection in the Astrakhan Region between 2000 and 2016 were identified and characterized. It was established that men of older ages are more prone to the disease (80 out of 125 cases - 64.0 %, 31-50 years old - 32 % and 51-70 years old - 14.4 %). Among the feminine population, CHF cases are also common within the same age range. High risk territories turned out to be 3 districts of the Region (Privolzhsky, Enotaevsky, Krasnoyarsky), medium risk - 3 districts, low risk - 4, and very low - 2. Risk group analysis revealed that during the last decade, CHF infection is more often registered in unemployed persons - 43.2 %, retired people - 17.6 %, and to a lesser degree - in salaried workers (10.4 %), agricultural laborers, and farm workers (8.8 %). In the majority of the cases (83-66.4 %) human infection with CHF occurred through the bite of a tick, or at the attempt to remove or crush it with unprotected hands. In 26 cases (20.8 %), risk factors were not identified. CHF in the Astrakhan Region has a pronounced spring - summer seasonality with the onset in the second half of April, peak values - in June (45 cases - 36 %) and a decline - in August. Among clinical forms of the diseases moderately severe was the prevalent one (83-66.4 %). Lethal cases were not registered.

Objective. Determination of the effectiveness of final disinfection treatment of virological laboratory rooms (with the passageway room between two entries) in the isolated zone used for work with pathogenic agents, of the maximum containment laboratory by fumigation with formaldehyde vapors, including the assessment of the optimal amount of formalin. Experimental evaluation of the suitability of the aerosol generator “Ultrasprayer P-60” for the final disinfection of the premises of the “contagious” zone with the “dry steam” of hydrogen peroxide. Materials and methods. The effectiveness of the final disinfection of the surfaces in the premises of the “infectious” zone of the maximum containment laboratory was evaluated using cambric test objects contaminated by the spore-forming test-culture B. thuringiensis. Results and discussion. As a result of experimental studies, the required amount of formalin was determined that is sufficient to completely inactivate possible infectious contaminants that may be potentially located on the surfaces of equipment and rooms located in the “contagious” zone of the maximum containment laboratory, during fumigation with formaldehyde vapors. The amount of formalin specified experimentally turned out to be 1.4 times more than the recommended by regulatory documentation for unventilated rooms, but 2-2.5 times less than that used for final disinfection of maximum containment laboratory previously. Disinfection treatment of the premises and equipment located in the “contagious” zone of the laboratory with 6 % hydrogen peroxide “dry steam”, which is the active agent of Disargent drug, sprayed through the «Ultrasprayer р-60» aerosol generator, was more effective than spray irrigation with 6 % hydrogen peroxide aerosol generated using pneumatic aerosol nozzles. At the same time, it was possible to achieve sufficiently complete inactivation of the test microorganism located on test objects at a concentration of 1·10⁶ cells/cm², by increasing the concentration of hydrogen peroxide sprayed by the device up to 10 %. However, even in that case, viable test microorganisms remained in the hidden cavities of the equipment and office machinery, which makes further studies relevant to establish the optimal concentration of hydrogen peroxide during the final disinfection with an «Ultrasprayer р-60» aerosol generator or similar equipment from other manufacturers.

Keeping microorganisms alive, saving initial practically vital properties, is a major issue in microbiology. Objective of this research was to study preservation of the key biological properties of lyophilized cultures of 18 F. tularensis strains of different subspecies from the cultures collection of the «48 Central Research Institute» of the Ministry of Defense of the Russian Federation under varying conditions of preliminary preparation (including animalization through the guinea pigs’ body or without it). The microbe storage life at below-freezing temperatures ranged from 5 to 50 years. Materials and methods. The survival of microbes in the process of drying and subsequent storage was determined in accordance with the commonly-accepted methods; morphological, cultural, biochemical, antigenic, and pathogenic properties of F. tularensis strain cultures with different storage term and conditions for preparation to lyophilization were assessed and compared with datasheet specification. The results and conclusions. The research showed that under preliminary stabilization of F. tularensis strain properties using animalization, the storage in lyophilized state at below-freezing temperatures under vacuum for up to 50 years or less protected them from changes in phenotypic properties. At the same time, after lyophilization of cultures, which were repeatedly sub-cultured on dense nutrient media without initial signs of properties’ breach, phenomena of dissociation, the decrease in titers of cultures in the agglutination reaction from 2 to 4 times, and an increase in LD50 index by times were found.

Objective. The analysis of epidemiological situation on Crimean hemorrhagic fever (CHF) in the Russian Federation at the current stage, identification of ways to improve the epidemiological surveillance and prophylaxis of the disease. Materials and methods. Data from statistical documentation and results of annual epizootiological monitoring of the CHF natural focus provided by the Administrations of the Rospotrebnadzor, Centers of Hygiene and Epidemiology in entities of the Southern and the North-Caucasian Federal Districts, Reference Centre for CHF monitoring, Research Anti-Plague Institutions and Plague Control stations were used for work. Results and conclusions. The CHF epidemio­logical situation remains unstable, the cases of the disease (including fatal) are registered every year. High activity of the CHF natural focus persists. The northward expansion of CHF natural focus boundaries is observed. The main causes of the unfavorable CHF epidemiological situation are associated with increase in the numbers and period of activity of ticks Hyalomma marginatum due to favorable climatic conditions. The list of priority measures to stabilize the CHF epidemiological situation developed by the Rospotrebnadzor has resulted in decrease in CHF cases by 51.9 % in 2017 compared to 2016 across all the territory of the south of the Russian Federation. The CHF morbidity in 2018 was 1.5 times lower than the average multi-year values (72 CHF patients). The number of CHF cases in comparison to 2017 has decreased by 1.3 times in the Stavropol Territory and by 1.4 times in the Rostov Region. The CHF morbidity has increased in the Astrakhan Region (by 3 times) and Volgograd Region (by 2.3 times). Nosocomial CCHF virus infections cases associated with non-compliance to anti-epidemic regime in hospitals while providing treatment of CHF patients were registered in 2011 (in the Rostov Region) and in 2016 (in the Stavropol Territory). This highlights the need to improve the training of health-care staff for admission of patients with this particularly dangerous infection.

Objective of the study was genetic typing of the strains and nucleic acid isolates of causative agents of natural focal infections, both bacterial and viral etiology, accumulation of data on genetic features of regional strains cir­culating in the Stavropol Territory. Material and methods. To study the genetic spectrum of causative agents of natural- focal infections, analysis of the strains and nucleic acids isolates detected in the samples of field and clinical material was carried out. Indication of causative agents of natural focal infections in the samples was carried out by PCR. For genetic typing of the strains and DNA/RNA isolates of natural focal infections agents, MLVA and sequencing of genome regions with subsequent phylogenetic analysis were used. The analysis of territorial distribution of the causative agent genetic variants and mapping was performed in ArcGIS 10.1. Results and conclusions. MLVA-25 typing of 20 strains of Francisella. tularensis, MLVA-10 typing of 4 Coxiella burnetii isolates, species identification of 20 isolates of Rickettsia sp., sub-species genetic typing of 40 RNA isolates of CCHF virus and 8 RNA isolates of hantaviruses circulating in the Stavropol Territory in 2016-2017 were performed. The studied strains of F. tularensis belong to eight MLVA genotypes. They are mainly confined to specific areas. The isolates of C. burnetii have the same MLVA type. Rickettsia, belonging to 5 species: R. massiliae R. raoultii, R. sibirica, R. aeschlimannii, R. slovaca, RNA-isolates of hantavirus of the «Tula» genotype and variants of the CCHF virus of the Europe-1 and Europe-3 genotypes were identified. The obtained data can be used in the epidemiological investigation of possible cases of infectious diseases to determine the source and pathways of infection.

Objective of the study was investigation of hantaviruses in a new natural reservoir - insectivores, their diversity and geographic distribution in the Western and Eastern Siberia. Materials and methods. Sorex shrews (71 specimens) were captured in Altai Republic, Altai, and Krasnoyarsk Territories, and Omsk Region. All samples were analyzed for hantavirus RNA using reverse transcription polymerase chain reaction with subsequent sequencing. Results and conclusions. A total of 12 viral RNA isolates from two Sorex species (S. araneus and S. roboratus) were genetically typed. Sequence analysis of the partial L and S segments identified two distinct hantaviruses. Kenkeme (KKMV) virus was detected in a flat-skulled shrew (S. roboratus) in Altai Territory. This virus was previously found in geographically remote sites in the Sakha Republic and China. New foci of Seewis virus circulation among common shrews (S. araneus), were found in the Omsk Region, Altai and Krasnoyarsk Territories. Previously published and new findings suggest that hantaviruses among shrews are widely distributed over the Russian Federation territory. The widespread circulation of SWSV and KKMV throughout Siberia is an important argument for investigation of their role in human infections.