The review presents the main results of scientific and technical cooperation between the Russian Federation and the Republic of Guinea over 10 years of joint work, since the deployment of a group of Russian specialists and mobile laboratories from the mobile complex of the specialized anti-epidemic team of the Rospotrebnadzor in August 2014 to provide practical and methodological assistance in eliminating the epidemic caused by the Ebola virus. The main areas of cooperation are the strengthening of laboratory and hospital facilities, joint research and training of specialists from specialized institutions in Guinea on biosafety issues. During the implementation of the Russian Federation programs of assistance to the Republic of Guinea in combating infectious diseases, public-private partnership mechanisms with UC “RUSAL” were involved, which made it possible to bring Russia’s participation in eradicating the epidemic of Ebola virus disease and subsequently strengthening Guinea’s national capacity to combat biological threats to the maximum effect.

Live tularemia vaccine is one of the most effective bacterial vaccines. However, it also has high residual virulence for laboratory animals and may cause adverse reactions in individuals with compromised immune systems. The development of a safe and effective tularemia vaccine is impeded by insufficient understanding of the protection correlates. The aim of this work is to review the literature on the development of post-vaccinal immune responses to live tularemia vaccines and recombinant vaccine candidate strains and to determine the immunological correlates of protection in the formation of specific immunity to Francisella tularensis. This review describes the main aspects of the development of innate and adaptive immune responses to the administration of live tularemia vaccines based on attenuated strains of F. tularensis 15 NIIEG and F. tularensis LVS in humans and in experimental tularemia infection in a mouse model. Studying the mechanisms of adaptive immunity and identifying immunological correlates of protection in experimental tularemia in a murine model is crucial for researching new vaccine strains and improving laboratory methods for assessing the T-cell component of immunity. The main focus is on the study of cellular mechanisms underlying the formation of protective immunity in experimental tularemia, the determination of immunological criteria for its evaluation and the role of identified indicators in long-term protection after the end of the active phase of the immune response induced by immunization with vaccines based on attenuated F. tularensis strains. We discuss the effects of vaccination on the differentiation, functional activity, and duration of specific central and effector CD4+ and CD8+ memory T-cells circulation in humans and mice.

Accidents during the work with infectious disease agents are one of the leading biological risk factors for employees, the public and the environment. Specialists in the field of biological safety should monitor and analyze information on these accidents in order to use the findings and implications to form a sustainable biosafety system both, at the facility and at the federal levels. To obtain the necessary information to analyze the causes and conditions of accidents, we have carried out a search of open data on the Internet. It has been found that the relevant information is more extensively and accessibly presented in foreign sources. Information on accidents that occurred abroad between 2010 and 2023 has been studied. Accidents associated with skin penetration and lesions were most often the obvious cause of laboratory acquired infection. Reports of similar accidents caused by injection needle sticks predominated. Accidents associated with breach of personal protective equipment (torn gloves) were a potential cause of infection when there was a concurrent violation of the skin integrity or in the case of skin lesions existing at the time of the accident. Cases of violation of the integrity of insulating personal protective equipment were described. Reports on accidents “with spillage” and “without spillage” (as stated in the Russian normative documents) have not been found. Among the investigated cases, most are associated with violations of various biological safety requirements.

The results of a review of the epizootiological and epidemiological situation on anthrax around the world in 2023 and the forecast of morbidity in the Russian Federation in 2024 are presented. In 2023, a complication of the epizootiological and epidemiological situation on this infection was recorded in Russia. Seven outbreaks of anthrax with infection of 14 farm animals and 19 humans were registered in five constituent entities of three federal districts (Volga, Siberian, and Central Federal Districts). Epizootiological and epidemiological instability due to the anthrax was detected in four neighboring countries: Azerbaijan, Kazakhstan, Kyrgyzstan, and Tajikistan. Anthrax among farm and wild animals was recorded in Africa, Asia, Europe, and North America. Cases of human disease were reported in Africa, Asia and Europe. Human infections occurred during contact with infected animals, products of animal origin, consumption of meat from sick/fallen livestock and wild animals. The incidence rate of anthrax in animals and humans in Russia in 2024 will correlate with the completeness of registration and specific immunization coverage of susceptible animals and persons from groups with high occupational risk of infection. With proper implementation of all preventive measures and effective surveillance of infection, anthrax incidence in the entities of the Russian Federation will amount to isolated cases.

Abrogation of obligatory vaccination against smallpox has lead to degradation of herd immunity and humanity has become vulnerable to long known infections, such as monkeypox (mpox), cowpox, camelpox, buffalopox and emerging ones, caused by viruses Alaska and Akhmeta. This situation demands availability of safe smallpox vaccines, the immunogenicity of which is comparable to vaccines used in the period of smallpox elimination. The aim of this review is to analyze the research of Japanese scientists on the production and investigation of properties of the smallpox vaccine LC16m8 and to assess further prospects for the use of the LC16m8 strain. The LC16m8 vaccine was obtained based on one of the Lister clones and has been licensed in Japan since 1975. Whole-genome sequencing revealed that its main difference from the genome of the original strain is a mutation in the B5R gene, which determines its safety for laboratory animals and humans. The immunogenicity of the vaccine based on this strain is comparable to the immunogenicity of the first generation vaccines: Lister, Dryvax, Ikeda. According to WHO recommendations, second generation vaccines ACAM 2000 and third generation vaccines based on the LC16m8 strain are reserve drugs. However, the established fact that the LC16m8 strain, when passaged in cell culture, spontaneously reverts to the original variant of the Lister strain led to genetic engineering work to delete the B5R gene to obtain the LC16m8Δ mutant, which is not capable of reversion. A vaccine based on the LC16m8Δ strain could technically be classified as a fourth generation drug, and taking into account the high immunogenicity and relative safety of this strain based on the results of preclinical studies, there is a real prospect of producing an advanced and effective reserve drug based on it. Thus, analysis of long-term data on the study of the LC16m8 vaccine indicates that this drug is superior to other analogues of the 1st, 2nd and 3rd generation in terms of effectiveness and safety. Further genetic engineering work with this strain, which made it possible to obtain a safe but immunogenic genovariant of the LC16m8Δ strain, is a clear example of a productive movement towards the development of safe and effective fourth generation vaccines.

The aim of the work was to analyze the epizootic and epidemiological situation on leptospirosis in the territory of the Russian Federation in 2023 and to forecast its development for 2024. In the period between 2000 and 2023, the long-term dynamics of morbidity in Russia tended to decrease. Leptospirosis incidence was mainly sporadic. In 2023, cases of this infection in humans were reported in all federal districts, with the exception of the North Caucasian one. The highest incidence rates were recorded in the Southern and Central Federal Districts. The results of testing material from small mammals using bacteriological, immunological and molecular-biological methods confirmed the circulation of pathogenic Leptospira in 50 constituent entities of the Russian Federation in all federal districts. Specific prevention measures were carried out: 20,114 people were vaccinated in 27 entities. The probability of human infection is higher in the territories of the Southern, Central, Northwestern, Volga and Ural Federal Districts. Imported cases of infection from regions with subequatorial and equatorial climates, which are actively visited by tourists, are not excluded.

The aim of the review is to forecast the incidence of rickettsial infections and Q fever in the Russian Federation for 2024 based on an analysis of the epidemiological situation in 2010–2023. The epidemic potential associated with these infections in Russia and other countries where there is an increased activity of foci with an expansion of the area of pathogen circulation has been assessed. An analysis of the incidence of epidemic typhus, Brill’s disease, Siberian tick-borne typhus (STT), Astrakhan spotted fever (ASF), Q fever, human granulocytic anaplasmosis, human monocytic ehrlichiosis in the Russian Federation in 2023 in comparison with long-term average values in 2010–2019 (COVID-19 pre-pandemic period) has been carried out. In 2023, the rates of registered incidence of rickettsial infections and Q fever in Russia as a whole decreased relative to the long-term average level of 2010–2019, and there is a significant downward trend in most regions. The exception is the Far Eastern Federal District, where the incidence rate of STT in 2023 increased by 1.5 times as compared to the period of 2010–2019, and the city of Sevastopol, where an increase in the incidence of Marseilles fever was detected. When assessing the intra-annual distribution of incidence in 2023, registration of STT in Russia was carried out from March to November inclusive, ASF – from May to October, and Q fever – from May to August.

The aim of the study was to compare outer membrane vesicles (OMVs) and their composition in virulent and avirulent (LPS-defective) strains of Fracisella tularensis of various subspecies. Materials and methods. The vesiculation process in F. tularensis bacteria was studied using transmission electron microscopy. OMVs preparations were obtained and characterized by their composition using immunological methods: antibody neutralization test, immunochromatographic analysis, dot and immunoblotting. Results and discussion. It has been found that all natural virulent strains with the S type lipopolysaccharide (LPS) are able to produce two forms of vesicles – spherical and tubular (“tubes”), specific for F. tularensis. OMVs formation has not been registered in avirulent LPS-defective strains. It is revealed that vesicles of strains of various subspecies show their own individual morphological features. The tubes of F. tularensis subsp. mediasiatica are larger in size as compared to those of the subsp. holarctica strain. This is probably the reason why vesicle preparations from F. tularensis subsp. mediasiatica obtained using filters with a diameter of pores being 0.22 μm contained a significantly reduced number of tubular forms. A method of disinfection of bacterial suspensions using gentamycine, which does not affect the morphology and antigenic activity of vesicles, is proposed. A comparative study of several series of concentrated OMVs preparations obtained from different strains has revealed that all samples had antigenic activity in the precipitation Ouchterlony test, antibody neutralization test, immunochromatografic assay, dot-blot and immunoblotting. Immunodominant antigen – LPS and several major antigenic proteins have been detected in the preparations. Differences in the composition of vesicle proteins in the strains of various F. tularensis subspecies have been identified.

The aim of the work was to study the effect of the azoximer bromide immunoadjuvant (polyoxidonium, PO) on certain molecular-genetic and proteomic properties of Yersinia pestis EV NIIEG strain, when added to the culture medium. Materials and methods. Y. pestis EV NIIEG was grown at 28 °C for 48 hours on LB agar pH 7.2 (Miller), with and without PO (EV+PO). Whole-genome sequencing of EV and EV+PO strains was performed on the Ion S5 XG generation II platform. Whole-genome SNP analysis and search for marker SNPs were conducted in the Wombac 2.0 program. Mass-spectra of Y. pestis EV extracts and EV+PO cells were recorded using a Microflex LT mass spectrometer. Protective properties of the test cultures were evaluated by the integral ImD50 index in BALB/c mice when infected with Y. pestis 231(708). Results and discussion. Comparative analysis has not revealed deletions, insertions and single nucleotide polymorphisms in the structure of Y. pestis EV+PO strain genome leading to a violation of the production of pathogenicity, immunogenicity and ensuring the vital activity factors of the plague pathogen. The MALDI-TOF mass spectrometry has shown that Y. pestis EV+PO strains changed the intensity of 22 % of the total number of peaks in the range of 2000–20000 Da. Most of the altered peaks in the UniProtKB protein bank belong to uncharacterized proteins and metabolic proteins. At the same time, the ImD50 was 2–3.3 times lower in cultures grown with the addition of PO than in Y. pestis EV. Thus, the addition of PO to Y. pestis EV NIIEG culture medium does not cause changes in the genes of pathogenicity and vital activity support factors of plague pathogen, but modulates its protein profile, which is accompanied by an increase in the protective potential of the EV vaccine strain.

The aim of the work was to obtain immune ascitic fluids (IAF) of mice to whole cells of R-variant cholera vibrios and to evaluate the possibility of their use for detection and characterization of atypical cholera vibrios. Materials and methods. A cycle of immunization of nonlinear white mice was performed. It included four injections of antigen with and without adjuvant, induction of ascitic fluid accumulation through intraperitoneal inoculation of murine myeloma cells. Experimental IAFs were studied in serologic and immunologic reactions on a set of strains of R-variant Vibrio cholerae, V. cholerae nonO1/nonO139, V. cholerae O1 and heterologous microorganisms. Results and discussion. The obtained IAFs are notable for high antibody titers in indirect enzyme immunoassay (up to 1:640000), and agglutinate atypical cholera vibrios at dilutions from 1:8 to 1:32 in slide-agglutination reaction. Cross-reactions were found in the three groups of V. cholerae strains studied, indicating the presence of similar antigens. Based on the results of electrophoretic separation and immunoblotting of cell lysates of the strains, the presence of common major proteins in the region of 55–60 and 25 kDa was established. Evident differences were observed for several minor proteins in the 30–55 kDa region, in particular, they were absent in the typical strains. It is also shown that experimental IAFs contain antibodies to epitopes of the core part of LPS and surface proteins, most of them being common to the studied groups of cholera vibrios. The obtained data allow us to draw the following conclusions: the possibility of detecting a larger number of V. cholerae R-variants is increased if the ELISA kit to R-vibrios is used; the use of ELISA method is preferable to the slide-agglutination reaction for serologic analysis of atypical strains. Combining IAFs in the form of a single preparation seems promising, as it allows for characterizing the spectrum of surface antigenic determinants of altered strains and expanding the possibilities of their detection.

The aim of the study is to obtain a comprehensive characterization of Yersinia pseudotuberculosis strains from the Aksai high-mountain and Balkhash desert foci of plague in Central Asia. Materials and methods. Investigation of the cultural, morphological and biochemical properties of the examined strains was carried out using conventional methods of laboratory diagnostics. Ion S5 XL System (Thermo Fischer Scientific) was used for whole-genome sequencing. Data processing and sequence assembly of raw reads de novo were performed using Ion Torrent Suite software package 5.12 and Newbler gsAssembler 2.6 (454 Life Sciences). To search for marker SNPs, the Wombac 2.0 program based on the BioLinux 8.0 operating system was applied. When constructing the dendrogram, the Maximum Likelihood method, the PhyML 3.1 program and the HKY85 model were used. Results and discussion. The studied strains from the Aksai high-mountain and Balkhash desert foci have properties characteristic of the Y. pseudotuberculosis species, are prototrophs and do not contain the pYV plasmid. According to phylogenetic analysis based on identified 109,641 core SNPs, they are closely related to strains of the pseudotuberculosis microbe from the Sarydzhaz high-mountain focus in the Kyrgyz Republic and the Republic of Kazakhstan, as well as to the O:3 serovar strain from Turkmenistan. The cluster of these Central Asian strains on the phylogenetic tree of Y. pseudotuberculosis is localized next to strains of the pseudotuberculosis microbe of O:3 serovar from various regions of the world. The results obtained testify to the circulation of a separate phylogeographic population of Y. pseudotuberculosis in the territory of natural plague foci in Central Asia. The characterized Y. pseudotuberculosis strains and their whole genome sequences can be used as reference ones for the Aksai and Balkhash natural plague foci of Central Asia.

The high medical and social significance of hemorrhagic fever with renal syndrome (HFRS) in Russia is a valid argument in favor of developing qualitatively new approaches to predicting epidemiological complications. The complex nature of interaction of factors determining the intensity of epidemic manifestations requires the continuation of the search for the most reliable prognostic criteria for pre-epidemic diagnosis of HFRS, providing the completeness of information that is necessary in modern conditions to optimize the epidemic process management. The aim of the work was to form an objective methodological basis for predicting the epidemiological situation on HFRS through the use of machine learning in modeling the effect of combinations of abiotic risk factors on the actual incidence of HFRS. Materials and methods. The study materials comprised the data on 10,788 cases of HFRS, registered in the Saratov Region between 1982 and 2022. More than 46 thousand values of meteorological indicators obtained from the archive of the database of meteorological observations for the period of 1981–2023 of the Saratov – South-East meteorological station, presented in the open access by the Hydrometeorological Center of Russia, are considered as factors likely to influence the epidemic process of HFRS. The development of a neural network forecasting model is based on a specialized module of the Loginom platform version 7.1. Results and discussion. The paper presents the advantages of neural network forecasting of complications of the epidemiological situation on HFRS based on the analysis of complex, nonlinear dependencies of the influence of abiotic factors on the morbidity among the population. A standard scenario for neural network forecasting of epidemic complications due to HFRS has been developed and a prognostic model of incidence in the Saratov Region has been tested. It is shown that the use of neural network algorithms allows to obtain a forecast of the possible development of the epidemiological situation on HFRS in the future with a probability of 98.8 %, which will ensure a qualitative transition from expert forecasting to independent analysis of epidemiological trends, significantly increasing the information capacities and importance of forecasting when planning and conducting preventive measures by the efforts of Rospotrebnadzor institutions.

The aim of the work was to evaluate the ability of monoclonal antibodies to inhibit the interaction of the receptor binding domain (RBD) in S protein of SARS-CoV-2 virus variants, Wuhan-Hu-1 and BQ 1.1, with the angiotensin-converting receptor 2 (ACE2). Materials and methods. In this study, recombinant RBDs of Wuhan-Hu-1 and BQ 1.1 variants were used as antigens. For mouse monoclonal antibody (mMCA) production, hybridomas were cultured in vivo in BALB/c mice. mMCAs were isolated from ascitic fluid by ammonium sulfate treatment followed by purification through column affinity chromatography with Protein G Sepharose sorbent. The specific activity of mMCAs was assessed by immunoblot with recombinant RBD of Wuhan-Hu-1 variant. To identify the most promising mMCA, the neutralizing activity of mMCA was evaluated by enzyme-linked immunosorbent assay (ELISA) via immobilizing RBD on the surface of a microplate and using ACE2 in the form of horseradish peroxidase conjugate. Recombinant antigens were produced in ExpiCHO-S cell line (Gibco, USA). Results and discussion. Three mMCAs have been described as a result of the study: 5C3, 3F11, 1E6. All antibodies belong to immunoglobulins of subclass G and specifically interact with the RBD in S protein of SARS-CoV-2 virus. The most effective inhibition of the interaction between ACE2 and the RBD of BQ 1.1 strain was observed for murine MCA 3F11 (65 %), while the interaction with the RBD of Wuhan-Hu-1 strain was inhibited by mMCA 5C3 (91 %). The identified characteristics allow for considering the antibodies as potential candidates for the development of antibody-based therapeutics, thus expanding the possibilities of therapy for SARS-CoV-2 virus infection.

Ensuring the preventive anti-plague vaccination and the rational use of immunoprophylaxis means entail an adequate and timely assessment of their effectiveness. In the absence of mass cases of plague, it is impossible to objectively assess the actual (epidemiological) effectiveness of anti-plague vaccination means and methods, therefore, the analysis of efficacy shifts towards studying individual indicators of the immune response to the introduction of a vaccine, and the immunological efficacy of vaccination becomes a key factor that ultimately ensures its epidemiological effect. The aim of the work – as part of a comprehensive evaluation – was to determine the nature of individual immune response and characterize the group immune responsiveness of persons vaccinated against plague in order to build up a methodology for individual and group adjustment of the anti-plague vaccination regimen. Materials and methods. We used an array of information data obtained during monitoring of post-vaccination immunity in individuals immunized with live plague vaccine (LPV), presented in the form of a database. To analyze diseases in the post-vaccination period among the vaccinated population, a five-year retrospective cohort study was conducted to determine the incidence of acute and exacerbation of chronic diseases in people vaccinated and not vaccinated against plague. Results and discussion. Persons vaccinated against plague were ranked according to the level of immune responsiveness. The nature of individual immune response was revealed and the group immunoreactivity of vaccinated individuals was characterized. The possibility of predicting the intensity of the immune response to vaccination has been determined. The frequency of adverse events following immunization (AEFI) in individuals annually vaccinated against plague has been assessed. As a result of the distribution of vaccinated individuals according to the level of immune responsiveness and taking into account AEFI, the possibility of forecasting the individual and group immunoreactivity of vaccinated individuals has been determined to justify timely correction of the LPV administration regimen.

The study is focused on the genetic determinants of the yersiniachelin (Ych) siderophore encoded by the ysu gene cluster and found only in Yersinia pestis and Yersinia pseudotuberculosis. The aim of the investigation was to analyze the genes encoding the biosynthesis of Ych and to assess the possibility of their use for intraspecies differentiation of Yersinia. Materials and methods. The study used complete nucleotide sequences of 583 Y. pestis strains and 300 Y. pseudotuberculosis strains from the NCBI database, as well as 38 Y. pestis and 88 Y. pseudotuberculosis strains from culture collection at the Rostov-on-Don Anti-Plague Institute of the Rospotrebnadzor. The genomes were analyzed using bioinformatics methods and PCR in silico and in vitro. Results and discussion. A comparison of the ysu cluster genes in two Yersinia species has revealed their high conservatism in the plague microbe, while differences in the structure of the transcription terminator of the Ych biosynthesis genes have been found in the pseudotuberculosis microbe. It turned out that the terminator contains nucleotide tandem repeats that differ in the number in different groups of Y. pseudotuberculosis strains, thus indicating their potential use for intraspecies differentiation of these bacteria. To assess the effect of the transcription terminator structure on the Ych expression by plague and pseudotuberculosis microbes, two recombinant plasmids containing PCR copies of Ych biosynthesis operons from Y. pestis KIM and Y. pseudotuberculosis YPIII have been constructed. The introduction of both plasmids into the Escherichia coli H1884 strain, devoid of its own siderophores, has demonstrated that the operon of the YPIII strain determines a significantly higher expression of Ych than that of the KIM strain. The results of the study show that the structure of the transcription terminator of the Ych biosynthesis operon has a considerable impact on the expression of this siderophore and can be used for intraspecies differentiation of Y. pseudotuberculosis strains during epidemiological monitoring.

In recent decades, the epidemiology of vector-borne infectious diseases has changed significantly due to global warming, which affects the habitats of vectors and increases the rate of spread of pathogens. This can lead to both the expansion of the boundaries of existing and the emergence of new natural foci of infectious diseases, including Crimean hemorrhagic fever (CHF). The aim of the study was to comprehensively assess the possible impact of climatic factors on the incidence of CHF in the endemic areas of Russia, Kazakhstan, Turkey and Iran in 1999–2022. Materials and methods. The data on the number of laboratory-confirmed cases of CHF in the endemic regions of Russia, Kazakhstan, Turkey and Iran were analyzed and compared with annual climatic indicators (average annual temperature, the highest and lowest average annual temperatures and average annual precipitation) starting from 1999. Results and discussion. During the observation period, the incidence of CHF in the regions under consideration was featured in a variety of trends. Correlation analysis revealed a positive relation between the average annual precipitation and CHF cases (rxy=0.553; p<0.001), while temperature parameters were not statistically significant. Regression analysis confirmed the importance of dummy variables representing countries and time period, but did not show statistically significant relations between climatic factors. The total (in the countries under consideration) average annual precipitation is a statistically significant factor (b=1.600; s.e.=0.192; p<0.001), which emphasizes the potential impact of changing climatic conditions on the spread of the Crimean-Congo hemorrhagic fever virus. The multiple linear regression method revealed a statistically significant effect of the highest air temperature (b=27.645; s.e.=7.859; p<0.001) and precipitation (b=1.473; s.e.=0.197; p<0.001) on the incidence of CHF. The study shows the need to include annual climate forecasting in CHF control strategies and to develop unified monitoring systems for a more accurate assessment of the epidemiological situation in endemic regions.

Cholera vibrios, isolated from surface water bodies during monitoring activities, can differ from typical ones in terms of agglutinability with diagnostic cholera sera, which makes it difficult to assign them to a specific serogroup. Therefore, the determination of the causes for these deviations through the study of the structure of genetic determinants responsible for the synthesis of O‑antigen (wb* clusters) is considered a relevant task. The aim of this work was to identify wb* clusters in the genomes of R-variant Vibrio cholerae, study their structure, and conduct phylogenetic analysis of the strains. Materials and methods. Full genome sequencing was performed using Illumina MiSeq and MinION platforms. The assembly was conducted de novo using the SPAdes assembler software (v.3.11.1). Manipulation of cluster sequences and data visualization were carried out using the BLAST program from the ncbi-blast-suite package version 2.13.0, Python scripts and packages such as pyGenomeViz and Biopython. The phylogenetic tree was constructed using the roary program (v.3.13.0). Full genome alignment was carried out using the nucmer and promer programs from the MUMmer 4 package version 4.0. Results and discussion. R-variant V. cholerae contains different types of wb* clusters in the genome, with most commonly occurring O23 and O59. A comparison has been made between translated amino acid sequences of wb* regions in R-variant strains and amino acid sequences of reference strains present in the NCBI database. Some of the analyzed clusters completely match with reference strains, while others show high variability. Phylogenetically, the strains primarily group together according to the wb* cluster type, regardless of the S/R phenotype. Classifying R-variant V. cholerae strains based on agglutinability is challenging. Molecular research methods, polymerase chain reaction, in particular, are necessary to determine the pathogenic potential of such strains.

Tick-borne encephalitis is a flavivirus disease, endemic to vast areas of Europe and Asia, caused by the tick-borne encephalitis virus from the genus Orthoflavivirus, transmitted through the bite of a tick. The course of infection is characterized by fever followed by the development of potentially fatal encephalitis. Serological diagnosis of tick-borne encephalitis is complicated by severe cross-reactivity with antibodies to other endemic and imported flavivirus infections. The aim of the study was to obtain a recombinant analogue of domain III of the surface protein E of the tick-borne encephalitis virus (EDIII-TBEV) and assess its ability to detect antibodies to the tick-borne encephalitis virus and differentiate them from antibodies to other flavivirus infections. Materials and methods. A comparative study was performed using panels of sera containing and not containing antibodies to the tick-borne encephalitis virus, and panels of samples with antibodies to yellow fever, dengue, and Zika viruses. The study was conducted using commercial tests and experimental kits based on EDIII-TBEV in the ELISA format and in the dot analysis format. Results and discussion. It has been shown that the use of experimental kits based on EDIII-TBEV makes it possible to effectively detect IgG antibodies to tick-borne encephalitis virus and, in contrast to commercial tests, to differentiate them from antibodies to the pathogens of dengue, yellow and Zika tropical fevers. A recombinant analogue of domain III of the surface protein E in the tick-borne encephalitis virus can be a useful capture reagent when creating diagnostic test systems in the format of enzyme-linked immunosorbent assay and dot-immunoassay for the differentiated detection of IgG antibodies to the tick-borne encephalitis virus.

The aim of the study was to determine the prevalence of leptospiroses and hemorrhagic fever with renal syndrome (HFRS) among residents of some administrative districts of the Leningrad Region. Materials and methods. 958 blood serum samples of conventionally healthy individuals living in the following territories of the Leningrad Region: Boksitogorsky, Volosovsky, Vyborgsky, Kingiseppsky, Lodeynopolsky, Luzhsky, Podporozhsky, Priozersky, Slantsevsky and Tikhvinsky districts – were analyzed by enzyme immunoassay. The retrospective epidemiological analysis of the incidence of leptospirosis and HFRS in the population of the Leningrad Region in 2011–2020 was carried out based on the data from the Rospotrebnadzor Administration and Forms No. 2 “Information on infectious and parasitic diseases”. Results and discussion. All in all, 54 cases of leptospirosis and 104 cases of HFRS were registered in the Leningrad Region in 2011–2020. The long-term average annual incidence rate (LTAAIR) for leptospirosis was 0.32. In Boksitogorsky, Vyborgsky, Lodeynopolsky, Podporozhsky and Slantsevsky districts, cases of leptospirosis were not recorded, but IgG-antibodies to Leptospira interrogans were detected in residents of those areas. The LTAAIR for HFRS was 0.63. There are no registered cases of HFRS in the Kingiseppsky, Podporozhsky, and Slantsevsky districts. IgG-antibodies to Orthohantavirus were detected in volunteers in all surveyed areas. The detection of specific antibodies in the blood sera of conventionally healthy people living in the Leningrad Region indicates contact of the population with pathogens of leptospirosis and HFRS. The lack of registered morbidity in some areas is probably due to their hypo-diagnosis, as evidenced by the detection of antibodies to the pathogens of these infections in people living in the corresponding territories.

Hemorrhagic fever with renal syndrome (HFRS) is registered annually among residents of Khabarovsk city, Russia. The aim of the study was to conduct a genetic analysis of hantaviruses, the causative agents of HFRS, in residents of Khabarovsk city and in Norway rats (Rattus norvegicus), a natural reservoir of Seoul virus (SEOV), captured in Khabarovsk and its suburbs. Materials and methods. Blood sera samples from 75 patients with HFRS, collected in 2016–2023 (blood plasma – in 2017) and samples from 1468 Norway rats, captured during 2011–2023, were investigated. Results and discussion. We have demonstrated the presence of the Seoul virus (SEOV) in samples of Norway rats from the city of Khabarovsk and the suburban settlement Priamursky, Jewish Autonomous Region; 2 RNA isolates of the SEOV virus, 33 isolates of the Hantaan virus (HTNV), 9 isolates of the Amur virus (AMRV) – in patients with HFRS from Khabarovsk. Phylogenetic analysis of partial S and L segments of the genome has revealed that three RNA isolates of SEOV from Norway rats and two isolates from HFRS patients are most closely related (99 % homology) to strains from China and are different from the variant of SEOV from Vladivostok. It is assumed that the urban focus of the Seoul virus in Khabarovsk and its environs was formed as a result of the importation of virus carriers from China, where this variant of the virus is widespread. The data obtained indicate that the incidence of HFRS in residents of Khabarovsk, caused by infection with the HTNV and AMRV viruses, is associated with visits to various rural areas of the Far East.

Mobile laboratories for implementing anti-epidemic measures in the territories of natural plague foci perform an important function of ensuring sanitary-epidemiological well-being of the country. The aim of the study was to determine the range of areas and tactics for deploying mobile laboratories to ensure the current tasks of immunological monitoring over the health status of the population at risk in the territory of a natural plague focus. Retrospective analysis of the results of long-term immunological monitoring of the risk contingent vaccinated against plague was carried out. The possibilities and prospects for using a mobile laboratory for immunological monitoring within the framework of ensuring the tasks and functions of the Rospotrebnadzor have been determined. Mobile laboratories for immunological monitoring expand the capacities to solve operational issues related to the provision of specific prophylaxis of particularly dangerous infectious diseases, and their deployment as part of other mobile units of the Sanitary-Epidemiological Service will contribute to a more accurate delimitation of the territory, volume, scope and priority of any given preventive measure.

The aim of the work was to conduct a comparative analysis of the existing national legal framework against the provisions of the International Health Regulations (IHR) (2005). The main issues of harmonization of the existing documentation in accordance with modern international requirements have been identified. A number of gaps and inconsistencies in the legislative acts that do not fully comply with the requirements of international legal acts recognized by the Republic of Tajikistan are revealed. Proposals for optimization and improvement of the national legal framework and regulatory documents, as well as for adaptation to the requirements of the IHR (2005) are presented.