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Over the last years, an increasing rate of ixodes tick bites has been registered in the northern regions of the European Russia. In addition, the number of subjects request medical assistance due to tick bites has been dramatically increased in the Komi Republic. In addition, incidence of tick-borne encephalitis was also increased particularly starting since 2009. However, highly limited data on pathogen genetic diversity related to viral tick-borne infections in this region are currently available. Taiga ticks (Ixodespersulcatus) collected from the Komi Republic southern and central part vegetation were examined to identify and genotype tick-borne viruses. Individual ticks were used to identify by RT-PCR viral RNA coupled to tick-borne encephalitis and Kemerovo viruses. Viral genome fragment sequencing allowed to unambiguously identify these viruses. It was found that viral RNA tick-borne encephalitis was detected in 6.8±1.2% individual ticks. Moreover, tick-linked isolate genotyping based on analyzing E protein gene fragment nucleotide sequence derived from tick-borne encephalitis discovered that 35% and 65% isolates belonged to the Far Eastern and Siberian subtype, respectively. In addition, subsequent phylogenetic analysis demonstrated that at least four variants of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus were detected, which were close to the viruses circulating in the Urals and Siberia. In contrast, prevalence of Kemerovo virus in taiga ticks was 0.8±0.2%. Sequencing of Kemerovo virus RNA-dependent RNA polymerase gene fragment showed around 94% homology with the remainder of the Kemerovo virus strains. Phylogenetic analysis of the Kemerovo virus genome fragments demonstrated at least two subtypes circulating in the Komi Republic. Thus, it was suggested that tick-borne encephalitis virus was introduced relatively recently from the Urals and Siberian region into the natural foci of the Komi Republic. Moreover, genetic differences found in Kemerovo virus strains presume for them a longer lasting evolution throughout the natural foci of this region. In addition, a potential role for birds and their ticks in rapid spreading of viral tick-borne infections in the Komi Republic is also discussed. Thus, the data on genetic diversity of the viral agents related to tick-born encephalitis and Kemerovo fever may be useful for improving their diagnostics, prevention and treatment in the Komi Republic.

The unfavorable epidemiological situation with tick-borne vector-borne infections may be characterized not only by an increase in the occurrence of already known diseases, but also by the identification of new infections and pathogens, the role of which remains poorly understood. An example of such pathogens is Yanggou tick virus (YGTV), which belongs to the group of segmented flavi-like viruses.The aim. To detect and molecular genetic characterization of YGTV found in Dermacentor nuttalli Ol. (1929) ticks on the territory of the Republic of Buryatia.Materials and methods. The study analyzed 350 individual samples of adult ticks of D. nuttalli species collected in the spring-summer period of 2023 on the territory of five districts of the Republic of Buryatia. The detection of YGTV RNA was performed by PCR followed by nucleotide sequence determination and phylogenetic analysis for each of the 4 genome segments.Results. In one sample of the tick D. nuttalli, collected in the Ivolginsky district of the Republic of Buryatia, YGTV RNA was detected, which was further confirmed by sequencing of the obtained genome fragment. The incidence of YGTV RNA among the studied D. nuttalli ticks in Buryatia was 0.3 % (95 % CI: 0.1–1.6). Primers were designed to obtain fragments of all four segments of the YGTV genome. The identified genetic variant of YGTV, when analyzed phylogenetically across all four segments, clearly clusters with YGTV sequences found earlier in China and Russia (the Republic of Altai and Tyva). The detected variant shows the highest sequence identity with the prototype strain Erzin14-T20074.Conclusion. The study shows for the first time the presence of YGTV in the territory of the Republic of Buryatia, which actualizes the need to monitor the circulation of this virus in natural foci of tick-borne infections in this territory, as well as to further clarify the boundaries of the spread of flavi-like viruses potentially dangerous for humans.

Viral hepatitis D (HDV infection) worsens the prognosis of HBV infection course in 80-90% of cases, accelerating fibrosis and leading to liver cirrhosis or hepatocellular carcinoma. Hepatitis D affects at least 125 000 people in Russia, and in the world, according to rough estimates, there are 15–20 million patients. The main measures to combat hepatitis D can be attributed to widespread scheduled vaccination against hepatitis B and the appointment of effective etiotropic therapy. A detailed study of the hepatitis D virus genome structure and its replication cycle allows the development of a number of drugs that target and block key mechanisms of the virus life cycle. This review provides a brief characterization of hepatitis D virus, its genome structure, key processes of its life cycle and mechanisms of genetic information realization. The review considers the main potential targets for targeted antiviral therapy of HDV infection and describes specific drugs (bulevirtide, lonafarnib, nucleic acid polymers). The review describes the mechanism of action of bulevirtide, which according to the current national clinical guidelines is a key element of antiviral therapy as monotherapy or in combination with pegylated interferons. Promising drugs affecting the processes of synthesis and post-translational modification of HDAg or reducing the production of surface proteins of hepatitis B virus are also considered. Further efforts are needed to develop safe, effective and cost-effective drugs against hepatitis D to ensure that treatment is widely available to those who desperately need it. Therefore, it is important that the life cycle of the hepatitis D virus be studied further, in greater detail, in order to develop highly effective antiviral drugs.

The circulation of a rather wide range of pathogens of natural-focal infectious diseases transmitted by ticks was detected in West Africa at different points of time: Borrelia, Rickettsia, Coxiella, Crimean-Congo hemorrhagic fever (CCHF), Bhanja, and bluetongue viruses, etc. Current epidemiological and epizootiological situation on natural-focal infectious diseases on the territory of the Republic of Guinea is not entirely clarified.The aim of this work was to identify genetic markers (RNA/DNA) of natural-focal infectious disease agents in samples of Ixodidae ticks collected in the Republic of Guinea, and to determine the spectrum of pathogens circulating in various landscape-geographical zones of the country.Materials and methods. To conduct research on the territory of all landscape-geographical zones of the Republic of Guinea, 4695 specimens of Ixodidae ticks of 11 species were collected. Taking into account the species appurtenance, gender, phase of development, as well as the site of collection, a panel of 1645 samples was compiled. Genetic markers of Crimean-Congo hemorrhagic fever and tick-borne encephalitis viruses, as well as Borrelia burgdorferi s.l., Ehrlichia chaffeensis, Ehrlichia muris, Anaplasma phagocytophilum, Coxiella burnetii, Rickettsia of the tick-borne spotted fever (TBSF) group, and Francisella tularensis were detected using polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR).Results and discussion. The following markers of natural-focal disease agents were found in the Ixodidae tick suspensions: DNA of Rickettsia of the TBSF group (25.6 % of all samples studied), DNA of C. burnetii (6.2 %), cDNA of B. burgdorferi s.l. (9.1 %), and RNA of the CCHF virus (2.5 %). The listed spectrum of pathogens has been registered in all landscape-geographical zones of Guinea. Genetic markers of tularemia, anaplasmosis, ehrlichiosis and tick-borne encephalitis pathogens have not been identified in this study. The results obtained made it possible to clarify the probable spectrum of tick-borne diseases in the territory of the Republic of Guinea, determined the need for further study of the circulation of natural-focal infectious disease agents in West Africa and conducting regular epizootiological monitoring.

Relevance. Hepatitis B often causes liver cirrhosis and hepatocellular carcinoma, especially among patients with HIV. Vaccination is the main prophylaxis of HBV for preventing infection and developing chronic disease. Studying the duration of postvaccination immunity and the expediency of revaccination in different age and risk groups is important for improving the strategy of immunoprophylaxis of B hepatitis.Aims. Study was to determine the level of post-vaccination immunity to HBV and specific antibodies (anti-HBc and anti-HBs) among HIV-positive patients and the healthy population of Novosibirsk and Tomsk.Materials and methods. 536 blood samples were taken from HIV-positive patients and 337 blood samples from healthy people (pregnant women and persons undergoing a routine medical examination). The presence of HBsAg, anti-HBs IgG, and anti-HBcIgG were determined in the samples.Results. The proportion of post-vaccination immunity decreased in older age groups with an increase in the proportion of post-exposure immunity. The proportion of HIV-positive patients who had contact with HBV was higher than among healthy people. Around 70% of people in each group had a low level of protective antibodies anti-HBs (lower than 100 IU). A high level of anti-HBs (higher than 400 IU) was determined in 10% of examined people. The proportion of low levels of anti-HBs increased with age, while average and high levels of post-vaccination immunity were less common with increasing age.Conclusion. A low proportion of HIV-positive people, who have been effectively vaccinated against hepatitis B, was noticed. Annual blood tests for the presence of HBsAg, anti-HBs, and anti-HBc, in combination with determining DNA HBV, can be recommended for HIV-positive patients who have a risk of developing an occult form of hepatitis B.

Nipah virus (Nipah virus, NiV) is a representative of the genus Henipavirus of the Paramyxoviridae family, the causative agent of a dangerous infectious disease with a wide range of clinical manifestations – from an asymptomatic (subclinical) form to severe encephalitis with fatal outcome. Despite the fact that the disease caused by this virus is registered only in the countries of Southeast Asia, the possibility of importing the pathogen to non-endemic territories is not excluded. Also, this pathogen is able to infect not only a large number of people, but also animals, causing serious diseases and significant economic damage, posing both, a medical and veterinary problem. This review presents the data available in the modern press on the structure and classification of the Nipah virus, possible cycles of its transmission, spread, methods of indication and identification in clinical and biological material, as well as the effectiveness of their use depending on the timing of the onset of the disease and available commercial diagnostic and preventive drugs.

The most common anthropozoonoses on the African continent are coxiellosis and Rift Valley fever. It is known that detection of specific IgG antibodies in the blood sera of farm animals is one of the indicators of the pathogen circulation in a certain territory. The aim of the work was to identify specific IgG antibodies in the blood sera of farm animals collected on the territory of the Republic of Guinea to pathogens of zoonotic infectious diseases: coxiellosis, brucellosis, glanders, CCHF, West Nile and Rift Valley fevers, using enzyme immunoassay (ELISA). Materials and methods. A panel of 970 samples of blood sera from farm animals inhabiting all landscape-geographical zones of Guinea was compiled for the work. Identification of specific antibodies was carried out using enzyme immunoassay with preparations recommended for veterinary studies. Results and discussion. Specific antibodies to zoonoses were detected in 700 out of 1074 samples (65.2 % of the total), including: to Coxiella burnetii – in 172 (16.0 %); to Brucella spp. – in 212 (19.7 %); viruses of Rift Valley fever – 85 (7.9 %); CCHF – in 139 (12.9 %) and West Nile fever – in 92 (8.6 %). Antibodies to Burkholderia mallei were not found in the tested material. Positive samples were registered in all landscape-geographical zones. Thus, an urgent task is to continue studying the circulation of pathogens of zoonoses and anthropozoonoses in the territory of the Republic of Guinea and to organize regular monitoring over the spread of zoonotic infectious diseases in collaboration with veterinary services, which will allow timely forecasting and coordinating prophylactic (anti-epidemic) measures to prevent cases of diseases.

The aim of the research was to study reproduction features of SARS-CoV-2 coronavirus strains of various genetic lines on Vero and Vero E6 cell culture.Materials and methods. The SARS-CoV-2 virus strains related to the variants of concern (VOC) circulating in the territory of the Russian Federation were used in the research. The strains of the SARS-CoV-2 virus were deposited in the State Collection of Pathogens of Viral Infections and Rickettsioses at the FBIS SSC VB “Vector” of the Rospotrebnadzor. The experiments were carried out on Vero and Vero E6 cell cultures. The dynamics of infectious virus accumulation was determined by titration of culture fluid samples 24, 48, 72, 96 hours after infection (MOI – from 1 to 0,00001 CPE50/cell). Plaque formation was studied on Vero E6 cell culture under 0.2 % agar coating. Image analysis and plaque size calculation were performed using GIMP (GNU Image Manipulation Program).Results and discussion. The study describes the dynamics of accumulation of infectious virus in the culture fluid depending upon multiplicity of infection for the strains of SARS-CoV-2 virus belonging to different genetic lines. Differences in the morphology of plaques on the monolayer of Vero E6 cell culture under agar coating are shown. SARS-CoV-2 virus strains related to Alfa and Delta VOC demonstrate maximum reproduction rate among the studied strains (infectious titer is higher than 7 lg TCID50/100µl). Omicron VOC forms small plaques under agar coating and at a low multiplicity of infection has a low reproduction rate. Thus, SARS-CoV-2 virus strains belonging to different genetic lines have significant differences in the rate of reproduction on Vero and Vero E6 cell culture.

Objective of the study was to assess the level of infection with Borrelia miyamotoi in ticks Ixodes persulcatus and Ixodes pavlovskyi collected in the south of Western Siberia.Materials and methods. 688 ticks I. persulcatus and I. pavlovskyi collected on the territory of Novosibirsk, Tomsk and Kemerovo Regions were examined. Borrelia DNA was detected by a two-round polymerase chain reaction with specifc primers to the omp66 gene region, followed by sequencing of the isolated fragments and phylogenetic analysis, including the sequences of prototype isolates published in the international GenBank database. Comparison and analysis of nucleotide sequences was carried out using the MEGA 7 software package. In parallel, the samples were examined for the presence of the agents of transmissible infections – West Nile fever and tick-borne encephalitis, anaplasmosis, ehrlichiosis, babesiosis, bartonellosis and candidate pathogens of tick-borne rickettsiosis through RT-PCR and PCR with species-specifc and genus-specifc primers.Results and discussion. The genetic material of B. miyamotoi was found in 2.2 % of I. persulcatus and I. pavlovskyi ticks in the Tomsk, Novosibirsk, and Kemerovo Regions and their appurtenance to the Asian genotype was determined. It was revealed that the degree of similarity of the omp66 gene fragments within the group of isolates of the Asian genotype was 100 %. No relation between B. miyamotoi and a specifc vector species was identifed.

Yellow fever is an acute infectious disease of viral nature, the causative agent of which is vector-borne –is transmitted through the bites of infected mosquitoes. Massive epidemics caused by the yellow fever virus are observed in the countries of Africa, South and Central America annually. Imported cases are also registered in non-endemic territories. The review presents the currently available data on the distribution, structure and classification of the yellow fever virus, the identification of its genetic variants depending on the geographical distribution, as well as modern methods of detection and identification of the pathogen in samples taken from sick and dead people. It considers the possibility of using virological, immunoserological and molecular-genetic methods for the diagnosis of yellow fever in different periods from the onset of the disease and in retrospective studies. The lists of diagnostic drugs of domestic and foreign production for the detection of agent markers (antigen, RNA), as well as specific antibodies of IgM and IgG classes, approved for use on the territory of the Russian Federation, are provided. The relevance of further development, improvement and introduction into laboratory practice of reagent kits that allow to detect the yellow fever virus in samples from sick people in a short time, with high efficiency and specificity is demonstrated. This will help to establish a diagnosis promptly and conduct timely anti-epidemic measures, as well as to determine the level of the population stratum immune to the pathogen in endemic regions and evaluate the effectiveness of immunization for the vaccinated contingent.

Dangerous viral infectious diseases pose a serious threat to human life and health, as their uncontrolled spread leads to the development of major outbreaks and epidemics. Rapid and accurate detection of the pathogen is an essential component of the fight against infectious diseases. This review is devoted to loop-mediated isothermal amplification (LAMP), which is one of the simplest and most reliable methods of molecular-genetic research that meets modern requirements. The simplicity of the analysis and registration of the obtained results, which is necessary under conditions with minimal laboratory capacities, makes it possible to consider this type of diagnostic technology as the most promising, which allows us to identify genetic markers (DNA or RNA) of pathogens of dangerous infectious diseases in the shortest possible time. Objective of the review is to summarize and systematize the data available to date on the use of LAMP for detecting RNA of dangerous infectious diseases caused by the Ebola,Marburg and Lassa viruses. The paper discusses the basic principles of the loop isothermal amplification reaction, the components that make up the reaction mixture and are used for the analysis, as well as methods for detecting the results obtained. When studying the information available in the literature sources about the advantages and disadvantages of LAMP, it is shown that in many cases, isothermal amplification is not inferior in sensitivity and specificity to the main molecular-genetic diagnostic methods currently used. Modifications that can be used for accelerated diagnostics of RNA-containing viruses are also considered.

The objectives of our study were to survey the prevalence of genetic markers for Rickettsia spp., Ehrlichia spp., Anaplasma spp., Babesia spp., and Theileria spp. in Hyalomma anatolicum ticks collected in southwestern Tajikistan and to perform sequencing and phylogenetic analysis of fragments of the 16S rRNA gene and groESL ope-ron from Ehrlichia spp. and fragments of the 18S rRNA gene of Theileria spp. detected in H. anatolicum ticks. Hyalomma anatolicum ticks collected in the Tursunzade and Rudaki districts of Tajikistan were tested for DNA of Rickettsia spp., Ehrlichia spp., Anaplasma spp., Babesia spp., and Theileria spp. by PCR with specific primers. The amplified fragments were sequenced and analyzed. DNA of Ehrlichia spp. (3.3 %) and Theileria spp. (3.3 %) was detected only in H. anatolicum ticks collected from the Rudaki district, and DNA of Ehrlichia spp. (0.7 %) was found in H. anatolicum ticks from the Tursunzade district. Sequence analysis of fragments of the 16S rRNA gene and groESL operon from Ehrlichia spp. revealed high similarity to Ehrlichia spp. The Tajik isolates of Theileria spp. were genotyped as Theileriaannulata based on the analysis of 18S rRNA gene sequences. The phylogenetic analysis demonstrates that Ehrlichia spp. isolates are highly similar to Ehrlichia spp. circulating in China and Brazil. The isolate Tajikistan-5 is closely related to the putative novel species Ehrlichia mineirensis. The Tajik isolates of Theileria spp. were clustered with T. annulata isolates from Turkey, Iran, Pakistan, and China by phylogenetic analyses.

Objective of the study. This work was carried out to identify markers (antigen and RNA) of CrimeanCongo hemorrhagic fever (CCHF) virus in samples from ticks, collected in all landscape-geographical areas of Guinea: Lower, Middle, Upper and Forest, to obtain up-to-date data on the distribution of the pathogen in the country.Materials and methods. Total of 4276 specimens of 8 species of ticks collected in 2016–2019 in the territory of the Republic of Guinea were studied, which were compiled into 1406 samples. Ectoparasites were collected from livestock animals, dogs, and small mammals. Viral antigen was detected using enzyme immunoassay (ELISA). The presence of RNA of the CCHF virus was determined by reverse transcription polymerase chain reaction (RT-PCR).Results and discussion. As a result of the studies, the antigen of the CCHF virus was detected in 21 samples (1.5 %), and RNA – in 37 (2.6 %). All samples, in which the viral antigen was detected, contained RNA of the CCHF virus. Positive results were obtained in samples from all geographical areas of the country. The main vectors and reservoirs of the pathogen in Guinea are ticks of the species Rh. sanguineus, Rh. geigyi, Rh. annulatus and Am. variegatum. The data obtained confirm the previously available information on the possibility of the pathogen circulation in this region and determine the need for further study of the spread of the CCHF virus in the territory of the Republic of Guinea.

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.

Introduction. Acute febrile diseases kill more than 250,000 people annually in West Africa. Malaria and typhoid fever traditionally occupy most of the total structure of registered fevers. However, these data do not fully reflect the true overall disease patterns in the West African region. This is due to the fact that diagnosis is mainly based on the clinical signs of the infectious process, suggesting that a certain number of diseases may be caused by arboviruses. The detection of specific antibodies (ABs) to infectious pathogens in the blood sera of residents of a particular area is a reliable indicator of the circulation of these pathogens in a particular territory. The aim of this study was to determine the prevalence of antibodies to a number of arboviruses: Dengue (DENV), West Nile (WNV) (family Flaviviridae), Crimean-Congo hemorrhagic fever (orthonairo)virus (CCHFV), Batai (Batai virus), Bhanja (BHAV) (order Bunyavirales), Chikungunya (CHIKV), and Sindbis (SINV) (family Togaviridae) in the population of the Republic of Guinea. Material and methods. In total, a panel of 2,620 blood serum samples from people living in all landscape and geographical areas of Guinea was collected for the study. Detection of IgG antibodies was performed using an enzyme-linked immunoassay (ELISA). Results. In total, ABs to Batai virus were detected in 144 samples (5.5%), BHAV in 58 (2.2%), WNV in 892 (34.0 %), DENV in 659 (25.2 %), CCHFV in 58 (2.2 %), CHIKV in 339 (12.9 %), and SINV in 52 samples (2.0 %). Discussion. The obtained results indicate serological evidence of the spectrum of arboviruses in the population of all landscape and geographical zones of the Republic of Guinea, confirming their active circulation in this territory. Conclusion. Given the high epidemiological significance of arbovirus infectious diseases, it is an urgent task to continue studying its share in the structure of febrile diseases in the territory of the Republic of Guinea.