Ekaterina I. Krivosheina

Yellow fever virus (YFV), transmitted by Aedes aegypti mosquitoes, poses a serious threat to public health in the countries of tropical and subtropical reg

The aim of the study was to create a control RNA sample for yellow fever virus (YFV) diagnostics using the LAMP method. Two control samples were obtained: recombinant plasmid DNA (pCR2.1-YFV-K+) and mRNA (RNA-YFV-K+). During the assessment of the analytical sensitivity by the LAMP method, it was found that both samples demonstrated a comparable detection limit of 104 copies/ml, which allows for effective detection of the viral genetic material in the first days of disease symptoms. A study of the sample stability showed that at a temperature of -15 to -25 °C, both samples retain their functionality even after tenfold defrosting/freezing. At a temperature of 2 to 8 °C, the samples are determined as positive for 7 days of storage. However, stability decreases at room temperature: for pCR2.1-YFV-K+ it remains up to 72 hours, and for RNA-YFV-K+ — up to 48 hours. To ensure stability, samples should be stored at low temperatures (-15 to -25°C or 2 to 8°C). Based on the results, RNA-YFV-K+ can be used as a control for analytical sensitivity and correctness of the reverse transcription reaction followed by amplification by the LAMP method, which is important for the detection of RNA-containing yellow fever virus.

The work is an overview of the loop-mediated isothermal amplification (LAMP) method and its application to diagnostics of hemorrhagic fevers. Its objective was to briefly characterize isothermal amplification and systematize the available data on diagnostics by this method of hemorrhagic fevers caused by pathogens belonging to the first pathogenicity group. The review describes the principle of LAMP operation, which is based on the use of chain-displacing activity of DNA polymerase. The advantages of the method, such as high sensitivity and specificity, simplicity of implementation and cost-effectiveness, are considered in detail. Various methods for detecting LAMP results are also discussed, including the turbidimetric method, the use of fluorescent dyes and immunochromatographic analysis. It is noted that LAMP has some limitations, such as the complexity of primer selection and the possibility of false negative results in the presence of mutations in the genome. However, in general, the method seems promising for rapid detection of viruses in the field. The review provides information on the developed diagnostic test systems based on LAMP for detecting RNA of especially dangerous viruses belonging to the Filoviridae and Arenaviridae families. It is noted that despite the promise of the method, at present none of the described test systems are registered or produced on a commercial basis. The conclusion emphasizes the need to develop and implement new methods for diagnosing dangerous viral infections to control the epidemiological situation and develop a strategy for anti-epidemic measures. LAMP is considered a promising method for creating rapid and cost-effective tests.

Introduction. Tomsk region is one of the territories of the Russian Federation with the highest possible incidence of tick-borne infections. However, the spectrum and genetic diversity of tick-borne pathogens remain insufficiently studied. Materials and methods. The study analyzed 534 ticks: Ixodes persulcatus (n = 107), I. pavlovskyi (n = 234) and Dermacentor reticulatus (n = 193), collected in 13 biotopes of Tomsk and its suburbs during 2023. Detection of genetic material of tick-borne pathogens was carried out by PCR and RT-PCR in individual ticks with subsequent sequencing and phylogenetic analysis of nucleotide sequences. Results. More than fourfold dominance of I. pavlovskyi and D. reticulatus ticks over the taiga tick was observed. Infection of I. persulcatus ticks with tick-borne encephalitis virus (TBEV) of the Siberian genotype amounted to 1.3%, in ticks of the Ixodes genus, the genetic material of Borrelia burgdorferi s.l. was detected in 8.5%, B. miyamotoi – in 2.1%, Anaplasma phagocytophilum — in 1.5%, and Rickettsia tarasevichiae — in 14.1%. R. raoultii infection of D. reticulatus ticks was identified in 48.7%, and Babesia canis DNA was detected in a single sample. Genotyping and phylogenetic analysis of genomic nucleotide sequences showed the presence of new, unusual for the region genetic variants of B. garinii, B. bavariensis, B. afzelii and the Siberian TBEV genotype (subclade V). Conclusion. In the territory of Tomsk and its suburbs, genetic material of 9 species of tick-borne pathogens, including their new genetic variants, was detected in ixodes ticks.

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.

One of the most common arboviruses in the world are representatives of the genus Orthoflavivirus (family Flaviviridae). On the territory of the Republic of Guinea, the circulation of such representatives of this family as the yellow fever virus (YFV), West Nile virus (WNV) and dengue virus (DENV) has been confirmed. The aim of the study was to determine the level of specific IgG class antibodies to YFV, DENV and WNV in residents of various landscape– geographical zones of the Republic of Guinea by the ELISA method. Materials and methods. For the study, a panel of 1559 blood serums from practically healthy people was compiled, which were collected in all landscape and geographical zones of the Republic of Guinea. The detection of specific IgG class antibodies to DENV and WNV was carried out with commercial diagnostic drugs, and for YFV — with an experimental ELISA test system based on an analogue of the third domain of protein E obtained at the State Research Center for Virology and Biotechnology “Vector” of Rospotrebnadzor. Results. When testing blood sera in 28.5% (95% CI: 26.3–30.7) of cases, IgG antibodies to YFV, to DENV — in 11.8%, (95% CI: 10.3–13.5) and to WNV — in 27.0% (95% CI: 24.8–29.3) were detected. Antibodies to three viruses simultaneously (YFV, DENV and WNV) were detected in 30 cases, to YFV and DENV — 14, YFV and WNV — 44, DENV and WNV — 56. Conclusion. The detection of antibodies to WNV and DENV confirms the fact of the continued circulation of these pathogens in the territory of the Republic of Guinea, which poses a health risk to the local population. A detailed study of the molecular genetic and antigenic properties of flaviviruses circulating in this area will allow the development of more specific diagnostic tools.

Background. Tick-borne bacterial and protozoal pathogens pose a significant public health problem. The aim of this study was to detect and genotype Borrelia, Rickettsia and Anaplasma in Ixodes ricinus and Dermacentor reticulatus ticks collected in the Kaliningrad region in 2021–2022. Materials and methods. The study included 862 I. ricinus and 803 D. reticulatus ticks (1665 in total) collected in 33 biotopes of the Kaliningrad region. Detection of the DNA of tick-borne pathogens was carried out in individual ticks by PCR using a set of specific primers, followed by sequencing and phylogenetic analysis. Results. The level of infection of I. ricinus ticks with Borrelia was 15.5%, and genotyping by the p66 gene sequence showed the presence of genetic material from four species: B. afzelii, B. garinii, B. valaisiana, and B. lusitaniae. In D. reticulatus ticks, no Borrelia genetic material was detected. The Rickettsia DNA has been found in both tick species. Moreover, the infection rate of I. ricinus ticks was 2.6%, and D. reticulatus — 21.2%. R. helvetica were found in I. ricinus ticks, and R. raoultii in meadow ticks when genotyping by gltA gene. Genetic markers of Anaplasma phagocytophilum have been found in I. ricinus and D. reticulatus ticks. Cases of co-infection of an individual tick have also been identified. Conclusion. Six different species of tick-borne pathogens were found in the I. ricinus and D. reticulatus ticks collected in the Kaliningrad region and R. helvetica, R. raoultii and A. phagocytophilum were identified for the first time.

Introduction. Tick-borne infections are of great importance for many regions of Russia, including Eastern Siberia. This unfavorable epidemiological situation can be characterized not only by the circulation of well-known tick-borne infections, but also by the identification of new pathogens, the role of which remains little or generally unexplored. Multicomponent flavi-like viruses can cause infectious diseases in humans and pose a threat to public health. The purpose of the study was the identification and molecular genetic characterization of the Alongshan virus (Flaviviridae, ALSV) isolates, transmitted by ticks in the south of Eastern Siberia. Materials and methods. Total 1060 ticks were collected and analyzed from the territory of the Republics of Khakassia, Tuva, Buryatia, Irkutsk Region and Transbaikal Territory (Zabaykalsky Krai) in the spring-summer period 2023. ALSV RNA was detected by RT-PCR followed by nucleotide sequence determination and phylogenetic analysis for each segment of the genome. Results. The ALSV infection rate in Ixodes persulcatus ticks collected in the Republic of Khakassia was 3.3% (95% CI: 1.4–7.5); in Irkutsk Oblast – 1.0% (95% CI: 0.3–3.7); in the Republic of Tuva – 0.9% (95% CI: 0.3–3.4) and in Transbaikal Krai – 0.7% (95% CI: 0.2–3.6). Sequences of all four segments of ALSV genetic variants circulating in I. persulcatus ticks in the south of Eastern Siberia are grouped with sequences found in China and clustered into the Asian subgroup transmitted by taiga ticks. The level of difference in the nucleotide sequences of genome fragments among the identified genetic variants of ALSV ranged from 2 to 3%. Conclusion. The article shows the widespread distribution of ALSV in I. persulcatus ticks in the Republics of Khakassia and Tyva, Irkutsk Oblast and Transbaikal Territory. The obtained data actualize monitoring of changes in the area of distribution of potentially dangerous for humans flavi-like viruses and their vectors.

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.

Introduction. Genus Flavivirus (family Flaviviridae) viruses profoundly contribute to the spread of arbovirus infections. In the territory of the Republic of Guinea, the circulation of flaviviruses such as yellow fever virus (YFV), West Nile virus (WNV) and dengue fever virus (DENV) has been confirmed. The aim of the study was to determine the level of IgG antibodies specific to YFV, DENV and WNV in the indigenous population in various landscape and geographical zones of the Republic of Guinea. Materials and methods. For the study, a panel of 1559 human blood sera were compiled, which were collected in all landscape and geographical zones. The detection of IgG antibodies against DENV and WNV was carried out by commercial test systems, YFV by an experimental ELISA test system based on an analog of the third domain of protein E. Results. While testing 1559 blood serum samples, 28.48% (95% CI: 26.3-30.7) of cases were found to have IgG antibodies against YFV, DENV in 11,8%, (95% CI: 10,3-13,5) and WNV in 27% (95% CI: 24,8-29,3). simultaneously, antibodies against the three viruses (YFV, DENV and WNV) were detected in 30 cases, YFV and DENV in 14, YFV and WNV in 44, DENV and WNV in 56 cases. Conclusions. The detection of antibodies to WNV and DENV confirms the continued circulation of these pathogens in the territory of the Republic of Guinea, which poses a risk to the health of the indigenous population. The level of IgG class antibodies against YFV is insufficient for formation of yellow fever herd immunity, because. according to the WHO, it should reach at least 80% of the total indigenous population.