Journal of microbiology, epidemiology and immunobiology

Introduction. The goal of the WHO Global Polio Eradication Initiative has not yet been solved, and the surveillance of diseases with acute flaccid paralysis (AFP) remains its key element. It is still relevant for ensuring the sanitary and epidemiological well-being of Russia.

Aim: analysis of indicators and results of polio/AFP surveillance in 2013-2024 for purposes of surveillance quality assessment and improvement.

Materials and methods. Information on surveillance indicators and results of virological investigation was obtained in national reporting documents.

Results. Over 12 years, 5,016 cases of AFP have been registered. Surveillance quality indicators were generally in line with WHO recommendations, but the COVID-19 pandemic had a negative impact on the detection of AFP cases at the clinical level. The majority of patients were children under 5 years of age (50.54%), boys (58.8%), the majority (82.46%) were vaccinated against polio. Polioviruses (PV) were isolated from 1.85% of cases, PV3 (48.4%) prevailed, non-polio enteroviruses — from 1.46% cases, CVB1–6 (34.9%) and EV-A71 (17.5%) were predominant. The majority of AFP cases (30.78%) were polyradiculoneuropathies, 34 cases (0.68%) were poliomyelitis. The occurrence of 30 cases of vaccine-associated paralytic poliomyelitis was associated with violations of sanitary and epidemiological requirements for its prevention. Four cases were associated with PV of vaccine origin (VDPV) types 1 and 3. The "age" of VDPVs corresponded to 1-2 years of circulation, there was no genetic evidence of human-to-human transmission.

Conclusion. High level of polio/AFP surveillance in Russia allowed to identify epidemiologically significant PVs and timely carry out anti-epidemic measures. The continuing threat of the international spread of poliomyelitis is the basis for future improving surveillance. The surveillance platform provides information about other (non-polio) pathogens that cause diseases with AFP syndrome.

The aim of this study was to examine spatio-temporal changes in the incidence of tick-borne encephalitis (TBE) in the Kirov Region over a thirty-year period.

Materials and methods. The data used were data on the incidence of TBE in the Kirov Region. Statistical hypotheses were tested at a significance level of 0.05. Statistical processing of the data was performed using the MS Excel19 and STATISTICA 10.0 software packages.

Results. An analysis of the temporal dynamics of TBE incidence in the Kirov Region (1994-2023) revealed the absence of a clear trend. Significant differences in the intensive TBE incidence rates (number of cases per 100,000 people) were found between the vegetation zones of the region in each of the aggregated time periods. In the middle taiga zone, statistically insignificant fluctuations in high incidence rates were recorded. In the southern taiga zone, a significant upward trend was observed, indicating a worsening epidemiological situation. In the coniferous-broadleaf forest zone, a significant downward trend was observed, with a significant decrease in incidence rates and interregional variability over the past decade.

Discussion. An inverse correlation was identified between the baseline incidence rate and its change during 1994–2003, indicating "regression to the mean"—a phenomenon that was absent in the subsequent 10-year period. This indicates a stabilization of the epidemiological situation and the emergence of new patterns of TBE distribution in the Kirov Region at this stage. This process may be influenced by numerous biotic and abiotic factors, the role of which requires further study.

Conclusion. The data obtained confirm the need for further study of this problem with the aim of optimizing existing prevention programs.

Objective. To identify features of the gut microbiome using 16S rRNA gene sequencing in inbred KK.Cg-a/a (KK) mice and the KK.Cg-Ay/a (Ay) subline with metabolic syndrome (MetS) caused by different genetic disorders, compared to the C57BL/6J (B6) mouse line lacking manifestations of the pathology.

Materials and methods. 3–4 months old male mice of three mouse lines were used: 1) KK mice with polygenic genomic disorders contributing to hyperglycemia, insulin resistance, and hyperinsulinemia; 2) the Ay substrain carrying an additional mutant dominant allele of the Agouti yellow coat color gene, exhibiting more severe MetS manifestations; 3) the B6 mouse line, not prone to obesity and diabetes (control group). All mice were of the same age (2 months) and sex (males) and received a normocaloric diet. Morphometry was performed for each animal, and biochemical parameters of blood serum were analyzed. PCR analysis of mRNA expression of neuropeptides and receptors in the hypothalamus was conducted. Mouse fecal samples were examined using 16S rRNA metagenomic analysis.

Results. As previously shown, in male mice with genome-wide disorders on a normocaloric diet, obesity and alterations in carbohydrate and lipid metabolism developed, being more pronounced in the Ay group. Animals of the Ay substrain differed from other mice by greater body and liver weight, higher plasma glucose and leptin concentrations, and increased expression of Neuropeptide Y (NPY), Pro-opiomelanocortin (POMC), and Tas1r3. In all animals with MetS, the microbiome differed from the control group by a lower abundance of the family Muribaculaceae and the genus Akkermansia, and an increased percentage of the phylum Bacteroidota (genera Alistipes, Odoribacter, and Bacteroides). A distinctive feature of the Ay microbiome was an increased percentage of the families Enterobacteriaceae and Oscillospiraceae (Ruminococcaceae).

Conclusion. Specific features of the gut microbiome characteristic of inbred animals with varying severities of energy metabolism disorders were identified. The models used can be employed to study the pathogenesis of MetS considering the role of microbiota, as well as to develop methods for predicting disease severity and correcting dysbiotic disturbances arising from energy metabolism disorders.

Introduction. The human leukocyte antigens (HLA) plays a huge role in the regulation of the immune response, the recognition and destruction of extracellular and intracellular pathogens and maintaining homeostasis. The study of the relationships between the polymorphism of HLA genes and the indicators of humoral and cellular immunity factors in people living in areas endemic for plague against the background of specific prevention in order to clarify and deepen the understanding of the fundamental mechanisms of the patho- and immunogenesis of this disease is an urgent area for research.

The aim of the study is to investigate the relationship between HLA class II genes and the indicators of humoral and cellular components of vaccine-induced immunity in people vaccinated with a live plague vaccine and living in the natural foci of plague of Siberia.

Materials and methods. The study involved 902 volunteers who live in the natural foci of plague in Siberia. The research complex included quantitative determination of the main classes of immunoglobulins in the blood serum; titer of specific antibodies to the Y. pestis capsule antigen; subpopulation content of blood cells with calculation of the immunoregulatory index; typing of HLA class II genes. The study used ELISA, flow cytometry, real-time PCR and statistical analysis.

Results. It has been established that the HLA class II allelic groups DRB1*09, *10, *12, *13, *14, and *15 as well as *04:01 (DQA1) and *03:05 (DQB1) can be significant genetic factors involved in the mechanisms of regulation of cellular and humoral immune system responses during the development of post-vaccination anti-plague immunity. DRB1*16 and DQB1*03:05 stand out in particular, causing deviations of important immunological indicators beyond the reference values. Probable associations of DRB1*09, *13, *14, and *15 with increased titers of specific IgG antibodies to the F1-antigen of Y. pestis have been identified indicating a significant influence in the formation of human humoral vaccine-induced anti-plague immunity.

Discussion. We have established a statistically significant association between allelic variants of HLA-II genes and variability in levels of immunoglobulins (IgE, IgG, etc.), cytokines (interleukin-4, interferon-γ), and lymphocyte subpopulations in blood, which confirms the key role of HLA polymorphism in individual immunological reactivity.

Conclusion. The obtained data indicate the potential of HLA typing for predicting the effectiveness of specific prophylaxis and for determining the characteristics of post-vaccination immunity formation in humans in plague-endemic territories.

Introduction. Continuous monitoring of the epidemiological situation is one of the key elements of a country's biological safety. The development and increasing accessibility of high-throughput sequencing technologies have led to the incorporation of genomic data into public health decision-making systems, known as genomic epidemiological surveillance. Effective implementation of genomic epidemiological surveillance for circulating pathogens requires finding a balance between data generation speed, estimation accuracy, and rational use of resources. Consequently, there is a need to develop evidence-based strategies for biological sample selection.

Aim: To justify the choice of methods for calculating the minimum sufficient sample size for sequencing depending on the objectives of epidemiological surveillance.

Materials and methods. This study presents a comparative analysis of two approaches to genomic monitoring: routine surveillance and targeted sentinel surveillance. The choice of statistical approaches for calculating the minimum sufficient sample size for each objective is justified, with specific examples that allow determining the required sequencing volume taking into account the current epidemiological situation and the prevalence of pathogen variants in the population.

Results. The study presents sample size calculation results depending on the objective: establishing the proportion of existing variants for routine surveillance, or detecting rare variants within sentinel surveillance at a predetermined prevalence threshold for a rare/new variant with a specified probability. For routine surveillance, the sample size was calculated based on the requirement for estimation precision of proportions (margin of error 5%) at a confidence level of 95%. For sentinel surveillance, the sample size was calculated under the condition that the probability of missing a variant (not detecting a single case) does not exceed 5%. The statistical results are presented in the form of graphs and calculation tables.

Conclusion. The proposed methods for calculating sample sizes for genomic monitoring depending on the objective can serve as a practical tool for epidemiological surveillance, increasing its efficiency. The use of these calculation methods will make it possible to obtain mathematically sound results regarding the genotypes of circulating pathogens and their degree of representation in the population.

Introduction. Immunohistochemical (IHC) analysis is one of the main methods for detecting and visualizing the protein determinants of the virus in organs. The nanoscale structures of viruses complicate the visualization of particle topography, which prevents a more detailed understanding of the pathogenesis of viral infections. Unfortunately, general IHC protocols are not universal and often their application in special cases is impossible. Optimizing the coloring methodology can significantly save research time. Based on this, this paper describes a step-by-step methodology for IHC staining of paraffin sections of animal organs infected with the SARS-CoV-2 virus.

The purpose of the study. Optimization of the chromogenic IHC staining protocol when working with infected material, using the example of SARS-CoV-2.

Materials and methods. IHC analysis was performed on paraffin sections of lung tissue of ferrets (Mustela putorius furo) infected with Omicron and Delta strains of SARS-CoV-2.

Results. During the study, it was demonstrated that the optimal exposure time for samples with hydrogen peroxide was at least 30 minutes. The use of BSA before the application of primary antibodies also contributed to a decrease in background staining, while the optimal concentration of the reagent was at least 1%. It is noteworthy that the addition of BSA to the primary antibody solution also contributed to a decrease in the non-specific signal. In the context of the current work, dilution of antibodies applied to S-protein by 1000 times was optimal to minimize the proportion of non-specific tissue staining.

Conclusion. In the work on optimizing the IHC protocol for paraffin sections, the main aspects affecting the staining quality were demonstrated and described. When working with material containing SARS-CoV-2, options for eliminating methodological mistakes were proposed.

The emergence of the norovirus GII.4 Sydney variant in 2012 caused a significant worldwide increase in gastroenteritis outbreaks. The article focuses on the problem of the emergence and further spread of the norovirus GII.4 Sydney variant, which is still one of the leading causes of viral gastroenteritis, especially in young children. The review summarizes data from the modern scientific literature on the detection of norovirus GII.4 Sydney and its recombinant forms — GII.4 Sydney[P31], GII.4 Sydney[P4 New Orleans], GII.4 Sydney[P16] и GII.4 Sydney[P12] in various countries. This review presents a comparison of the amino acid composition of the antigenic epitopes in the main capsid protein (VP1). The analysis focuses on four recombinants of the Sydney variant and includes a comparison with other variants (Grimsby 1995, Farmington Hills 2002, Hunter 2004, Yerseke 2006a, Den Haag 2006b, New Orleans 2009).