Vol 103, No 4 (2026)

Introduction. Genetic monitoring of hepatitis A virus (HAV) is an important tool for surveillance of this infection and the identification of hepatitis A outbreaks.

The aim of the study was to analyze the genetic diversity of HAV variants involved in sporadic and cluster cases of hepatitis A in 2022–2025.

Materials and methods. A total of 402 HAV VP1/2A partial sequences isolated from sporadic and cluster cases in 2022–2025 in various regions of the Russian Federation were analyzed. Phylogenetic trees were constructed using a Bayesian approach implemented in the Beast2 software package using HAV sequences isolated in regions of the Russian Federation and neighboring countries since 1998. To assess changes in genetic diversity, p-distance values were analyzed in four HAV sequence samples, divided based on virus genotype and the year the sequences were isolated — before or after 2020.

Results. The persistent circulation of two HAV genotypes, IA and IIIA, was demonstrated. The share of genotype IA was 78.4%, genotype IIIA — 12.7%, and imported genotype IB — 8.9%. Both genotypes, IA and IIIA, contribute to both sporadic and outbreak cases. 98% of HAV genotype IA isolates belonged to a single lineage originating from the strain that caused the 2010 outbreak in Moscow. Analysis of p-distance values confirmed a decrease in HAV genetic diversity — for genotype IA before 2020, this indicator ranged from 0.000 to 0.316, and from 0.000 to 0.087 in 2020–2024. For genotype IIIA, a decrease in the p-distance indicator was also noted, from 0.000–0.080 before 2020 to 0.000–0.029 in 2020–2024.

Conclusion. The obtained results indicate a decrease in the genetic diversity of HAV against the background of a decrease in hepatitis A incidence rates, and suggest that analysis of longer regions of the viral genome might be required for molecular surveillance and outbreak investigation in the future, if the trend of decreasing genetic diversity of the virus remain.

Introduction. COVID-19, caused by SARS-CoV-2, remains a significant global health issue. Since late 2021, the Omicron variant has become dominant, characterized by high transmissibility but reduced virulence. Studying the regional characteristics of the epidemic process during its circulation is essential for assessing the transformation of the COVID-19 epidemic process and the emergence of circulation patterns approaching endemicity.

Objective. Analysis of the epidemiological situation of COVID-19 in the Northwestern Federal District of the Russian Federation during the period of dominance of the SARS-CoV-2 Omicron variant.

Materials and methods. An analysis of Rospotrebnadzor statistical data on morbidity, case fatality rate, age structure, and severity of COVID-19 in the Northwestern Federal District (NWFD) for 2022–2024 was conducted. To study genetic diversity, S-gene sequencing was performed on 16,008 samples from COVID-19 patients across 11 subjects of the Northwestern Federal District to determine the genetic lineages of circulating strains.

Results. A decrease in annual morbidity was observed, from 1,768,558 cases in 2022 to 145,482 in 2024. Morbidity exhibited a wave-like pattern with peaks associated with the succession of Omicron subvariants. A shift in morbidity towards the 65+ age group was noted (an increase in proportion from 12.0% to 22.7%). The proportion of severe forms has decreased significantly (from 3.7% to 0.2%), and case fatality rate decreased from 4.4% to 0.2%, while the proportion of mild and asymptomatic cases increased.

Conclusion. The data suggest the emergence of features of SARS-CoV-2 circulation in the NWFD approaching an endemic pattern, accompanied by a decrease in severe cases and case fatality rate amid the continued replacement of Omicron subvariants. At the same time, the decline in reported morbidity should be interpreted with caution because it may have been affected by changes in testing coverage, case ascertainment, and registration practices. The results confirm the need to maintain molecular epidemiological surveillance; expanded genomic monitoring, including whole-genome sequencing, is required for the detection and detailed characterization of new potentially significant variants.

Introducion. Ricin is a glycoprotein phytotoxin that is characterised by high toxicity and relatively simple extraction methods. Monoclonal antibodies (mAbs) against ricin represent a key component in the development of immunodiagnostic test systems and preparations for the specific prevention and treatment of toxin poisoning.

The aim of the present study was to obtain and characterise mouse monoclonal antibodies specific to the ricin B subunit.

Materials and methods. Monoclonal antibodies were produced using a hybridoma technology, with the recombinant ricin B subunit (RTB) having been used as the antigen for immunising BALB/c mice. Hybridisation was performed by electrofusion, using the Sp2/0-Ag14 myeloma cell line as the partner cells. The stable hybridoma production was then carried out in vivo in mice. The specificity of the obtained mAbs was then assessed by Western blotting against RTB and native ricin. The parameters of the affinity interaction between the obtained antibodies and RTB were determined by surface plasmon resonance. The selection of the optimal antibodies pair for RTB detection was determined using a sandwich-format enzyme-linked immunosorbent assay (ELISA). In order to assess the neutralising activity of the antibodies against ricin, in vitro tests were carried out using the Vero В cell line, and in vivo tests were conducted using a mouse model.

Results. Consequently, 13 mAbs specific to RTB and ricin were obtained and characterised. Following a thorough evaluation of the strength of affinity interaction and the selection of optimal antibody combinations for RTB detection, it was determined that four mAbs (RTB-F1-2, RTB-F1-16, RTB-F2-10 and RTB-F5-1) were identified as promising candidates for the purpose of developing diagnostic test systems. mAbs RTB-F1-15, RTB-F1-16, RTB-F2-10 and RTB-F5-1 demonstrated significant neutralising activity in in vitro tests against ricin at a dose of 8 × IC₅₀. Intravenous administration of the mAbs RTB-F2-10 ensured 100% survival of mice following intraperitoneal ricin intoxication at a dose of 3 × LD₅₀.

Conclusion. The feasibility of utilising high-affinity mAbs (RTB-F1-2, RTB-F1-16, RTB-F2-10 and RTB-F5-1) for the design of diagnostic test systems has been demonstrated through experimental means. The data obtained on the neutralising properties of the mAb RTB-F2-10 in in vitro and in vivo tests allows it to be considered as a basis for the development of a therapeutic agent using chimerisation and humanisation strategies.

Introduction. Cystic fibrosis is an autosomal recessive genetic disorder caused by mutations in the CFTR gene and characterized by involvement of the exocrine glands. Of particular clinical importance for patients with cystic fibrosis are bacteria Burkholderia cenocepacia, due to their propensity for persistence and the development of chronic lower respiratory tract infection, which remains the leading cause of death in this patient population.

The aim of the study was to analyze the presence of genetic determinants associated with the production of pathogenicity factors in B. cenocepacia isolates from respiratory samples of patients with cystic fibrosis before the start of targeted therapy and for 36 months after its start, regardless of the specific type of targeted therapy.

Materials and methods. 151 B. cenocepacia isolates from respiratory samples of 12 patients with cystic fibrosis in the Samara Region were studied, while 32 isolates (21.2%) were isolated from patients before the start of targeted therapy, and 119 (78.8%) after its start for 36 months. The genetic profiles of the strains were analyzed for the presence of 13 genes associated with the production of a number of B. cenocepacia pathogenicity factors of different groups: fliC, fliJ, rpoN, shvR, luxR, atsR, rpfF, katA, katB, hppD, mgtC, zmpA, zmpB. At the second stage of the study, the occurrence of combinations of genes grouped by their functions was assessed: genes associated with bacterial motility and adhesion (fliC, fliJ, rpoN, shvR); genes associated with quorum sensing systems and biofilm formation (shvR, luxR, atsR, rpfF); genes encoding virulence factors associated with evasion of the immune response, tissue damage and existence in conditions of micronutrient deficiency (katA, katB, hppD, mgtC, zmpA, zmpB).

Results. During targeted therapy, a statistically significant increase in the prevalence of katA genes (associated with protection against peroxide under iron-deficient conditions) and the ability to grow in the presence of carbon sources was observed (p < 0.05). The mgtC-fliC gene combination, associated with survival inside macrophages and loss of motility, was found in 25.0% of isolates before targeted therapy and increased to 45.4% of isolates during targeted therapy, with statistically significant differences.

Conclusion. Against the background of targeted therapy, there is a tendency to increase the frequency of strains with genes associated with the possibility of survival inside phagocytes and resistance to oxidative stress (katA, katB, mgtC, rpfF, zmpA, zmpB). In isolates obtained against the background of targeted therapy, there was no significant change in the occurrence of regulatory genes for quorum sensing systems and biofilm formation.

Introduction. Current challenges associated with the rising of antimicrobial resistance (AMR) and the limitations of the use of chemical disinfectants (potential side effects, the need for precautions, negative impact on some materials, and short-term effectiveness) are stimulating the search for alternative approaches to disinfection. Biological disinfection using probiotic bacteria and bacteriophages is considered a promising method for managing the hospital environment.

Objectives. This paper aims to systematically analyze the effectiveness and use of biological disinfection agents (probiotic bacterial consortia and bacteriophages) in healthcare settings compared to traditional chemical methods.

A systematic literature search was performed in PubMed/MEDLINE, Scopus, Web of Science, CyberLeninka, and eLIBRARY.RU databases for the period from 2010 to 2025. Using the PRISMA 2020 methodology, 58 publications that met the inclusion criteria were selected: original studies devoted to the use of biological agents for disinfecting surfaces and equipment in healthcare settings in comparison with chemical methods.

Probiotic consortia based on Bacillus spp. were found to form a stable microbiome on surfaces with regular use, reducing the frequency of pathogen recolonization. In multicenter trials, international researchers demonstrated a reduction in the contamination of objects with methicillin-resistant Staphylococcus aureus (MRSA) and the incidence of hospital-acquired infections from 4.8% to 2.3% over 6 months. Bacteriophages demonstrate high efficacy against bacteria, including those forming biofilms of Pseudomonas aeruginosa and Klebsiella pneumoniae on medical equipment (a 4-log reduction in CFU), whereas chemical agents (chlorhexidine) are often unable to completely destroy the biofilm matrix and are effective primarily against planktonic forms of microorganisms. The most promising approaches are considered to be combined strategies: “chemical disinfection followed by colonization with a probiotic consortium” or “chemical disinfection followed by the use of bacteriophages”.

Biological disinfection is a scientifically proven, targeted method for managing hospital microbiota that does not replace, but rather strategically complements chemical disinfection. Its implementation in Russian healthcare facilities requires the development of standardized protocols and large-scale sanitary-microbiological and clinical-epidemiological studies.

After smallpox eradication was certified in 1980, the international community faced the question of the fate of the remaining collections of Variola virus (VARV). Debate over their destruction has continued for more than four decades.

Objective. To conduct a historical-chronological analysis of World Health Organization (WHO) and World Health Assembly (WHA) documents in order to trace changes in the arguments and approaches concerning the retention and possible destruction of VARV stocks.

Resolutions of the World Health Assembly, WHO documents, and materials from the WHO Advisory Committee on Variola Virus Research were analyzed as sources; historical-chronological and comparative methods were employed.

After storage was centralized in two WHO collaborating centers, the proposed timelines for destruction were repeatedly reconsidered. In 1999, the WHA authorized temporary retention to allow further international research; in 2002, retention was continued subject to results-oriented and time-limited studies. During the 2010s, risks associated with advances in synthetic biology became more prominent in the discussion. In 2019, the WHA extended the research programme for a further five years.

Conclusion. The history of this issue reflects not a linear progression toward a final decision to destroy the VARV, but rather a periodic review of retention timelines and research conditions. The WHO Advisory Committee plays a pivotal scientific advisory role in evaluating the necessity, direction, and outcomes of VARV research, and its expert findings inform deliberations regarding the future of the stocks. The current WHO approach is characterized by a combination of rigorous research oversight, biosafety requirements, and periodic reviews of the research program.