Vol 15, No 5 (2025)

Noroviruses are non-enveloped viruses of the family Caliciviridae. The norovirus variants that infect humans are highly contagious and are a leading cause of outbreaks for nonbacterial gastroenteritis. In the etiological pattern of acute viral intestinal infections, noroviruses hold the second place after rotaviruses. In countries with widespread use of rotavirus vaccines, the incidence of rotavirus infection has declined, whereas noroviruses have become the leading cause of nonbacterial gastroenteritis. A further decline in the incidence of intestinal infections can be achieved by using a vaccine against norovirus, however work on developing this vaccine is still underway. This review provides information on the circulation of genetic norovirus variants, its antigenic epitopes from structural and non-structural proteins, specific immune response, the regulatory activity of viral proteins, and formation of individual and collective immunity against noroviruses. The presented data indicate that immunity generated by norovirus infection has a limited duration and is apparently restricted by the norovirus genotype. The narrow specificity of immunity and the high level of genetic virus variation complicate targeted vaccine development. The long-term and very active circulation of noroviruses of the gene variant GII.4 Sydney 2012 suggests that it has properties that prevent the specific immunity formation in human population. Identification of such properties may be important for developing effective vaccine. Evaluating the protective significance of the immune response to the VP2 protein and virus’s non-structural proteins is also of considerable interest. Until these questions are solved, the most obvious candidates for the norovirus vaccine are capsid proteins VP1 of the gene variant GII.4 Sydney 2012, as well as other most relevant virus variants. Currently circulating strains of the GII.17 genotype exemplify such relevant variants. It also seems likely that, if the vaccine is successfully designed, periodic modification of its antigenic composition will be required in accordance with the epidemiological situation.

Interleukin-27 (IL-27) is a cytokine with multifaceted effects on immune responses. It is composed of two subunits: IL-27p28 и EBI3. The receptor complex for IL-27 consists of the heterodimeric IL-27R, which includes IL-27Rα and gp130. This receptor is expressed on various cell types, including T lymphocytes, B cells, NK cells, dendritic cells, macrophages, as well as endothelial and epithelial cells. Initially, IL-27 was primarily associated with Th1-mediated immune responses, but it is now recognized to also exhibit anti-inflammatory functions. IL-27 is mainly produced by antigen-presenting cells, such as dendritic cells and macrophages, but can also be secreted by adaptive immune cells. Its production is linked to infectious and autoimmune processes. The key effects of this cytokine include: direct modulation of effector CD4⁺ and CD8⁺ T-cell functions, stimulation of anti-inflammatory IL-10 production, recruitment of specialized regulatory T cells (Treg). In vitro, IL-27 promotes the proliferation of naïve CD4⁺ T lymphocytes through simultaneous binding to CD3 and the T-cell receptor. Additionally, this cytokine enhances CD4⁺ T-cell mobilization by increasing the secretion of chemokines and adhesion molecules. At the same time, IL-27 exerts anti-inflammatory effects, particularly by suppressing Th17-mediated immune responses. Despite its dual functionality, IL-27 is frequently associated with the progression of infectious processes in in vitro experiments and murine models. It serves as a crucial modulator of immune responses, capable of both activating protective mechanisms and restraining excessive inflammation. This study, based on literature data and the personal findings, highlights the diverse roles of IL-27 in viral infections such as influenza, HIV, COVID-19, and hepatitis B and C. The potential of IL-27 as a laboratory marker for clinical progression of viral infections remains to be fully elucidated. Its levels in peripheral blood are influenced by multiple factors, including the presence or absence of comorbidities. Thus, IL-27 is a key cytokine involved in the immunopathogenesis of viral infections. Investigating its diagnostic and differential significance in the aforementioned conditions may become a relevant scientific challenge.

While creating chimeric antigen receptor (CAR) NK cells, it is necessary to conduct a stage of these immune cell enrichment. Feeder cells are most often used in methods for the effective NK cell expansion. The human embryonic kidney cell line containing the SV40 T-antigen (HEK 293T) is most often used for research purposes in various areas, since it is easily subjected to genetic modifications. This property indicates the potential for modifying HEK 293T cells to express tumor antigens or proinflammatory cytokines, which can be used to activate and enrich NK cells. In this work, we assessed the effect of unmodified HEK 293T cell culture on cytotoxicity and expression of NK and NKT cell activation markers in long-term cultivation in the presence of non-irradiated autologous feeder cells. The study used peripheral blood mononuclear cells collected from healthy volunteer donors. Proliferation was stimulated using antibodies against CD3 and CD28 receptors or mitomycin C-treated HEK 293T cell culture. Cell proliferation was assessed by direct cell counting added with trypan blue dye. Cytotoxicity was determined on HG3, T47D-HER2+, K562 target cultures. Flow cytometry with labeled monoclonal antibodies was used to analyze the expression of surface receptors. Four different methods for lymphocyte activation using HEK 293T were proposed. We found that when using the HEK 293T cell line, an increased percentage of CD3^–CD56⁺ cells in the population was observed in all activation modes, as well as increased expression of NK cell activation markers — NKp30 and NKG2D, in addition, the proportion of CD16⁺ and CD3⁺CD4⁺ lymphocytes increased relative to activation with monoclonal antibodies alone. Of the proposed options for coincubation of lymphocytes with HEK 293T feeder cells, the most effective NK cells expansion was described for the protocol involving the use of the HEK 293T cell line once before the onset of incubation without proliferation additionally stimulated with monoclonal antibodies. This approach resulted in higher proportion of CD56⁺ lymphocytes reaching to 60% as early as on day 4 of cultivation. Thus, HEK 293T cells stimulate NK cells division, therefore, they can be used as feeder cells in a CAR NK cell product development.

In recent years, it has been of interest to search for alternative, so-called surrogate models to investigate bacterial pathogenicity. The current work was aimed at comparing two biological models (using white mice and Galleria mellonella larvae) to evaluate the pathogenic potential of community-acquired pneumonia agents. All the studied strains were isolated from the sputum of patients at the Rostov-on-Don Anti-Plague Institute of Rospotrebnadzor and identified by time-of-flight mass spectrometry. The virulence of the pathogen strains was evaluated when white mice and G. mellonella larvae were experimentally infected by microbes at various doses (CFU/ml). It was found that the hypermucoid variant of Klebsiella pneumoniae caused death of white mice at a dose of < 10³ CFU/mouse, whereas the classical morphotype was apathogenic even at a dose of 10⁶ CFU/mouse. At the same time, when the larvae were infected with two morphotypes, no difference in pathogenicity was observed. Other clinical isolates of the Enterobacteriacea family caused no disease in white mice even at an infection dose of 10⁶ CFU/mouse. However, E. coli and E. kobei caused the lethal process in (90%) in G. mellonella larvae. The exception was E. cloacae, which caused death in as few as 10% of individuals. In contrast to white mice, 100% of larvae died upon infection with Stenotrophomonas maltophilia, Chryseobacterium gleum, Rhizobium radiobacter, and Pantoea agglomerans. The virulence study of different staphylococcal species showed that S. aureus and S. haemolyticus had a high pathogenic potential for larvae, whereas S. epidermidis and S. saprophyticus were characterized by significantly lower potential to cause infection. In the surrogate model, clinical isolates of various fungal species: C. albicans, C. tropicalis, and G. capitatum — were most pathogenic for larvae, whereas C. glabrata and C. krusei, known as most invasive species, caused the delayed death of several individuals. Thus, the pathogenicity study of various microbial species requires to choose most appropriate biological model.

Background. COVID-19 is a major human infectious disease with devastating economic and public health impacts globally. Oxidative stress plays a pivotal role in the pathogenesis and progression of various viral infections. The aim of the present study was to evaluate oxidative stress biomarkers in COVID-19 patients with different severity to healthy participants. Materials and methods. This case-control study was conducted on 60 patients with COVID-19 infection (30 moderate and 30 severe) and 30 matched healthy controls referred to Baqiyatallah Hospital, Tehran from March until July 2020. Serum levels of total antioxidant capacity (TAC) and oxidative stress biomarkers such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities and levels of glutathione (GSH) and malondialdehyde (MDA) were measured using biochemical methods. Results. In terms of gender, the healthy control group consisted of 17 males and 13 females, and the group of moderate patients included 20 males and 10 females and severe COVID-19 patients included 14 males and 16 females, which were not statistically significant (p = 0.295). Also, the mean age in severe COVID-19 patients (46.6±12.8) was not significantly different from the healthy control (43.8±12; p = 0.683) and moderate (45.60±13.30; p = 0.953) groups. The results showed that SOD and CAT activities and MDA level in moderate and severe of COVID-19 patients were higher than the healthy individuals, while GPx and GR activities and GSH and TAC levels were significantly lower. SOD and GPx activities and MDA level in severe of COVID-19 patients were significantly different from moderate patients. However, CAT and GR activities and TAC level in severe cases was not significantly different from moderate patients. Conclusion. Oxidative stress plays an important role in the pathogenesis of COVID-19 infection as indicated by the enhancement of lipid peroxidation, depletion of GSH and alteration in antioxidant enzymes. The systemic oxidative stress is directly related to the severity of the pathogenesis. Therefore, substances with antioxidant properties may be a potential choice for the treatment of COVID-19 infection.

Introduction. HIV entry into host cells requires CD4 receptors and CCR5 co-receptors. Natural CCR5 ligands can inhibit HIV through steric blocking and receptor internalization. Although CCL2 is primarily a CCR2 ligand, emerging evidence suggests possible CCR5 interaction, challenging conventional views of chemokine specificity. Natural CCL2 missense mutations provide valuable insights into receptor interaction mechanisms and their potential role in HIV infection modulation, offering new perspectives on viral entry inhibition strategies. Materials and methods. The wild-type complex was modeled using AlphaFold Server with rigorous validation. From UniProt database, we selected 41 CCL2 mutations within predicted CCR5 binding sites based on structural analysis. For each variant, we generated mutant protein structures and complex models using FoldX algorithm in YASARA environment. We calculated binding energies, complex stability, and interaction energy parameters, while conducting detailed analysis of atomic contacts and hydrogen bonding patterns. Functional impact of mutations was assessed using PolyPhen-2 algorithm. Results. Molecular modeling identified 35 CCL2 residues forming the comprehensive CCR5 interface. Five specific mutations (P78H, S57C, I28V, N29A, K79A) significantly enhanced CCR5 binding affinity, reducing interaction energy compared to wild type. P78H and S57C variants showed the strongest effects and were consistently predicted as “probably damaging”. K79A demonstrated substantially improved binding while maintaining reasonable interfacial contacts. Detailed structural analysis revealed these mutations optimize the binding interface through strategic reorganization of molecular interactions and improved complementarity. Discussion. Our findings demonstrate that specific natural CCL2 mutations can substantially enhance CCR5 binding affinity, revealing unexpected plasticity in chemokine-receptor recognition systems. The most impactful mutations suggest evolutionary mechanisms for modulating HIV entry pathways through natural genetic variation. These results provide structural insights into how sequence variations might influence viral pathogenesis through altered receptor specificity and binding kinetics. Conclusion. This computational study identifies key CCL2 mutations that significantly enhance CCR5 binding, expanding our understanding of chemokine system flexibility and evolutionary adaptation. The results support further experimental investigation of natural CCL2 variants as potential modulators of HIV infection and contribute to fundamental knowledge of virus-host interactions at molecular level.

A viral infection can interfere with implantation processes, affecting angiogenesis and endometrial receptivity, invasive trophoblast activity, and disrupting the balance of immune factors. The aim of the study was to assess endometrial microbiota composition, to measure the levels of α-defensin, growth factors in infertile women with viral infection. Materials and methods. 80 female infertile patients aged 26–46 years were examined divided into two groups: main group — women with endometrium-bearing viruses found in their (25 patients), and comparison group — 55 women without endometrium-bearing viruses. The endometrial microbiota was studied using molecular biological tests. α-Defensin (DEFa1), fibroblast growth factor 2 (FGF2), and transforming growth factor beta 1 (TGF-β1) in the endometrium were determined by ELISA. Results. Viruses were detected in endometrium 31.3% of the examined women. Herpesviridae viruses accounted for 34%, while Human Papillomavirus — 66%. Lactobacillus spp. most often dominated in endometrial microbiota in both groups (group 1–68% (17/25), group 2–78% (43/55)). The second most common microbial community types were Gardnerella vaginalis and Atopobium vaginae (Fannyhessea vaginae), which accounted for 20% and 15% in groups 1 and 2, respectively. In group 1, the highest viral load was found in endometrial samples with a high concentration of L. iners, as well as upon a decline or absence of Lactobacillus spp. (p < 0.05). The concentration of L. crispatus and L. jensenii was significantly higher in group 2 (p < 0.05). Patients with endometrium-bearing viruses had increased DEFα levels comprising 4.32 ng/ml (0.497; 16.1) compared with patients without endometrium-bearing viruses (0.7 ng/ml (0.7; 20)), as well as decreased levels of TGFb — 2 ng/ml (0.2; 9.8) and 4.54 ng/ml (0;16), respectively (p < 0.05). Conclusions. Viral damage to the endometrium is associated with an increased concentration of L. iners, or with a deficiency or absence of Lactobacillus spp., as well as with an increased level of DEFα, active against viruses, and a decrease in TGF β1, indicating a violation of endometrial tissue homeostasis.

An increased risk of infection with hepatitis B virus (HBV) more often detected by testing for HBsAg remains in healthcare professionals. Hiv-HBc is also considered a reliable HBV marker and is recommended as an “epidemiological” screening for former HBV exposure, but is less commonly used in practice. The aim of the study was to determine the incidence of anti-HBc in groups of unvaccinated and HBV-vaccinated medical workers. The study sample consisted of 1.597 blood serum samples collected from medical workers who underwent primary three-dose hepatitis B vaccination and 46 unvaccinated employees aged 18 years and older from five inpatient and outpatient medical organizations. Blood serum samples were tested for anti-HBs and anti-HBc antibodies using enzyme-linked immunosorbent assay. A comparative analysis for the presence of blood anti-HBc revealed that during the primary hepatitis B vaccination, anti-HBc seroconversion in the vaccinated and unvaccinated cohort was 35.4% and 76.1%, respectively, which is twice as more than in the vaccinated (p < 0.001) subjects. The results of seroconversion in the vaccinated group indicate that the vaccination was carried out upon HBV infection or latent hepatitis B. The lack of seroconversion was noted in 23.9% and in 64.6% of unvaccinated and of vaccinated employees, respectively (p < 0.001). Accordingly, anti- HBc are detected 2.7 times less frequently in vaccinated individuals compared to the unvaccinated cohort. The presence of anti-HBc was not found to depend on the level of humoral immunity. The specific gravity of anti-HBc+ in the groups with anti-HBs < 10 mIU/ml and anti-HBs > 10 mIU/ml is almost the same in both groups — 23.8% and 23.7%, respectively. Distribution of anti-HBс post-immunization was as follows: group 1 (3 months — 5 years); group 2 (6–15 years old) and group 3 (16–23 years old) with and without total anti-HBV antibodies showed the lowest number (5.4% and 3.4%) of individuals with anti-HBs among vaccinated subjects in group 1, which indirectly evidences about the effect of vaccination in preventing infection with the virus in the next 5 years. The study results point at a need for pre-vaccination anti-HBс testing to determine prevalence of infection and identify groups requiring further in-depth HBV testing.

Leptospirosis is an acute zoonotic infection caused by pathogenic bacteria from the genus Leptospira. Leptospirosis creates significant though underdiagnosed public health problems in Africa. The Republic of Guinea (Guinea) is a country in West Africa, its capital is Conakry. The study objective was to assess the prevalence of the leptospirosis in febrile patients in the Republic of Guinea. We analyzed 827 blood serum samples obtained from febrile patients who applied to municipal health services, in the period from 2020 to 2024. RT-PCR was used to test 627 blood serum samples for the presence of genetic material of pathogenic Leptospira spp. Genotyping of positive samples was performed with the help of primers selected for a fragment of the secY gene. As a result of our study, IgG antibodies to Leptospira spp. were detected in 202 blood serum samples, which amounted to 24.4%.154 blood serum samples (18.6%) were positive for IgM to Leptospira spp. In 80 of the 276 positive samples both antibodies (IgG and IgM) were detected, 122 samples contained only IgG, while 74 only IgM. Leptospira spp. DNA was detected in 5 (0.8%) of 657 serum samples tested for the presence genetic markers of pathogenic leptospira. Sanger sequencing was applied to all 5 samples, and for three samples it resulted in successful leptospira genotyping, but it failed for two other samples may be due to insufficient amount of DNA or its degradation. When analyzed according to the BLAST algorithm, the obtained sequences revealed 100% similarity to those of L. kirschneri that was further confirmed by clustering when constructing the phylogenetic tree. Our study revealed high level of antibodies to leptospirosis in febrile patients, which bear witness to the wide spread of this pathogen in the Republic of Guinea. Joint research with international organizations can provide valuable information on the epidemiology of leptospirosis and improve control and prevention of the disease.

Various spectrometry (time-of-flight mass spectrometry, Raman spectrometry) types are used in the identification of microbial strains. Atomic emission spectrometry allows for the evaluation of the elemental sample composition, which can also be used in laboratory practice, because bacterial cells with different biological properties exert unique composition. The aim of the study was to determine the elemental composition of hypermucoid Klebsiella pneumoniae in order to identify AES-markers promising for differentiating various Klebsiella subpopulations. Materials and methods. The elemental composition of 30 Klebsiella pneumoniae strains isolated from the sputum of intensive care unit patients was studied. All Klebsiella strains were isolated from sputum in etiologically significant quantities, followed by verification with “RealBest DNA Klebsiella pneumoniae/Pseudomonas aeruginosa (kit 1)” commercial test system (Vector Best, Russia). The study design was presented as a one-time study: group 1 — hypermucoid K. pneumoniae (n = 12), group 2 — classic K. pneumoniae (n = 18). The hypermucoid phenotype of the strains was determined using the string test. The content of elements was studied using an AES-ISP 9820 atomic emission spectrometer with inductively coupled plasma (Shimadzu, Japan), pre-automated sample preparation using a TOPEX+ (PreeKem Ltd, China). The data are presented as percentages by mass with a 95% confidence interval. The χ² test was used to compare the relative numbers. Differences were considered statistically significant at p < 0.05. Results. In Klebsiella with hypermucoid colony phenotype, the elemental mass fraction was found as follows: nickel — 7.5 times (χ²₍₁₎ = 14.8, p = 0.0001), manganese — 4 times (χ²₍₁₎ = 8.475, p = 0.0036), iron — 2.6 times (χ²₍₁₎ = 10.25, p = 0.0014), potassium — 2 times (χ²₍₁₎ = 67.39, p = 0.0001), sulfur — 1.5 times (χ²₍₁₎ = 33.27, p = 0.0001), copper — 1.4 times (χ²₍₁₎ = 4.784, p = 0.03) higher than that of classical strains. The identified features of the elemental composition indirectly evidence about physiological characteristics of this Klebsiella subpopulation. Conclusion. Inductively coupled plasma atomic emission spectroscopy allowed to identify the elemental composition of slime-forming K. pneumoniae, which makes this method promising for differentiating between “classic” and “hypermucoid” Klebsiella subpopulations. Nickel, manganese, and iron may be considered promising AES-markers.

Lactoflora viewed from associative symbiosis standpoint will allow for a comprehensive study of the various functions of these bacteria that determine the mechanisms of integrative interactions of microbiota with human body. The aim of the study: to search for effective antagonists targeting pathogens that cause oral cavity and periodontal inflammatory diseases based on “friend or foe” microbial recognition. The study involved 19 volunteers. Clinical material samples collected from patients were examined in the Laboratory of Microbiome, Regenerative Medicine and Cell Technologies at the Tyumen State Medical University. The smears from the inflammatory tissues of the oral mucosa were analyzed using standard bacteriological method. Biofilm formation was examined using the modified macrometric method. Metabolite output and “friend or foe” microbial recognition in the oral microsymbiocenosis were carried out according to the method, with its activity not including metabolites-related effect serving as a control. Microsymbionts-related biofilm formation as a universal physiological function was selected as a system-forming factor in microsymbiocenosis establishment. Lactobacillus spp. were chosen as the study object as normobiota and because they are found in both studied biotopes and can serve as a basis for new probiotics. Streptococcus spp., Staphylococcus aureus, Candida аlbicans were chosen as the associative microbiota as the etiological factors of inflammatory diseases in oral cavity and periodontal tissues. It was experimentally proven that the metabolic products of Lactobacillus spp. obtained from the oral cavity and pre-incubated with same biotope Streptococcus spp. (separately with each) significantly increased the activity of biofilm formation of the latter suggesting increased or preserved adaptive capabilities as an indicator of «relevant» microsymbionts for lactobacilli (p < 0.05). Metabolic products derived from Lactobacillus spp., obtained from two study biotopes, pre-incubated with metabolites of Staphylococcus aureus, Candida аlbicans, significantly reduced biofilm-forming activity of pathogens (p < 0.05). A decrease in film-forming activity is a marker of microsymbiont “foreignness” for lactobacilli during formation of bacterial-fungal associations. Lactobacillus spp., isolated from the gastrointestinal tract, are antagonists of Streptococcus mutans, Streptococcus mitis, Streptococcus uberis. And Lactobacillus spp., obtained from the oral cavity, on the contrary, are synergists of such pathogens. The data obtained open up avenues for understanding inter-microbial microsymbiont interactions and can be used both as diagnostic tools and for optimal selection of “candidates” in proposing new probiotics and synbiotics.