Background/Objectives: Epitope-based mRNA vaccines represent a promising strategy for eliciting protective T-cell immunity against SARS-CoV-2 and as well as for non-infectious mRNA-based vaccines. However, how the structural architecture of vaccine constructs (including epitope arrangement, linker composition, signal peptide presence, and the combination of MHC class I and II epitopes) shapes the quality of T-cell responses remains poorly understood. Methods: Ten tandem minigene mRNA constructs (Cons1–10) encoding different combinations of MHC class I and class II epitopes from SARS-CoV-2 proteins (S, N, M, ORF3a) were designed, encapsulated in lipid nanoparticles, and administered to C57BL/6 mice. Immunogenicity was assessed by cytokine profiling (IFN-γ, IL-2, IL-4, IL-10) and T-cell proliferation assays. Protective efficacy was evaluated in K18-hACE2 transgenic mice challenged with SARS-CoV-2. Results: Constructs lacking a signal peptide and enriched in MHC class I-restricted epitopes induced robust Th1 responses and strong CD8+ T-cell proliferation, achieving up to 66% survival following lethal challenge. In contrast, constructs associated with elevated IL-10 and IL-4 production conferred limited protection (11–33%), consistent with functional skewing towards regulatory or Th2-associated immune profiles. Conclusions: These findings establish a direct link between construct design parameters and T-cell polarization quality, and provide a rational framework for next-generation epitope-based mRNA vaccine development.

IntroductionThe mRNA platform has revolutionised vaccine technology by offering a universal, rapid, and easily scalable production process. Two main types of mRNA vectors exist—linear (cap‑dependent) and circular (cap‑independent)—each with distinct advantages. Although both vector types are continuously being improved, a comprehensive comparative analysis of the most efficient existing vectors of each type has been lacking.MethodsWe compared the expression efficiency, protective activity, and therapeutic activity of circular and linear mRNA vectors. Linear vectors were tested in different configurations: containing either N1‑methylpseudouridine or uridine, and capped with either ARCA (m7G(5′)ppp(5′)G) or CleanCap (m7G(5′)ppp(5′)m2G). Circular vectors contained either the commonly used IRES of coxsackievirus B3 or a new IRES of human rhinovirus B6. Expression levels were evaluated using a luciferase reporter assay and target protein expression. Protective activity was assessed through both active immunization (immunogenicity and subsequent SARS-Cov2 challenge) and passive immunization (recombinant antibody production and toxin challenge).ResultsPreliminary luciferase assays showed that modified linear vectors achieved significantly higher expression levels both in vitro and in vivo. A similar, though less pronounced, difference was observed for target protein expression. In active immunization studies, immunogenicity and protective activity of circular vector were equal to those of linear. While for passive immunization model, linear vectors conferred significantly better protection than circular vectors, that correlates directly with their higher protein expression levels observed in vivo.DiscussionDespite the markedly higher expression levels observed with modified linear vectors both in vitro and in vivo we didn`t observe the superiority in immunogenicity or protection in active immunization experiment. At the same time for passive immunization, requiring high expression levels of target protein linear vectors seems to be better choice.

mRNA-based therapeutics represent a highly promising platform for the prevention and treatment of diseases. However, further optimization is required to improve mRNA stability and translational efficiency. The 5' untranslated region (5' UTR) is a critical regulatory element that governs pre-initiation complex assembly and directly influences protein expression levels, making it an important target for rational design. The diverse challenges facing mRNA therapeutics necessitate the development of improved 5' UTR elements adaptable to specific applications. In this study, we evaluated the effects of five different 5' UTR variants, selected based on published data, on firefly luciferase (FLuc) production in cell culture and in an in vivo bioluminescence imaging model in animals. Subsequently, all variants were tested as components of mRNA vaccines against SARS-CoV-2. Our findings demonstrate that the H1.2-TISU and Synth 5' UTRs with mRNA constructs produce increased levels of reporter protein expression in mice, whereas mRNA constructs incorporating the H1.2-TISU 5' UTR demonstrated enhanced humoral immunogenicity compared to the 5' UTR derived from human alpha-globin (HBA) mRNA. Thus, the identified 5' UTRs (H1.2-TISU and Synth) represent promising, in vivo-validated candidates for incorporation into mRNA-based therapeutics and may substantially enhance their efficacy.

Polymicrobial biofilms resistant to antibiotic therapy are often associated with different severe human diseases, including skin and soft tissue injuries, local mucosal and dental infections, post-traumatic and chronic osteomyelitis, and implant-associated infections. A possible treatment option for these challenging infections may be the use of enzybiotics containing bacteriolytic enzymes (or lysins). However, elimination of polymicrobial infections requires an effective combination of enzymes to expand the narrow activity spectrum of individual lysins and to ensure successful treatment. We screened ten bacteriolytic enzymes for their antibacterial and biochemical properties, including effective doses, rate of action, spectrum of action, as well as effects of pH, temperature, and buffer systems on enzymes activity. The selected Gram-negative bacteria-targeting enzyme was further modified with an antimicrobial peptide to improve its stability. This engineered lysin GRC-ML07 was studied in combination with Gram-positive bacteria-targeting enzymes. Our results convincingly demonstrate that combinations of lysins with different substrate specificity and Gram specificity result in synergistic and additive effects against pathogenic bacteria, such as Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacterales. Importantly, this was shown for both planktonic cells and biofilms, including polymicrobial consortia, as combinations significantly decreased bactericidal concentrations of enzymes against Gram-positive and Gram-negative bacteria and improved antibiofilm properties. This novel antibacterial enzybiotic composition was also safe in in vitro experiments.

Background/Objectives: While tick-borne encephalitis virus (TBEV) is genetically relatively conserved, the significant antigenic divergence between its main circulating subtypes hinders the development of broadly effective antiviral treatments and vaccines. Current inactivated TBEV vaccines offer limited cross-protection against heterologous strains, as evidenced by cases among vaccinated individuals in endemic regions. The aim of this study was to design a candidate mRNA vaccine and evaluate the breadth of protective immunity it elicits. Methods: Ten candidate mRNA-PrM/E-LNP vaccines were comparatively evaluated for immunogenicity and protective efficacy in BALB/c mice. Immunogenicity was assessed by measuring antigen-specific IgG titers via ELISA and neutralizing antibody titers against a panel of TBEV strains using a virus-neutralization test. Protective efficiency was determined in a lethal challenge model, where immunized mice were challenged with one of seven distinct TBEV strains. Results: Vaccination with all tested mRNA-PrM/E-LNP candidates conferred 100% survival in mice following a lethal challenge with each of the seven TBEV strains (100 LD50). The construct mRNA-PrM/E—Krasny Yar-8 demonstrated the highest immunogenicity, inducing antigen-specific antibodies with a geometric mean titer (GMT) of 1:6625, as well as the broadest virus-neutralizing activity against both homologous and heterologous TBEV strains in vitro. Conclusions: The mRNA platform represents a promising strategy for developing TBEV vaccines, demonstrating high immunogenicity and cross-protective efficacy against diverse viral strains.

BackgroundDuring the COVID-19 pandemic, adenoviral vector-based Sputnik V vaccine was used to vaccinate the civilian population of 74 countries worldwide. As part of laboratory monitoring of the effectiveness of the Sputnik V vaccine, a decrease in effectiveness was detected against Omicron BA.5 and XBB variants. XBB variant quickly displaced all previously circulating variants, so the antigen composition of the Sputnik V vaccine was changed to the XBB variant.MethodsThe Gam-COVID-Vac XBB (Sputnik V XBB) vaccine was developed, manufactured, and stored by Gamaleya NRCEM (Moscow, Russia). Two open prospective clinical study of the safety, reactogenicity and immunogenicity of the Sputnik V XBB vaccine was conducted in 50 adult participants over 18 years old and 50 adolescent participants 12–17 years old (ClinicalTrials.gov Identifier: NCT06068569 and NCT06068556). Immunogenicity study included ELISA assay for detection glycoprotein S of the Omicron XBB variant and neutralization assay with viable SARS-CoV-2 virus Omicron ХВВ.1.5, ХВВ.1.9.1, ХВВ.1.16, EG.5.1, ВА.2.86, JN.1, KS.1, XFG.3, NY.2 and PY.2 variants.ResultsSafety profile of the Sputnik V XBB vaccine was consistent with the previous formulation, and no new safety concerns were reported. There were no cases of serious AEs. Seroconversion of antigen-specific IgG on day 42 was 100% in adults and 87.5% in adolescents. We showed robust NtAb response to circulating SARS-CoV-2 variants (ХВВ.1.5, ХВВ.1.9.1, ХВВ.1.16, EG.5.1, ВА.2.86, JN.1, KS.1, XFG.3, NY.2 and PY.2) in vaccinated adults and adolescents, seroconversion rate of NtAb against any circulating variant was 96% in adults and 94% in adolescents.ConclusionThe results of the clinical trials demonstrated a favorable safety profile and a high level of immunogenicity of Sputnik V XBB in adults and adolescents.Clinical Trial RegistrationClinicalTrials.gov, identifiers NCT06068569 and NCT06068556.

This study introduces a novel five-component LNP formulation incorporating ionizable lipid combination ALC-0315 and SM-102 with cholesterol, DSPC, and DMG-PEG-2000. LNP-5 was designed for efficient delivery of mRNA and saRNA. We employed a Design of Experiments approach and microfluidics to optimize the formulation parameters, achieving high encapsulation efficiencies (>80%) for both RNA types. Physicochemical characterization by dynamic light scattering confirmed a controlled size (80-120 nm) and low polydispersity (<0.2). The morphology of investigated LNP-5 was studied by STEM in comparison with LNP-4 (with SM-102 or ALC-0315). Notably, LNP-5 demonstrated superior in vivo mRNA delivery efficiency and enhanced target protein expression compared to conventional LNP-4. The study compares the in vivo performance of mRNA and saRNA platforms formulated in novel LNP-5 lipid nanoparticles containing dual ionizable lipids. While LNP-mRNA delivery provides rapid and intense but transient reporter expression, LNP-saRNA mediates a gradual increase in protein production, peaking at day 7 post-injection. Quantitative RT-PCR analysis reveals superior saRNA persistence and a 4.3-fold higher copy number relative to mRNA by day 7, confirming active intracellular replication of the saRNA platform. These findings demonstrate that LNP-5 efficiently delivers both platforms, with saRNA offering a more sustained therapeutic window due to its self-amplifying properties.

The receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein remains a central target for antiviral drug development. Recent in silico studies have revealed an expansion of amyloidogenic regions within the RBD of the Omicron variant, raising the possibility that amyloid-prone peptide fragments could modulate Spike function or host-virus interactions. In this study, we combined experimental assays with multiscale computational modeling to systematically characterise two short RBD-derived peptides: Pep-2 (YFPLQSYGFQ) from the ancestral Wuhan strain and Pep-3 (YFPLRSYSFR) from the Omicron BA.1 variant, the latter being predicted to have higher amyloidogenic potential. Cell-based assays demonstrated that neither peptide exhibited intrinsic cytotoxic or cytostatic effects on human lung fibroblasts or A549 lung adenocarcinoma cells at physiologically relevant concentrations, whereas significant cytotoxicity was observed in Vero E6 cells. In infection models with the B.1.1.1 (Wuhan) and BA.1 (Omicron) variants, the peptides unexpectedly enhanced virus-induced cytopathic effects at lower concentrations but inhibited viral infection at higher concentrations, indicating to a dose-dependent modulatory role for these short amyloidogenic RBD fragments. Fluorescence spectroscopy measurements did not detect the formation of stable thioflavin-T-positive amyloid fibrils. Computational analyses revealed that both peptides interact with the Spike RBD via multiple energetically favorable yet spatially heterogeneous modes, mostly outside the ACE2-binding site. Moreover, their predicted binding affinities for the ACE2 receptor were comparable, suggesting an additional route of interaction via the host receptor. Collectively, our findings demonstrate that these short amyloidogenic RBD-derived peptides exert a complex antiviral profile, with their interactions with both viral and host factors potentially shaping infection outcomes. This highlights the importance of spatially targeted and conformationally constrained peptide designs to effectively harness amyloidogenic features for antiviral therapy.

Introduction. Currently, HIV infection remains a global public health issue. Border areas may be significant in the context of the HIV epidemic due to the instability of the population composition and constant migration flows, which, in turn, may affect the epidemic situation of several border states. This study aimed to analyse current trends of HIV infection in the border region of Russia on the example of the Belgorod region. Materials and methods. The main HIV infection indicators: incidence, prevalence, mortality and lethality, testing and therapy coverage and its success were analysed. Also, we analysed sociodemographic and clinical-epidemiological characteristics among newly diagnosed HIV-infected patients; social status in relation to labour employment among all people living with HIV (PLWH) and the rates of testing and detection of HIV infection among foreign citizens. The data were obtained between 2016–2024. Quantitative data were assessed for normal distribution using the Kolmogorov–Smirnov test. The χ² test and the Spearman correlation coefficient (r) were employed to statistically evaluate the differences between the proportions. Subsequently, the statistical differences were assessed using the relevant criteria Results. The data obtained show a significant downward trend in HIV incidence and upward trend in prevalence. The identified moderate upward trend in mortality, together with an analysis of the causes of death among people living with HIV (PLWH), highlight the necessity for multidisciplinary clinical monitoring of the aging cohort of PLWH. The coverage of HIV testing and therapy increased over time. For the first time, 95% therapy coverage was noted. Analysis of CD4-cell indicators revealed significant differences between subgroups by age and route of infection. A decrease in the proportion of unemployed in the PLWH population was noted. Moreover, the identified increase in the detection of HIV infection among the working population substantiates the importance of the existing workplace testing programs, as well as their continuation and expansion. The proportion of foreign citizens tested for HIV correlated with the number of tests performed (r = 0.883, p = 0.002): an increase in the coverage of foreign citizens with HIV-1 testing was accompanied by an increase in the proportion of detected HIV cases. It is important to take into account that a significant correlation does not exclude the influence of parameters not studied; it can be assumed that foreign citizens currently remain under-tested and the number of HIV-positive individuals may be somewhat underestimated. Conclusions. A comprehensive study of HIV infection trends in a border region of Russia was conducted, using the Belgorod Region as an example. The results are of direct value to health authorities in the Belgorod region and can be used for planning and adjusting regional programs to combat HIV infection.

Introduction. Tick cell lines are widely used to study the biology of ticks and tick-borne pathogens, especially viruses. Most of the cell cultures currently available have been obtained from tick embryonic cells and can be infected with viruses. The HAE/CTVM8 cell line was obtained from Hyalomma anatolicum ticks and is often used for isolation of novel viruses. The aim of the work is to study the HAE/CTVM8 cell line using high-throughput sequencing in order to search for viruses in it. Materials and methods. The HAE/CTVM8 cell culture fluid was ultracentrifuged. The resulting pellet was used for high-throughput sequencing after RNA extraction, reverse transcription reaction, and synthesis of the second strand. The resulting reads were filtered by length and quality in the Trimmomatic program, after which the contigs were assembled using the SPAdes program and analyzed for the presence of viral sequences. The final assembly of the virus genome was carried out in the Ugene program. Sequence alignment was performed by the MAFFT program. The phylogenetic trees were constructed using the IQ-TREE program. Results. We have identified the persistence of one virus, Liman tick virus (LMTV), in HAE/CTVM8 cell culture. Phylogenetically LMTV belongs to the Chuviridae – novel family, that consists of viruses detected by high-throughput sequencing, the virological characteristics of which are currently unknown. Conclusion. The obtained information is of significant importance when utilizing HAE/CTVM8 cell culture in scientific research and during the process of isolating new viruses. Our study shows that this cell line with persistent LMTV is a ready-to-use system for studying Chuviridae reproduction

With the rise of antibiotic resistance, there is a need for innovative drugs with alternative mechanisms of action. Endolysins meet most of the requirements, but are limited for parenteral use due to their short blood circulation time. In this article, a number of modifications to the ML06-engineered, lysin-targeting Gram-negative bacteria are proposed to improve its pharmacokinetic parameters. Genetic modification with albumin-binding and dimerization domains ranging from 11–12 aa to 45 aa at both the C- and N-termini has resulted in six enzymes that do not exhibit critically reduced antibacterial properties in vitro, and in the case of the ABP1 modification, an improved antibacterial rate and spectra of enzymes. The ML06-ABP1, ML06-ABP2, and HDD-ML06 modifications also retained activity in blood serum and significantly increased serum stability. A pharmacokinetic study of the three modifications in mice showed that ML06-ABP2 and HDD-ML06 have a prolonged half-life compared to the ML06 half-life. In addition, the serum Cmax concentration for HDD-ML06 (22.2 μg/mL) was significantly increased compared to ML06 (Cmax < 5 μg/mL). Our results allow for a comparison of the different types of modifications that are useful in the development of parenteral antibacterials.

Background. Despite the availability of several licensed inactivated vaccines, the development of new vaccines against the Tick-borne encephalitis virus (TBEV) remains an important task, especially in countries endemic to this pathogen. The risk of infec-tion with TBEV increases every year because of increase in the number of ticks, the emergence of tick carriers into new territo-ries, and active human activity in areas of TBEV natural foci. Annual reports of vaccination failures have prompted us to search for approaches to creating a new vaccine. Objectives. In our study, we used the same PrM and E antigens to produce three vac-cine candidates against tick-borne encephalitis (TBE): 1) a live attenuated YFV 17DD-UN vaccine strain, 2) recombinant adenovi-rus (rAd) vectors, and 3) mRNA encapsulated in lipid nanoparticles (LNP). Methods. We generated and assessed the immunogen-icity and protective efficacy of three candidate TBEV vaccines based on mRNA, simian adenovirus type 25, and a chimera of the YFV 17DD-UN attenuated strain. Results. Analysis of the virus-neutralizing titers in the blood sera of immunized mice revealed a statistically significant difference among the three candidate vaccines. The immunogenicity and protective efficacy of the can-didate mRNA-LNP vaccine were found to be higher than those of the other two vaccines. Conclusions. Based on the results of our study, it can be concluded that the mRNA-based platform is more promising for the creation of a vaccine against TBEV. ### Competing Interest Statement The authors have declared no competing interest.

Identifying population groups at greatest risk of hepatitis C virus (HCV) infection is essential for targeting screening and treatment. We analyzed the seroprevalence of antibodies to HCV (anti-HCV) and HCV RNA in serum samples from 37,291 conditionally healthy volunteers collected between 2018 and 2022, and from 4764 individuals sampled in 2008, totaling 42,055 participants. In 2018–2022, anti-HCV prevalence varied by region, ranging from 1.1 to 1.4% in Belgorod, Moscow, and St. Petersburg to 1.8–2.1% in Dagestan, Tatarstan, Novosibirsk, Tyva, and southern Yakutia, and reaching 3.4–5.2% in Khabarovsk and the Arctic zone of Yakutia. In 2008, prevalence in Moscow, Rostov, Sverdlovsk, Tyva, and Yakutia ranged from 1.7% to 3.3%. A significant decline over time was observed: from a mean of 2.6 ± 0.5% in 2008 to 1.9 ± 0.1% in 2018–2022 (p < 0.01). In recent years, men were more frequently anti-HCV-positive than women (2.5 ± 0.2% vs. 1.5 ± 0.2%, p < 0.01), whereas no sex differences were noted in 2008. The age of a sharp prevalence increase shifted from the 20–29 cohort in 2008 to the 30–39 cohort in 2018–2022. Based on the demographic structure, we estimate ~3.23 million anti-HCV carriers in Russia. HCV RNA was detectable in only one-third of seropositive individuals, identifying them as candidates for antiviral therapy. Thus, in contemporary Russia, men aged over 30 years have the highest risk of HCV infection and should be prioritized for targeted screening.

Identifying population groups at greatest risk of hepatitis C virus (HCV) infection is essential for targeting screening and treatment. We analyzed the seroprevalence of antibodies to HCV (anti-HCV) and HCV RNA in serum samples from 37,291 conditionally healthy volunteers collected between 2018 and 2022, and from 4,764 individuals sampled in 2008, totaling 42,055 participants. In 2018–2022, anti-HCV prevalence varied by region, ranging from 1.1–1.4% in Belgorod, Moscow, and St. Petersburg to 1.8–2.1% in Dagestan, Tatarstan, Novosibirsk, Tyva, and southern Yakutia, and reaching 3.4–5.2% in Khabarovsk and the Arctic zone of Yakutia. In 2008, prevalence in Moscow, Rostov, Sverdlovsk, Tyva, and Yakutia ranged from 1.7% to 3.3%. A significant decline over time was observed: from a mean of 2.6 ± 0.5% in 2008 to 1.9 ± 0.1% in 2018–2022 (p < 0.01). In recent years, men were more frequently anti-HCV–positive than women (2.5 ± 0.2% vs 1.5 ± 0.2%, p < 0.01), whereas no sex differences were noted in 2008. The age of sharp prevalence increase shifted from the 20–29 cohort in 2008 to the 30–39 cohort in 2018–2022. Based on demographic structure, we estimate ~3.23 million anti-HCV carriers in Russia. HCV RNA was detectable in only one-third of seropositive individuals, identifying them as candidates for antiviral therapy. Thus, in contemporary Russia, men over 30 years have the highest risk of HCV infection and should be prioritized for targeted screening.

Background/Objectives: Tuberculosis (TB) remains the leading cause of death from a single infectious agent worldwide. In line with the World Health Organization’s (WHO) goal to end TB by 2035, the rapid development and clinical implementation of new, effective vaccines is urgently needed. To support global TB control efforts, we developed a novel candidate subunit multistage vaccine. Methods: This vaccine incorporates multiple Mycobacterium tuberculosis antigens expressed during both dormant and active stages of infection, fused into a single recombinant protein (ESAT6-CFP10-Ag85A-Rv2660c-Rv1813c). The antigen was encapsulated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles along with the pattern recognition receptor (PRR) agonists monophosphoryl lipid A (MPLA) and muramyl dipeptide (MDP), which function as adjuvants. Results: Using a mixed intramuscular/nasal prime-boost regimen, the vaccine elicited a mixed Th1/Th17 cell-mediated immune response, as well as a robust humoral response characterized by sustained systemic IgG (lasting at least one year) and prominent local secretory IgA. The vaccine demonstrated protective efficacy as a prophylactic booster following BCG priming in both murine and guinea pig models and was also effective in a therapeutic setting in a murine infection model. Conclusions: The results of this study provide empirical evidence that multistage tuberculosis vaccines represent a promising strategy for achieving global TB control.

BackgroundTick-borne encephalitis (TBE) is a significant public health challenge in Russia. Vaccination is one of the most effective measures to control TBE. The aim of our study was to assess the state of anti-TBE virus population immunity, including artificial post-vaccine and natural post-infection immunity, in the context of characteristics of the epidemic process in Russia.Materials and methodsDuring the period from 2018 to 2020, we studied 28,395 conditionally healthy volunteers from various regions of Russia, without age and gender restrictions. Blood serum samples were tested for anti-TBE virus IgG antibodies. All volunteers completed questionnaires to collect demographic data, information about residence, TBE vaccination, and tick bites.ResultsOur study included participants from non-endemic (Moscow and the Republic of Dagestan) and endemic regions (Moscow Region, St. Petersburg, Leningrad Region, Novosibirsk Region, Khabarovsk Region). In regions with the highest protection against TBE, such as Novosibirsk Region and Khabarovsk Region, the proportions of individuals with seropositive and protective antibody titers were below 45% and 35%, respectively. The lowest rate of protective immunity was found among children (25.4% in Novosibirsk Region and 22% in Khabarovsk Region) and those aged 60 and older (27.3% and 25.1%, respectively). Situation was even more challenging in St. Petersburg and Leningrad Region, where the rate of protective antibody titers ranged from 4.3% to 8.7%. The highest vaccination coverage was found among volunteers from Novosibirsk Region and Khabarovsk Region: 32.5% and 27.4%. In St. Petersburg and Leningrad Region, vaccination coverage was ranged from 10.4% to 11.3%, while in other regions it was below 6%. The rates of post-vaccine protective immunity were 63.1% in Khabarovsk Region, 71.6% in Novosibirsk Region and up to 50% in other regions. The rates of post-infection immunity were 33.4% in Novosibirsk Region, 42.4% in Khabarovsk Region and below 12% in other regions.ConclusionsOur results demonstrated diversity of population immunity level and structure in different regions of Russia. The analysis showed that study participants are at risk of TBE infection, especially high in endemic regions, due to insufficient level of population immunity, vaccination coverage, and protective post-vaccine immunity.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic tick-borne virus causing severe human disease and representing a significant public health threat. The absence of licensed vaccines and specific antiviral therapies highlights the need for well-characterized experimental models suitable for studying viral pathogenicity and evaluating medical countermeasures. In this study, we established and characterized an integrated in vitro and in vivo platform for CCHFV research. Virus propagation was optimized by comparing Vero E6 and SW-13 cell lines. SW-13 cells supported efficient CCHFV replication resulting in pronounced virus-induced cytopathic effects, whereas no detectable cytopathic effects were observed in Vero E6 cells. Virus titers determined by cytopathic effect based endpoint dilution and antigen ELISA coincided, supporting the use of SW-13 cells for virus stock preparation. Using virus stocks generated in SW-13 cells, interferon-deficient mice were infected with different doses of CCHFV to assess dose-dependent pathogenicity. Infection resulted in severe disease and high mortality across all tested doses. Based on survival analysis, a dose of 10 TCID50; was selected for further characterization, which revealed progressive weight loss and high viral loads in peripheral organs. Overall, this study establishes a robust IFN knockout mouse model suitable for studying CCHFV pathogenicity, comparing viral genovariants, and evaluating vaccines, antiviral compounds, and neutralizing antibodies. ### Competing Interest Statement The authors have declared no competing interest. Ministry of Health of the Russian Federation, https://ror.org/01p8ehb87

Introduction. The problem of vaccine-preventable infections requires assessing the state of herd immunity through serological monitoring. The aim. To study the epidemiological features of measles, rubella and mumps and to estimate their seroprevalence in the last decade in Moscow. Materials and methods. Forms of federal statistical observation; State reports «On the state of sanitary and epidemiological well-being of the Moscow population»; official EMISS data for 2012–2023 were used to conduct a retrospective analysis of incidence. Blood serum samples (n = 7458) from healthy individuals stratified by age were tested for the presence of IgG antobodies to measles, rubella and mumps using the ELISA. Statistical data processing was performed using Microsoft Excel and SPSS Statistics v.27 (IBM). Results. The analysis of epidemiological situation in Moscow in 2012–2023 revealed the presence of multidirectional trends: wave-like increase in the incidence of measles, stabilization of rubella cases registration and unstable incidence of mumps with an upward trend. A high prevalence of IgG antibodies to rubella virus was determined, preventing the spread of infection among the population. The formed level of herd immunity to mumps does not allow reducing the incidence to sporadic cases. The observed trend of increasing measles incidence can be explained by the accumulation of non-immune individuals among the population. Conclusion. The significant proportion of seronegative individuals indicate the necessity to adjust vaccination prevention tactics and implement measures for mopping-up and catch-up immunization of the population against measles and mumps, especially in risk age groups.

The development of new and effective antibacterials for pharmaceutical or cosmetic skin care that have a low potential for the emergence and expansion of bacterial resistance is of high demand in scientific and applied research. Great hopes are placed on alternative agents such as bactericidal peptidoglycan hydrolases, depolymerases, etc. Enzybiotic-based preparations are being studied for the treatment of various infections and, among others, can be used as topical formulations and dressings with protein-polysaccharide complexes. Here, we investigate the antibiofilm properties of a novel enzybiotic cocktail of phage endolysin LysSi3 and bacteriocin lysostaphin, formulated in the alginate gel matrix and its ability to control the opportunistic skin-colonizing bacteria Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, as well as mixed-species biofilms. Our results propose that the application of SiL-gel affects different components of biofilm extracellular polymeric substances, disrupts the matrix, and eliminates the bacteria embedded in it. This composition is highly effective against biofilms composed of Gram-negative and Gram-positive species and does not possess significant cytotoxic effects. Our data form the basis for the development of antibacterial skin care products with a gentle but effective mode of action.

The COVID-19 pandemic has made it possible to study many aspects of the laboratory diagnosis of this infection, including the assessment of the viral load and viral activity of SARS-CoV-2. The review presents data on modern views on the virological characteristics of the SARS-CoV-2 virus, however, many aspects of this problem remain debatable. The issues of the relationship between the level of viral load and the clinical profile of patients are proposed for discussion, and the possibility of using the obtained data in practical healthcare is discussed. The control of viral load in patients with COVID-19 has not only a certain clinical significance, but is also undoubtedly important in the epidemiological aspect. Monitoring of a number of SARS-CoV-2 parameters. will allow to solve practical problems in the context of the ongoing pandemic.