A novel skin test for an in vivo assessment of SARS-CoV-2-specific T-cell immunity was developed using CoronaDermPS, a multiepitope recombinant polypeptide encompassing MHC II–binding CD4+ T-cell epitopes of the SARS-CoV-2 structural proteins (S, E, M) and full length nucleocapsid (N). In silico epitope prediction and modeling guided antigen design, which was expressed in Escherichia coli, was purified (>95% purity) and formulated for intradermal administration. Preclinical evaluation in guinea pigs, mice, and rhesus macaques demonstrated a robust delayed type hypersensitivity (DTH) response at optimal doses (10–75 µg), with no acute or chronic toxicity, mutagenicity, or adverse effects on reproductive organs. An integrated clinical analysis included 374 volunteers stratified by vaccination status (EpiVacCorona, Gam-COVID-Vac, CoviVac) prior to COVID-19 infection (Wuhan/Alpha, Delta, Omicron variants), and SARS-CoV-2–naïve controls. Safety assessments across phase I–II trials recorded 477 adverse events, of which >88% were mild and self-limiting; no severe or anaphylactic reactions occurred. DTH responses were measured at 24 h, 72 h, and 144 h post-injection by papule and hyperemia measurements. Overall, 282/374 participants (75.4%) exhibited a positive skin test. Receiver operating characteristic analysis yielded an overall AUC of 0.825 (95% CI: 0.726–0.924), sensitivity 79.5% (95% CI: 75.1–83.3%), and specificity 85.5% (95% CI: 81.8–88.7%), with comparable diagnostic accuracy across vaccine, and variant subgroups (AUC range 0.782–0.870). CoronaDerm-PS–based skin testing offers a simple, reproducible, and low-cost method for qualitative evaluation of T-cell–mediated immunity to SARS-CoV-2, independent of specialized laboratory equipment (Eurasian Patent No. 047119). Its high safety profile and consistent performance across diverse cohorts support its utility for mass screening and monitoring of cellular immune protection following infection or vaccination.

The aim of this work was to obtain and study antiviral properties of a drug for intranasal use containing yeast double-stranded RNA (dsRNA) and recombinant human interferon alpha-2b (IFN-α2b) incorporated into a delivery system (molecular construct). Material and methods. Molecular constructs carrying IFN-α2b and dsRNA were obtained by our original method. For present study, the samples of intranasal dosage forms of three formulations were chosen: 50 µg of dsRNA and 10, 50 or 100 IU of IFN-α2b per one dose. The in vitro antiviral activity of the composition preparations was determined by inhibition of cytopathic effect (CPE) of murine encephalomyocarditis virus (EMCV), Columbia strain, in mouse L929 and L-68 cell cultures. The in vivo protective properties of the preparations were studied in white outbred ICR male mice intranasally infected with 10 lethal dose, 50 %, of influenza virus strain A/Aichi/2/68 (H3N2). The protection coefficient was calculated by average life expectancy and death of animals. Results and discussion. All the composition preparations used in this study demonstrated the ability to inhibit the destructive effect of the test virus and increase the number of viable cells in L929 and L-68 cultures. The enhancement of the protective effect was observed with increasing IFN-α2b content in the drug formulation. The greatest antiviral activity was shown for the preparation containing 50 µg of dsRNA and 100 IU of IFN-α2b per dose. A composition preparation of the same formulation, administered intranasally three times at a dose of (2.5 mg dsRNA and 5000 IU IFN-α2b)/kg according to the therapeutic and prophylactic regimen, protected 50 % of animals from death, which was not observed in a group administered with dsRNA alone. IFN-α2b used at a dose equivalent to its content in the composition preparation had a similar but less pronounced effect. Conclusions. The results of the in vitro and in vivo experiments have confirmed the fact that combining interferon and its inducer enhances the antiviral effect of the composition drug compared to that of its components used separately. The data obtained testify to the prospects for the development of intranasal forms of antiviral drugs using a combination of interferon and dsRNA incorporated in a delivery system.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional cytokine with therapeutic applications in oncology and neurodegenerative diseases. However, its clinical use is limited by the high cost of eukaryotic production systems. Here, we developed a cost-effective Escherichia coli-based platform for high-yield production of biologically active recombinant human GM-CSF (rhGM-CSF) using SUMO fusion technology. The engineered pET-SUMO-GM plasmid enabled expression of a 33 kDa fusion protein, accounting for 23-25% of total cellular protein, though it primarily accumulated in inclusion bodies. A multi-step purification strategy-including nickel affinity chromatography, Ulp protease cleavage, and hydrophobic chromatography-yielded >99.5% pure rhGM-CSF. In vitro functional assays demonstrated equivalent activity to the WHO international standard (ED50: 0.045 vs. 0.043 ng/mL in TF-1 cell proliferation). In vivo, the preparation significantly restored neutrophil counts (3.4-fold increase, p ≤ 0.05) in a murine cyclophosphamide-induced myelosuppression model. Our results establish a scalable, prokaryotic-based method to produce functional rhGM-CSF, overcoming solubility and folding challenges while maintaining therapeutic efficacy. This approach could facilitate broader clinical and research applications of GM-CSF, particularly in resource-limited settings.

West Nile fever is an infectious disease caused by the West Nile virus (WNV), which is transmitted by mosquitoes. Epidemiological surveillance confirms the potential risk of WNV infection in human populations. The lack of specific antiviral therapeutics and vaccines against WNV underscores the urgent need to develop effective therapeutic approaches. In this study, a recombinant chimeric monoclonal antibody (mAb) 900 was generated based on the broadly neutralizing and protective murine mAb 9E2. The antigen-binding regions of the murine mAb were fused with the constant domains (CH2-CH3) of human IgG1. Two key amino acid clusters, M252/S254/T256 and H433/N434, were introduced into the CH2-CH3 domains to enhance the affinity of mAb 900 for the neonatal Fc receptor (FcRn). The engineered mAb 900 was produced in CHO cells and purified to high homogeneity. Biophysical characterization confirmed its stability and correct dimeric assembly. Comparative analysis demonstrated that mAb 900 retained the high antigen-binding affinity and potent virus-neutralizing activity of its murine predecessor. Most importantly, mAb 900 demonstrated significant protective efficacy in a lethal mouse model of WNV infection. These results establish the proof of concept for mAb 900 as a promising candidate for further preclinical development against WNV infection.

Vitamin D3 transporter (DBP) is a multifunctional protein. Site-specific deglycosylation results in its conversion to group-specific component protein-derived macrophage activating factor (GcMAF), which is capable of activating macrophages. It has been shown that depending on precursor conversion conditions, the resulting GcMAF activates mouse peritoneal macrophages towards synthesis of either pro- (IL-1β, TNF-α—M1 phenotype) or anti-inflammatory (TGF-β, IL-10—M2 phenotype) cytokines. The condition for the transition of the direction of the inflammatory response of macrophages when exposed to GcMAF is the initial glycosylated state of the population of DBP molecules and the associated effective deglycosylation of DBP by β-galactosidase. In vivo experiments with GcMAF exhibiting anti-inflammatory properties on models of induced arthritis in mice and cystitis in rats indicate a significant anti-inflammatory effect of the macrophage activator. The feasibility of unidirectional induction of anti-inflammatory properties of macrophages allows creation of combined therapeutic platforms where M2 macrophages are among the key therapeutic components.

Aim of the study: to compare the antitumor efficacy and immunogenicity of vaccines with the same antigens but different adjuvants: Ridostin Pro or Poly(I:C); to evaluate the effect of Ridostin Pro and Poly(I:C) on the cytokine profile of serum and the immunophenotype of mouse spleen cells. Material and Methods. To evaluate the antitumor efficacy of vaccines with different adjuvants, two transplantable tumor lines were used: melanoma B16-F10 and EG 7-OVA lymphoma (expressing ovalbumin) for C57BL/6 mice. Against melanoma B16-F10, vaccination with the peptide TRP2 180–188 with the studied adjuvants was performed in a mixed (preventive/therapeutic) and therapeutic regimens. Ovalbumin with adjuvants was vaccinated against EG 7 lymphoma in a therapeutic mode. The immunogenicity of vaccines with different adjuvants in mice without tumors was evaluated by the ELISPOT method. In this case, the peptide TRP2 180–188 and the protein ovalbumin also served as antigens. The cytokine profile of blood serum and changes in the immunophenotype of mouse spleen cells after administration of Ridostin Pro or Poly(I:C) were studied using flow cytometry. Results. In the B16-F10 model, vaccination in a mixed mode protected mice from tumor formation, and the mice lived for more than 100 days. For B16-F10 and EG 7, vaccination in the therapeutic mode led only to inhibition of tumor growth. Ridostin Pro and Poly(I:C) showed a similar ability to develop specific immunity to the peptide TRP2 and ovalbumin. Ridostin Pro increased cytokine levels in the blood serum of mice more strongly than Poly(I:C). Both drugs caused similar changes in the immunophenotype of spleen cells, but Ridostin Pro increased the number of CD 69+ T cells more strongly than Poly(I:C). Conclusion. The comparison of two drugs as adjuvants for antitumor vaccines showed that the domestic drug Ridostin Pro did not inferior in effectiveness to Poly(I:C) on mouse models. In this regard, Ridostin Pro can be considered as a promising adjuvant for antitumor vaccines and deserves further study.

Novel coronavirus disease 2019, caused by the SARS-CoV-2, initiate humoral and cellular immune responses against diverse virus antigens. The assessment of SARS-CoV-2-specific is mainly carried out in routine practice by determining specific immunoglobulins. However, high variability in S-protein structure in new genovariants of SARS-CoV-2 virus and the lack of correlation between specific antibodies and CD8+ T-lymphocytes underlie false negative responses, and mass assessment of cellular immunity is complicated due to the complexity of applying ELISPOT and cytofluorometry techniques. To solve this issue, a diagnostic method was developed for assessing SARS-CoV-2-specific cellular immune response, which is based on a skin test followed by evaluating a delayed-type hypersensitivity reaction involving antigen-specific memory T-lymphocytes. A diagnostic preparation CoronaDerm-PS is based on Cord_PS, which is a hybrid recombinant protein consisting of parts of the SARS-CoV-2 structural proteins S, M, N, E. The specific activity of this chimeric antigen was analyzed in cultured T-lymphocyte activation test by assessing interferon-γ production using cytofluorometry. To investigate the chimeric antigen specific activity, a preclinical safety study with CoronaDerm-PS preparation in experimental animals was conducted. A dose-dependent developing skin reaction was observed in 90–100% of guinea pigs vaccinated by EpiVacCorona, CoviVac, Gam-COVID-Vac, which confirms a potential for assessing post-vaccination cellular immunity using CoronaDerm-PS preparation. Upon this, the presence of functionally active T-cell-antigenic epitopes in the recombinant polypeptide allows to evaluate SARS-CoV-2-specific response illustrated by detected response after Gam-COVID-Vac (S-protein) and EpiVacCorona (N-protein) vaccination. Thus, a skin test based on CoronaDerm-PS preparation may be a promising diagnostic tool for rapid mass screening requiring no specialized laboratory equipment for assessing populational SARS-CoV-2-specific immunity. Such a test is distinguished by advantages such as ease of analysis, high specificity and sensitivity. The final decision-making on using this test in a real-world practice may achieved after conducting further clinical safety and effectiveness trials.

Background. Polysaccharides are known to possess adjuvant properties, they are biodegradable, safe, and are of low-labor production. In this regard, the development of polysaccharide-based adjuvants is an urgent task.The aim. To develop a method for obtaining mannans from the cell walls of Saccharomyces cerevisiae yeast and to study their adjuvant properties using subunit vaccine model.Materials and methods. The preparation of mannans was obtained from the Saccharomyces cerevisiae yeast by enzymatic and alkaline hydrolysis. Its adjuvant properties were assessed in BALB/c mice immunized with the recombinant receptor-binding domain (RBD) of the SARS-CoV-2 (S) protein (Delta (B.1.617.2)). The titers of specific antibodies in the blood sera were determined by ELISA assays using the recombinant RBD (Wuhan-Hu-1 and Delta), and the recombinant (S) protein (Wuhan-Hu-1, Delta and Omicron) as antigens. The titers of virus-neutralizing antibodies were determined using virus-neutralization tests with the SARS-CoV-2 virus strains Wuhan – hCoV19/Australia/VIC01/2020 (Wuhan-Hu-1), Delta – hCoV-19/Russia/PSK-2804/2021 (Delta (B.1.617.2)), and Omicron 1 – hCoV-19/Russia/Moscow171619-031221/2021 (Omicron (B.1.1.529)).Results. The developed scheme allowed for obtaining up to 200 mg of mannans from 10 g of yeast cell debris. Double, with a two-week interval, immunization with RBD (50 μg) in combination with mannans (40 μg and 10 μg) induced the production of specific antibodies in titers from 1:2477330 to 1:188360. The titer of virus-neutralizing antibodies to the Delta – hCoV-19/Russia/PSK-2804/2021 was 1:485 (40 μg of mannans per mouse).Conclusions. We developed a scheme for obtaining a low-toxic preparation of mannans from the Saccharomyces cerevisiae yeast. The highest adjuvant activity was achieved when using mannans at the dose of 40 µg per mouse. Blood sera obtained from the immunized animals neutralized both homologous and heterologous SARS-CoV-2 strains.

Background. Adjuvant is necessary for enhancing the efficacy of cancer peptide vaccines. Our previous work has demonstrated the efficacy of TRL-3 agonists, which include Poly(I:C) and Ridostin Pro, as part of peptide neoantigen vaccines against murine melanoma B16-F10. Aim. To evaluate the antitumor efficacy of Ridostin Pro or Poly(I:C) against murine lymphoma E.G7-OVA. Materials and methods. The study was performed on C57Bl / 6 mice with subcutaneously transplanted E.G7-OVA lymphoma containing the complete chicken ovalbumin sequence. The antitumor effects of Ridostin Pro and Poly(I:C) were evaluated in monotherapy as well as in vaccines containing chicken ovalbumin in addition to the adjuvant. The antitumor effect of Ridostin Pro and Poly(I:C) was evaluated when used in different vaccination regimens: in one case treatment was started after tumour transplantation and in the other case before tumour transplantation. The criteria of antitumor response were inhibition of tumour growth, increased survival of mice and cure. Results. Ridostin Pro and Poly(I:C) both as part of the vaccine and when administered without ovalbumin increased the percentage of tumour growth inhibition and survival of mice with E.G7-OVA lymphoma. In a regime where vaccination with ovalbumin and Ridostin Pro or Poly(I:C) was started before tumour transfection, a complete cure of the mice was shown. Conclusion. Ridostin Pro and Poly(I:C) enhance the antitumor effect of a peptide vaccine against E.G7-OVA lymphoma.

To increase the effectiveness and immunogenicity of modern vaccines, especially subunit ones, it is required to use adjuvants. Polysaccharides, due to their safety and biocompatibility, are desirable candidates for the creation of vaccine adjuvants. The aim of our study was to develop a method for obtaining beta-Glucans from the yeast Saccharomyces cerevisiae cell wall, and evaluate their adjuvant properties. The high purity and non-toxicity of the resulting preparation was achieved by using enzyme complexes of cellulase and protease in combination with ultrasound (22 kHz) at the purification stage. The developed scheme allows for the yield of beta-Glucans up to 2 g from 100 g of the biomass of wet cells. The adjuvant properties of beta-Glucans were studied in 50 male BALB/c mice, weighing 16–18 g. Immunization was performed twice, with a 14-day interval, intramuscularly, 200 μl per animal. The recombinant receptor-binding domain (RBD) of the surface S protein of the SARS-CoV-2 virus (Wuhan-Hu-1 and B.1.617.2 (Delta)) was used as an antigen, at a dose of 50 μg per animal. A positive control group was administered with the antigen combined with aluminum hydroxide. As a negative control, mice injected with the saline solution were used. The titers of specific antibodies in the blood sera were determined by ELISA assays. RBD (Wuhan-Hu-1 and Delta), and S protein (Wuhan-Hu-1, Delta and Omicron) were used as antigens. The titers of virus-neutralizing antibodies were measured in neutralization tests using SARS-CoV-2 virus strains Wuhan-Hu-1, Delta (B.1.617.2) and Omicron (B.1.1.529). The results of the study have shown that beta-Glucans have the ability to enhance the production of specific and virus-neutralizing antibodies in mice immunized with RBD. The titers of specific and virus neutralizing antibodies are comparable to their levels in the group immunized with RBD and Al(OH)₃. It has been found in the experiments in white outbred ICR mice that the preparation belongs to practically non-toxic substances. Therefore, it can be concluded that the use of beta-Glucans could become a preferable alternative to the conventional adjuvants based on aluminum salts, being biocompatible, biodegradable and non-toxic substances of low labor-intensive production.

Проведено исследование генеративной токсичности вакцины ЭпиВакКорона. Вакцину ЭпиВакКорона крысам Вистар вводили внутримышечно в дозах: равной одной вакцинирующей для человека, пересчитанной с учетом разницы в площади поверхности тела — 23 мкг/кг, и в 10 раз ее превышающей — 230 мкг/кг. Контролем служил физиологический раствор. Вакцину вводили 2 раза в неделю самцам в течение 48 дней, самкам — в течение 15 дней до спаривания. Получавших вакцину самок и самцов ссаживали с интактными крысами противоположного пола на 10 – 14 дней. Введение вакцины ЭпиВакКорона в дозах 23 и 230 мкг/кг самкам не влияло на показатели спаривания — индексы покрытия и зачатия, а также на индекс фертильности самок. Введение вакцины ЭпиВакКорона в дозах 23 и 230 мкг/кг самцам не влияло на индекс фертильности самцов и ссаженных с ними интактных самок. При введении вакцины самцам в дозе 230 мкг/кг наблюдали преходящее снижение индекса покрытия самок на 13 % (p << 0,011), связанное c наличием одного нефертильного самца в группе и с отсутствием эструса в течение 12 дней у одной из интактных самок. При этом наблюдали одновременное преходящее увеличение индекса зачатия у самок на 14 % (p << 0,011), предположительно связанное с восстановлением самцов после курса инъекций вследствие более позднего наступления дня первого эструса у ссаженных с ними самок. Количество желтых тел беременности, живых и погибших плодов, мест имплантации, показатели пред- и постимплантационной смертности потомства у вакцинированных самок и интактных самок, спарившихся с получавшими вакцину самцами, не отличались от показателей контрольных животных. Полученные данные свидетельствуют об отсутствии у вакцины ЭпиВакКорона в дозах 23 и 230 мкг/кг признаков генеративной токсичности.

The relevance of the search for new vaccine adjuvants is growing along with the increase in the number of current vaccine preparations, especially those developed on the basis of proteins. Some cytokines are known to exert adjuvant properties. The present work is devoted to the study of adjuvant activity of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) and constructs based on it. Earlier, we developed a technology for isolation and purification of GM-CSF from the E. coli SG20050/p280_2GM producer strain, as well as a technology for conjugating polyglucin:spermidine complexes with rhGM-CSF. Double-stranded RNA was used to obtain molecular constructs on the basis of rhGM-CSF conjugate. To assemble constructs, the ratio of the components was calculated for one dose of the preparation to contain 5-40 mg of rhGM-CSF and 100 mg of double-stranded RNA. The effectiveness of the formation of molecular constructs was evaluated by dsRNA electrophoretic mobility shift in a 1% agarose gel. The effectiveness of the resulting adjuvants was determined in ELISA assays by measuring the titers of specific antibodies in mouse sera against ovalbumin or recombinant receptor-binding domain of the surface S protein of the severe acute respiratory syndrome coronavirus 2 (Delta variant (B.1.617.2). The experiments were carried out in 100 male BALB/c mice weighing 16-18 g. Mice were immunized twice, with a 14-day interval, by intramuscular injection of 200 mL per animal. Recombinant receptor-binding domain of the surface protein of SARS-CoV-2 was administered at a dose of 50 mg/animal, ovalbumin – at two doses – 1 mg or 5 mg/animal. Corresponding antigen was used as a positive control, a saline solution – as a negative control. It was shown that the maximum effect was achieved by immunization with a construct based on double-stranded RNA and rhGM-CSF conjugated to polyglucin-spermidine. The use of a conjugate without double-stranded RNA as an adjuvant also improved humoral response. The use of native rhGM-CSF did not increase the titers of specific antibodies. Thus, it was found that rhGM-CSF being a part of a polysaccharide conjugate or a molecular construct exerted an ability to enhance the humoral immune response to protein antigens.

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a myelopoietic growth factor that exerts pleiotropic effect not only on the differentiation of immature progenitor cells into polymorphonuclear neutrophils, monocytes/macrophages and dendritic cells, but also controls the functioning of differentiated cells. GM-CSF is currently being investigated in clinical trials as an immunomodulator and adjuvant. However, a wide range of biological activities and, sometimes, paradoxical effects of this cytokine require more thorough studies of its action, in order to predict its efficacy under different conditions of immunotherapy. In this work, we have studied the effect of recombinant human GM-CSF on metabolic activity of mouse peritoneal exudate cells in primary cell cultures. Metabolic (redox) activity of the cells was assessed by their ability to reduce nitroblue tetrazolium (NBT) in the course of MF- and Fc-dependent phagocytosis triggered by addition of opsonized zymosan, or sheep erythrocytes to the culture medium. We have shown the dose-dependent stimulatory effect of GM-CSF on the oxidative metabolism of phagocytic peritoneal macrophages and neutrophils. Upon culturing the pepton-elicited cells at wide range of GM-CSF concentrations (5 to 40,000 ng/mL) for 2 and 24 hours, a more pronounced effect of the substance was observed for neutrophils. The GM-CSF preparation caused a significant increase (by 13-17%) in the redox activity of neutrophils induced by opsonized zymosan that persisted at a low dose range, and was retained after 24 hours. The stimulatory effect of GM-CSF on macrophages with NBT index increase by 16% was observed in the short-term cultures. In general, the elicited cells of both types showed a more pronounced response to lower concentrations of GM-CSF (5-125 ng/mL), and weaker effect at higher doses of the preparation. A similar dependence was found when studying the resident macrophages. Culturing of resident cells with GM-CSF at the doses of 5,000 to 40,000 ng/mL for 24 hours caused a significantly increased redox activity of the cells induced by zymosan, or sheep erythrocytes (by 33-52%). In both cases, the maximal response was detected at a dose of 5,000 ng/mL and decreased with increasing dose. The stimulatory effect of GM-CSF upon resident macrophages was more pronounced as compared to elicited cells, which was characterized by the prolonged period of cell activation (up to 24 hours of culture). The data obtained are of interest, in view of prospective usage of GM-CSF as a component of immunomodulatory and adjuvant therapy for various infectious diseases.

The State Research Center of Virology and Biotechnology “VECTOR” of the Federal Service for the Oversight of Consumer Protection and Welfare (Rospotrebnadzor) has developed the peptide-based EpiVacCorona vaccine, which is the first synthetic peptide-based antiviral vaccine for mass immunization in international vaccinology. An early clinical trial (Phase I–II) demonstrated that the EpiVacCorona vaccine is a safe product. The “Multicenter double-blind, placebo-controlled, comparative, randomized trial to assess the tolerability, safety, immunogenicity and prophylactic efficacy of the EpiVacCorona COVID-19 vaccine based on peptide antigens in 3000 volunteers aged 18 years and older” was performed regarding vaccine safety. The key objectives of the study were to evaluate the safety and prophylactic efficacy of the two-dose EpiVacCorona vaccine administered via the intramuscular route. The results of the clinical study (Phase III) demonstrated the safety of the EpiVacCorona vaccine. Vaccine administration was accompanied by mild local reactions in ≤27% of cases and mild systemic reactions in ≤14% of cases. The prophylactic efficacy of the EpiVacCorona COVID-19 vaccine after the completion of the vaccination series was 82.5% (CI95 = 75.3–87.6%). The high safety and efficacy of the vaccine give grounds for recommending this vaccine for regular seasonal prevention of COVID-19 as a safe and effective medicinal product.

Background: Since most of the modern human population has no anti-smallpox immunity, it is extremely important to develop and implement effective drugs for the treatment of smallpox and other orthopoxvirus infections. The objective of this study is to determine the main characteristics of the chemical substance NIOCH-14 and its safety and bioavailability in the body of laboratory animals. Methods: The safety of NIOCH-14 upon single- or multiple-dose intragastric administration was assessed according to its effect on the main hematological and pathomorphological parameters of laboratory mice and rats. In order to evaluate the pharmacokinetic parameters of NIOCH-14 administered orally, a concentration of ST-246, the active metabolite of NIOCH-14, in mouse blood and organs was determined by tandem mass spectrometry and liquid chromatography. Results: The intragastric administration of NIOCH-14 at a dose of 5 g/kg body weight caused neither death nor signs of intoxication in mice. The intragastric administration of NIOCH-14 to mice and rats at doses of 50 and 150 µg/g body weight either as a single dose or once daily during 30 days did not cause animal death or critical changes in hematological parameters and the microstructure of internal organs. The tissue availability of NIOCH-14 administered orally to the mice at a dose of 50 µg/g body weight, which was calculated according to concentrations of its active metabolite ST-246 for the lungs, liver, kidney, brain, and spleen, was 100, 69.6, 63.3, 26.8 and 20.3%, respectively. The absolute bioavailability of the NIOCH-14 administered orally to mice at a dose of 50 µg/g body weight was 22.8%. Conclusion: Along with the previously determined efficacy against orthopoxviruses, including the smallpox virus, the substance NIOCH-14 was shown to be safe and bioavailable in laboratory animal experiments.

Group-specific component macrophage-activating factor (GcMAF) is the vitamin D3-binding protein (DBP) deglycosylated at Thr420. The protein is believed to exhibit a wide range of therapeutic properties associated with the activation of macrophagal immunity. An original method for GcMAF production, DBP conversion to GcMAF, and the analysis of the activating potency of GcMAF was developed in this study. Data unveiling the molecular causes of macrophage activation were obtained. GcMAF was found to interact with three CLEC10A derivatives having molecular weights of 29 kDa, 63 kDa, and 65 kDa. GcMAF interacts with high-molecular-weight derivatives via Ca2+-dependent receptor engagement. Binding to the 65 kDa or 63 kDa derivative determines the pro- and anti-inflammatory direction of cytokine mRNA expression: 65 kDa—pro-inflammatory (TNF-α, IL-1β) and 63 kDa—anti-inflammatory (TGF-β, IL-10). No Ca2+ ions are required for the interaction with the canonical 29 kDa CLEC10A. Both forms, DBP protein and GcMAF, bind to the 29 kDa CLEC10A. This interaction is characterized by the stochastic mRNA synthesis of the analyzed cytokines. Ex vivo experiments have demonstrated that when there is an excess of GcMAF ligand, CLEC10A forms aggregate, and the mRNA synthesis of analyzed cytokines is inhibited. A schematic diagram of the presumable mechanism of interaction between the CLEC10A derivatives and GcMAF is provided. The principles and elements of standardizing the GcMAF preparation are elaborated.

A recombinant strain for producing human gamma interferon (IFN-γ) E. coli BL 21/pET-IFN-γ was constructed to provide a high level of its expression. A method has been developed for obtaining a soluble form of recombinant IFN-γ, consisting of the processes of producing a biomass of a producer strain containing a target protein at a level of 32–37% of the total content of cellular proteins, protein isolation, and purification. The purification process included the stages of disintegration, clarification of the cell lysate, chromatographic purification, and dialysis. The developed method makes it possible to obtain up to 5 mg of the drug from 1 g of wet biomass with a purity of at least 95% and high specific (antiviral) activity.

Despite the rapid development and approval of several COVID vaccines based on the full-length spike protein, there is a need for safe, potent, and high-volume vaccines. Considering the predominance of the production of neutralizing antibodies targeting the receptor-binding domain (RBD) of S-protein after natural infection or vaccination, it makes sense to choose RBD as a vaccine immunogen. However, due to its small size, RBD exhibits relatively poor immunogenicity. Searching for novel adjuvants for RBD-based vaccine formulations is considered a good strategy for enhancing its immunogenicity. Herein, we assess the immunogenicity of severe acute respiratory syndrome coronavirus 2 RBD conjugated to a polyglucin:spermidine complex (PGS) and dsRNA (RBD-PGS + dsRNA) in a mouse model. BALB/c mice were immunized intramuscularly twice, with a 2-week interval, with 50 µg of RBD, RBD with Al(OH)3, or conjugated RBD. A comparative analysis of serum RBD-specific IgG and neutralizing antibody titers showed that PGS, PGS + dsRNA, and Al(OH)3 enhanced the specific humoral response in animals. There was no significant difference between the groups immunized with RBD-PGS + dsRNA and RBD with Al(OH)3. Additionally, the study of the T-cell response in animals showed that, unlike adjuvants, the RBD-PGS + dsRNA conjugate stimulates the production of specific CD4+ and CD8+ T cells in animals.