INTRODUCTION. Rotavirus vaccines based on virus-like particles (VLPs), non-infectious recombinant proteins of human rotavirus A that mimic the structure of the native virus, show promise for preventive vaccination. Presumably, the optimal method to determine the potency of VLP-based rotavirus vaccines is the enzyme-linked immunosorbent assay (ELISA) method used to measure the titre of specific IgG antibodies to rotavirus A proteins in serum samples from vaccinated animals.AIM. This study aimed at assessing the potency of a VLP-based rotavirus vaccine by developing and validating an analytical procedure using ELISA to determine the levels of antibodies to the VP2 and VP6 proteins of rotavirus A in serum samples from vaccinated guinea pigs.MATERIALS AND METHODS. The potency of the VLP-based rotavirus vaccine was determined in vivo in three types of experimental animals, including BALB/c mice, agouti guinea pigs, and newborn minipigs. The animals received three intramuscular injections of the vaccine at a dose of 30 µg. This study used the indirect ELISA method to quantify VP2- and VP6-specific immunoglobulin G (IgG) antibodies and the virus-neutralisation test to measure neutralising antibodies (nAbs) to rotavirus A in animal serum samples. The study involved calculating the geometric mean titres (GMTs) of antibodies. The authors validated the analytical procedure for potency assessment on two batches of the vaccine using standard statistical analysis methods.RESULTS. The study compared VP2- and VP6-specific IgG and nAb levels 14 days after the first, second, and third vaccinations. The authors observed a significant increase in antibody titres and statistically significant (p<0.05) differences between groups as early as after the second vaccination. Double vaccination induced rotavirus-specific IgGs and nAbs in newborn minipigs (GMTs of 200.0 and 108.9, respectively) and guinea pigs (GMTs of 12,800 and 2,600, respectively). Vaccinated mice demonstrated a significant increase in rotavirus-specific IgG levels (GMT of 572,440). Guinea pigs were selected as a relevant model for validating the ELISA-based potency assessment procedure. The validation study used a double vaccination scheme. The validation using two batches of the VLP-based rotavirus vaccine indicated that the ELISA-based analytical procedure met the acceptance criteria for specificity, repeatability, and intermediate precision. The repeatability assessment resulted in a coefficient of variation (CV) of 12.4% for batch 1 and a CV of 7.7% for batch 2, whereas the intermediate precision assessment showed a CV of 6.9% for batch 1 and a CV of 10.2% for batch 2, which were within the acceptance criteria for both validation parameters (CV≤15%).CONCLUSIONS. The authors developed and validated an ELISA-based analytical procedure for assessing the potency of VLP-based preventive rotavirus vaccines. According to the study results, ELISA is applicable to the control of the potency of VLP-based preventive rotavirus vaccines.

Introduction. The COVID-19 pandemic caused by SARS-CoV-2 has created serious health problems worldwide. The most effective way to prevent the occurrence of new epidemic outbreaks is vaccination. One of the modern and effective approaches to vaccine development is the use of virus-like particles (VLPs). The aim of the study is to develop a technology for production of VLP based on recombinant SARS-CoV-2 proteins (E, M, N and S) in insect cells. Materials and methods. Synthetic genes encoding coronavirus proteins E, M, N and S were used. VLP with various surface proteins of strains similar to the Wuhan virus, Delta, Alpha and Omicron were developed and cloned into the pFastBac plasmid. The proteins were synthesized in the baculovirus expression system and assembled into VLP in the portable Trichoplusia ni cell. The presence of insertion in the baculovirus genome was determined by PCR. ELISA and immunoblotting were used to study the antigenic activity of VLP. VLP purification was performed by ultracentrifugation using 20% sucrose. Morphology was assessed using electron microscopy and dynamic light scattering. Results. VLPs consisting of recombinant SARS-CoV-2 proteins (S, M, E and N) were obtained and characterized. The specific binding of antigenic determinants in synthesized VLPs with antibodies to SARS-CoV-2 proteins has been demonstrated. The immunogenic properties of VLPs have been studied. Conclusion. The production and purification of recombinant VLPs consisting of full-length SARS-CoV-2 proteins with a universal set of surface antigens have been developed and optimized. Self-assembling particles that mimic the coronavirus virion induce a specific immune response against SARS-CoV-2.

INTRODUCTION:Rotavirus infection is one of the main concerns in infectious pathology in humans, mammals and birds. Newborn piglets or rodents are usually being used as a laboratory model for the evaluation of immunogenicity and efficacy for all types of vaccines against rotavirus A (RVA), and the use of ELISA for the detection of virus-specific antibodies of specific isotype is an essential step of this evaluation.OBJECTIVE:Development of indirect solid-phase ELISA with VP2/VP6 rotavirus VLP as an antigen to detect and assess the distribution of RVA-specific IgG, IgM and IgA in the immune response to rotavirus A.MATERIALS AND METHODS:VP2/VP6 rotavirus VLP production and purification, electron microscopy, PAGE, immunoblotting, ELISA, virus neutralization assay.RESULTS:The study presents the results of development of a recombinant baculovirus with RVA genes VP2-eGFP/VP6, assessment of its infectious activity and using it for VLP production. The morphology of the VP2/VP6 rotavirus VLPs was assessed, the structural composition was determined, and the high antigenic activity of the VLP was established. VLP-based ELISA assay was developed and here we report results for RVA-specific antibody detection in sera of different animals.CONCLUSION:The developed ELISA based on VP2/VP6 rotavirus VLP as a universal antigen makes it possible to detect separately IgG, IgM and IgA antibodies to rotavirus A, outlining its scientific and practical importance for the evaluation of immunogenicity and efficacy of traditional vaccines against rotavirus A and those under development.

It has recently been shown that the titer of the SARS-CoV-2 virus decreases in a cell culture when the cell suspension is irradiated with electromagnetic waves at a frequency of 95 GHz. We assumed that a frequency range in the gigahertz and sub-terahertz ranges was one of the key aspects in the “tuning” of flickering dipoles in the dispersion interaction process of the surfaces of supramolecular structures. To verify this assumption, the intrinsic thermal radio emission in the gigahertz range of the following nanoparticles was studied: virus-like particles (VLP) of SARS-CoV-2 and rotavirus A, monoclonal antibodies to various RBD epitopes of SARS-CoV-2, interferon-α, antibodies to interferon-γ, humic–fulvic acids, and silver proteinate. At 37 °C or when activated by light with λ = 412 nm, these particles all demonstrated an increased (by two orders of magnitude compared to the background) level of electromagnetic radiation in the microwave range. The thermal radio emission flux density specifically depended on the type of nanoparticles, their concentration, and the method of their activation. The thermal radio emission flux density was capable of reaching 20 μW/(m2 sr). The thermal radio emission significantly exceeded the background only for nanoparticles with a complex surface shape (nonconvex polyhedra), while the thermal radio emission from spherical nanoparticles (latex spheres, serum albumin, and micelles) did not differ from the background. The spectral range of the emission apparently exceeded the frequencies of the Ka band (above 30 GHz). It was assumed that the complex shape of the nanoparticles contributed to the formation of temporary dipoles which, at a distance of up to 100 nm and due to the formation of an ultrahigh strength field, led to the formation of plasma-like surface regions that acted as emitters in the millimeter range. Such a mechanism makes it possible to explain many phenomena of the biological activity of nanoparticles, including the antibacterial properties of surfaces.

Introduction. In Russia, almost half of the cases of acute intestinal infections of established etiology in 2022 are due to rotavirus infection (RVI). There is no specific treatment for rotavirus gastroenteritis. There is a need to develop modern, effective and safe vaccines to combat rotavirus infection that are not capable of multiplying (replicating) in the body of the vaccinated person. A promising approach is to create vaccines based on virus-like particles (VLPs). Objective. Study of the safety and immunogenicity of a vaccine against rotavirus infection based on virus-like particles of human rotavirus A in newborn minipigs with multiple intramuscular administration. Materials and methods. Newborn minipigs were used as an animal model in this study. The safety of the tested vaccine was assessed based on thermometry data, clinical examination, body weight gain, clinical and biochemical blood parameters, as well as necropsy and histological examination. When studying the immunogenic properties of the Gam-VLP-rota vaccine in doses of 30 and 120 µg, the cellular, humoral and secretory immune response was studied. Results. The results of assessing the general condition of animals during the immunization period, data from clinical, laboratory and pathomorphological studies indicate the safety of the vaccine against human rotavirus infection based on VLP (Gam-VLP-rota) when administered three times intramuscularly. Good local tolerance of the tested vaccine was demonstrated. The results of the assessment of humoral immunity indicate the formation of a stable immune response after three-time immunization with Gam-VLP-rota, stimulation of the production of antigen-specific IgG antibodies and their functional activity to neutralize human rotavirus A. It was shown that following the triple immunization with the minimum tested concentration of 30 µg/dose, animals developed a cell-mediated immune response. The results of the IgA titer in blood serum and intestinal lavages indicate the formation of both a systemic immunological response and the formation of specific secretory immunity to human rotavirus A. Conclusion. Thus, three-time intramuscular immunization of minipigs with the Gam-VLP-rota vaccine forms stable protective humoral and cellular immunity in experimental animals. Evaluated vaccine is safe and has good local tolerability.

Group A rotavirus (RVA) infection is the leading cause of hospitalization of children under 5 years old, presenting with symptoms of acute gastroenteritis. The aim of our study was to explore the genetic diversity of RVA among patients admitted to Moscow Infectious Disease Clinical Hospital No. 1 with symptoms of acute gastroenteritis. A total of 653 samples were collected from May 2019 through March 2020. Out of them, 135 (20.67%) fecal samples were found to be positive for rotavirus antigen by ELISA. RT-PCR detected rotavirus RNA in 80 samples. Seven G-genotypes (G1, G2, G3, G4, G8, G9, and G12) and three P-genotypes (P[8], P[4], and P[6]) formed 9 different combinations. The most common combination was G9P[8]. However, for the first time in Moscow, the combination G3P[8] took second place. Moreover, all detected viruses of this combination belonged to Equine-like G3P[8] viruses that had never been detected in Russia before. The genotype G8P[8] and G9P[4] rotaviruses were also detected in Moscow for the first time. Among the studied rotaviruses, there were equal proportions of Wa and DS-1-like strains; previous studies showed that Wa-like strains accounted for the largest proportion of rotaviruses in Russia.

INTRODUCTION:Rotavirus infection is the leading cause of acute gastroenteritis among infants. The development of new vaccines against rotavirus A is urgent because the virus has many genotypes, some of which have regional prevalence. Virus-like particles (VLP) is a promising way to create effective and safe vaccine preparations.The purpose of the study is to develop the technology for the production of VLP, containing VP2, VP4, VP6 and VP7 of viral genotypes prevalent on the territory of the Russian Federation, and to give its molecular genetic and virological characteristics.MATERIAL AND METHODS:The virulent strain Wa G1P[8] of human RV A adapted to MARC-145 cell culture has been used. It was cultured and purified according to the method described by the authors earlier. Standard molecular genetic and cytological methods were used: gene synthesis; cloning into transfer plasmids; recombinant baculoviruses production in Bac-to-Bac expression system; VLP production in the insect cells; centrifugation in sucrose solution; enzyme-linked immunosorbent assay (ELISA); electron microscopy (EM); polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analysis.RESULTS:VP4 and VP7 of the six most represented in Russia genotypes: G1, G2, G4, G9, P4, P8, as well as VP2 and VP6 were selected for VLP production. Recombinant baculoviruses were obtained with codon frequencies optimized for insect cells. Cabbage loopper (Trichoplusia ni) cell culture was coinfected with different combinations of baculoviruses, and VLP consisting of 2-4 proteins were produced. VLP were purified by centrifugation. The size and morphology of the particles matched the rotavirus A virion (by EM). The presence of rotavirus A proteins in VLP was confirmed by the ELISA, SDS-PAGE and western blot analysis.CONCLUSION:The technology for the synthesis of three-layer VLP consisting of VP2, VP4, VP6 and VP7 has been developed and optimized. The resulting VLP composition represents 6 serotypes of VP4 and VP7, which are most represented on the territory of Russia, and can be used for vaccine development.

Method of determination of polysorbate 20 and polysorbate 80 in recombinant protein drugs based on spectrophotometry has been designed. Isolation of polysorbate from solution is carried out by solid phase extraction followed by elution of polysorbate with acetonitrile. Acetonitrile solution is evaporated and then polysorbate is derivatized with ferrous-thiocyanate reagent. Obtained derivative is extracted into organic phase and optical density is measured. The most optimal conditions of derivatization, extraction into organic phase and measurment was chosen. The validation was performed: specificity, linearity, accuracy, precision, robustness, limit of quantification.

The aim of this work was to compare biological activities of three variants of bacterially expressed human recombinant erythropoietin (EPO) with additional protein domains: 6His-s-tag-EPO protein carrying the s-tag (15-a.a. oligopeptide from bovine pancreatic ribonuclease A) at the N-terminus and HBD-EPO and EPO-HBD proteins containing heparin-binding protein domains (HBD) of the bone morphogenetic protein 2 from Danio rerio at the N- and C-termini, respectively. The commercial preparation Epostim (LLC Pharmapark, Russia) produced by synthesis in Chinese hamster ovary cells was used for comparison. The EPO variant with the C-terminal HBD domain connected by a rigid linker (EPO-HBD) possesses the best properties as compared to HBD-EPO with the reverse domain arrangement. It was ~13 times more active in vitro (i.e., promoted proliferation of human erythroleukemia TF-1 cells) and demonstrated a higher rate of association with the erythropoietin receptor. EPO-HBD also exhibited the greatest binding to the demineralized bone matrix (DBM) and more prolonged release from the DBM among the four proteins studied. Subcutaneous administration of EPO-HBD immobilized on DBM resulted in significantly more pronounced vascularization of surrounding tissues in comparison with the other proteins and DBM alone. Therefore, EPO-HBD displayed better performance with regard to all the investigated parameters than other examined EPO variants, and it seems promising to study the possibility of its medical use.

Recombinant human erythropoietin (EPO) with additional N-terminal heparin-binding protein domain (HBD) from bone morphogenetic protein 2 was synthesized in Escherichia coli cells. A procedure for HBD-EPO purification and refolding was developed for obtaining highly-purified HBD-EPO. The structure of recombinant HBD-EPO was close to that of the native EPO protein. HBD-EPO contained two disulfide bonds, as shown by MALDI-TOF mass spectrometry. The protein demonstrated in vitro biological activity in the proliferation of human erythroleukemia TF-1 cell test and in vivo activity in animal models. HBD-EPO increased the number of reticulocytes in the blood after subcutaneous injection and displayed local angiogenic activity after subcutaneous implantation of demineralized bone matrix (DBM) discs with immobilized HBD-EPO. We developed a quantitative sandwich ELISA method for measuring HBD-EPO concentration in solution using rabbit polyclonal serum and commercial monoclonal anti-EPO antibodies. Pharmacokinetic properties of HBD-EPO were typical for bacterially produced EPO. Under physiological conditions, HBD-EPO can reversibly bind to DBM, which is often used as an osteoplastic material for treatment of bone pathologies. The data on HBD-EPO binding to DBM and local angiogenic activity of this protein give hope for successful application of HBD-EPO immobilized on DBM in experiments on bone regeneration.

The method for the assessment of biological activity of erythropoietin preparations in vitro on TF-1 sensitive cells culture has been developed. The special characteristics of measurements and calculations of the biological activity of erythropoietin with different levels of glycosylation in vivo and in vitro. Linear response ranges for cell lines to erythropoietin and its hyperglycosylated analogue differ and make (0.39-0.56 ng/ml) and (3.1-12.5 ng/ml), respectively. The results have shown the possibility of using cellular test for comparing and assaying the activity of erythropoietin analogues in standard international units of biological activity (IU) set for erythropoietin.

Проведена коррекция маннозных гликанов в биосимилярном рекомбинантном моноклональном антителе к фактору некроза опухолей альфа при культивировании клеток линии СНО. Показана эффективность внесения в среду 20 нМ ионофорного антибиотика монензина для повышения доли высокоманнозной гликоформы Man5, что сочеталось с ухудшением роста и продуктивностью клеточной линии. Подтверждено, что содержание гликоформы Man5 в профиле гликозилирования биосимилярного моноклонального антитела может быть приведено в соответствие с содержанием гликозилированных форм в оригинальном препарате путем внесения сахарозы в концентрации 60 мМ, как наиболее предпочтительного агента, который позволяет сохранить культуральные характеристики и продуктивность клеточной линии.

Three variants of human recombinant erythropoietin (rhEPO) with additional N-terminal protein domains were obtained by synthesis in an Escherichia coli heterologous expression system. These domains included (i) maltose-binding protein (MBP), (ii) MBP with six histidine residues (6His) in N-terminal position, (iii) s-tag (15-a.a. oligopeptide derived from bovine pancreatic ribonuclease A) with N-terminal 6His. Both variants of the chimeric protein containing MBP domain were prone to aggregation under nondenaturing conditions, and further purification of EPO after the domain cleavage by enterokinase proved to be impossible. In the case of 6His-s-tag-EPO chimeric protein, the products obtained after cleavage with enterokinase were successfully separated by column chromatography, and rhEPO without additional domains was obtained. Results of MALDI-TOF mass spectrometry showed that after refolding 6His-s-tag-EPO formed a structure similar to that of one of native EPO with two disulfide bonds. Both 6His-s-tag-EPO and rhEPO without additional protein domains purified after proteolysis possessed the same biological activity in vitro in the cell culture.

The recombinant E7 oncoprotein gene of type 16 human papilloma virus (conjugated with the heat shock protein 70 (E7(16)-HSP70)) was expressed in Saccharomyces cerevisiae yeast cells. A number of chromatographic isolations were conducted to obtain the target protein and its primary identification and to establish its originality. The use of metal chelate chromatography was based on selective binding of sorbent active groups with a poly-histidine fragment at C-terminus of the target protein polypeptide sequence, while the use of affine chromatography was based on the association with ATP-binding regions of E7 and HSP70. The degree of purity of the target protein after both procedures did not exceed 70%, indicating the presence of many low-molecular admixtures and products of the target molecule oligomerization. The use of chromatographic purification under denaturing conditions using strong reducing agents allowed isolation of the target protein, the monomer content in which exceeded 97%. The target protein originality was established by immunoblotting and electrophoresis; the correspondence of its primary structure to the declared sequence was demonstrated by mass-spectrophotometry.

Data concerning selection and validation of analytical methods for quality assessment of recombinant proteins used for preparation of therapeutic vaccine against recurrent respiratory papillomatosis and anogenital condilomatose are represented. Selection of methods for purity, homogeneity and identity estimation of recombinant proteins containing different type of antigenic subunits had been demonstrated. Critical quality parameters of therapeutical vaccine's active pharmaceutical ingredient had been established. Obtained results provided the framework for development of regulatory documents describing therapeutic vaccine active components in following sections : Identity, Protein content, Purity, Host cell DNA, Host cell proteins.

A nickel-chelate affinity chromatography has been used to isolate fused proteins of Hsp70-E7 from yeast lysate at the initial stage of the work. The low purity of the monomeric Hsp70-E7 in the final fraction was associated with the occurrence of dimeric and tetrameric forms of the target protein and low-molecular impurities. A modification of the purification procces by the addition of reduced L-glutathione to inhibit the formation of unwanted disulfide bonds permitted to increase the purity of the target protein by reducing the content of the oligomerized products. Further changes in the purification protocol, namely the reduction of hydrophobic interactions by the introduction of glycerol, significantly reduced the amount of low-molecular impurities. For a finer purification of E7-HSP70, a two-stage process of anion-exchange chromatography that made it possible to effectively eliminate low-molecular impurities was used. The assessment of the final material by electrophoresis under non-reducing conditions showed that the purity of the monomeric forms of either of the proteins was higher than 95%.