Search

Squalene-based adjuvant compositions that can provide effective induction of specific humoral immune response have been developed. Recombinant receptor-binding domain (RBD) of surface S-protein of SARS-CoV-2 was used to evaluate the properties of the composition. Immunization of mice with the developed squalene-based compositions in combination with RBD allows obtaining high titers of specific antibodies: from 10 5 to 2×10 6 . The blood sera from immunized mice exhibit neutralizing activity against SARS-CoV-2 Delta variant (B.1.617.2) with a titer up to 1:2000., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature.)

We performed a search for nanoantibodies that specifically interact with the receptor-binding domain (RBD) of the SARS-CoV-2 surface protein. The specificity of single-domain antibodies from the blood sera of a llama immunized with RBD of SARS-CoV-2 surface protein S (variant B.1.1.7 (Alpha)) was analyzed by ELISA. Recombinant trimers of the SARS-CoV-2 spike protein were used as antigens. In this work, a set of single-domain antibodies was obtained that specifically bind to the RBD of the SARS-CoV-2 virus., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature.)

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.

During the COVID-19 pandemic, the development of prophylactic vaccines, including those based on new platforms, became highly relevant. One such platform is the creation of vaccines combining DNA and protein components in one construct. For the creation of DNA vaccine, we chose the full-length spike protein (S) of the SARS-CoV-2 virus and used the recombinant receptor-binding domain (RBD) of the S protein produced in CHO-K1 cells as a protein component. The immunogenicity of the developed combined vaccine and its individual components was compared and the contribution of each component to the induction of the immune response was analyzed. The combined DNA/protein vaccine possesses the advantages of both underlying approaches and is capable of inducing both humoral (similar to subunit vaccines) and cellular (similar to DNA vaccines) immunity., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature.)

Identification of factors behind the level and duration of persistence of the SARS-CoV-2 antibodies in the blood is assumed to set the direction for studying humoral immunity mechanisms against COVID-19, optimizing the strategy for vaccine use, antibody-based drugs, and epidemiological control of COVID-19. Objective: This study aimed to study the relationship between clinical and demographic characteristics and the level of IgG antibodies to the RBD of SARS-CoV-2 spike protein after COVID-19 in the long term. Residents of the Altai Region of Western Siberia of Russia, Caucasians, aged from 27 to 93 years (median 53.0 years), who recovered from COVID-19 between May 2020 and February 2021 ( n = 44) took part in this prospective observational study. The titer of IgG antibodies to the RBD of SARS-CoV-2 spike protein was measured repeatedly in the blood at 4-13 months from the beginning of the clinical manifestation of COVID-19 via the method of enzyme-linked immunosorbent assay. The antibody titer positively correlated with age ( p = 0.013) and COVID-19 pneumonia ( p = 0.002) at 20-40 and 20-24 weeks from the onset of COVID-19 symptoms, respectively. Age was positively associated with antibody titer regardless of history of COVID-19 pneumonia (beta regression coefficient p = 0.009). The antibody titer decreased in 15 (34.1%) patients, increased in 10 (22.7%) patients, and did not change in 19 (43.2%) patients from the baseline to 48-49 weeks from the onset of COVID-19 symptoms, with seropositivity persisting in all patients. Age and COVID-19 pneumonia are possibly associated with higher IgG antibodies to the spike protein RBD of SARS-CoV-2 following COVID-19 in the long term. Divergent trends of anti-RBD IgG levels in adults illustrate inter-individual differences at 4-13 months from the onset of COVID-19 symptoms.

Currently, SARS-CoV-2 spike receptor-binding-domain (RBD)-based vaccines are considered one of the most effective weapons against COVID-19. During the first step of assessing vaccine immunogenicity, a mouse model is often used. In this paper, we tested the use of five experimental animals (mice, hamsters, rabbits, ferrets, and chickens) for RBD immunogenicity assessments. The humoral immune response was evaluated by ELISA and virus-neutralization assays. The data obtained show hamsters to be the least suitable candidates for RBD immunogenicity testing and, hence, assessing the protective efficacy of RBD-based vaccines.

Aptamer selection against novel infections is a complicated and time-consuming approach. Synergy can be achieved by using computational methods together with experimental procedures. This study aims to develop a reliable methodology for a rational aptamer in silico et vitro design. The new approach combines multiple steps: (1) Molecular design, based on screening in a DNA aptamer library and directed mutagenesis to fit the protein tertiary structure; (2) 3D molecular modeling of the target; (3) Molecular docking of an aptamer with the protein; (4) Molecular dynamics (MD) simulations of the complexes; (5) Quantum-mechanical (QM) evaluation of the interactions between aptamer and target with further analysis; (6) Experimental verification at each cycle for structure and binding affinity by using small-angle X-ray scattering, cytometry, and fluorescence polarization. By using a new iterative design procedure, structure- and interaction-based drug design (SIBDD), a highly specific aptamer to the receptor-binding domain of the SARS-CoV-2 spike protein, was developed and validated. The SIBDD approach enhances speed of the high-affinity aptamers development from scratch, using a target protein structure. The method could be used to improve existing aptamers for stronger binding. This approach brings to an advanced level the development of novel affinity probes, functional nucleic acids. It offers a blueprint for the straightforward design of targeting molecules for new pathogen agents and emerging variants., (© 2022 Wiley-VCH GmbH.)

Despite the fact that a range of vaccines against COVID-19 have already been created and are used for mass vaccination, the development of effective, safe, technological, and affordable vaccines continues. We have designed a vaccine that combines the recombinant protein and DNA vaccine approaches in a self-assembled particle. The receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 was conjugated to polyglucin:spermidine and mixed with DNA vaccine (pVAXrbd), which led to the formation of particles of combined coronavirus vaccine (CCV-RBD) that contain the DNA vaccine inside and RBD protein on the surface. CCV-RBD particles were characterized with gel filtration, electron microscopy, and biolayer interferometry. To investigate the immunogenicity of the combined vaccine and its components, mice were immunized with the DNA vaccine pVAXrbd or RBD protein as well as CCV-RBD particles. The highest antigen-specific IgG and neutralizing activity were induced by CCV-RBD, and the level of antibodies induced by DNA or RBD alone was significantly lower. The cellular immune response was detected only in the case of DNA or CCV-RBD vaccination. These results demonstrate that a combination of DNA vaccine and RBD protein in one construct synergistically increases the humoral response to RBD protein in mice.

The receptor-binding domain (RBD) of the protein S SARS-CoV-2 is considered to be one of the appealing targets for developing a vaccine against COVID-19. The choice of an expression system is essential when developing subunit vaccines, as it ensures the effective synthesis of the correctly folded target protein, and maintains its antigenic and immunogenic properties. Here, we describe the production of a recombinant RBD protein using prokaryotic (pRBD) and mammalian (mRBD) expression systems, and compare the immunogenicity of prokaryotic and mammalian-expressed RBD using a BALB/c mice model. An analysis of the sera from mice immunized with both variants of the protein revealed that the mRBD expressed in CHO cells provides a significantly stronger humoral immune response compared with the RBD expressed in E.coli cells. A specific antibody titer of sera from mice immunized with mRBD was ten-fold higher than the sera from the mice that received pRBD in ELISA, and about 100-fold higher in a neutralization test. The data obtained suggests that mRBD is capable of inducing neutralizing antibodies against SARS-CoV-2.

The development of preventive vaccines became the first order task in the COVID-19 pandemic caused by SARS-CoV-2. This paper reports the construction of the pVAX-RBD plasmid containing the Receptor-Binding Domain (RBD) of the S protein and a unique signal sequence 176 which promotes target protein secretion into the extracellular space thereby increasing the efficiency of humoral immune response activation. A polyglucine-spermidine conjugate (PGS) was used to deliver pVAX-RBD into the cells. The comparative immunogenicity study of the naked pVAX-RBD and pVAX-RBD enclosed in the PGS envelope showed that the latter was more efficient in inducing an immune response in the immunized mice. In particular, RBD-specific antibody titers were shown in ELISA to be no higher than 1 : 1000 in the animals from the pVAX-RBD group and 1 : 42000, in the pVAX-RBD-PGS group. The pVAX-RBD-PGS construct effectively induced cellular immune response. Using ELISpot, it has been demonstrated that splenocytes obtained from the immunized animals effectively produced INF-y in response to stimulation with the S protein-derived peptide pool. The results suggest that the polyglucine-spermidine conjugate-enveloped pVAX-RBD construct may be considered as a promising DNA vaccine against COVID-19.

The preparation and study of the biological properties of the pVAKS-GPVM DNA immunogen containing a gene encoding Marburgvirus glycoprotein are described. The specificity of blood serum antibodies of guinea pigs immunized with DNA immunogen was analyzed by ELISA. Inactivated viral preparation, recombinant glycoprotein (GP) obtained in the prokaryotic system and virus-like particles based on the recombinant vesicular stomatitis virus exhibiting Marburgvirus GP were used as the antigens. The neutralizing activity of antibodies of immunized animals was tested in vitro using a pseudovirus system. It was demonstrated that the developed immunogen administered to guinea pigs induced the production of specific antibodies that neutralize virus-like particles and Marburgvirus in cultured Vero cells.

The development of preventive vaccines became the first order task in the COVID-19 pandemic caused by SARS-CoV-2. This paper reports the construction of the pVAX-RBD plasmid containing the Receptor-Binding Domain (RBD) of the S protein and a unique signal sequence 176 which promotes target protein secretion into the extracellular space thereby increasing the efficiency of humoral immune response activation. A polyglucine-spermidine conjugate (PGS) was used to deliver pVAX-RBD into the cells. The comparative immunogenicity study of the naked pVAX-RBD and pVAX-RBD enclosed in the PGS envelope showed that the latter was more efficient in inducing an immune response in the immunized mice. In particular, RBD-specific antibody titers were shown in ELISA to be no higher than 1 : 1000 in the animals from the pVAX-RBD group and 1 : 42 000, in the pVAX-RBD-PGS group. The pVAX-RBD‒PGS construct effectively induced cellular immune response. Using ELISpot, it has been demonstrated that splenocytes obtained from the immunized animals effectively produced INF-γ in response to stimulation with the S protein-derived peptide pool. The results suggest that the polyglucine-spermidine conjugate-enveloped pVAX-RBD construct may be considered as a promising DNA vaccine against COVID-19., Competing Interests: Conflict of interest. The authors declare they have no conflict of interest., (© Pleiades Publishing, Inc. 2021, ISSN 0026-8933, Molecular Biology, 2021, Vol. 55, No. 6, pp. 889–898. © Pleiades Publishing, Inc., 2021.Russian Text © The Author(s), 2021, published in Molekulyarnaya Biologiya, 2021, Vol. 55, No. 6, pp. 987–998.)

Extinction enhancement and nonlinear near-resonant absorption of potassium polytitanate nanoplatelets were experimentally studied in the near-UV region. Phenomenological models such as the one-oscillator Lorentz model for dielectric function and the two-level model with the depleted ground state were used to interpret the experimental data. The introduced model parameters demonstrate the adequately high sensitivity to variations in nanoplatelet morphology and chemical environment.

Analysis of the structure functions of intensity fluctuations of scattered laser light was applied to monitor the phase separation in probed disperse media. UV-cured mixtures of a liquid crystal and prepolymer were studied during the formation of the structure of dispersive polymer-liquid crystal (DPLC) composites. The experimentally observed features of light beating induced by dynamic light scattering in DPLC systems (the scaling properties of the structure functions, the narrowing of the beating spectrum for certain weight fractions of the liquid-crystalline component) were interpreted in terms of the discrete scattering model using the results of statistical modeling.

Two new, metal-rich nickel-tin sulfides Ni(6)SnS(2) and Ni(9)Sn(2)S(2) were found by establishing phase relations in the ternary Ni-Sn-S system at 540 degrees C. Their single crystals were prepared by means of chemical vapor transport reactions. Single crystal X-ray diffraction was used for the determination of their crystal structures. Both compounds crystallize in a tetragonal system (I4/mmm, No. 139, Z = 2, a = 3.646(1) A, c = 18.151(8) A for Ni(6)SnS(2), and a = 3.678(1) A, c = 25.527(8) A for Ni(9)Sn(2)S(2)). Their crystal structures represent a new structure type and can be considered as assembled from bimetallic nickel-tin and nickel-sulfide slabs alternating along the crystallographic c axis. DFT band structure calculations showed the bonding within the bimetallic slabs to have a delocalized, multicenter nature, typical for metallic systems, and predominantly classical, pairwise bonding between nickel and sulfur.