Protective Activity of Inactivated Rabies Vaccine Using Flagellin-Based Adjuvant.

Rabies is a zoonotic disease with high lethality. Most human deaths are associated with the bites received from dogs and cats. Vaccination is the most effective method of preventing rabies disease in both animals and humans. In this study, the ability of an adjuvant based on recombinant Salmonella typhimurium flagellin to increase protective activity of the inactivated rabies vaccine in mice was evaluated. A series of inactivated dry culture vaccine for dogs and cats "Rabikan" (strain Shchelkovo-51) with addition of an adjuvant at various dilutions were used. The control preparation was a similar series of inactivated dry culture vaccine without an adjuvant. Protective activity of the vaccine preparations was evaluated by the NIH potency test, which is the most widely used and internationally recommended method for testing effectiveness of the inactivated rabies vaccines. The value of specific activity of the tested rabies vaccine when co-administered with the adjuvant was significantly higher (48.69 IU/ml) than that of the vaccine without the adjuvant (3.75 IU/ml). Thus, recombinant flagellin could be considered as an effective adjuvant in the composition of future vaccine preparations against rabies virus.

Effect of the Coat Protein N-Terminal Domain Structure on the Structure and Physicochemical Properties of Virions of Potato Virus X and Alternanthera Mosaic Virus.

The amino acid sequences of the coat proteins (CPs) of the potexviruses potato virus X (PVX) and alternanthera mosaic virus (AltMV) share ~40% identity. The N-terminal domains of these proteins differ in the amino acid sequence and the presence of the N-terminal fragment of 28 residues (ΔN peptide) in the PVX CP. Here, we determined the effect of the N-terminal domain on the structure and physicochemical properties of PVX and AltMV virions. The circular dichroism spectra of these viruses differed significantly, and the melting point of PVX virions was 10-12°C higher than that of AltMV virions. Alignment of the existing high-resolution 3D structures of the potexviral CPs showed that the RMSD value between the Cα-atoms was the largest for the N-terminal domains of the two compared models. Based on the computer modeling, the ΔN peptide of the PVX CP is fully disordered. According to the synchrotron small-angle X-ray scattering (SAXS) data, the structure of CPs from the PVX and AltMV virions differ; in particular, the PVX CP has a larger portion of crystalline regions and, therefore, is more ordered. Based on the SAXS data, the diameters of the PVX and AltMV virions and helix parameters in solution were calculated. The influence of the conformation of the PVX CP N-terminal domain and its position relative to the virion surface on the virion structure was investigated. Presumably, an increased thermal stability of PVX virions vs. AltMV is provided by the extended N-terminal domain (ΔN peptide, 28 amino acid residues), which forms additional contacts between the adjacent CP subunits in the PVX virion.

Recombinant Protein Vaccines against Human Betacoronaviruses: Strategies, Approaches and Progress.

Betacoronaviruses have already troubled humanity more than once. In 2002-2003 and 2012, the SARS-CoV and MERS-CoV, respectively, caused outbreaks of respiratory syndromes with a fatal outcome. The spread of the SARS-CoV-2 coronavirus has become a pandemic. These three coronaviruses belong to the genus Betacoronavirus and have a zoonotic origin. The emergence of new coronavirus infections in the future cannot be ruled out, and vaccination is the main way to prevent the spread of the infection. Previous experience in the development of vaccines against SARS and MERS has helped to develop a number of vaccines against SARS-CoV-2 in a fairly short time. Among them, there are quite a few recombinant protein vaccines, which seem to be very promising in terms of safety, minimization of side effects, storage and transportation conditions. The problem of developing a universal betacoronavirus vaccine is also still relevant. Here, we summarize the information on the designing of vaccines based on recombinant proteins against highly pathogenic human betacoronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2.

Identification of the Channelrhodopsin Genes in the Green and Cryptophytic Algae from the White and Black Seas.

Due to the unique capability of modulating cell membrane potential upon photoactivation, channelrhodopsins of green (Chlorophyta) and cryptophytic (Cryptophyta) algae are widely employed in optogenetics, a modern method of light-dependent regulation of biological processes. To enable the search for new genes perspective for optogenetics, we have developed the PCR tests for the presence of genes of the cation and anion channelrhodopsins. Six isolates of green algae Haematococcus and Bracteacoccus from the White Sea region and 2 specimens of Rhodomonas sp. (Cryptophyta) from the regions of White and Black Seas were analyzed. Using our PCR test we have demonstrated the known Haematococcus rhodopsin genes and have discovered novel rhodopsin genes in the genus of Bracteacoccus. Two distantly homologous genes of anion channelrhodopsins were also identified in the cryptophytic Rhodomonas sp. from the White and Black Seas. These results indicate that the developed PCR tests might be useful tool for a broad-range screening of the Chlorophyta and Cryptophyta algae to identify unique channelrhodopsin genes.

Structurally Modified Plant Viruses and Bacteriophages with Helical Structure. Properties and Applications.

Structurally modified virus particles can be obtained from the rod-shaped or filamentous virions of plant viruses and bacteriophages by thermal or chemical treatment. They have recently attracted attention of the researchers as promising biogenic platforms for the development of new biotechnologies. This review presents data on preparation, structure, and properties of the structurally modified virus particles. In addition, their biosafety for animals is considered, as well as the areas of application of such particles in biomedicine. A separate section is devoted to one of the most relevant and promising areas for the use of structurally modified plant viruses - design of vaccine candidates based on them.

Chilling Upregulates Expression of the PsbS and LhcSR Genes in the Chloroplasts of the Green Microalga Lobosphaera incisa IPPAS C-2047.

Non-photochemical quenching (NPQ) of excited chlorophyll states is essential for protecting the photosynthetic apparatus (PSA) from the excessive light-induced damage in all groups of oxygenic photosynthetic organisms. The key component of the NPQ mechanism in green algae and some other groups of algae and mosses is the LhcSR protein of the light harvesting complex (LHC) protein superfamily. In vascular plants, LhcSR is replaced by PsbS, another member of the LHC superfamily and a subunit of photosystem II (PSII). PsbS also performs the photoprotective function in mosses. For a long time, PsbS had been believed to be nonfunctional in green algae, although the corresponding gene was discovered in the genome of these organisms. The first evidence of the PsbS accumulation in the model green alga Chlamydomonas reinhardtii in response to the increase in irradiance was obtained only six years ago. However, the observed increase in the PsbS content was short-termed (on an hour-timescale). Here, we report a significant (more than three orders of magnitude) and prolonged (four days) upregulation of PsbS expression in response to the chilling-induced high-light stress followed by a less significant (~ tenfold) increase in the PsbS expression for nine days. This is the first evidence for the long-term upregulation of the PsbS expression in green alga (Chlorophyta) in response to stress. Our data indicate that the role of PsbS in the PSA of Chlorophyta is not limited to the first-line defense against stress, as it was previously assumed, but includes full-scale participation in the photoprotection of PSA from the environmental stress factors.

The Effect of Chilling on the Photosynthetic Apparatus of Microalga Lobosphaera incisa IPPAS C-2047.

Photosynthetic organisms have developed a set of mechanisms aimed at preventing photo-oxidative reactions in the photosynthetic apparatus (PSA) initiated by excessively absorbed light energy. Along with high irradiance, other stressors, e.g., chilling temperatures, can lead to the absorption of the excess of light energy and hence to photo-oxidative stress. Here, we studied induction of photoprotective mechanisms in response to chilling (0°C) at a low irradiance (50 µmol PAR photons m-2·s-1) in the cells of microalga Lobosphaera incisa IPPAS C-2047. After 4 days of incubation at a low temperature, L. incisa IPPAS C-2047 cells showed a notable decrease in the photochemical activity of photosystem II (PSII) and in the efficiency of photosynthetic electron transport, as well as a significant increase in the thermal dissipation of the absorbed light energy in the light-harvesting antenna. In contrast, most conventional markers of PSA acclimation to excess light energy [total chlorophyll and carotenoid content; violaxanthin cycle pigment content and de-epoxidation state; photosynthetic antenna, PSII, and photosystem I (PSI) ratio] remained virtually unchanged. The content of major unsaturated fatty acids also remained almost unaffected, except for arachidonic acid (increased by 40%) recently assumed to activate violaxanthin de-epoxidase by adjusting its lipid microenvironment. Significant changes (4-7-fold increase) were observed in the expression of the gene encoding protective protein LhcSR. Pre-conditioning at 5°C prior to the acclimation to 0°C augmented the PSA photochemical activity. Our data show that the mid-term (4-d) acclimation of L. incisa IPPAS C-2047 to a chilling temperature at a low irradiance triggers the PSA response resembling, in part, the response to high light but relying mostly on the LhcSR protein-dependent quenching of excitation in the photosynthetic antenna.

Improved soybean transformation for efficient and high throughput transgenic production.

Although genetic transformation of soybean dates back to over two decades, the process remains inefficient. Here, we report the development of an organogenesis-based transformation method of soybean that resulted in an average transformation frequency of 18.7%. This improved method resorts to Agrobacterium-mediated transformation of the split-seed explant with an attached partial embryonic axis obtained from an imbibed seed. In addition to the split-seed explant, Agrobacterium strain and preparation were shown to be important for improved transformation. Transformation with Agrobacterium tumefaciens EHA105 generated higher transformation frequencies and number of low copy events compared to the strain EHA101. In this system, phosphinothricin acetyl transferase conferring tolerance to glufosinate was successfully employed for efficiently producing transgenic events. Around 48% of the T1 progeny was demonstrated to be heritable based on molecular analysis and screening with the herbicide Liberty®. This method was shown to be applicable to different genotypes and a few elite lines showed high transformation frequencies. This split-seed system with an attached partial embryonic axis serves not only as an efficient means for high throughput transgenic production for basic research studies but also for the commercial development of transgenic soybean products.

Novel Universal Recombinant Rotavirus A Vaccine Candidate: Evaluation of Immunological Properties.

Rotavirus infection is a leading cause of severe dehydrating gastroenteritis in children under 5 years of age. Although rotavirus-associated mortality has decreased considerably because of the introduction of the worldwide rotavirus vaccination, the global burden of rotavirus-associated gastroenteritis remains high. Current vaccines have a number of disadvantages; therefore, there is a need for innovative approaches in rotavirus vaccine development. In the current study, a universal recombinant rotavirus antigen (URRA) for a novel recombinant vaccine candidate against rotavirus A was obtained and characterised. This antigen included sequences of the VP8* subunit of rotavirus spike protein VP4. For the URRA, for the first time, two approaches were implemented simultaneously-the application of a highly conserved neutralising epitope and the use of the consensus of the extended protein's fragment. The recognition of URRA by antisera to patient-derived field rotavirus isolates was proven. Plant virus-based spherical particles (SPs), a novel, effective and safe adjuvant, considerably enhanced the immunogenicity of the URRA in a mouse model. Given these facts, a URRA + SPs vaccine candidate is regarded as a prospective basis for a universal vaccine against rotavirus.

Examination of biologically active nanocomplexes by nanoparticle tracking analysis.

Nanoparticle tracking analysis (NTA) was first applied to biologically active nanocomplexes to obtain concurrent information on their size, state of aggregation, concentration, and antigenic specificity in liquid. The subject of the NTA was an immunogenic complex (a candidate nanovaccine) comprised of spherical particles (SPs) generated by thermal remodeling of the tobacco mosaic virus and Rubella virus tetraepitopes exposed on the surface of SP.

Plant Viruses as Adjuvants for Next-Generation Vaccines and Immunotherapy.

Vaccines are the cornerstone of infectious disease control and prevention. The outbreak of SARS-CoV-2 has confirmed the urgent need for a new approach to the design of novel vaccines. Plant viruses and their derivatives are being used increasingly for the development of new medical and biotechnological applications, and this is reflected in a number of preclinical and clinical studies. Plant viruses have a unique combination of features (biosafety, low reactogenicity, inexpensiveness and ease of production, etc.), which determine their potential. This review presents the latest data on the use of plant viruses with different types of symmetry as vaccine components and adjuvants in cancer immunotherapy. The discussion concludes that the most promising approaches might be those that use structurally modified plant viruses (spherical particles) obtained from the Tobacco mosaic virus. These particles combine high adsorption properties (as a carrier) with strong immunogenicity, as has been confirmed using various antigens in animal models. According to current research, it is evident that plant viruses have great potential for application in the development of vaccines and in cancer immunotherapy.

Ewing sarcoma treatment: a gene therapy approach.

Ewing sarcoma (ES) is an aggressive malignant tumor, characterized by non-random chromosomal translocations that produce fusion genes. Fusion genes and fusion protein products are promising targets for gene therapy. Therapeutic approaches and strategies vary based on target molecules (nucleotides, proteins) of interest. We present an extensive literature review of active molecules for gene therapy and methods of gene therapy delivery, both of which are necessary for successful treatment.

Immunogenic compositions assembled from tobacco mosaic virus-generated spherical particle platforms and foreign antigens.

We reported recently that RNA-free spherical particles (SPs) generated by thermal remodelling of tobacco mosaic virus (TMV) are capable of binding GFP to their surface. Here, we show that SPs represent a universal particle platform that can form compositions by binding a diversity of various foreign proteins/epitopes of viral and non-viral origin to their surface. Numerous molecules of a foreign protein linked to the SP surface were revealed by immunogold electron microscopy. Several SP-based compositions were obtained containing one of the following foreign antigens: antigenic determinant A of rubella virus E1 glycoprotein; a recombinant protein containing the M2e epitope of influenza virus A protein M2; a recombinant antigen consisting of three epitopes of influenza virus A haemagglutinin; potato virus X (PVX) coat protein (CP); BSA; and PVX CP fused with the epitope of plum pox virus CP. The 'mixed' compositions could be also assembled by binding two different foreign antigens to each of the SPs. Immunogenicity of foreign antigens adsorbed or linked covalently to SPs in the SP-based compositions was examined. The antigenic specificity of foreign antigens was retained, whereas their immunogenicity increased significantly. It was inferred that SPs exhibit immunopotentiating activity, in particular in the form of compositions comprising SP and foreign antigen linked covalently to their surface by formaldehyde.

Designing Stable Bacillus anthracis Antigens with a View to Recombinant Anthrax Vaccine Development.

Anthrax is a disease caused by Bacillus anthracis that affects mammals, including humans. Recombinant B. anthracis protective antigen (rPA) is the most common basis for modern anthrax vaccine candidates. However, this protein is characterised by low stability due to proteolysis and deamidation. Here, for the first time, two modification variants leading to full-size rPA stabilisation have been implemented simultaneously, through deamidation-prone asparagine residues substitution and by inactivation of proteolysis sites. Obtained modified rPA (rPA83m) has been demonstrated to be stable in various temperature conditions. Additionally, rPA1+2 containing PA domains I and II and rPA3+4 containing domains III and IV, including the same modifications, have been shown to be stable as well. These antigens can serve as the basis for a vaccine, since the protective properties of PA can be attributed to individual PA domains. The stability of each of three modified anthrax antigens has been considerably improved in compositions with tobacco mosaic virus-based spherical particles (SPs). rPA1+2/rPA3+4/rPA83m in compositions with SPs have maintained their antigenic specificity even after 40 days of incubation at +37 °C. Considering previously proven adjuvant properties and safety of SPs, their compositions with rPA83m/rPA1+2/rPA3+4 in any combinations might be suitable as a basis for new-generation anthrax vaccines.

Applications of methods of psychological support developed for astronauts for use in medical settings.

Over the past 40 years, psychological support (PS) for cosmonauts and astronauts has remained an important part of the regular biomedical provision of space crews during extended orbital flights. It includes well-developed principles and a set of methods that have proven its effectiveness for the maintenance of behavioral health under extreme conditions of space flight. The main principle of PS in flight is to restore the usual sensory input to compensate for the monotony and lack of external stimuli as a result of a long stay under isolation and confinement. Risk factors for the psychological health and well-being defined for the astronauts, such as sensory and social deprivation, monotony, confinement, and lack of privacy, also remain part and parcel of several civil professions. These include polar wintering, submarines, working on oil platforms, and ocean fishing. Most of these factors also adversely affect the recovery rate of a large contingent of medical institutions, especially bedridden patients with chronic diseases. Finally, due to the negative epidemiological situation associated with the spread of COVID-19, an increasingly wide range of citizens forced to be in self-isolation faces negative manifestations of the deprivation phenomena described previously. Several cases of successful use of PS under isolation, monotony, crowding, and confinement are presented. Thus, we assume that the use of psychological support methods developed for space flights could be extremely relevant in civil medicine and everyday life.

Vaccine Candidate Against COVID-19 Based on Structurally Modified Plant Virus as an Adjuvant.

A recombinant vaccine candidate has been developed based on the major coronaviruses' antigen (S protein) fragments and a novel adjuvant-spherical particles (SPs) formed during tobacco mosaic virus thermal remodeling. The receptor-binding domain and the highly conserved antigenic fragments of the S2 protein subunit were chosen for the design of recombinant coronavirus antigens. The set of three antigens (Co1, CoF, and PE) was developed and used to create a vaccine candidate composed of antigens and SPs (SPs + 3AG). Recognition of SPs + 3AG compositions by commercially available antibodies against spike proteins of SARS-CoV and SARS-CoV-2 was confirmed. The immunogenicity testing of these compositions in a mouse model showed that SPs improved immune response to the CoF and PE antigens. Total IgG titers against both proteins were 9-16 times higher than those to SPs. Neutralizing activity against SARS-CoV-2 in serum samples collected from hamsters immunized with the SPs + 3AG was demonstrated.

New formulation of a recombinant anthrax vaccine stabilised with structurally modified plant viruses.

Anthrax is a disease caused by Bacillus anthracis. The most promising approach to the development of anthrax vaccine is use of the anthrax protective antigen (PA). At the same time, recombinant PA is a very unstable protein. Previously, the authors have designed a stable modified recombinant anthrax protective antigen with inactivated proteolytic sites and substituted deamidation sites (rPA83m). As a second approach to recombinant PA stabilisation, plant virus spherical particles (SPs) were used as a stabiliser. The combination of these two approaches was shown to be the most effective. Here, the authors report the results of a detailed study of the stability, immunogenicity and protectiveness of rPA83m + SPs compositions. These compositions were shown to be stable, provided high anti-rPA83m antibody titres in guinea pigs and were able to protect them from a fully virulent 81/1 Bacillus anthracis strain. Given these facts, the formulation of rPA83m + SPs compositions is considered to be a prospective anthrax vaccine candidate.

Long-term humoral immunogenicity, safety and protective efficacy of inactivated vaccine against reindeer rabies.

The core element of the reindeer rabies eradication strategy is regular application of vaccines to obtain and uphold a vaccination coverage sufficient for the ceasing of rabies virus transmission. This article presents the results of reindeer humoral immunity intensity and duration study after the immunization with two form of inactivated rabies vaccines (adjuvanted liquid vaccine and non-adjuvanted lyophilized vaccine) based on the Shchelkovo-51 rabies virus strain. Efficiency of post-vaccine immunity was assessed by measuring the animal blood serum virus-neutralizing antibody level in a neutralization test. The study determined the efficient rabies vaccine injection dose as equal to 3 ml. A single dose of 3 ml of these vaccines induced stable production of specific neutralizing antibodies in reindeer as early as 7 day after administration, and by 30 days after immunization, it significantly exceeded the minimal threshold level accepted by OIE. Two doses of vaccines administration with an interval of 30 days are required to achieve a strong immunity with the rabies-specific virus-neutralizing antibody titer of more than 0.5 IU/ml for at least 2 years. Our data do not support the benefit of an adjuvanted vaccine for the prevention of rabies in reindeer.

Thermal transition of native tobacco mosaic virus and RNA-free viral proteins into spherical nanoparticles.

Spherical nanoparticles (SNPs) were generated by two-step thermal remodelling of native tobacco mosaic virus (TMV) at 94 °C. Particles of irregular shape and varying size were generated by TMV at 90 °C. They could be converted into SNPs by heating at 94 °C and were considered to be intermediate precursors of SNPs. In addition to SNP monomers (53 nm diameter), generated by individual TMV virions, large SNPs (100-800 nm diameter) were assembled. The size of the SNPs depended on the TMV concentration. The SNPs could be generated by distinct forms of RNA-free TMV coat protein (CP) aggregates and individual CP subunits. A one-step SNP assembly appeared to occur in these cases. These results show that SNPs represent a new type of particle nanoplatform for producing compositions of SNPs with foreign protein molecules bound to their surface.

The complete nucleotide sequence of Alternanthera mosaic virus infecting Portulaca grandiflora represents a new strain distinct from phlox isolates.

A southeastern European isolate of Alternanthera mosaic virus (AltMV-MU) of the genus Potexvirus (family Flexiviridae) was purified from the ornamental plant Portulaca grandiflora. The complete nucleotide sequence (6606 nucleotides) of AltMV-MU genomic RNA was defined. The AltMV-MU genome is different from those of all isolates described earlier and is most closely related to genomes of partly sequenced portulaca isolates AltMV-Po (America) and AltMV-It (Italy). Phylogenetic analysis supports the view that AltMV-MU belongs to a new "portulaca" genotype distinguishable from the "phlox" genotype.