The Newcastle disease virus (NDV), an avian paramyxovirus, induces the highly contagious Newcastle disease in poultry. Newcastle disease outbreaks, common in many developing countries, have been recorded worldwide for a century. Poultry, even vaccinated stocks, together with wild and synanthropic birds, serve as reservoirs of NDV. Despite the extensive use of commercial NDV vaccines, Newcastle disease outbreaks frequently occur in vaccinated chickens, resulting in great economic losses. The primary limitation of commercial Newcastle disease vaccines is their restricted compatibility with emerging novel NDV strains. The advancement of vaccines and vaccination techniques is anticipated to reduce the propagation of pathogenic NDV strains and consequently alleviate losses in poultry production. This review examines the NDV genotypes and strains implicated in both current and historical Newcastle disease outbreaks, and evaluates existing and candidate NDV vaccines, emphasizing recent innovations and novel techniques. Our aim was to delineate critical subjects for future inquiry and to furnish extensive data that could aid researchers in understanding the current advancements and existing problems in Newcastle disease vaccination prophylactics. The emergence of a new generation of vaccines employing advanced technologies may substantially improve the efficacy of Newcastle disease prevention and control.

The use of computer simulation methods has become an indispensable component in identifying drugs against the SARS-CoV-2 coronavirus. There is a huge body of literature on application of molecular modelling to predict inhibitors against target proteins of SARS-CoV-2. To keep our review clear and readable, we limited ourselves primarily to works that use computational methods to find inhibitors and test the predicted compounds experimentally either in target protein assays or in cell culture with live SARS-CoV-2. Some works containing results of experimental discovery of corresponding inhibitors without using computer modelling are included as examples of a success. Also, some computational works without experimental confirmations are also included if they attract our attention either by simulation methods or by databases used. This review collects studies that use various molecular modelling methods: docking, molecular dynamics, quantum mechanics, machine learning, and others. Most of these studies are based on docking, and other methods are used mainly for post-processing to select the best compounds among those found through docking. Simulation methods are presented concisely, information is also provided on databases of organic compounds that can be useful for virtual screening, and the review itself is structured in accordance with coronavirus target proteins.

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.

This review addresses the ongoing global challenge posed by emerging and evolving viral diseases, underscoring the need for innovative vaccine development strategies. It focuses on the modern approaches to creating vaccines based on recombinant proteins produced in different expression systems, including bacteria, yeast, plants, insects, and mammals. This review analyses the advantages, limitations, and applications of these expression systems for producing vaccine antigens, as well as strategies for designing safer, more effective, and potentially ‘universal’ antigens. The review discusses the development of vaccines for a range of viral diseases, excluding SARS-CoV-2, which has already been extensively studied. The authors present these findings with the aim of contributing to ongoing research and advancing the development of antiviral vaccines.

This data article is related to the previous research, which addressed the development of a COVID-19 recombinant vaccine candidate. Here, we present the additional data in support of the safety and protective efficacy evaluation of two COVID-19 vaccine candidates based on the coronaviruses' S protein fragments and a structurally modified plant virus - spherical particles. The effectiveness of the experimental vaccines was studied against the SARS-CoV-2 virus in an in vivo infection model in female Syrian hamsters. The body weight of vaccinated laboratory animals was monitored. The histological assessment data of the infected with the SARS-CoV-2 virus hamsters' lungs are provided.

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.

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.

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.

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.

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.

Purpose Recombinant rotavirus A vaccines are being developed as an alternative to existing live oral attenuated vaccines. One of the main problems in the production of such vaccines is the genetic diversity of the strains that are in circulation. The goal of this study was to create an antigen panel for modern broad-spectrum recombinant rotavirus A vaccine. Materials and Methods The antigens of rotavirus were cloned and expressed in Escherichia coli. Antigenic specificity was investigated by Western blot analysis, which was performed using commercial polyclonal antisera to several RVA strains. Phylogenetic analysis was based on the amino acid sequences of the VP8* protein fragment of human RVA isolates representing genotypes P[4], P[6], and P[8]. Results A universal panel of antigens was established, including consensus and conserved sequences of structural proteins VP8*, VP5*, and VP7, which are the main targets of neutralizing antibodies. For the first time, a consensus approach was used in the design of extended antigens based on VP8* (genotypes P[4], P[6], and P[8]) and VP5* (genotype P[8]) proteins' fragments. In addition, a gene coding the protein (ep-875) containing several copies of conserved short neutralizing epitopes of VP8*, VP7, and VP5* was created. Western blot analysis demonstrated that three synthetic VP8*-based antigens were not recognized by commercial antiserum against rotavirus strains isolated more than 35 years ago, but the specific activity of the VP5* and ep-875 antigens was confirmed. The problems of serological mismatch of vaccine strains and antigens with currently circulating strains are discussed. Conclusion Five antigens representing sequences of structural proteins belonging to different genotypes can be used in various combinations (from mono- to pentavalent mixtures) for the development of an effective broad-spectrum rotavirus vaccine.

Anthrax is a zoonotic disease caused by the gram-positive spore-forming bacteria Bacillus anthracis. There is a need for safe, highly effective, long-term storage vaccine formulations for mass vaccination. However, the development of new subunit vaccines based on recombinant protective antigen (rPA) faces the problem of vaccine antigen instability. Here, the potential of simultaneous application of two different approaches to stabilize rPA was demonstrated. Firstly, we employed spherical particles (SPs) obtained from the tobacco mosaic virus (TMV). Previously, we had reported that SPs can serve as an adjuvant and platform for antigen presentation. In the current work, SPs were shown to increase the stability of the full-size rPA without loss of its antigenic properties. The second direction was site-specific mutagenesis of asparagine residues to avoid deamidation that causes partial protein degradation. The modified recombinant protein comprising the PA immunogenic domains 3 and 4 (rPA3 + 4) was stable during storage at 4 and 25°C. rPA3 + 4 interacts with antibodies to rPA83 both individually and as a part of a complex with SPs. The results obtained can underpin the development of a recombinant vaccine with a full-size modified rPA (with similar amino acid substitutions that stabilize the protein) and SPs.

A genetically engineered chimeric virus crTMV-CP-PLRV composed of the crucifer-infecting tobacco mosaic virus (crTMV) RNA and the potato leafroll virus (plrv) coat protein (CP) was obtained by agroinfiltration of Nicotiana benthamiana with the binary vector pCambia-crTMV-CPPLRV. The significant levels of the chimeric virus enabled direct visualization of crTMV-CP-PLRV in the cell and to investigate the mechanism of the pathogenesis. Localization of the crTMV-CP-PLRV in plant cells was examined by immunoblot techniques, as well as light, and transmission electron microscopy. The chimera can transfer between vascular and nonvascular tissues. The chimeric virus inoculum is capable to infect N. benthamiana mechanically. The distinguishing feature of the chimeric virus, the RNA virus with the positive genome, was found to localize in the nucleolus. We also investigated the role of the N-terminal sequence of the PLRV P3 coat protein in the cellular localization of the virus. We believe that the gene of the PLRV CP can be substituted with genes from other challenging-to-study plant pathogens to produce other useful recombinant viruses.

Introduction: Anthrax is a dangerous bio-terror agent because Bacillus anthracis spores are highly resilient and can be easily aerosolized and disseminated. There is a threat of deliberate use of anthrax spores aerosol that could lead to serious fatal diseases outbreaks. Existing control measures against inhalation form of the disease are limited. All of this has provided an impetus to the development of new generation vaccines. Areas сovered: This review is devoted to challenges and achievements in the design of vaccines based on the anthrax recombinant protective antigen (rPA). Scientific databases have been searched, focusing on causes of PA instability and solutions to this problem, including new approaches of rPA expression, novel rPA-based vaccines formulations as well as the simultaneous usage of PA with other anthrax antigens. Expert opinion: PA is a central anthrax toxin component, playing a key role in the defense against encapsulated and unencapsulated strains. Subunit rPA-based vaccines have a good safety and protective profile. However, there are problems of PA instability that are greatly enhanced when using aluminum adjuvants. New adjuvant compositions, dry formulations and resistant to proteolysis and deamidation mutant PA forms can help to handle this issue. Devising a modern anthrax vaccine requires huge efforts.

Spherical particles (SPs) generated by thermally denatured tobacco mosaic virus (TMV) coat protein can act as an adjuvant, as they are able to enhance the magnitude and longevity of immune responses to different antigens.Here, the toxicity of TMV SPs was assessed prior to it being offered as a universal safe adjuvant for the development of vaccine candidates. The evaluation included nonclinical studies of a local tolerance following the single administration of TMV SPs, and of the local and systemic effects following repeated administrations of TMV SPs. These were conducted in mice, rats and rabbits. General health status, haematology and blood chemistry parameters were monitored on a regular basis. Also, reproductive and development toxicity were studied. No significant signs of toxicity were detected following single or repeated administrations of the adjuvant (TMV SPs).The absence of toxicological effects following the injection of TMV SPs is promising for the further development of recombinant vaccine candidates with TMV SPs as an adjuvant.

This data article is related to the research article entitled "Assessment of structurally modified plant virus as a novel adjuvant in toxicity studies" (Nikitin et al., 2018), devoted to the safety study of structurally modified plant virus - spherical particles (SPs). SPs are generated by thermally denatured tobacco mosaic virus (TMV) coat protein and act as effective adjuvant for development of new vaccine candidates. This article reports the additional results on the toxicity studies of TMV SPs. The weight coefficients of laboratory animals internal organs complements the data of the subchronic toxicity studies. Also plaque-forming cell assay, delayed-type hypersensitivity test and peritoneal macrophage assay as a part of immunotoxicity studies of TMV SPs are presented.

Large quantities of potato leafroll virus (PLRV) antigen are difficult to obtain because this virus accumulates in plants at a low titer. To overcome this problem, we constructed a binary vector containing chimeric cDNA, in which the coat protein (CP) gene of the crucifer infecting tobacco mosaic virus (crTMV) was substituted for the coat protein gene of PLRV. The PLRV movement protein (MP) gene, which overlaps completely with the CP gene, was doubly mutated to eliminate priming of the PLRV MP translation from ATG codons with no changes to the amino acid sequence of the CP. The untranslated long intergenic region located upstream of the CP gene was removed from the construct. Transcribed powerful tobamovirus polymerase of the produced vector synthesized PLRV CP gene that was, in turn, translated into the protein. CP PLRV packed RNAs from the helical crTMV in spherical virions. Morphology, size and antigenic specificities of the wild-type and chimeric virus were similar. The yield of isolated chimera was about three orders higher than the yield of native PLRV. The genetic manipulations facilitated the generation of antibodies against the chimeric virus, which recognize the wild-type PLRV.