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

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.

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.

Dataset on safety and protective efficacy studies of COVID-19 vaccine candidates based on structurally modified plant virus in female hamsters

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.

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.

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.

Plant Viruses: New Opportunities under the Pandemic

During the pandemic, an urgent task has become to develop new vaccine platforms that will help fight the infection caused by SARS-CoV-2 and quickly respond to newly emerging pathogens. Plant viruses can make a significant contribution to the solution of this problem. Phytoviruses, having the properties of any viral particles (self-assembly, immunogenicity, nanosize), are safe for humans since plants and mammals have no common infectious agents. As a result of thermal rearrangement of the tobacco mosaic virus, spherical particles of a protein nature have been obtained, which have unique immunostimulation and adsorption properties and can play the role of a universal adjuvant platform to create vaccines. Based on these particles, a scheme for obtaining vaccine preparations is proposed. This technology resembles a toy construction set for children. The basis is spherical particles, on the surface of which there are toy blocks-antigens. The "blocks" can be removed, added, or replaced, and this does not take much time and resources. Based on spherical particles, a polyvalent vaccine candidate against COVID-19 has been created as an adjuvant platform.

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.

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.