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The ongoing pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a grave threat to global public health and imposes a severe burden on the entire human society. Like other coronaviruses, the SARS-CoV-2 genome encodes spike (S) glycoproteins, which protrude from the surface of mature virions. The S glycoprotein plays essential roles in virus attachment, fusion and entry into the host cell. Surface location of the S glycoprotein renders it a direct target for host immune responses, making it the main target of neutralizing antibodies. In the light of its crucial roles in viral infection and adaptive immunity, the S protein is the focus of most vaccine strategies as well as therapeutic interventions. In this review, we highlight and describe the recent progress that has been made in the biosynthesis, structure, function, and antigenicity of the SARS-CoV-2 S glycoprotein, aiming to provide valuable insights into the design and development of the S protein-based vaccines as well as therapeutics.

The rice immune receptor XA21 is activated by the sulfated microbial peptide required for activation of XA21-mediated immunity X (RaxX) produced by Xanthomonas oryzae pv. oryzae (Xoo). Mutational studies and targeted proteomics revealed that the RaxX precursor peptide (proRaxX) is processed and secreted by the protease/transporter RaxB, the function of which can be partially fulfilled by a noncognate peptidase-containing transporter component B (PctB). proRaxX is cleaved at a Gly–Gly motif, yielding a mature peptide that retains the necessary elements for RaxX function as an immunogen and host peptide hormone mimic. These results indicate that RaxX is a prokaryotic member of a previously unclassified and understudied group of eukaryotic tyrosine sulfated ribosomally synthesized, posttranslationally modified peptides (RiPPs). We further demonstrate that sulfated RaxX directly binds XA21 with high affinity. This work reveals a complete, previously uncharacterized biological process: bacterial RiPP biosynthesis, secretion, binding to a eukaryotic receptor, and triggering of a robust host immune response.

The first successful use of nanoparticles (NPs) for vaccination was reported almost 40 years ago with a virus-like particle-based vaccine against Hepatitis B. Since then, the term NP has been expanded to accommodate a large number of novel nano-sized particles engineered from a range of materials. The great interest in NPs is likely not only a result of the two successful vaccines against hepatitis B and Human Papilloma Virus (HPV) that use this technology, but also due to the versatility of those small-sized particles, as indicated by the wide range of applications reported so far, ranging from medicinal and cosmetics to purely technical applications. In this review, we will focus on the use of NPs, especially virus-like particles (VLPs), in the field of vaccines and will discuss their employment as vaccines, antigen display platforms, adjuvants and drug delivery systems.

The possibility of enhancing the immune response to a DNA vaccine encoding an artificial polyepitope T-cell immunogen containing a large number of conserved epitopes from different proteins of SARS-CoV-2 virus (pBSI-COV-Ub) was assessed by additional introduction of a plasmid encoding the secreted receptor-binding domain of the of SARS-CoV-2 S protein (pVAXrbd). Both a specific humoral response and a cellular response of broad specificity were observed in animals co-injected with pBSI-COV-Ub and pVAXrbd. This indicates the potential of this approach as a vaccine strategy.

Licensed vaccines or therapeutics are rarely available for pathogens with epidemic or pandemic potential. Developing interventions for specific pathogens and defining generalizable approaches for related pathogens is a global priority and inherent to the UN Sustainable Development Goals. Nipah virus (NiV) poses a significant epidemic threat, and zoonotic transmission from bats-to-humans with high fatality rates occurs almost annually. Human-to-human transmission of NiV has been documented in recent outbreaks leading public health officials and government agencies to declare an urgent need for effective vaccines and therapeutics. Here, we evaluate NiV vaccine antigen design options including the fusion glycoprotein (F) and the major attachment glycoprotein (G). A stabilized prefusion F (pre-F), multimeric G constructs, and chimeric proteins containing both pre-F and G were developed as protein subunit candidate vaccines. The proteins were evaluated for antigenicity and structural integrity using kinetic binding assays, electron microscopy, and other biophysical properties. Immunogenicity of the vaccine antigens was evaluated in mice. The stabilized pre-F trimer and hexameric G immunogens both induced serum neutralizing activity in mice, while the post-F trimer immunogen did not elicit neutralizing activity. The pre-F trimer covalently linked to three G monomers (pre-F/G) induced potent neutralizing antibody activity, elicited responses to the greatest diversity of antigenic sites, and is the lead candidate for clinical development. The specific stabilizing mutations and immunogen designs utilized for NiV were successfully applied to other henipaviruses, supporting the concept of identifying generalizable solutions for prototype pathogens as an approach to pandemic preparedness.

Electroporation (EP) allows for the transport of molecules into the cytoplasm with significant effectiveness by forming transient pores in the cell membrane using electric pulses. This can be used for cellular transport (RE—reversible electroporation) or ablation (IRE—irreversible electroporation). The first of described options fortifies medicine with novel possibilities: electrochemotherapy (ECT), which creates promising perspectives for cancer treatment, and gene electrotransfer (GET), a powerful method of DNA delivery as well as immunogen electrotransfer. The review constitutes a comprehensive explanation of the mechanism of EP in the case of GET, its present and prospective employment in medicine, including gene delivery, vaccinations, therapy, and transfection, are also presented.

Nipah virus (NiV) represents a significant pandemic threat with zoonotic transmission from bats-to-humans with almost annual regional outbreaks characterized by documented human-to-human transmission and high fatality rates. Currently, no vaccine against NiV has been approved. Structure-based design and protein engineering principles were applied to stabilize the fusion (F) protein in its prefusion trimeric conformation (pre-F) to improve expression and increase immunogenicity. We covalently linked the stabilized pre-F through trimerization domains at the C-terminus to three attachment protein (G) monomers, forming a chimeric design. These studies detailed here focus on mRNA delivery of NiV immunogens in mice, assessment of mRNA immunogen-specific design elements and their effects on humoral and cellular immunogenicity. The pre-F/G chimera elicited a strong neutralizing antibody response and a superior NiV-specific Tfh and other effector T cell response compared to G alone across both the mRNA and protein platforms. These findings enabled final candidate selection of pre-F/G Fd for clinical development.

To establish an indirect competitive ELISA ( ci- ELISA) for the detection of guanidino acetic acid (GAA) residues in animal feed, in this study, GAA was coupled to carrier proteins via the active ester method to obtain an anti-GAA complete antigen (GAA-BSA) and a detection antigen (GAA-OVA). BALB/c mice were immunized with GAA-BSA, after which anti-GAA monoclonal antibodies were prepared via hybridoma and other techniques. An ic- ELISA method was developed by optimizing the reaction conditions and the accuracy, precision and specificity of the method were determined. The results showed that GAA was successfully coupled to the carrier protein; a hybridoma cell line (2C4) against GAA was obtained, and the IC 50 value of the monoclonal antibody was 4.65 µg/kg; The average recovery rate of GAA spiked in animal feed by this method was 87.4%, and its intra-assay coefficients of variation were greater than the inter-assay coefficients of variation in all assays; no cross-reaction with the other competing reactants was detected. The indirect competitive ELISA method developed in this study was able to fulfil the requirements for the determination of GAA r esidues in animal feed.

Generating antibodies targeting native membrane proteins presents various challenges because these proteins are often embedded in the lipid bilayer, possess various extracellular and intracellular domains, and undergo post-translational modifications. These properties of MPs make it challenging to preserve their stable native conformations for immunization or antibody generation outside of the membranes. In addition, MPs are often hydrophobic due to their membrane-spanning regions, making them difficult to solubilize and purify in their native form. Therefore, employing purified MPs for immunogen preparation may result in denaturation or the loss of native structure, rendering them inadequate for producing antibodies recognizing native conformations. Despite these obstacles, various new approaches have emerged to address these problems. We outline recent advancements in designing and preparing immunogens to produce antibodies targeting MPs. Strategies outlined here are relevant for producing antibodies for research, diagnostics, and therapies and designing immunogens for vaccination purposes.

Vaccination stands as one of the most transformative interventions in the history of human civilization. In medicine, vaccination stands as a cornerstone that has saved countless lives across generations. Nevertheless, conventional vaccine development remains encumbered by prolonged timelines, substantial financial investment, and high attrition rates particularly during late-stage clinical trials underscoring the urgent need for more efficient and systematic approaches. In recent years, artificial intelligence (AI) has emerged as a transformative force across the biomedical sciences, offering unprecedented computational capacity to process and interpret complex biological datasets. The convergence of AI with vaccinology represents a significant methodological advancement which has the potential to fundamentally redefine the vaccine development paradigm. AI integrates advances in machine learning, multi-omics data analysis, and high-performance computing to accelerate antigen discovery, epitope prediction, immunogen design, and clinical evaluation. This development represents a paradigm shift toward faster, more precise, and scalable strategies for vaccine development. This review critically examines the current landscape of AI applications in vaccine development, with particular emphasis on recent advancements, translational challenges, and the prospective role of AI in shaping the future of immunization science.