Search Results (36)

Background/Objectives: Self-amplifying RNA (saRNA) vectors enable high-level transgene expression from minimal initial doses. While alphavirus-based saRNA systems are widely used, they suffer from limitations, including large genome size, complex replicase machinery, and cellular toxicity. Nodamura virus (NoV) offers a promising alternative due to its compact genome (3.2 kb) and low cytotoxicity. This study aimed to elucidate NoV RNA1 replication mechanisms and develop a novel NoV-based saRNA vector platform. Methods: We established a Schizosaccharomyces pombe system to investigate NoV RNA1 replication and protein A localization. N-terminal deletion mutants and ER-targeting chimeras were constructed to characterize membrane targeting determinants. Based on mechanistic insights, we developed NovaVec by inserting transgenes at the RNA3⁴²² site within the subgenomic RNA3 region. In vivo performance was evaluated using lipid nanoparticle-encapsulated NovaVec expressing nanoluciferase or monkeypox A33R antigen in BALB/c mice. Results: We identified redundant mitochondrial targeting domains (amino acids 2-15 and 16-33) in NoV protein A, where either domain was sufficient for proper localization and replication. The replication machinery could be functionally redirected to the endoplasmic reticulum while maintaining replication competence. Lipid nanoparticle-encapsulated NovaVec achieved sustained transgene expression for 54 days in mice, significantly outperforming conventional mRNA vectors that lost signal within 14 days. The NovaVec-based monkeypox A33R vaccine elicited robust antigen-specific humoral immunity with titers reaching approximately 1:12,800 following booster immunization. Conclusions: With its compact genome encoding only a single replicase protein, minimal cytopathic effects, and demonstrated capacity for long-term protein expression, NovaVec represents a highly promising next-generation saRNA platform for vaccines. Full article

The medical field now uses mRNA therapeutics to deliver fast programmable treatment options through versatile vaccination platforms. The worldwide adoption of mRNA therapeutics faces a major obstacle because these molecules require extreme cold storage and transportation systems. mRNA stability establishes a fundamental scientific and industrial challenge which requires researchers to unite formulation design with process control and material engineering for cold-chain independence. Current knowledge about RNA hydrolysis and lipid oxidation and water-mediated degradation is combined with new methods for solid-state stabilization through lyophilization and spray-freeze-drying and thin-film technologies. Mechanism such as vitrification, water replacement and excipient RNA interactions are assessed to establish the fundamental chemical properties needed for extended product stability. Advanced mRNA development strategies are also examined, including self-amplifying and circular RNA structures and nano-glass and metal–organic frameworks and artificial intelligence-based predictive design for creating stable mRNA formulations at room temperature. This review examines manufacturing and regulatory and logistical obstacles which affect real-world implementation of mRNA therapeutics through assessments of production scale and product quality tests and packaging strength and tropical environment testing. The combination of research findings presents a path to develop mRNA medicines which maintains their effectiveness when stored at 25 °C or above, thus enabling worldwide access to RNA-based treatments. The development of mRNA into a durable therapeutic platform requires scientists to merge molecular research with process development and regulatory standardization. Full article

mRNA vaccines represent a revolutionary advance in vaccinology, boasting advantages like rapid development, robust immunogenicity and flexible antigen design over traditional vaccines. This review systematically summarizes the core research progress of mRNA vaccines, including their structural composition with five functional elements and novel subtypes (linear mRNA, self-amplifying RNA, circular RNA) with unique biological characteristics and application value. It elaborates on the immune activation mechanism of mRNA vaccines, which mimic natural viral infection to trigger both innate and adaptive immunity, and analyzes mainstream delivery systems (lipid nanoparticles, dendritic cells, protamine, exosomes, polymers) with their respective performance, advantages and bottlenecks. This review also details the clinical application status of mRNA vaccines in infectious diseases (influenza, rabies, monkeypox, SARS-CoV-2, HIV, parasites) and cancer therapy, highlighting promising preclinical and clinical results of candidate vaccines and combined therapeutic regimens. Additionally, it addresses the current limitations of mRNA vaccines, such as delivery inefficiency, production costs, and cold chain constraints. Finally, this review prospects the future development direction, emphasizing that the optimization of delivery systems, antigen design and production processes will further promote the clinical translation and diversified application of mRNA vaccines in disease prevention and treatment. Full article

Background: Self-amplifying mRNA (sa-mRNA) represents a promising platform for vaccines and gene therapies, offering sustained protein expression at low doses through self-replication. For vaccines targeting respiratory pathogens, pulmonary delivery of sa-mRNA lipid nanoparticles (LNPs) is particularly advantageous, enabling direct delivery to the infection site and induction of mucosal immunity. Objective: In this study, we evaluated the stability of sa-mRNA–LNPs under refrigerated and frozen conditions and developed a dry powder formulation suitable for inhalation, produced by freeze-drying followed by cryomilling with leucine. Methods: sa-mRNA–LNPs formulated in HEPES buffer with 20% (w/v) sucrose were stored for up to 8 weeks as liquid or freeze-dried samples at various temperatures (−80 °C, −20 °C, 4 °C, and 20 °C). Biological stability was assessed by transfection efficiency in HeLa cells, while physical stability was characterized by encapsulation efficiency, zeta potential, particle size, and polydispersity index. Results: Liquid formulations remained stable for at least 8 weeks at −80 °C and −20 °C but rapidly lost stability at 4 °C and 20 °C. Freeze-drying effectively preserved sa-mRNA–LNP functionality and structural integrity for up to 8 weeks at 4 °C, with only minor structural changes. Subsequent cryomilling in the presence of 4 wt-% leucine produced a respirable dry powder while retaining approximately 60% of the original sa-mRNA–LNP functionality. Although cryomilling induced some structural alterations, the remaining functional fraction remained stable during storage. The resulting powders displayed favorable aerosol performance for deep lung delivery, as demonstrated by cascade impaction (MMAD = 4.13 ± 0.26 µm). Conclusions: In conclusion, freeze-drying effectively preserved sa-mRNA–LNP integrity at 4 °C, whereas cryomilling with leucine produced a respirable dry powder suitable for pulmonary delivery, providing a foundation for globally accessible, needle-free sa-mRNA vaccines against respiratory diseases. Full article

Infectious Bursal Disease (IBD) is an immunosuppressive viral disease caused by the Infectious Bursal Disease Virus (IBDV). It primarily affects young chickens, targeting the bursa of Fabricius, and poses significant economic threats to the poultry industry. To date, in addition to strict biosecurity measures, large-scale immunization is the optimal strategy and effective method to prevent and control IBDV infection. The emergence of new variant strains has made it more urgent to develop new vaccination strategies against IBD. Over the past few decades, many high-quality vaccines have been available on the market for the control of IBD, which can provide solid protection against the infections and diseases caused by classic IBDV to very virulent IBDV that had been continuously evolving and were endemic worldwide. However, viruses are not static. As they continue to circulate and evolve in the fields, novel antigenic variant viruses have been emerged in the last few years, and vaccines need to keep up with their pace. Collectively, this review summarizes the strategic evolution of IBDV vaccines from traditional methods to cutting-edge molecular platforms, providing promising strategies for developing the next-generation vaccines with higher safety, efficacy, and the ability to keep pace with the antigenic drift in IBDV. Full article

Background: Self-amplifying mRNA (saRNA) holds promising application prospects. However, due to the inclusion of a replicase sequence, its extended length leads to premature termination during in vitro transcription (IVT), resulting in poor product integrity. This study aims to optimize the IVT process for saRNA vaccines to enhance integrity, thereby addressing the key challenge in saRNA vaccine manufacturing. Method: Guided by the Quality by Design (QbD) framework, Design of Experiment (DoE) methodology was employed to design diverse combinations of process parameters for IVT reactions. Predictive models were established to identify critical process parameters (CPPs) influencing integrity and yield. An optimized parameter set and process design space, meeting predefined yield and integrity standards, were developed. The impact of integrity on the immunogenicity of saRNA vaccines was further investigated. Results: Mg²⁺ concentration exerted the most pronounced effect on saRNA integrity. Under optimized IVT conditions, integrity exceeded 85%. Mathematical modeling simulations defined the IVT design space, meeting the preset criteria of ≥80% integrity and ≥600 μg/100 μL yield while accommodating longer saRNA constructs. Notably, murine model data revealed that higher saRNA integrity significantly enhanced antigen-specific antibody and T-cell responses. Conclusion: This study successfully established a multivariate IVT design space fulfilling preset integrity and yield criteria, providing critical data references for the industrialization and quality specification development of saRNA vaccines. Full article

Deoxyribonucleic acid (DNA) vaccines have re-emerged as a versatile and scalable platform by advances in synthetic biology and delivery systems, positioning them as powerful tools in the post-mRNA vaccine era. Historically considered less potent than viral or mRNA-based platforms, recent breakthroughs have dramatically improved their immunogenicity, safety, and precision. These innovations include synthetic gene circuits, self-amplifying DNA (saDNA), and DNA-encoded monoclonal antibodies (DMAbs), which enable programmable expression and robust immune activation. Clinically, DNA vaccines are expanding into diverse applications, from infectious disease prevention to therapeutic cancer immunotherapy and treatment of immune-mediated conditions. Compared to mRNA vaccines, DNA vaccines offer compelling advantages in terms of thermal stability, ease of manufacturing, and long-term storage. Furthermore, novel adjuvants, electroporation methods, and formulation strategies such as lyophilization and encapsulation continue to broaden their clinical potential. This review explores the full scope of DNA vaccine technology and its engineering foundations, emerging disease applications, and interdisciplinary innovations, while evaluating its comparative performance and future role in global vaccine strategy. With an emphasis on both mechanistic insights and translational feasibility, we propose a roadmap to integrate DNA vaccines into the next generation of precision immunotherapy. Full article

RNA-based cancer vaccines have emerged as transformative immunotherapeutic platforms, leveraging advances in mRNA technology and personalized medicine approaches. Recent clinical breakthroughs, particularly the success of mRNA-4157 combined with pembrolizumab in melanoma patients, have demonstrated significant improvements in efficacy, with a 44% reduction in recurrence risk compared to checkpoint inhibitor monotherapy. Breakthrough results from pancreatic cancer vaccines and novel glioblastoma treatments using layered nanoparticle delivery systems mark 2024–2025 as a pivotal period for RNA cancer vaccine development. Current RNA vaccine platforms include conventional mRNA, self-amplifying RNA, trans-amplifying RNA, and emerging circular RNA technologies, with over 120 clinical trials currently underway across various malignancies. Critical advances in delivery optimization include next-generation lipid nanoparticles with tissue-specific targeting and novel nanoengineered systems achieving rapid immune system reprogramming. Manufacturing innovations focus on automated platforms, reducing production timelines from nine weeks to under four weeks for personalized vaccines, while costs remain challenging at over $ 100,000 per patient. Artificial intelligence integration is revolutionizing neoantigen selection through advanced algorithms and CRISPR-enhanced platforms, while regulatory frameworks are evolving with new FDA guidance for therapeutic cancer vaccines. Non-coding RNA applications, including microRNA and long non-coding RNA therapeutics, represent emerging frontiers with potential for enhanced immune modulation. With over 60 candidates in clinical development and the first commercial approvals anticipated by 2029, RNA cancer vaccines are positioned to become cornerstone therapeutics in personalized oncology, offering transformative hope for cancer patients worldwide. Full article

The emergence of complex and rapidly evolving pathogens necessitates innovative vaccine platforms that move beyond traditional methods. This review explores the transformative potential of next-generation vaccine technologies, focusing on the combined use of synthetic biology, nanotechnology, and systems immunology. Synthetic biology provides modular tools for designing antigenic components with improved immunogenicity, as seen in mRNA, DNA, and peptide-based platforms featuring codon optimization and self-amplifying constructs. At the same time, nanotechnology enables precise antigen delivery and controlled immune activation through engineered nanoparticles such as lipid-based carriers, virus-like particles, and polymeric systems to improve stability, targeting, and dose efficiency. Systems immunology aids these advancements by analyzing immune responses through multi-omics data and computational modeling, which assists in antigen selection, immune profiling, and adjuvant optimization. This approach enhances both humoral and cellular immunity, solving challenges like antigen presentation, response durability, and vaccine personalization. Case studies on SARS-CoV-2, Epstein–Barr virus, and Mycobacterium tuberculosis highlight the practical application of these platforms. Despite promising progress, challenges include scalability, safety evaluation, and ethical concerns with data-driven vaccine designs. Ongoing interdisciplinary collaboration is crucial to fully develop these technologies for strong, adaptable, globally accessible vaccines. This review emphasizes next-generation vaccines as foundational for future immunoprophylaxis, especially against emerging infectious diseases and cancer immunotherapy. Full article

Self-amplifying RNA-based (saRNA) technology represents the last frontier in using synthetic RNA in vaccinology. Typically, saRNA consists of positive-strand RNA molecules of viral origin (almost exclusively from alphaviruses) where the sequences of structural proteins are replaced with the open reading frame coding the antigen of interest. For in vivo delivery, they are complexed with lipid nanoparticles (LNPs), just like current COVID-19 vaccines based on synthetic messenger RNA (mRNA). Given their ability to amplify themselves inside the cell, optimal intracellular levels of the immunogenic antigen can be achieved by delivering lower amounts of saRNA molecules compared to mRNA-based vaccines. However, the excessive intracellular accumulation of saRNA may represent a relevant drawback since, as already described in alphavirus-infected cells, the recipient cell may react by incorporating excessive RNA molecules into extracellular vesicles (EVs). These EVs can shed and enter neighboring as well as distant cells, where the EV-associated saRNA can start a new replication cycle. This mechanism could lead to an unwanted and unnecessary spread of saRNA throughout the body, posing relevant safety issues. This perspective article discusses the molecular mechanisms through which saRNAs can be transmitted among different cells/tissues. In addition, a simple way to control the possible excessive saRNA intercellular propagation through the co-expression of an EV-anchored protein inhibiting the saRNA replication is proposed. Based on current knowledge, a safety improvement of saRNA-based vaccines appears to be mandatory for their usage in healthy humans. Full article

Background: The COVID-19 pandemic highlighted the need for innovative vaccine platforms that elicit durable immunity. Self-amplifying RNA (saRNA) vaccines offer rapid production and dose-sparing advantages over traditional mRNA platforms. In Uganda’s first SARS-CoV-2 vaccine trial (NCT04934111), we assessed the safety and immunogenicity of a saRNA vaccine encoding the SARS-CoV-2 spike (S) glycoprotein in seronegative and seropositive adults. Methods: This non-randomised phase 1 trial (December 2021–April 2022) enrolled 42 healthy adults (18–45 years), including 12 seronegative and 30 seropositive for SARS-CoV-2. Participants received two 5 μg doses of saRNA vaccine, four weeks apart. Reactogenicity was assessed using diary cards for seven days post-vaccination, and adverse events were monitored throughout the 24-week study. Binding and neutralising antibody levels were quantified using ELISA and pseudovirus neutralisation assays. Findings: The vaccine was well tolerated, with only mild-to-moderate adverse events, including fatigue, headache, and chills. No serious vaccine-related events occurred. Among seronegative participants, 91.6% seroconverted after two doses (median S-IgG: 3695 ng/mL, p < 0.001). In the seropositive participants, S-IgG rose modestly from 7496 to 11,028 ng/mL after the second dose. Neutralising titres increased modestly across WT, BA.2, and A.23.1 variants, with no significant differences between groups. Conclusion: The saRNA SARS-CoV-2 vaccine was safe and immunogenic, inducing robust spike glycoprotein-specific antibody responses, particularly in seronegative participants. This trial demonstrates the potential of saRNA vaccines for broader use. Full article

Objectives: The COVID-19 pandemic has brought mRNA vaccines to the forefront due to their widespread use. In this study, we explored the potential advantages of the self-amplifying mRNA (saRNA) vaccine over conventional mRNA vaccines. Methods: Initially, we optimized lipid nanoparticle formulations and employed dT20 affinity chromatography purification to improve the intracellular expression of saRNA. Subsequently, we demonstrated that saRNA exhibited sustained expression for up to one month, both in vitro and in vivo, in contrast to mRNA. Finally, we developed a saRNA-based COVID-19 vaccine and achieved superior immune protection in mice compared to mRNA vaccine by co-delivering the B18R-encoding mRNA. Results: The co-delivery of B18R-mRNA with the saRNA vaccine significantly enhanced neutralizing antibody responses, outperforming those induced by the mRNA vaccine alone. This co-delivery strategy effectively regulated the early innate immune activation triggered by saRNA, facilitating a more robust adaptive immune response. Conclusions: The optimization strategies we used in this study highlight the potential of saRNA vaccines to offer stronger and more durable immune protection. The insights gained from this study not only promote the advancement of saRNA vaccine development but also provide practical guidance for their broader application in the fight against infectious diseases. Full article

Self-amplifying RNA is synthetic nucleic acid engineered to replicate within cells without generating viral particles. Derived from alphavirus genomes, saRNA retains the non-structural elements essential for replication while replacing the structural elements with an antigen of interest. By enabling efficient intracellular amplification, saRNA offers a promising alternative to conventional mRNA vaccines, enhancing antigen expression while requiring lower doses. However, this advantage comes with challenges. In this review, we highlight the key limitations of saRNA technology and explore potential strategies to overcome them. By identifying these challenges, we aim to provide insights that can guide the future design of saRNA-based therapeutics, extending their potential beyond vaccine applications. Full article

Background: Self-amplifying mRNA vaccines have the potential to increase the magnitude and duration of protection against COVID-19 by boosting neutralizing antibody titers and cellular responses. Methods: In this study, we used the immunogenicity data from a phase 3 randomized trial comparing the immunogenicity of ARCT-154, a self-amplifying mRNA COVID-19 vaccine, with BNT162b2 mRNA COVID-19 vaccine to estimate the relative vaccine efficacy (rVE) of the two vaccines over time in younger (<60 years) and older (≥60 years) adults. Results: By day 181 post-vaccination, the rVE against symptomatic and severe Wuhan-Hu-1 disease was 9.2–11.0% and 1.2–1.5%, respectively, across age groups whereas the rVE against symptomatic and severe Omicron BA.4/5 disease was 26.8–48.0% and 5.2–9.3%, respectively, across age groups. Sensitivity analysis showed that varying the threshold titer for 50% protection against severe disease up to 10% of convalescent sera revealed incremental benefits of ARCT-154 over BNT162b2, with an rVE of up to 28.0% against Omicron BA.4/5 in adults aged ≥60 year. Conclusions: Overall, the results of this study indicate that ARCT-154 elicits broader and more durable immunogenicity against SARS-CoV-2, translating to enhanced disease protection, particularly for older adults against Omicron BA.4/5. Full article

Acute adverse reactions to COVID-19 mRNA vaccines are a major concern, as autopsy reports indicate that deaths most commonly occur on the same day of or one day following vaccination. These acute reactions may be due to cytokine storms triggered by lipid nanoparticles (LNPs) and anaphylaxis induced by polyethene glycol (PEG), both of which are vital constituents of the mRNA-LNP vaccines. Kounis syndrome, in which anaphylaxis triggers acute coronary syndrome (ACS), may also be responsible for these cardiovascular events. Furthermore, COVID-19 mRNA-LNP vaccines encompass adjuvants, such as LNPs, which trigger inflammatory cytokines, including interleukin (IL)-1β and IL-6. These vaccines also produce spike proteins which facilitate the release of inflammatory cytokines. Apart from this, histamine released from mast cells during allergic reactions plays a critical role in IL-6 secretion, which intensifies inflammatory responses. In light of these events, early reduction of IL-1β and IL-6 is imperative for managing post-vaccine cytokine storms, ACS, and myocarditis. Corticosteroids can restrict inflammatory cytokines and mitigate allergic responses, while colchicine, known for its IL-1β-reducing capabilities, could also prove effective. The anti-IL-6 antibody tocilizumab also displays promising treatment of cytokine release syndrome. Aside from its significance for treating anaphylaxis, epinephrine can induce coronary artery spasms and myocardial ischemia in Kounis syndrome, making accurate diagnosis essential. The upcoming self-amplifying COVID-19 mRNA-LNP vaccines also contain LNPs. Given that these vaccines can cause a cytokine storm and allergic reactions post vaccination, it is crucial to consider corticosteroids and measure IL-6 levels for effective management. Full article