An overview of rational design of mRNA-based therapeutics and vaccines

Development of multi-epitope mRNA vaccine against Clostridioides difficile using reverse vaccinology and immunoinformatics approaches

Clostridioides difficile (C. difficile), as the major pathogen of diarrhea in healthcare settings, has become increasingly prevalent within community populations, resulting in significant morbidity and mortality. However, the therapeutic options for Clostridioides difficile infection (CDI) remain limited, and as of now, no authorized vaccine is available to combat this disease. Therefore, the development of a novel vaccine against C. difficile is of paramount importance. In our study, the complete proteome sequences of 118 strains of C. difficile were downloaded and analyzed. We found four antigenic proteins that were highly conserved and can be used for epitope identification. We designed two vaccines, WLcd1 and WLcd2, that contain the ideal T-cell and B-cell epitopes, adjuvants, and the pan HLA DR-binding epitope (PADRE) sequences. The biophysical and chemical assessments of these vaccine candidates indicated that they were suitable for immunogenic applications. Molecular docking analyses revealed that WLcd1 bonded with higher affinity to Toll-like receptors (TLRs) than WLcd2. Furthermore, molecular dynamics (MD) simulations, performed using Gmx_MMPBSA v1.56, confirmed the binding stability of WLcd1 with TLR2 and TLR4. The preliminary findings suggested that this multi-epitope vaccine could be a promising candidate for protection against CDI; however, experimental studies are necessary to confirm these predictions.

mRNA-based therapeutic strategies for cancer treatment

In the rapidly evolving landscape of medical research, the emergence of RNA-based therapeutics is paradigm shifting. It is mainly driven by the molecular adaptability and capacity to provide precision in targeting. The coronavirus disease 2019 pandemic crisis underscored the effectiveness of the mRNA therapeutic development platform and brought it to the forefront of RNA-based interventions. These RNA-based therapeutic approaches can reshape gene expression, manipulate cellular functions, and correct the aberrant molecular processes underlying various diseases. The new technologies hold the potential to engineer and deliver tailored therapeutic agents to tackle genetic disorders, cancers, and infectious diseases in a highly personalized and precisely tuned manner. The review discusses the most recent advancements in the field of mRNA therapeutics for cancer treatment, with a focus on the features of the most utilized RNA-based therapeutic interventions, current pre-clinical and clinical developments, and the remaining challenges in delivery strategies, effectiveness, and safety considerations.

mRNA therapies: Pioneering a new era in rare genetic disease treatment

Rare genetic diseases, often referred to as orphan diseases due to their low prevalence and limited treatment options, have long posed significant challenges to our medical system. In recent years, Messenger RNA (mRNA) therapy has emerged as a highly promising treatment approach for various diseases caused by genetic mutations. Chemically modified mRNA is introduced into cells using carriers like lipid-based nanoparticles (LNPs), producing functional proteins that compensate for genetic deficiencies. Given the advantages of precise dosing, biocompatibility, transient expression, and minimal risk of genomic integration, mRNA therapies can safely and effectively correct genetic defects in rare diseases and improve symptoms. Currently, dozens of mRNA drugs targeting rare diseases are undergoing clinical trials. This comprehensive review summarizes the progress of mRNA therapy in treating rare genetic diseases. It introduces the development, molecular design, and delivery systems of mRNA therapy, highlighting their research progress in rare genetic diseases based on protein replacement and gene editing. The review also summarizes research progress in various rare disease models and clinical trials. Additionally, it discusses the challenges and future prospects of mRNA therapy. Researchers are encouraged to join this field and collaborate to advance the clinical translation of mRNA therapy, bringing hope to patients with rare genetic diseases.

Learning of clinical pharmacology by future prescribers in Bologna: Teachers' and students' reflections on the way forward

AIMS

In this reflection paper, the authors, based on their experience as teachers and students of the courses of Pharmacology at the University of Bologna, reflect on their specific roles towards innovation in the teaching of Clinical Pharmacology.

METHODS

Strengths, weaknesses and challenges are presented as identified during the teaching and learning experience in the currently evolving medical degree programmes of the University in light of current trends in medical education.

RESULTS

Keeping in mind the identified challenges together with the features proposed for the model prescriber (knowledgeable, contemporary, communicative and safe), we indicate some ways to improve the students' experience and make sure they develop up-to-date skills in Clinical Pharmacology taking advantage of recent ongoing collaborations at European level. International collaboration is indeed necessary to adequately address the current challenges of teaching clinical pharmacology.

CONCLUSION

Our shared conclusion is that empowering students with a scientifically sound method to retrieve relevant information and developing their skills to communicate in an interprofessional and, wherever possible, international environment is the key to prepare future prescribers and, ultimately, to improve patient safety.

Anion exchange HPLC monitoring of mRNA in vitro transcription reactions to support mRNA manufacturing process development

mRNA technology has recently demonstrated the ability to significantly change the timeline for developing and delivering a new vaccine from years to months. The potential of mRNA technology for rapid vaccine development has recently been highlighted by the successful development and approval of two mRNA vaccines for COVID-19. Importantly, this RNA-based approach holds promise for treatments beyond vaccines and infectious diseases, e.g., treatments for cancer, metabolic disorders, cardiovascular conditions, and autoimmune diseases. There is currently significant demand for the development of improved manufacturing processes for the production of mRNA therapeutics in an effort to increase their yield and quality. The development of suitable analytical methods for the analysis of mRNA therapeutics is critical to underpin manufacturing development and the characterisation of the drug product and drug substance. In this study we have developed a high-throughput, high-performance liquid chromatography (HPLC) workflow for the rapid analysis of mRNA generated using in vitro transcription (IVT). We have optimised anion exchange (AEX) HPLC for the analysis of mRNA directly from IVT. Chromatography was performed in under 6 min enabling separation of all of the key components in the IVT, including nucleoside triphosphates (NTPs), Cap analogue, plasmid DNA and mRNA product. Moreover, baseline separation of the NTPs was achieved, which facilitates accurate quantification of each NTP such that their consumption may be determined during IVT reactions. Furthermore, the HPLC method was used to rapidly assess the purification of the mRNA product, including removal of NTPs/Cap analogue and other contaminants after downstream purification, including solid phase extraction (SPE), oligo deoxythymidine (oligo-dT) affinity chromatography and tangential flow filtration (TFF). Using the developed method excellent precision was obtained with calibration curves for an external mRNA standard and NTPs giving correlation coefficients of 0.98 and 1.0 respectively. Intra- and inter-day studies on retention time stability of NTPs, showed a relative standard deviation ≤ 0.3% and ≤1.5% respectively. The mRNA retention time variability was ≤0.13%. This method was then utilised to monitor the progress of an IVT reaction for the production of Covid spike protein (C-Spike) mRNA to measure the increasing yield of mRNA alongside the consumption of NTPs during the reaction.

Enzymatic isolation and microfluidic electrophoresis analysis of residual dsRNA impurities in mRNA vaccines and therapeutics

The versatility, rapid development, and ease of production scalability of mRNA therapeutics have placed them at the forefront of biopharmaceutical research. However, despite their vast potential to treat diseases, their novelty comes with unsolved analytical challenges. A key challenge in ensuring sample purity has been monitoring residual, immunostimulatory dsRNA impurities generated during the in vitro transcription of mRNA. Here, we present a method that combines an enzyme, S1 nuclease, to identify and isolate dsRNA from an mRNA sample with a microfluidic electrophoresis analytical platform to characterize the impurity. After the method was developed and optimized, it was tested with clinically relevant, pseudouridine-modified 700 and 1800 bp dsRNA and 818-4451 nt mRNA samples. While the treatment impacted the magnitude of the fluorescent signal used to analyze the samples due to the interference of the buffer with the labeling of the sample, this signal loss was mitigated by 8.8× via treatment optimization. In addition, despite the mRNA concentration being up to 400× greater than that of the dsRNA, under every condition, there was a complete disappearance of the main mRNA peak. While the mRNA peak was digested, the dsRNA fragments remained physically unaffected by the treatment, with no change to their migration time. Using these samples, we detected 0.25% dsRNA impurities in mRNA samples using 15 μL with an analytical runtime of 1 min per sample after digestion and were able to predict their size within 8% of the expected length. The short runtime, sample consumption, and high throughput compatibility make it suitable to support the purity assessment of mRNA during purification and downstream.

Harnessing eukaryotic retroelement proteins for transgene insertion into human safe-harbor loci

Current approaches for inserting autonomous transgenes into the genome, such as CRISPR-Cas9 or virus-based strategies, have limitations including low efficiency and high risk of untargeted genome mutagenesis. Here, we describe precise RNA-mediated insertion of transgenes (PRINT), an approach for site-specifically primed reverse transcription that directs transgene synthesis directly into the genome at a multicopy safe-harbor locus. PRINT uses delivery of two in vitro transcribed RNAs: messenger RNA encoding avian R2 retroelement-protein and template RNA encoding a transgene of length validated up to 4 kb. The R2 protein coordinately recognizes the target site, nicks one strand at a precise location and primes complementary DNA synthesis for stable transgene insertion. With a cultured human primary cell line, over 50% of cells can gain several 2 kb transgenes, of which more than 50% are full-length. PRINT advantages include no extragenomic DNA, limiting risk of deleterious mutagenesis and innate immune responses, and the relatively low cost, rapid production and scalability of RNA-only delivery.

Biosafety and regulatory issues of RNA therapeutics

RNA therapy has recently emerged as a therapy targeting specific genes or proteins. With its outstanding advantages, this therapy has opened promising doors for treating and preventing diseases. The great application potential has driven the need for a comprehensive understanding of these therapies, particularly on biosafety and regulatory issues. This chapter began by discussing the risks to RNA therapy, such as off-target effects, immunogenicity and immune responses, and long-term effects. Since then, this therapy's intricate landscape of biosafety issues has been elucidated. Common biosecurity measures applied around the world have also been reviewed. In addition, this chapter emphasized the importance of regulations and laws in applying RNA therapy to prevent and treat human and animal diseases. At the same time, the current legal regulations in the world for RNA therapies have also been thoroughly discussed. To sum up, this chapter has provided a comprehensive perspective on biosafety and regulatory issues for developing RNA therapies. Understanding the biosafety and regulatory issues in RNA therapy can help researchers use this promising new technology safely and effectively in the future.

Neoantigen vaccine nanoformulations based on Chemically synthesized minimal mRNA (CmRNA): small molecules, big impact

Recently, chemically synthesized minimal mRNA (CmRNA) has emerged as a promising alternative to in vitro transcribed mRNA (IVT-mRNA) for cancer therapy and immunotherapy. CmRNA lacking the untranslated regions and polyadenylation exhibits enhanced stability and efficiency. Encapsulation of CmRNA within lipid-polymer hybrid nanoparticles (LPPs) offers an effective approach for personalized neoantigen mRNA vaccines with improved control over tumor growth. LPP-based delivery systems provide superior pharmacokinetics, stability, and lower toxicity compared to viral vectors, naked mRNA, or lipid nanoparticles that are commonly used for mRNA delivery. Precise customization of LPPs in terms of size, surface charge, and composition allows for optimized cellular uptake, target specificity, and immune stimulation. CmRNA-encoded neo-antigens demonstrate high translational efficiency, enabling immune recognition by CD8+ T cells upon processing and presentation. This perspective highlights the potential benefits, challenges, and future directions of CmRNA neoantigen vaccines in cancer therapy compared to Circular RNAs and IVT-mRNA. Further research is needed to optimize vaccine design, delivery, and safety assessment in clinical trials. Nevertheless, personalized LPP-CmRNA vaccines hold great potential for advancing cancer immunotherapy, paving the way for personalized medicine.

Engineering a Novel Modular Adenoviral mRNA Delivery Platform Based on Tag/Catcher Bioconjugation

mRNA vaccines have attracted widespread research attention with clear advantages in terms of molecular flexibility, rapid development, and potential for personalization. However, current mRNA vaccine platforms have not been optimized for induction of CD4/CD8 T cell responses. In addition, the mucosal administration of mRNA based on lipid nanoparticle technology faces challenges in clinical translation. In contrast, adenovirus-based vaccines induce strong T cell responses and have been approved for intranasal delivery. To leverage the inherent strengths of both the mRNA and adenovirus platforms, we developed a novel modular adenoviral mRNA delivery platform based on Tag/Catcher bioconjugation. Specifically, we engineered adenoviral vectors integrating Tag/Catcher proteins at specific locales on the Ad capsid proteins, allowing us to anchor mRNA to the surface of engineered Ad viruses. In proof-of-concept studies, the Ad-mRNA platform successfully mediated mRNA delivery and could be optimized via the highly flexible modular design of both the Ad-mRNA and protein bioconjugation systems.

Advancing personalized medicine in brain cancer: exploring the role of mRNA vaccines

Advancing personalized medicine in brain cancer relies on innovative strategies, with mRNA vaccines emerging as a promising avenue. While the initial use of mRNA vaccines was in oncology, their stunning success in COVID-19 resulted in widespread attention, both positive and negative. Regardless of politically biased opinions, which relate more to the antigenic source than form of delivery, we feel it is important to objectively review this modality as relates to brain cancer. This class of vaccines trigger robust immune responses through MHC-I and MHC-II pathways, in both prophylactic and therapeutic settings. The mRNA platform offers advantages of rapid development, high potency, cost-effectiveness, and safety. This review provides an overview of mRNA vaccine delivery technologies, tumor antigen identification, combination therapies, and recent therapeutic outcomes, with a particular focus on brain cancer. Combinatorial approaches are vital to maximizing mRNA cancer vaccine efficacy, with ongoing clinical trials exploring combinations with adjuvants and checkpoint inhibitors and even adoptive cell therapy. Efficient delivery, neoantigen identification, preclinical studies, and clinical trial results are highlighted, underscoring mRNA vaccines' potential in advancing personalized medicine for brain cancer. Synergistic combinatorial therapies play a crucial role, emphasizing the need for continued research and collaboration in this area.

Regulatory perspective for quality evaluation of lipid nanoparticle-based mRNA vaccines in China

In recent years, urgent unmet medical needs due to the COVID-19 pandemic have accelerated the application of mRNA technology in vaccine development, leading to some of the first approvals of mRNA vaccines in human history by regulatory agencies around the world. For market authorization, comprehensive chemistry, manufacturing and control (CMC) information is required to assure the safety and quality consistency of mRNA vaccines. Evaluating mRNA vaccines for new virus variants poses a challenge for regulators, given the rapid optimization and development based on prior platform knowledge to accelerate the development process, which is traditionally limited for biological products. Here we summarize the current regulatory considerations of CMC evaluation on mRNA vaccines based on the scientific knowledge available, which will be updated with the advance of mRNA biology and pharmaceutical science.

In Vitro Transcribed RNA-Based Platform Vaccines: Past, Present, and Future

mRNA was discovered in 1961, but it was not used as a vaccine until after three decades. Recently, the development of mRNA vaccine technology gained great impetus from the pursuit of vaccines against COVID-19. To improve the properties of RNA vaccines, and primarily their circulation time, self-amplifying mRNA and trans-amplifying mRNA were developed. A separate branch of mRNA technology is circular RNA vaccines, which were developed with the discovery of the possibility of translation on their protein matrix. Circular RNA has several advantages over mRNA vaccines and is considered a fairly promising platform, as is trans-amplifying mRNA. This review presents an overview of the mRNA platform and a critical discussion of the more modern self-amplifying mRNA, trans-amplifying mRNA, and circular RNA platforms created on its basis. Finally, the main features, advantages, and disadvantages of each of the presented mRNA platforms are discussed. This discussion will facilitate the decision-making process in selecting the most appropriate platform for creating RNA vaccines against cancer or viral diseases.

The clinical progress and challenges of mRNA vaccines

Owing to the breakthroughs in the prevention and control of the COVID-19 pandemic, messenger RNA (mRNA)-based vaccines have emerged as promising alternatives to conventional vaccine approaches for infectious disease prevention and anticancer treatments. Advantages of mRNA vaccines include flexibility in designing and manipulating antigens of interest, scalability in rapid response to new variants, ability to induce both humoral and cell-mediated immune responses, and ease of industrialization. This review article presents the latest advances and innovations in mRNA-based vaccines and their clinical translations in the prevention and treatment of infectious diseases or cancers. We also highlight various nanoparticle delivery platforms that contribute to their success in clinical translation. Current challenges related to mRNA immunogenicity, stability, and in vivo delivery and the strategies for addressing them are also discussed. Finally, we provide our perspectives on future considerations and opportunities for applying mRNA vaccines to fight against major infectious diseases and cancers. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.

Recent Advances and Innovations in the Preparation and Purification of In Vitro-Transcribed-mRNA-Based Molecules

The coronavirus disease 2019 (COVID-19) pandemic poses a disruptive impact on public health and the global economy. Fortunately, the development of COVID-19 vaccines based on in vitro-transcribed messenger RNA (IVT mRNA) has been a breakthrough in medical history, benefiting billions of people with its high effectiveness, safety profile, and ease of large-scale production. This success is the result of decades of continuous RNA research, which has led to significant improvements in the stability and expression level of IVT mRNA through various approaches such as sequence optimization and improved preparation processes. IVT mRNA sequence optimization has been shown to have a positive effect on enhancing the mRNA expression level. The innovation of IVT mRNA purification technology is also indispensable, as the purity of IVT mRNA directly affects the success of downstream vaccine preparation processes and the potential for inducing unwanted side effects in therapeutic applications. Despite the progress made, challenges related to IVT mRNA sequence design and purification still require further attention to enhance the quality of IVT mRNA in the future. In this review, we discuss the latest innovative progress in IVT mRNA design and purification to further improve its clinical efficacy.

Future prospects in mRNA vaccine development

The recent advancements in messenger ribonucleic acid (mRNA) vaccine development have vastly enhanced their use as alternatives to conventional vaccines in the prevention of various infectious diseases and treatment of several types of cancers. This is mainly due to their remarkable ability to stimulate specific immune responses with minimal clinical side effects. This review gives a detailed overview of mRNA vaccines currently in use or at various stages of development, the recent advancements in mRNA vaccine development, and the challenges encountered in their development. Future perspectives on this technology are also discussed.

Recent Advances in Messenger Ribonucleic Acid (mRNA) Vaccines and Their Delivery Systems: A Review

Messenger ribonucleic acid (mRNA) was found as the intermediary that transfers genetic information from DNA to ribosomes for protein synthesis in 1961. The emergency use authorization of the two covid-19 mRNA vaccines, BNT162b2 and mRNA-1273, is a significant achievement in the history of vaccine development. Because they are generated in a cell-free environment using the in vitro transcription (IVT) process, mRNA vaccines are risk-free. Moreover, chemical modifications to the mRNA molecule, such as cap structures and changed nucleosides, have proved critical in overcoming immunogenicity concerns, achieving sustained stability, and achieving effective, accurate protein production in vivo. Several vaccine delivery strategies (including protamine, lipid nanoparticles (LNPs), polymers, nanoemulsions, and cell-based administration) were also optimized to load and transport RNA into the cytosol. LNPs, which are composed of a cationic or a pH-dependent ionizable lipid layer, a polyethylene glycol (PEG) component, phospholipids, and cholesterol, are the most advanced systems for delivering mRNA vaccines. Moreover, modifications of the four components that make up the LNPs showed to increase vaccine effectiveness and reduce side effects. Furthermore, the introduction of biodegradable lipids improved LNP biocompatibility. Furthermore, mRNA-based therapies are expected to be effective treatments for a variety of refractory conditions, including infectious diseases, metabolic genetic diseases, cancer, cardiovascular and cerebrovascular diseases. Therefore, the present review aims to provide the scientific community with up-to-date information on mRNA vaccines and their delivery systems.

Recent trends in RNA informatics: a review of machine learning and deep learning for RNA secondary structure prediction and RNA drug discovery

Computational analysis of RNA sequences constitutes a crucial step in the field of RNA biology. As in other domains of the life sciences, the incorporation of artificial intelligence and machine learning techniques into RNA sequence analysis has gained significant traction in recent years. Historically, thermodynamics-based methods were widely employed for the prediction of RNA secondary structures; however, machine learning-based approaches have demonstrated remarkable advancements in recent years, enabling more accurate predictions. Consequently, the precision of sequence analysis pertaining to RNA secondary structures, such as RNA-protein interactions, has also been enhanced, making a substantial contribution to the field of RNA biology. Additionally, artificial intelligence and machine learning are also introducing technical innovations in the analysis of RNA-small molecule interactions for RNA-targeted drug discovery and in the design of RNA aptamers, where RNA serves as its own ligand. This review will highlight recent trends in the prediction of RNA secondary structure, RNA aptamers and RNA drug discovery using machine learning, deep learning and related technologies, and will also discuss potential future avenues in the field of RNA informatics.

Hematogenous Routing of Exogenous mRNA Delivered Into the Amniotic Fluid

INTRODUCTION

Therapies based on exogenous messenger RNA (mRNA) administration have emerged as a powerful novel strategy for the actual or potential treatment of an assortment of diseases, including congenital surgical pathologies. We sought to determine whether the minimally invasive transamniotic route could be an alternative for prenatal mRNA delivery.

METHODS

Pregnant Sprague-Dawley dams underwent laparotomy followed by volume-matched intra-amniotic injections in all their fetuses (n = 120) of either a suspension of a custom firefly luciferase mRNA encapsulated by a lipid- and synthetic cationic polymer-based composite, or of a suspension of the same encapsulation components without mRNA, on gestational day 17 (E17; term = E21-22). On E18, E19, E20, and E21, samples from 14 fetal anatomical sites and maternal serum were procured for the screening of mRNA incorporation by host cells by measurement of luciferase activity via microplate luminometry. Statistical analysis was by Mann-Whitney U-test, including Bonferroni-adjustment.

RESULTS

Overall survival was 87.5% (105/120). Controlled by the encapsulating composite without mRNA, luciferase activity was detected in the animals that received encapsulated mRNA in the following fetal annexes: amniotic fluid, amnion, chorion, umbilical cord, and placenta (P = 0.033 to <0.001), as well as in the following fetal sites: liver, stomach, intestines, and lungs (P = 0.043-0.002).

CONCLUSIONS

Packaged exogenous mRNA can be incorporated by the fetus at least at select anatomical sites after simple intra-amniotic administration in a rodent model. The pattern and chronology of mRNA incorporation are compatible with transplacental hematogenous routing, as well as with fetal swallowing/aspiration. Further study of transamniotic mRNA administration is warranted.

Revolutionizing viral disease vaccination: the promising clinical advancements of non-replicating mRNA vaccines

The mRNA vaccine technology was developed rapidly during the global pandemic of COVID-19. The crucial role of the COVID-19 mRNA vaccine in preventing viral infection also have been beneficial to the exploration and application of other viral mRNA vaccines, especially for non-replication structure mRNA vaccines of viral disease with outstanding research results. Therefore, this review pays attention to the existing mRNA vaccines, which are of great value for candidates for clinical applications in viral diseases. We provide an overview of the optimization of the mRNA vaccine development process as well as the good immune efficacy and safety shown in clinical studies. In addition, we also provide a brief description of the important role of mRNA immunomodulators in the treatment of viral diseases. After that, it will provide a good reference or strategy for research on mRNA vaccines used in clinical medicine with more stable structures, higher translation efficiency, better immune efficacy and safety, shorter production time, and lower production costs than conditional vaccines to be used as preventive or therapeutic strategy for the control of viral diseases in the future.

Regulation of pre-mRNA splicing: roles in physiology and disease, and therapeutic prospects

The removal of introns from mRNA precursors and its regulation by alternative splicing are key for eukaryotic gene expression and cellular function, as evidenced by the numerous pathologies induced or modified by splicing alterations. Major recent advances have been made in understanding the structures and functions of the splicing machinery, in the description and classification of physiological and pathological isoforms and in the development of the first therapies for genetic diseases based on modulation of splicing. Here, we review this progress and discuss important remaining challenges, including predicting splice sites from genomic sequences, understanding the variety of molecular mechanisms and logic of splicing regulation, and harnessing this knowledge for probing gene function and disease aetiology and for the design of novel therapeutic approaches.

mRNA therapeutics: new vaccination and beyond

The idea of mRNA therapy had been conceived for decades before it came into reality during the Covid-19 pandemic. The mRNA vaccine emerges as a powerful and general tool against new viral infections, largely due to its versatility and rapid development. In addition to prophylactic vaccines, mRNA technology also offers great promise for new applications as a versatile drug modality. However, realizing the conceptual potential faces considerable challenges, such as minimal immune stimulation, high and long-term expression, and efficient delivery to target cells and tissues. Here we review the applications of mRNA-based therapeutics, with emphasis on the innovative design and future challenges/solutions. In addition, we also discuss the next generation of mRNA therapy, including circular mRNA and self-amplifying RNAs. We aim to provide a conceptual overview and outlook on mRNA therapeutics beyond prophylactic vaccines.

Aerosolized Pulmonary Delivery of mRNA Constructs Attenuates Severity of Escherichia coli Pneumonia in the Rat

Acute respiratory distress syndrome (ARDS), a rapid onset inflammatory lung disease with no effective specific therapy, typically has pathogenic etiology termed pneumonia. In previous studies nuclear factor-κB (NF-κB) inhibitor α super-repressor (IκBα-SR) and extracellular superoxide dismutase 3 (SOD3) reduced pneumonia severity when prophylactically delivered by viral vector. In this study, mRNA coding for green fluorescent protein, IκBα-SR, or SOD3 was complexed with cationic lipid, passed through a vibrating mesh nebulizer, and delivered to cell culture or directly to rats undergoing Escherichia coli pneumonia. Injury level was then assessed at 48 h. In vitro, expression was observed as early as 4 h in lung epithelial cells. IκBα-SR and wild-type IκBα mRNAs attenuated inflammatory markers, while SOD3 mRNA induced protective and antioxidant effects. In rat E. coli pneumonia, IκBα-SR mRNA reduced arterial carbon dioxide (pCO2) and reduced lung wet/dry ratio. SOD3 mRNA improved static lung compliance and alveolar-arterial oxygen gradient (AaDO2) and decreased bronchoalveolar lavage (BAL) bacteria load. White cell infiltration and inflammatory cytokine concentrations in BAL and serum were reduced by both mRNA treatments compared to scrambled mRNA controls. These findings indicate nebulized mRNA therapeutics are a promising approach to ARDS therapy, with rapid expression of protein and observable amelioration of pneumonia symptoms.

mRNA in the Context of Protein Replacement Therapy

Protein replacement therapy is an umbrella term used for medical treatments that aim to substitute or replenish specific protein deficiencies that result either from the protein being absent or non-functional due to mutations in affected patients. Traditionally, such an approach requires a well characterized but arduous and expensive protein production procedure that employs in vitro expression and translation of the pharmaceutical protein in host cells, followed by extensive purification steps. In the wake of the SARS-CoV-2 pandemic, mRNA-based pharmaceuticals were recruited to achieve rapid in vivo production of antigens, proving that the in vivo translation of exogenously administered mRNA is nowadays a viable therapeutic option. In addition, the urgency of the situation and worldwide demand for mRNA-based medicine has led to an evolution in relevant technologies, such as in vitro transcription and nanolipid carriers. In this review, we present preclinical and clinical applications of mRNA as a tool for protein replacement therapy, alongside with information pertaining to the manufacture of modified mRNA through in vitro transcription, carriers employed for its intracellular delivery and critical quality attributes pertaining to the finished product.

CoDe: a web-based tool for codon deoptimization

Summary

We have developed a web-based tool, CoDe (Codon Deoptimization) that deoptimizes genetic sequences based on different codon usage bias, ultimately reducing expression of the corresponding protein. The tool could also deoptimize the sequence for a specific region and/or selected amino acid(s). Moreover, CoDe can highlight sites targeted by restriction enzymes in the wild-type and codon-deoptimized sequences. Importantly, our web-based tool has a user-friendly interface with flexible options to download results.

Availability and implementation

The web-based tool CoDe is freely available at https://web.iitm.ac.in/bioinfo2/codeop/landing_page.html.

Supplementary information

Supplementary data are available at Bioinformatics Advances online.

mRNA vaccine-a desirable therapeutic strategy for surmounting COVID-19 pandemic

As an acute respiratory infectious disease, COVID-19 threatens the safety of global public health. Given the current lack of specific treatment against this disease, research and development of vaccines have become sharp weapons for overcoming the pandemic. mRNA vaccines have become the lead in COVID-19 vaccination strategies due to their advantages, such as rapid industrial production and efficacy. A total of 137 COVID-19 vaccines have entered the clinical trial stage, among which 23 are mRNA vaccines, accounting for 17% of the total vaccines. Herein, we summarize the research and developmental processes of mRNA vaccines as well as the approach for protecting the human body against infection. Focusing on the latest clinical trial data of two COVID-19 mRNA vaccines from Pfizer and Modena, we discuss their effectiveness and safety. Finally, we analyze the challenges and problems that mRNA vaccines face in controlling the COVID-19 pandemic.

Liquid Chromatography-Mass Spectrometry-Based Qualitative Profiling of mRNA Therapeutic Reagents Using Stable Isotope-Labeled Standards Followed by the Automatic Quantitation Software Ariadne

mRNA-based medicines are a promising modality for preventing virus-caused illnesses, including COVID-19, and treating various types of cancer and genetic diseases. To develop such medicines, methods to characterize long mRNA molecules are needed for quality control and metabolic analysis. Here, we developed an analytical platform based on isotope-dilution liquid chromatography-mass spectrometry (LC-MS) that quantitatively characterizes long, modified mRNAs by comparing them to a stable isotope-labeled reference with an identical sequence to that of the target medicine. This platform also includes database searching using the mass spectra as a query, which allowed us to confirm the primary structures of 200 to 4300 nt mRNAs including chemical modifications, with sequence coverage at 100%, to detect/identify defects in the sequences, and to define the efficiencies of the 5'-capping and integrity of the polyadenylated tail. Our findings indicated that this platform should be valuable for quantitatively characterizing mRNA vaccines and other mRNA medicines.

Advances in nanoparticle-based mRNA delivery for liver cancer and liver-associated infectious diseases

The liver is a vital organ that functions to detoxify the body. Liver cancer and infectious diseases such as influenza and malaria can fatally compromise liver function. mRNA delivery is a relatively new means of therapeutic treatment which enables expression of tumor or pathogenic antigens, and elicits immune responses for therapeutic or prophylactic effect. Novel nanoparticles with unique biological properties serving as mRNA carriers have allowed mRNA-based therapeutics to become more clinically viable and relevant. In this review, we highlight recent progress in development of nanoparticle-based mRNA delivery systems for treatment of various liver diseases. First, we present developments in nanoparticle systems used to deliver mRNAs, with specific focus on enhanced cellular uptake and endosomal escape achieved through the use of these nanoparticles. To provide context for diseases that target the liver, we provide an overview of the function and structure of the liver, as well as the role of the immune system in the liver. Then, mRNA-based therapeutic approaches for addressing HCC are highlighted. We also discuss nanoparticle-based mRNA vaccines for treating hepatotropic infectious diseases. Finally, we present current challenges in the clinical translation of nanoparticle-based mRNA delivery systems and provide outlooks for their utilization in treating liver-related diseases.

mRNA vaccines in the prevention and treatment of diseases

Messenger ribonucleic acid (mRNA) vaccines made their successful public debut in the effort against the COVID-19 outbreak starting in late 2019, although the history of mRNA vaccines can be traced back decades. This review provides an overview to discuss the historical course and present situation of mRNA vaccine development in addition to some basic concepts that underly mRNA vaccines. We discuss the general preparation and manufacturing of mRNA vaccines and also discuss the scientific advances in the in vivo delivery system and evaluate popular approaches (i.e., lipid nanoparticle and protamine) in detail. Next, we highlight the clinical value of mRNA vaccines as potent candidates for therapeutic treatment and discuss clinical progress in the treatment of cancer and coronavirus disease 2019. Data suggest that mRNA vaccines, with several prominent advantages, have achieved encouraging results and increasing attention due to tremendous potential in disease management. Finally, we suggest some potential directions worthy of further investigation and optimization. In addition to basic research, studies that help to facilitate storage and transportation will be indispensable for practical applications.

Message in a bottle: mRNA vaccination for influenza

Current influenza vaccines, while being the best method of managing viral outbreaks, have several major drawbacks that prevent them from being wholly-effective. They need to be updated regularly and require extensive resources to develop. When considering alternatives, the recent deployment of mRNA vaccines for SARS-CoV-2 has created a unique opportunity to evaluate a new platform for seasonal and pandemic influenza vaccines. The mRNA format has previously been examined for application to influenza and promising data suggest it may be a viable format for next-generation influenza vaccines. Here, we discuss the prospect of shifting global influenza vaccination efforts to an mRNA-based system that might allow better control over the product and immune responses and could aid in the development of a universal vaccine.

Vaccinia Virus Attenuation by Codon Deoptimization of the A24R Gene for Vaccine Development

Poxviruses have large DNA genomes, and they are able to infect multiple vertebrate and invertebrate animals, including humans. Despite the eradication of smallpox, poxvirus infections still remain a significant public health concern. Vaccinia virus (VV) is the prototypic member in the poxviridae family and it has been used extensively for different prophylactic applications, including the generation of vaccines against multiple infectious diseases and/or for oncolytic treatment. Many attempts have been pursued to develop novel attenuated forms of VV with improved safety profiles for their implementation as vaccines and/or vaccines vectors. We and others have previously demonstrated how RNA viruses encoding codon-deoptimized viral genes are attenuated, immunogenic and able to protect, upon a single administration, against challenge with parental viruses. In this study, we employed the same experimental approach based on the use of misrepresented codons for the generation of a recombinant (r)VV encoding a codon-deoptimized A24R gene, which is a key component of the viral RNA polymerase. Similar to our previous studies with RNA viruses, the A24R codon-deoptimized rVV (v-A24cd) was highly attenuated in vivo but able to protect, after a single intranasal dose administration, against an otherwise lethal challenge with parental VV. These results indicate that poxviruses can be effectively attenuated by synonymous codon deoptimization and open the possibility of using this methodology alone or in combination with other experimental approaches for the development of attenuated vaccines for the treatment of poxvirus infection, or to generate improved VV-based vectors. Moreover, this approach could be applied to other DNA viruses. IMPORTANCE The family poxviridae includes multiple viruses of medical and veterinary relevance, being vaccinia virus (VV) the prototypic member in the family. VV was used during the smallpox vaccination campaign to eradicate variola virus (VARV), which is considered a credible bioterrorism threat. Because of novel innovations in genetic engineering and vaccine technology, VV has gained popularity as a viral vector for the development of vaccines against several infectious diseases. Several approaches have been used to generate attenuated VV for its implementation as vaccine and/or vaccine vector. Here, we generated a rVV containing a codon-deoptimized A24R gene (v-A24cd), which encodes a key component of the viral RNA polymerase. v-A24cd was stable in culture cells and highly attenuated in vivo but able to protect against a subsequent lethal challenge with parental VV. Our findings support the use of this approach for the development of safe, stable, and protective live-attenuated VV and/or vaccine vectors.

Advances in mRNA and other vaccines against MERS-CoV

Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic human coronavirus (CoV). Belonging to the same beta-CoV genus as severe acute respiratory syndrome coronavirus-1 (SARS-CoV-1) and SARS-CoV-2, MERS-CoV has a significantly higher fatality rate with limited human-to-human transmissibility. MERS-CoV causes sporadic outbreaks, but no vaccines have yet been approved for use in humans, thus calling for continued efforts to develop effective vaccines against this important CoV. Similar to SARS-CoV-1 and SARS-CoV-2, MERS-CoV contains 4 structural proteins, among which the surface spike (S) protein has been used as a core component in the majority of currently developed MERS-CoV vaccines. Here, we illustrate the importance of the MERS-CoV S protein as a key vaccine target and provide an update on the currently developed MERS-CoV vaccines, including those based on DNAs, proteins, virus-like particles or nanoparticles, and viral vectors. Additionally, we describe approaches for designing MERS-CoV mRNA vaccines and explore the role and importance of naturally occurring pseudo-nucleosides in the design of effective MERS-CoV mRNA vaccines. This review also provides useful insights into designing and evaluating mRNA vaccines against other viral pathogens.

Advances in COVID-19 mRNA vaccine development

To date, the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has determined 399,600,607 cases and 5,757,562 deaths worldwide. COVID-19 is a serious threat to human health globally. The World Health Organization (WHO) has declared COVID-19 pandemic a major public health emergency. Vaccination is the most effective and economical intervention for controlling the spread of epidemics, and consequently saving lives and protecting the health of the population. Various techniques have been employed in the development of COVID-19 vaccines. Among these, the COVID-19 messenger RNA (mRNA) vaccine has been drawing increasing attention owing to its great application prospects and advantages, which include short development cycle, easy industrialization, simple production process, flexibility to respond to new variants, and the capacity to induce better immune response. This review summarizes current knowledge on the structural characteristics, antigen design strategies, delivery systems, industrialization potential, quality control, latest clinical trials and real-world data of COVID-19 mRNA vaccines as well as mRNA technology. Current challenges and future directions in the development of preventive mRNA vaccines for major infectious diseases are also discussed.

mRNA Therapeutic Modalities Design, Formulation and Manufacturing under Pharma 4.0 Principles

In the quest for a formidable weapon against the SARS-CoV-2 pandemic, mRNA therapeutics have stolen the spotlight. mRNA vaccines are a prime example of the benefits of mRNA approaches towards a broad array of clinical entities and druggable targets. Amongst these benefits is the rapid cycle "from design to production" of an mRNA product compared to their peptide counterparts, the mutability of the production line should another target be chosen, the side-stepping of safety issues posed by DNA therapeutics being permanently integrated into the transfected cell's genome and the controlled precision over the translated peptides. Furthermore, mRNA applications are versatile: apart from vaccines it can be used as a replacement therapy, even to create chimeric antigen receptor T-cells or reprogram somatic cells. Still, the sudden global demand for mRNA has highlighted the shortcomings in its industrial production as well as its formulation, efficacy and applicability. Continuous, smart mRNA manufacturing 4.0 technologies have been recently proposed to address such challenges. In this work, we examine the lab and upscaled production of mRNA therapeutics, the mRNA modifications proposed that increase its efficacy and lower its immunogenicity, the vectors available for delivery and the stability considerations concerning long-term storage.