Protective efficacy of in vitro synthesized, specific mRNA vaccines against influenza A virus infection

Modified mRNA-Based Vaccines Against Coronavirus Disease 2019

The pandemic of coronavirus disease 2019 (COVID-19) continuously causes deaths worldwide, representing a considerable challenge to health care and economic systems with a new precedent in human history. Many therapeutic medicines primarily focused on preventing severe organ damage and complications, which can be fatal in some confirmed cases. The synthesized modified mRNA (modRNA) represents a nonviral, integration-free, zero-footprint, efficient, and safe strategy for vaccine discovery. modRNA-based technology has facilitated the rapid development of the first COVID-19 vaccines due to its cost- and time-saving properties, thus initiating a new era of prophylactic vaccines against infectious diseases. Recently, COVID-19 modRNA vaccines were approved, and a large-scale vaccination campaign began worldwide. To date, results suggest that the modRNA vaccines are highly effective against virus infection, which causes COVID-19. Although short-term studies have reported that their safety is acceptable, long-term safety and protective immunity remain unclear. In this review, we describe two major approved modRNA vaccines and discuss their potential myocarditis complications.

Optimization of non-coding regions for a non-modified mRNA COVID-19 vaccine

The CVnCoV (CureVac) mRNA vaccine for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was recently evaluated in a phase 2b/3 efficacy trial in humans1. CV2CoV is a second-generation mRNA vaccine containing non-modified nucleosides but with optimized non-coding regions and enhanced antigen expression. Here we report the results of a head-to-head comparison of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in non-human primates. We immunized 18 cynomolgus macaques with two doses of 12 μg lipid nanoparticle-formulated CVnCoV or CV2CoV or with sham (n = 6 per group). Compared with CVnCoV, CV2CoV induced substantially higher titres of binding and neutralizing antibodies, memory B cell responses and T cell responses as well as more potent neutralizing antibody responses against SARS-CoV-2 variants, including the Delta variant. Moreover, CV2CoV was found to be comparably immunogenic to the BNT162b2 (Pfizer) vaccine in macaques. Although CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded more robust protection with markedly lower viral loads in the upper and lower respiratory tracts. Binding and neutralizing antibody titres were correlated with protective efficacy. These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of a non-modified mRNA SARS-CoV-2 vaccine in non-human primates.

Formulation and Delivery Technologies for mRNA Vaccines

mRNA vaccines have become a versatile technology for the prevention of infectious diseases and the treatment of cancers. In the vaccination process, mRNA formulation and delivery strategies facilitate effective expression and presentation of antigens, and immune stimulation. mRNA vaccines have been delivered in various formats: encapsulation by delivery carriers, such as lipid nanoparticles, polymers, peptides, free mRNA in solution, and ex vivo through dendritic cells. Appropriate delivery materials and formulation methods often boost the vaccine efficacy which is also influenced by the selection of a proper administration route. Co-delivery of multiple mRNAs enables synergistic effects and further enhances immunity in some cases. In this chapter, we overview the recent progress and existing challenges in the formulation and delivery technologies of mRNA vaccines with perspectives for future development.

Demystifying mRNA vaccines: an emerging platform at the forefront of cryptic diseases

Messenger RNA (mRNA) vaccines have been studied for decades, but only recently, during the COVID-19 pandemic, has the technology garnered noteworthy attention. In contrast to traditional vaccines, mRNA vaccines elicit a more balanced immune response, triggering both humoral and cellular components of the adaptive immune system. However, some inherent hurdles associated with stability, immunogenicity, in vivo delivery, along with the novelty of the technology, have generated scepticism in the adoption of mRNA vaccines. Recent developments have pushed to bypass these issues and the approval of mRNA-based vaccines to combat COVID-19 has further highlighted the feasibility, safety, efficacy, and rapid development potential of this platform, thereby pushing it to the forefront of emerging therapeutics. This review aims to demystify mRNA vaccines, delineating the evolution of the technology which has emerged as a timely solution to COVID-19 and exploring the immense potential it offers as a prophylactic option for other cryptic diseases.

Acute Mild Pancreatitis Following COVID-19 mRNA Vaccine in an Adolescent

A 17-year-old male was referred to the emergency room with sharp abdominal pain, pallor, sweating, and vomiting 12 h after the administration of his first Pfizer-BioNTech vaccine for coronavirus disease 2019 (COVID-19). He had abdominal pain, an increase in serum lipase value of > 3 times the upper limits of normal, and magnetic resonance imaging (MRI) findings consistent with acute mild pancreatitis (AP). He was started on treatment with fluid therapy and non-steroidal anti-inflammatory drugs for pain management, after which he recovered rapidly and was discharged on the fourth day after hospitalization. The available data are difficult to interpret as AP is a relatively frequent disease, but its occurrence after vaccination seems extremely rare. Although it is a rare event, AP should be considered after COVID-19 vaccination, especially in those exhibiting abdominal tenderness and vomiting, which should be promptly treated and adequately investigated.

The Development of mRNA Vaccines for Infectious Diseases: Recent Updates

mRNA-based technologies have been of interest for the past few years to be used for therapeutics. Several mRNA vaccines for various diseases have been in preclinical and clinical stages. With the outbreak of the COVID-19 pandemic, the emergence of mRNA vaccines has transformed modern science. Recently, two major mRNA vaccines have been developed and approved by global health authorities for administration on the general population for protection against SARS-CoV-2. They have been proven to be successful in conferring protection against the ongoing SARS-CoV-2 and its emerging variants. This will draw attention to various mRNA vaccines against infectious diseases that are in the early stages of clinical trials. mRNA vaccines offer several advantages ranging from rapid design, generation, manufacturing, and administration and have strong potential to be used against various diseases in the future. Here, we summarize the mRNA-based vaccines in development against various infectious diseases.

Development of multivalent mRNA vaccine candidates for seasonal or pandemic influenza

Recent approval of mRNA vaccines for emergency use against COVID-19 is likely to promote rapid development of mRNA-based vaccines targeting a wide range of infectious diseases. Compared to conventional approaches, this vaccine modality promises comparable potency while substantially accelerating the pace of development and deployment of vaccine doses. Already demonstrated successfully for single antigen vaccines such as for COVID-19, this technology could be optimized for complex multi-antigen vaccines. Herein, utilizing multiple influenza antigens, we demonstrated the suitability of the mRNA therapeutic (MRT) platform for such applications. Seasonal influenza vaccines have three or four hemagglutinin (HA) antigens of different viral subtypes. In addition, influenza neuraminidase (NA), a tetrameric membrane protein, is identified as an antigen that has been linked to protective immunity against severe viral disease. We detail the efforts in optimizing formulations of influenza candidates that use unmodified mRNA encoding full-length HA or full-length NA encapsulated in lipid nanoparticles (LNPs). HA and NA mRNA-LNP formulations, either as monovalent or as multivalent vaccines, induced strong functional antibody and cellular responses in non-human primates and such antigen-specific antibody responses were associated with protective efficacy against viral challenge in mice.

Cross-Reactivity Conferred by Homologous and Heterologous Prime-Boost A/H5 Influenza Vaccination Strategies in Humans: A Literature Review

Avian influenza viruses from the A/H5 A/goose/Guangdong/1/1996 (GsGd) lineage pose a continuing threat to animal and human health. Since their emergence in 1997, these viruses have spread across multiple continents and have become enzootic in poultry. Additionally, over 800 cases of human infection with A/H5 GsGd viruses have been reported to date, which raises concerns about the potential for a new influenza virus pandemic. The continuous circulation of A/H5 GsGd viruses for over 20 years has resulted in the genetic and antigenic diversification of their hemagglutinin (HA) surface glycoprotein, which poses a serious challenge to pandemic preparedness and vaccine design. In the present article, clinical studies on A/H5 influenza vaccination strategies were reviewed to evaluate the breadth of antibody responses induced upon homologous and heterologous prime-boost vaccination strategies. Clinical data on immunological endpoints were extracted from studies and compiled into a dataset, which was used for the visualization and analysis of the height and breadth of humoral immune responses. Several aspects leading to high immunogenicity and/or cross-reactivity were identified, although the analysis was limited by the heterogeneity in study design and vaccine type used in the included studies. Consequently, crucial questions remain to be addressed in future studies on A/H5 GsGd vaccination strategies.

mRNA Vaccine Protects against Zika Virus

Zika virus (ZIKV), a mosquito-borne flavivirus, has recently triggered global concern due to severe health complications. In 2015, a large ZIKV outbreak occurred in the Americas and established a link between ZIKV and microcephaly in newborn babies, spontaneous abortion, persistent viremia, and Guillain–Barré syndrome. While antivirals are being developed and prevention strategies focus on vector control, a safe and effective Zika vaccine remains unavailable. Messenger RNA (mRNA) vaccine technology has arisen as a flexible, simplified, and fast vaccine production platform. Here, we report on an mRNA vaccine candidate that encodes the pre-membrane and envelope (prM–E) glycoproteins of ZIKV strain Brazil SPH2015 and is encapsulated in lipid nanoparticles (LNPs). Our ZIKV prM–E mRNA-LNP vaccine candidate induced antibody responses that protected in AG129 mice deficient in interferon (IFN) alpha/beta/gamma (IFN-α/β/γ) receptors. Notably, a single administration of ZIKV prM–E mRNA-LNP protected against a lethal dose of ZIKV, while a two-dose strategy induced strong protective immunity. E-specific double-positive IFN-γ and TNF-α T-cells were induced in BALB/c mice after immunizations with a two-dose strategy. With the success of mRNA vaccine technology in facing the coronavirus (COVID-19) pandemic, our data support the development of prM–E RNActive^® as a promising mRNA vaccine against Zika to counter future epidemics.

mRNA, a Revolution in Biomedicine

The perspective of using messenger RNA (mRNA) as a therapeutic molecule first faced some uncertainties due to concerns about its instability and the feasibility of large-scale production. Today, given technological advances and deeper biomolecular knowledge, these issues have started to be addressed and some strategies are being exploited to overcome the limitations. Thus, the potential of mRNA has become increasingly recognized for the development of new innovative therapeutics, envisioning its application in immunotherapy, regenerative medicine, vaccination, and gene editing. Nonetheless, to fully potentiate mRNA therapeutic application, its efficient production, stabilization and delivery into the target cells are required. In recent years, intensive research has been carried out in this field in order to bring new and effective solutions towards the stabilization and delivery of mRNA. Presently, the therapeutic potential of mRNA is undoubtedly recognized, which was greatly reinforced by the results achieved in the battle against the COVID-19 pandemic, but there are still some issues that need to be improved, which are critically discussed in this review.

Delivery of synthetic mRNAs for tissue regeneration

In recent years, nucleic acid-based therapeutics have gained increasing importance as novel treatment options for disease prevention and treatment. Synthetic messenger RNAs (mRNAs) are promising nucleic acid-based drugs to transiently express desired proteins that are missing or defective. Recently, synthetic mRNA-based vaccines encoding viral proteins have been approved for emergency use against COVID-19. Various types of vehicles, such as lipid nanoparticles (LNPs) and liposomes, are being investigated to enable the efficient uptake of mRNA molecules into desired cells. In addition, the introduction of novel chemical modifications into mRNAs increased the stability, enabled the modulation of nucleic acid-based drugs, and increased the efficiency of mRNA-based therapeutic approaches. In this review, novel and innovative strategies for the delivery of synthetic mRNA-based therapeutics for tissue regeneration are discussed. Moreover, with this review, we aim to highlight the versatility of synthetic mRNA molecules for various applications in the field of regenerative medicine and also discuss translational challenges and required improvements for mRNA-based drugs.

Enabling online determination of the size-dependent RNA content of lipid nanoparticle-based RNA formulations

The potential of lipid nanoparticles (LNPs) as nucleic acid delivery vehicles has been demonstrated in recent years, culminating in the emergency use approval of LNP-based mRNA SARS-CoV-2 vaccines in late 2020. The determination of RNA content relative to LNP size can be important to the understanding of efficacy and adverse effects. This work presents the first description of a facile and rapid analytical method for online, size-dependent RNA payload distribution measurement using data from multi-angle light scattering, ultraviolet and refractive index detectors following separation of the LNPs by size-exclusion chromatography. The analysis was validated by size-based fractionation of the LNPs with subsequent offline analysis of the fractions. Four LNPs formulated with different PEG-lipids and different lipid compositions were tested. Good agreement was observed between the online and offline size-based RNA distributions among all four LNPs, demonstrating the utility of the online method for LNP-encapsulated RNA in general, and suggesting a means for simplified biophysical quantitation of a dosing-related critical quality attribute.

Messenger RNA-based vaccines: Past, present, and future directions in the context of the COVID-19 pandemic

mRNA vaccines have received major attention in the fight against COVID-19. Formulations from companies such as Moderna and BioNTech/Pfizer have allowed us to slowly ease the social distancing measures, mask requirements, and lockdowns that have been prevalent since early 2020. This past year's focused work on mRNA vaccines has catapulted this technology to the forefront of public awareness and additional research pursuits, thus leading to new potential for bionanotechnology principles to help drive further innovation using mRNA. In addition to alleviating the burden of COVID-19, mRNA vaccines could potentially provide long-term solutions all over the world for diseases ranging from influenza to AIDS. Herein, we provide a brief commentary based on the history and development of mRNA vaccines in the context of the COVID-19 pandemic. Furthermore, we address current research using the technology and future directions of mRNA vaccine research.

Yeasts in nanotechnology-enabled oral vaccine and gene delivery

Oral vaccine and gene delivery systems must be engineered to withstand several different physiological environments, such as those present in the oral cavity, stomach, and jejunum, each of which exhibits varying pH levels and enzyme distributions. Additionally, these systems must be designed to ensure appropriate gastrointestinal absorption and tissue/cellular targeting properties. Yeasts-based delivery vehicles are excellent candidates for oral vaccine and oral gene therapies as many species possess cellular characteristics resulting in enhanced resistance to the harsh gastrointestinal (GI) environment and facilitated passage across the mucosal barrier. Yeast capsules can stimulate and modulate host immune responses, which is beneficial for vaccine efficacy. In addition, recombinant modification of yeasts to express cell penetrating proteins and injection mechanisms along with efficient cell adhering capabilities can potentially improve transfection rates of genetic material. In this literature review, we present evidence supporting the beneficial role yeast-based delivery systems can play in increasing the efficacy of oral administration of vaccines and gene therapies.

A Review of UK-Registered and Candidate Vaccines for Bovine Respiratory Disease

Vaccination is widely regarded as a cornerstone in animal or herd health and infectious disease management. Nineteen vaccines against the major pathogens implicated in bovine respiratory disease are registered for use in the UK by the Veterinary Medicines Directorate (VMD). However, despite annual prophylactic vaccination, bovine respiratory disease is still conservatively estimated to cost the UK economy approximately £80 million per annum. This review examines the vaccine types available, discusses the surrounding literature and scientific rationale of the limitations and assesses the potential of novel vaccine technologies.

The Importance of RNA-Based Vaccines in the Fight against COVID-19: An Overview

In recent years, vaccine development using ribonucleic acid (RNA) has become the most promising and studied approach to produce safe and effective new vaccines, not only for prophylaxis but also as a treatment. The use of messenger RNA (mRNA) as an immunogenic has several advantages to vaccine development compared to other platforms, such as lower coast, the absence of cell cultures, and the possibility to combine different targets. During the COVID-19 pandemic, the use of mRNA as a vaccine became more relevant; two out of the four most widely applied vaccines against COVID-19 in the world are based on this platform. However, even though it presents advantages for vaccine application, mRNA technology faces several pivotal challenges to improve mRNA stability, delivery, and the potential to generate the related protein needed to induce a humoral- and T-cell-mediated immune response. The application of mRNA to vaccine development emerged as a powerful tool to fight against cancer and non-infectious and infectious diseases, for example, and represents a relevant research field for future decades. Based on these advantages, this review emphasizes mRNA and self-amplifying RNA (saRNA) for vaccine development, mainly to fight against COVID-19, together with the challenges related to this approach.

Influenza Neuraminidase Characteristics and Potential as a Vaccine Target

Neuraminidase of influenza A and B viruses plays a critical role in the virus life cycle and is an important target of the host immune system. Here, we highlight the current understanding of influenza neuraminidase structure, function, antigenicity, immunogenicity, and immune protective potential. Neuraminidase inhibiting antibodies have been recognized as correlates of protection against disease caused by natural or experimental influenza A virus infection in humans. In the past years, we have witnessed an increasing interest in the use of influenza neuraminidase to improve the protective potential of currently used influenza vaccines. A number of well-characterized influenza neuraminidase-specific monoclonal antibodies have been described recently, most of which can protect in experimental challenge models by inhibiting the neuraminidase activity or by Fc receptor-dependent mechanisms. The relative instability of the neuraminidase poses a challenge for protein-based antigen design. We critically review the different solutions that have been proposed to solve this problem, ranging from the inclusion of stabilizing heterologous tetramerizing zippers to the introduction of inter-protomer stabilizing mutations. Computationally engineered neuraminidase antigens have been generated that offer broad, within subtype protection in animal challenge models. We also provide an overview of modern vaccine technology platforms that are compatible with the induction of robust neuraminidase-specific immune responses. In the near future, we will likely see the implementation of influenza vaccines that confront the influenza virus with a double punch: targeting both the hemagglutinin and the neuraminidase.

Hydrophobic Optimization of Functional Poly(TPAE-co-suberoyl chloride) for Extrahepatic mRNA Delivery following Intravenous Administration

Messenger RNA (mRNA) has generated great attention due to its broad potential therapeutic applications, including vaccines, protein replacement therapy, and immunotherapy. Compared to other nucleic acids (e.g., siRNA and pDNA), there are more opportunities to improve the delivery efficacy of mRNA through systematic optimization. In this report, we studied a high-throughput library of 1200 functional polyesters for systemic mRNA delivery. We focused on the chemical investigation of hydrophobic optimization as a method to adjust mRNA polyplex stability, diameter, pKa, and efficacy. Focusing on a region of the library heatmap (PE4K-A17), we further explored the delivery of luciferase mRNA to IGROV1 ovarian cancer cells in vitro and to C57BL/6 mice in vivo following intravenous administration. PE4K-A17-0.2C8 was identified as an efficacious carrier for delivering mRNA to mouse lungs. The delivery selectivity between organs (lungs versus spleen) was found to be tunable through chemical modification of polyesters (both alkyl chain length and molar ratio in the formulation). Cre recombinase mRNA was delivered to the Lox-stop-lox tdTomato mouse model to study potential application in gene editing. Overall, we identified a series of polymer-mRNA polyplexes stabilized with Pluronic F-127 for safe and effective delivery to mouse lungs and spleens. Structure–activity relationships between alkyl side chains and in vivo delivery were elucidated, which may be informative for the continued development of polymer-based mRNA delivery.

A New Generation of Vaccines in the Age of Immunotherapy

PURPOSE OF REVIEW

Cancer vaccines are one of the most extensively studied immunotherapy type in solid tumors. Despite favorable presuppositions, so far, the use of cancer vaccines has been associated with disappointing results. However, a new generation of vaccines has been developed, promising to revolutionize the immunotherapy field.

RECENT FINDINGS

In this review, we aim to highlight the advances in cancer vaccines and the remaining hurdles to overcome. Cancer vaccination has experienced tremendous progress in the last decade, with myriad promising developments. Future efforts should focus on optimization of target identification, streamlining of most appropriate vaccination strategies, and adjuvant development, as well as predictive biomarker identification. Cautious optimism is warranted in the face of early successes seen in recent clinical trials for oncolytic vaccines. If an approach were to prove successful, it could revolutionize cancer therapy the way ICIs did in the previous decade.

Nucleic acid delivery for therapeutic applications

Recent medical advances have exploited the ability to address a given disease at the underlying level of transcription and translation. These treatment paradigms utilize nucleic acids - including short interfering RNA (siRNA), microRNA (miRNA), antisense oligonucleotides (ASO), and messenger RNA (mRNA) - to achieve a desired outcome ranging from gene knockdown to induced expression of a selected target protein. Towards this end, numerous strategies for encapsulation or stabilization of various nucleic acid structures have been developed in order to achieve intracellular delivery. In this review, we discuss several therapeutic applications of nucleic acids directed towards specific diseases and tissues of interest, in particular highlighting recent technologies which have reached late-stage clinical trials and received FDA approval.

Review Article: vaccination for patients with inflammatory bowel disease during the COVID-19 pandemic

BACKGROUND

Poor immune responses are frequently observed in patients with inflammatory bowel disease (IBD) receiving established vaccines; risk factors include immunosuppressants and active disease.

AIMS

To summarise available information regarding immune responses achieved in patients with IBD receiving established vaccines. Using this information, to identify risk factors in the IBD population related to poor vaccine-induced immunity that may be applicable to vaccines against COVID-19.

METHODS

We undertook a literature review on immunity to currently recommended vaccines for patients with IBD and to COVID-19 vaccines and summarised the relevant literature.

RESULTS

Patients with IBD have reduced immune responses following vaccination compared to the general population. Factors including the use of immunomodulators and anti-TNF agents reduce response rates. Patients with IBD should be vaccinated against COVID-19 at the earliest opportunity as recommended by International Advisory Committees, and vaccination should not be deferred because a patient is receiving immune-modifying therapies. Antibody titres to COVID-19 vaccines appear to be reduced in patients receiving anti-TNF therapy, especially in combination with immunomodulators after one vaccination. Therefore, we should optimise any established risk factors that could impact response to vaccination in patients with IBD before vaccination.

CONCLUSIONS

Ideally, patients with IBD should be vaccinated at the earliest opportunity against COVID-19. Patients should be in remission and, if possible, have their corticosteroid dose minimised before vaccination. Further research is required to determine the impact of different biologics on vaccine response to COVID-19 and the potential for booster vaccines or heterologous prime-boost vaccinations in the IBD population.

mRNA vaccines for infectious diseases: principles, delivery and clinical translation

Over the past several decades, messenger RNA (mRNA) vaccines have progressed from a scepticism-inducing idea to clinical reality. In 2020, the COVID-19 pandemic catalysed the most rapid vaccine development in history, with mRNA vaccines at the forefront of those efforts. Although it is now clear that mRNA vaccines can rapidly and safely protect patients from infectious disease, additional research is required to optimize mRNA design, intracellular delivery and applications beyond SARS-CoV-2 prophylaxis. In this Review, we describe the technologies that underlie mRNA vaccines, with an emphasis on lipid nanoparticles and other non-viral delivery vehicles. We also overview the pipeline of mRNA vaccines against various infectious disease pathogens and discuss key questions for the future application of this breakthrough vaccine platform.

Polyplex nanomicelle delivery of self-amplifying RNA vaccine

Self-amplifying RNA (SaRNA) is a burgeoning platform that exploits the replication machinery of alphaviruses such as Venezuelan equine encephalitis (VEE) virus or Sindbis virus (SIN). SaRNA has been used for development of human vaccines, but has not been evaluated for porcine vaccine development. Porcine reproductive and respiratory syndrome virus (PRRSV) causes tremendous economic losses to the worldwide pork industry, but current vaccines trigger delayed neutralizing antibody response and confer only partial protection. Here we first compared two SaRNA systems based on VEE and SIN, and demonstrated that in vitro transcribed VEE-based SaRNA conferred prolonged reporter gene expression and RNA amplification in pig cells with low cytotoxicity, but SIN-based SaRNA imparted evident cytotoxicity and limited gene expression in pig cells. Transfection of VEE-based SaRNA that encodes the major PRRSV antigen dNGP5 (SaRNA-dNGP5) conferred persistent expression for at least 28 days in pig cells. We next complexed SaRNA-dNGP5 with the polyaspartamide block copolymer PEG-PAsp(TEP) to form polyplex nanomicelle with high packaging efficiency and narrow size distribution. The polyplex nanomicelle enabled sustained dNGP5 expression and secretion in vitro. Compared with the commercial PRRS vaccine, nanomicelle delivery of SaRNA-dNGP5 into animal models accelerated the induction of potent neutralizing antibodies with minimal side effects, and elicited stronger IL-4 and IFN-γ responses against homologous and heterologous PRRSV. These properties tackle the problems of current vaccines and implicate the potential of SaRNA-dNGP5 nanomicelle as an effective PRRS vaccine.

Vaccination of older adults: Influenza, pneumococcal disease, herpes zoster, COVID-19 and beyond

Preserving good health in old age is of utmost importance to alleviate societal, economic and health care-related challenges caused by an aging society. The prevalence and severity of many infectious diseases is higher in older adults, and in addition to the acute disease, long-term sequelae, such as exacerbation of underlying chronic disease, onset of frailty or increased long-term care dependency, are frequent. Prevention of infections e.g. by vaccination is therefore an important measure to ensure healthy aging and preserve quality of life. Several vaccines are specifically recommended for older adults in many countries, and in the current SARS-CoV-2 pandemic older adults were among the first target groups for vaccination due to their high risk for severe disease. This review highlights clinical data on the influenza, Streptococcus pneumoniae and herpes zoster vaccines, summarizes recent developments to improve vaccine efficacy, such as the use of adjuvants or higher antigen dose for influenza, and gives an overview of SARS-CoV-2 vaccine development for older adults. Substantial research is ongoing to further improve vaccines, e.g. by developing universal influenza and pneumococcal vaccines to overcome the limitations of the current strain-specific vaccines, and to develop novel vaccines against pathogens, which cause considerable morbidity and mortality in older adults, but for which no vaccines are currently available. In addition, we need to improve uptake of the existing vaccines and increase awareness for life-long vaccination in order to provide optimal protection for the vulnerable older age group.

Early approval of COVID-19 vaccines: Pros and cons

The development of safe and effective vaccines has been an overriding priority for controlling the 2019-coronavirus disease (COVID-19) pandemic. From the onset, COVID-19 has caused high mortality and economic losses and yet has also offered an opportunity to advance novel therapeutics such as DNA and mRNA vaccines. Although it is hoped that the swift acceptance of such vaccines will prevent loss of life, rejuvenate economies and restore normal life, there could also be significant pitfalls. This perspective provides an overview of future directions and challenges in advancing promising vaccine platforms to widespread therapeutic use.

Better, Faster, Stronger: mRNA Vaccines Show Promise for Influenza Vaccination in Older Adults

Older adults have diminished immune responses that lead to increased susceptibility and severity of infectious diseases. Influenza is a leading killer of older adults despite the availability of seasonal influenza vaccination. Influenza vaccines are strain specific, and their efficacy varies greatly year to year based on how well the vaccine virus matches the circulating strains. Additionally, older adults have reduced vaccination responses. The COVID-19 pandemic highlighted the increased mortality rate in older adults for infectious disease, and brought vaccine development to the forefront. The speed of vaccine development was met with an equally impressive vaccine efficacy. Interestingly, both mRNA-based COVID-19 vaccines currently available have shown similar efficacy in both young and older adults. mRNA vaccine production has significantly reduced the production timeline compared to current influenza vaccines, making them particularly attractive for influenza vaccine development. Faster production coupled with improved efficacy would be a tremendous advancement in protecting older adults from influenza morbidity and mortality.

mRNA delivery via non-viral carriers for biomedical applications

As an emerging new class of nucleic acid drugs, messenger RNA (mRNA) has huge potential in immunotherapy, regenerative medicine, vaccine, and gene editing. Comparing with siRNA and pDNA, mRNA is more vulnerable to nucleases in vivo. However, the lack of effective and safe delivery methods impedes the broad application of mRNA-based therapeutics. Up to now, the delivery of mRNA remains largely unexplored, and therefore, is a hot topic in the field of gene therapy. In this review, we will summarize the ongoing challenges in mRNA-based therapeutics and unmet requirements for delivery vehicles in terms of the unique structure of mRNA. We then highlight the advancement in mRNA delivery in both fundamental research and clinical applications. Finally, a prospective will be proposed upon reviewing the current progress in mRNA delivery.

Antigen modifications improve nucleoside-modified mRNA-based influenza virus vaccines in mice

Nucleoside-modified, lipid nanoparticle-encapsulated mRNAs have recently emerged as suitable vaccines for influenza viruses and other pathogens in part because the platform allows delivery of multiple antigens in a single immunization. mRNA vaccines allow for easy antigen modification, enabling rapid iterative design. We studied protein modifications such as mutating functional sites, changing secretion potential, and altering protein conformation, which could improve the safety and/or potency of mRNA-based influenza virus vaccines. Mice were vaccinated intradermally with wild-type or mutant constructs of influenza virus hemagglutinin (HA), neuraminidase (NA), matrix protein 2 (M2), nucleoprotein (NP), or matrix protein 1 (M1). Membrane-bound HA constructs elicited more potent and protective antibody responses than secreted forms. Altering the catalytic site of NA to reduce enzymatic activity decreased reactogenicity while protective immunity was maintained. Disruption of M2 ion channel activity improved immunogenicity and protective efficacy. A comparison of internal proteins NP and M1 revealed the superiority of NP in conferring protection from influenza virus challenge. These findings support the use of the nucleoside-modified mRNA platform for guided antigen design for influenza virus with extension to other pathogens.

Development of an mRNA-LNP Vaccine against SARS-CoV-2: Evaluation of Immune Response in Mouse and Rhesus Macaque

Among the vaccines have been developed thus far against SARS-CoV-2, the mRNA-based ones have demonstrated more promising results regarding both safety and efficacy. Two remarkable features of the mRNA vaccines introduced by the Pfizer/BioNTech and Moderna companies are the use of (N¹-methyl-pseudouridine-) modified mRNA and the microfluidics-based production of lipid nanoparticles (LNPs) as the carrier. In the present study, except Anti-Reverse Cap Analog (ARCA), no other nucleoside analogs were employed to synthesize Spike-encoding mRNA using the in vitro transcription (IVT) method. Furthermore, LNPs were prepared via the ethanol injection method commonly used for liposome formation as an alternative for microfluidics-based approaches. The produced mRNA-LNP vaccine was evaluated for nanoparticles characteristics, encapsulation and transfection efficiencies, in vitro cytotoxicity as well as stability and storability. The safety of vaccine was assessed in Balb/c mice injected with mRNA-LNPs containing 10 µg of spike-encoding mRNA. Eventually, the vaccine efficacy in inducing an immune response against SARS-CoV-2 was studied in Balb/c and C57BL/6 mice (received either 1 or 10 µg of mRNA) as well as in rhesus macaque monkeys (infused with mRNA-LNPs containing 100 µg of mRNA). The ELISA and virus neutralizing test (VNT) results showed a significant augmentation in the level of neutralizing antibodies against SARS-CoV-2. Moreover, the ELISA assay showed virus-specific IFN-γ secretion in immunized mice as a marker of T_H1 cell-based immune response, whereas favorably no change in the production of IL-4 was detected.

Universally Immune: How Infection Permissive Next Generation Influenza Vaccines May Affect Population Immunity and Viral Spread

Next generation influenza vaccines that target conserved epitopes are becoming a clinical reality but still have challenges to overcome. Universal next generation vaccines are considered a vital tool to combat future pandemic viruses and have the potential to vastly improve long-term protection against seasonal influenza viruses. Key vaccine strategies include HA-stem and T cell activating vaccines; however, they could have unintended effects for virus adaptation as they recognise the virus after cell entry and do not directly block infection. This may lead to immune pressure on residual viruses. The potential for immune escape is already evident, for both the HA stem and T cell epitopes, and mosaic approaches for pre-emptive immune priming may be needed to circumvent key variants. Live attenuated influenza vaccines have not been immunogenic enough to boost T cells in adults with established prior immunity. Therefore, viral vectors or peptide approaches are key to harnessing T cell responses. A plethora of viral vector vaccines and routes of administration may be needed for next generation vaccine strategies that require repeated long-term administration to overcome vector immunity and increase our arsenal against diverse influenza viruses.

Review of Influenza Virus Vaccines: The Qualitative Nature of Immune Responses to Infection and Vaccination Is a Critical Consideration

Influenza viruses have affected the world for over a century, causing multiple pandemics. Throughout the years, many prophylactic vaccines have been developed for influenza; however, these viruses are still a global issue and take many lives. In this paper, we review influenza viruses, associated immunological mechanisms, current influenza vaccine platforms, and influenza infection, in the context of immunocompromised populations. This review focuses on the qualitative nature of immune responses against influenza viruses, with an emphasis on trained immunity and an assessment of the characteristics of the host–pathogen that compromise the effectiveness of immunization. We also highlight innovative immunological concepts that are important considerations for the development of the next generation of vaccines against influenza viruses.

Synthetic modified messenger RNA for therapeutic applications

Synthetic modified messenger RNA (mRNA) has manifested great potentials for therapeutic applications such as vaccines and gene therapies, with the recent mRNA vaccines for global pandemic COVID-19 (corona virus disease 2019) attracting the tremendous attention. The chemical modifications and delivery vehicles of synthetic mRNAs are the two key factors for their in vivo therapeutic applications. Chemical modifications like nucleoside methylation endow the synthetic mRNAs with high stability and reduced stimulation of innate immunity. The development of scalable production of synthetic mRNA and efficient mRNA formulation and delivery strategies in recent years have remarkably advanced the field. It is worth noticing that we had limited knowledge on the roles of mRNA modifications in the past. However, the last decade has witnessed not only new discoveries of several naturally occurring mRNA modifications but also substantial advances in understanding their roles on regulating gene expression. It is highly necessary to reconsider the therapeutic system made by synthetic modified mRNAs and delivery vectors. In this review, we will mainly discuss the roles of various chemical modifications on synthetic mRNAs, briefly summarize the progresses of mRNA delivery strategies, and highlight some latest mRNA therapeutics applications including infectious disease vaccines, cancer immunotherapy, mRNA-based genetic reprogramming and protein replacement, mRNA-based gene editing.

Statement of significance

The development of synthetic mRNA drug holds great promise but lies behind small molecule and protein drugs largely due to the challenging issues regarding its stability, immunogenicity and potency. In the last 15 years, these issues have beensubstantially addressed by synthesizing chemically modified mRNA and developing powerful delivery systems; the mRNA therapeutics has entered an exciting new era begun with the approved mRNA vaccines for the COVID-19 infection disease. Here, we provide recent progresses in understanding the biological roles of various RNA chemical modifications, in developing mRNA delivery systems, and in advancing the emerging mRNA-based therapeutic applications, with the purpose to inspire the community to spawn new ideas for curing diseases.

An Update on mRNA-Based Viral Vaccines

With the success of COVID-19 vaccines, newly created mRNA vaccines against other infectious diseases are beginning to emerge. Here, we review the structural elements required for designing mRNA vaccine constructs for effective in vitro synthetic transcription reactions. The unprecedently speedy development of mRNA vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was enabled with previous innovations in nucleoside modifications during in vitro transcription and lipid nanoparticle delivery materials of mRNA. Recent updates are briefly described in the status of mRNA vaccines against SARS-CoV-2, influenza virus, and other viral pathogens. Unique features of mRNA vaccine platforms and future perspectives are discussed.

[The new generation of messenger RNA (mRNA) vaccines against influenza]

En la actualidad existen múltiples tipos de vacunas frente a la gripe. La irrupción de la tecnología de ácidos nucleicos utilizada en las vacunas frente al SARS-CoV-2 hace pensar en su aplicación futura frente a esta infección. Frente a la gripe se han desarrollado 2 tipos de vacunas basadas en el ARN mensajero (ARNm): las convencionales o no replicativas y las autoamplificables o replicativas (auARNm), ambas incluidas en nanopartículas lipídicas. Los estudios en animales realizados con las primeras han mostrado su intensa capacidad para inducir anticuerpos e inmunidad celular Th-1 frente a la hemaglutinina gripal con escasos efectos secundarios. Los ensayos en humanos han mostrado una seroconversión del 87% y una seroprotección del 100%. Las vacunas auARNm han obtenido resultados en animales semejantes, pero a una concentración 64 veces inferior a la convencional. Las vacunas basadas en las plataformas de ARNm cumplen los requisitos establecidos por la OMS para vacunas de gripe de la generación siguiente.

Protamine-Controlled Reversible DNA Packaging: A Molecular Glue

Packaging paternal genome into tiny sperm nuclei during spermatogenesis requires 10⁶-fold compaction of DNA, corresponding to a 10-20 times higher compaction than in somatic cells. While such a high level of compaction involves protamine, a small arginine-rich basic protein, the precise mechanism at play is still unclear. Effective pair potential calculations and large-scale molecular dynamics simulations using a simple idealized model incorporating solely electrostatic and steric interactions clearly demonstrate a reversible control on DNA condensates formation by varying the protamine-to-DNA ratio. Microscopic states and condensate structures occurring in semidilute solutions of short DNA fragments are in good agreement with experimental phase diagram and cryoTEM observations. The reversible microscopic mechanisms induced by protamination modulation should provide valuable information to improve a mechanistic understanding of early and intermediate stages of spermatogenesis where an interplay between condensation and liquid-liquid phase separation triggered by protamine expression and post-translational regulation might occur. Moreover, recent vaccines to prevent virus infections and cancers using protamine as a packaging and depackaging agent might be fine-tuned for improved efficiency using a protamination control.

Immunogenicity of Low-Dose Prime-Boost Vaccination of mRNA Vaccine CV07050101 in Non-Human Primates

Many different vaccine candidates against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, are currently approved and under development. Vaccine platforms vary from mRNA vaccines to viral-vectored vaccines, and several candidates have been shown to produce humoral and cellular responses in small animal models, non-human primates, and human volunteers. In this study, six non-human primates received a prime-boost intramuscular vaccination with 4 µg of mRNA vaccine candidate CV07050101, which encodes a pre-fusion stabilized spike (S) protein of SARS-CoV-2. Boost vaccination was performed 28 days post prime vaccination. As a control, six animals were similarly injected with PBS. Humoral and cellular immune responses were investigated at time of vaccination, and two weeks afterwards. No antibodies could be detected at two and four weeks after prime vaccination. Two weeks after boost vaccination, binding but no neutralizing antibodies were detected in four out of six non-human primates. SARS-CoV-2 S protein-specific T cell responses were detected in these four animals. In conclusion, prime-boost vaccination with 4 µg of vaccine candidate CV07050101 resulted in limited immune responses in four out of six non-human primates.

Engineered ε-decalactone lipomers bypass the liver to selectively in vivo deliver mRNA to the lungs without targeting ligands

RNA drugs hold real potential for tackling devastating diseases that are currently resistant to small molecule drugs or monoclonal antibodies. However, since these drugs are unstable in vivo and unable to pass through cellular membranes their clinical realization is limited by their successful delivery to target sites. Herein we report on the design of a combinatorial library of polyester lipomers based on the renewable monomer, ε-decalactone (ε-DL), via organocatalytic ring-opening polymerization for mRNA delivery. The ε-DL lipomers showed a surprisingly efficient ability to target the lungs upon intravenous administration. Interestingly, most of the lipomers achieved functional EGFP expression in the lungs, while minimally transfecting hepatocytes and splenic cells. This simple approach for the design of biodegradable materials has the potential for the clinical translation of genetic medicines for the treatment of lung diseases.

Immunogenicity of low dose prime-boost vaccination of mRNA vaccine CV07050101 in non-human primates

Many different vaccine candidates against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent of COVID-19, are currently approved and under development. Vaccine platforms vary from mRNA vaccines to viral-vectored vaccines, and several candidates have been shown to produce humoral and cellular responses in small animal models, non-human primates and human volunteers. In this study, six non-human primates received a prime-boost intramuscular vaccination with 4 µg of mRNA vaccine candidate CV07050101, which encodes a pre-fusion stabilized spike (S) protein of SARS-CoV-2. Boost vaccination was performed 28 days post prime vaccination. As a control, six animals were similarly injected with PBS. Humoral and cellular immune responses were investigated at time of vaccination, and two weeks afterwards. No antibodies could be detected two and four weeks after prime vaccination. Two weeks after boost vaccination, binding but no neutralizing antibodies were detected in 4 out of 6 non-human primates. SARS-CoV-2 S protein specific T cell responses were detected in these 4 animals. In conclusion, prime-boost vaccination with 4 µg of vaccine candidate CV07050101 resulted in limited immune responses in 4 out of 6 non-human primates.

Use of Protamine in Nanopharmaceuticals-A Review

Macromolecular biomolecules are currently dethroning classical small molecule therapeutics because of their improved targeting and delivery properties. Protamine-a small polycationic peptide-represents a promising candidate. In nature, it binds and protects DNA against degradation during spermatogenesis due to electrostatic interactions between the negatively charged DNA-phosphate backbone and the positively charged protamine. Researchers are mimicking this technique to develop innovative nanopharmaceutical drug delivery systems, incorporating protamine as a carrier for biologically active components such as DNA or RNA. The first part of this review highlights ongoing investigations in the field of protamine-associated nanotechnology, discussing the self-assembling manufacturing process and nanoparticle engineering. Immune-modulating properties of protamine are those that lead to the second key part, which is protamine in novel vaccine technologies. Protamine-based RNA delivery systems in vaccines (some belong to the new class of mRNA-vaccines) against infectious disease and their use in cancer treatment are reviewed, and we provide an update on the current state of latest developments with protamine as pharmaceutical excipient for vaccines.

mRNA-lipid nanoparticle COVID-19 vaccines: Structure and stability

A drawback of the current mRNA-lipid nanoparticle (LNP) COVID-19 vaccines is that they have to be stored at (ultra)low temperatures. Understanding the root cause of the instability of these vaccines may help to rationally improve mRNA-LNP product stability and thereby ease the temperature conditions for storage. In this review we discuss proposed structures of mRNA-LNPs, factors that impact mRNA-LNP stability and strategies to optimize mRNA-LNP product stability. Analysis of mRNA-LNP structures reveals that mRNA, the ionizable cationic lipid and water are present in the LNP core. The neutral helper lipids are mainly positioned in the outer, encapsulating, wall. mRNA hydrolysis is the determining factor for mRNA-LNP instability. It is currently unclear how water in the LNP core interacts with the mRNA and to what extent the degradation prone sites of mRNA are protected through a coat of ionizable cationic lipids. To improve the stability of mRNA-LNP vaccines, optimization of the mRNA nucleotide composition should be prioritized. Secondly, a better understanding of the milieu the mRNA is exposed to in the core of LNPs may help to rationalize adjustments to the LNP structure to preserve mRNA integrity. Moreover, drying techniques, such as lyophilization, are promising options still to be explored.

The COVID-19 Vaccine Landscape

The history of vaccine development spans centuries. At first, whole pathogens were used as vaccine agents, either inactivated or attenuated, to reduce virulence in humans. Safety and tolerability were increased by including only specific proteins as antigens and using cell culture methods, while novel vaccine strategies, like nucleic acid- or vector-based vaccines, hold high promise for the future. Vaccines have generally not been employed as the primary tools in outbreak response, but this might change since advances in medical technology in the last decades have made the concept of developing vaccines against novel pathogens a realistic strategy. Wandering the uncharted territory of a novel pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we can learn from other human Betacoronaviridae that emerged in the last decades, SARS-CoV-1 and MERS-CoV. We can identify the most likely target structures of immunity, establish animal models that emulate human disease and immunity as closely as possible, and learn about complex mechanisms of immune interaction such as cross-reactivity or antibody-dependent enhancement (ADE). However, significant knowledge gaps remain. What are the correlates of protection? How do we best induce immunity in vulnerable populations like the elderly? Will the immunity induced by vaccination (or by natural infection) wane over time? To date, at least 149 vaccine candidates against SARS-CoV-2 are under development. At the time of writing, at least 17 candidates have already progressed past preclinical studies (in vitro models and in vivo animal experiments) into clinical development. This chapter will provide an overview of this rapidly developing field.

The evolution and future of influenza pandemic preparedness

The influenza virus is a global threat to human health causing unpredictable yet recurring pandemics, the last four emerging over the course of a hundred years. As our knowledge of influenza virus evolution, distribution, and transmission has increased, paths to pandemic preparedness have become apparent. In the 1950s, the World Health Organization (WHO) established a global influenza surveillance network that is now composed of institutions in 122 member states. This and other surveillance networks monitor circulating influenza strains in humans and animal reservoirs and are primed to detect influenza strains with pandemic potential. Both the United States Centers for Disease Control and Prevention and the WHO have also developed pandemic risk assessment tools that evaluate specific aspects of emerging influenza strains to develop a systematic process of determining research and funding priorities according to the risk of emergence and potential impact. Here, we review the history of influenza pandemic preparedness and the current state of preparedness, and we propose additional measures for improvement. We also comment on the intersection between the influenza pandemic preparedness network and the current SARS-CoV-2 crisis. We must continually evaluate and revise our risk assessment and pandemic preparedness plans and incorporate new information gathered from research and global crises.

An Updated Review of SARS-CoV-2 Vaccines and the Importance of Effective Vaccination Programs in Pandemic Times

Since the worldwide COVID-19 pandemic was declared a year ago, the search for vaccines has become the top priority in order to restore normalcy after 2.5 million deaths worldwide, overloaded sanitary systems, and a huge economic burden. Vaccine development has represented a step towards the desired herd immunity in a short period of time, owing to a high level of investment, the focus of researchers, and the urge for the authorization of the faster administration of vaccines. Nevertheless, this objective may only be achieved by pursuing effective strategies and policies in various countries worldwide. In the present review, some aspects involved in accomplishing a successful vaccination program are addressed, in addition to the importance of vaccination in a pandemic in the face of unwillingness, conspiracy theories, or a lack of information among the public. Moreover, we provide some updated points related to the landscape of the clinical development of vaccine candidates, specifically, the top five vaccines that are already being assessed in Phase IV clinical trials (BNT162b2, mRNA-1273, AZD1222, Ad26.COV2.S, and CoronaVac).

mRNA-based SARS-CoV-2 vaccine candidate CVnCoV induces high levels of virus-neutralising antibodies and mediates protection in rodents

mRNA technologies have recently proven clinical efficacy against coronavirus disease 2019 and are among the most promising technologies to address the current pandemic. Here, we show preclinical data for our clinical candidate CVnCoV, a lipid nanoparticle-encapsulated mRNA vaccine that encodes full-length, pre-fusion stabilised severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein. In contrast to previously published approaches, CVnCoV is exclusively composed of naturally occurring nucleotides. Immunisation with CVnCoV induced strong humoral responses with high titres of virus-neutralising antibodies and robust T-cell responses. CVnCoV vaccination protected hamsters from challenge with wild-type SARS-CoV-2, demonstrated by the absence of viral replication in the lungs. Hamsters vaccinated with a suboptimal dose of CVnCoV leading to breakthrough viral replication exhibited no evidence of vaccine-enhanced disease. Overall, data presented here provide evidence that CVnCoV represents a potent and safe vaccine candidate against SARS-CoV-2.

mRNA vaccines manufacturing: Challenges and bottlenecks

Vaccines are one of the most important tools in public health and play an important role in infectious diseases control. Owing to its precision, safe profile and flexible manufacturing, mRNA vaccines are reaching the stoplight as a new alternative to conventional vaccines. In fact, mRNA vaccines were the technology of choice for many companies to combat the Covid-19 pandemic, and it was the first technology to be approved in both United States and in Europe Union as a prophylactic treatment. Additionally, mRNA vaccines are being studied in the clinic to treat a number of diseases including cancer, HIV, influenza and even genetic disorders. The increased demand for mRNA vaccines requires a technology platform and cost-effective manufacturing process with a well-defined product characterisation. Large scale production of mRNA vaccines consists in a 1 or 2-step in vitro reaction followed by a purification platform with multiple steps that can include Dnase digestion, precipitation, chromatography or tangential flow filtration. In this review we describe the current state-of-art of mRNA vaccines, focusing on the challenges and bottlenecks of manufacturing that need to be addressed to turn this new vaccination technology into an effective, fast and cost-effective response to emerging health crises.

Quantum Biotech and Internet of Virus Things: Towards a Theoretical Framework

Quantumization, the process of converting information into quantum (qubit) format, is a key enabler for propelling a new and distinct infrastructure in the pharmaceutical space. Quantum messenger RNA (QmRNA) technology, an indispensable constituent of quantum biotech (QB), is a compelling alternative to conventional vaccine methods because of its capacity for rapid development, high efficacy, and low-cost manufacturing to combat infectious diseases. Internet of Virus Things (IoVT), a biological version of Internet of Things (IoT), comprises applications to fight against pandemics and provides effective vaccine administration. The integration of QB and IoVT constitutes the QBIoVT system to advance the prospect of QmRNA vaccine discovery within a few days. This research disseminates the QBIoVT system paradigm, including architectural aspects, priority areas, challenges, applications, and QmRNA research engine design to accelerate QmRNA vaccines discovery. A comprehensive review of the literature was accomplished, and a context-centered methodology was applied to the QBIoVT paradigm forensic investigations to impel QmRNA vaccine discovery. Based on the above rumination, the principal motive for this study was to develop a novel QBIoVT theoretical framework which has not been produced through earlier theories. The proposed framework shall inspire future QBIoVT system research activities to improve pandemics detection and protection.

The Limitless Future of RNA Therapeutics

Recent advances in the generation, purification and cellular delivery of RNA have enabled development of RNA-based therapeutics for a broad array of applications. RNA therapeutics comprise a rapidly expanding category of drugs that will change the standard of care for many diseases and actualize personalized medicine. These drugs are cost effective, relatively simple to manufacture, and can target previously undruggable pathways. It is a disruptive therapeutic technology, as small biotech startups, as well as academic groups, can rapidly develop new and personalized RNA constructs. In this review we discuss general concepts of different classes of RNA-based therapeutics, including antisense oligonucleotides, aptamers, small interfering RNAs, microRNAs, and messenger RNA. Furthermore, we provide an overview of the RNA-based therapies that are currently being evaluated in clinical trials or have already received regulatory approval. The challenges and advantages associated with use of RNA-based drugs are also discussed along with various approaches for RNA delivery. In addition, we introduce a new concept of hospital-based RNA therapeutics and share our experience with establishing such a platform at Houston Methodist Hospital.

In the Era of mRNA Vaccines, Is There Any Hope for HIV Functional Cure?

Over 36 million people worldwide are infected with HIV. Antiretroviral therapy (ART) has proven to be highly effective to prevent HIV-1 transmission, clinical progression and death. Despite this success, the number of HIV-1 infected individuals continues increasing and ART should be taken for life. Therefore, there are two main priorities: the development of preventive vaccines to protect from HIV acquisition and achieve an efficient control of HIV infection in the absence of ART (functional cure). In this sense, in the last few years, there has been a broad interest in new and innovative approaches such as mRNA-based vaccines. RNA-based immunogens represent a promising alternative to conventional vaccines because of their high potency, capacity for rapid development and potential for low-cost manufacture and safe administration. Some mRNA-based vaccines platforms against infectious diseases have demonstrated encouraging results in animal models and humans. However, their application is still limited because the instability and inefficient in vivo delivery of mRNA. Immunogens, design, immunogenicity, chemical modifications on the molecule or the vaccine delivery methods are all crucial interventions for improvement. In this review we, will present the current knowledge and challenges in this research field. mRNA vaccines hold great promises as part of a combined strategy, for achieving HIV functional cure.