Therapeutic Repurposing Approach: New Opportunity for Developing Drugs Against COVID-19

The coronavirus disease 2019 (COVID-19) pandemic initiated by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has encouraged the repurposing of various drugs to treat the morbidity, mortality, and extent of the disease. Nowadays, the COVID-19 pandemic is a major health concern as it has already affected the whole world in all aspects. Drug repurposing is considered a new potential strategy as it is a cost-effective and less time-consuming process to establish a new indication for existing drugs. The present chapter has focused on the pathophysiology of COVID-19 and the reuse of the drugs based on pharmacological mechanisms. In the literature, various drugs like favipiravir, lopinavir, ritonavir, arbidol, chloroquine, hydroxychloroquine, interferons, etc. have been reported for repurposing purposes against COVID-19. Most of them are effective in in vitro and clinical studies. Drugs act mainly on viral entry, viral replication, angiotensin-converting enzyme-2 (ACE2), inflammatory mechanisms, etc. Based on viral pathogenesis and the mechanism of drugs using in silico, in vitro, and clinical studies, repurposing medicines might be considered an excellent opportunity to cure COVID-19. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Repurposing Drugs for Viruses and Cancer: A Novel Drug Repositioning Strategy for COVID-19

The high infection capacity and rapid mutations in coronavirus disease 2019 (COVID-19) has been no stranger to many. The etiological agent that contributed to this global health crisis is by no means the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). COVID-19 is characterized by an episode of immune fluctuations, followed by hyperactivation of inflammatory responses, known as the cytokine storm. The rapid progression of the COVID-19 pandemic calls for new and promising antiviral therapeutics. Repositioning anticancer drugs against the virus is very much explored due to the common similar pathways or targeting structures, opening new windows for many possibilities. As such, the repurposing of zidovudine for Friend leukemia virus and ouabain for Ebola virus are among the successful examples. Other potential FDA-approved anticancer drugs to be repositioned for COVID-19 include imatinib, saracatinib, and homoharringtonine, which have been studied for other coronaviruses in the past. Furthermore, current anticancer drugs like carmofur, carfilzomib, zotatifin, plitidepsin, and toremifene have gained interesting outcomes with respect to SARS-CoV-2. It is well recognized that to achieve viral replication, viruses antagonise or hijack host proteins and signaling pathways to gain productive infection, with SARS-CoV-2 indeed being no exception. This review aims to discuss the drug repositioning approaches concerning previously established anticancer drugs on viruses, especially on SARS-CoV-2. We accentuate this idea with specific examples of how potential anticancer inhibitors can effectively be used against SARS-CoV-2 as well as the limitations and future perspectives of drug repositioning. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Drug Repurposing for COVID-19 Therapy: Pipeline, Current Status and Challenges

Repurposed drugs such as Remdesivir, Fabipiravir and Molnupiravir became life saver drugs during the peak of the COVID-19 pandemic, attesting the efficacy of the repurposing approach. By definition, drug repurposing is the process of identification of new therapeutic use of an existing drug or drug candidate that has already passed the safety, toxicity and pharmacology tests for human use. Although drug repurposing approach involves a significant level of challenge, affordability and faster discovery pipeline outweighs the risks in the event of emergency situations like the current COVID-19 pandemic. In this chapter, we provide a brief summary of the advantages of the drug repurposing approach, followed by an overview of the drug repurposing pipeline and finally end with an update on the status of drug repurposing in developing effective anti-viral therapeutics against COVID-19. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

AI for Drug Repurposing in the Pandemic Response

Given the time criticality of finding treatments for the novel COVID-19 pandemic disease, drug repurposing has proved to be a vital strategy as the first response while de novo drug and vaccine developments are underway. Furthermore, Artificial Intelligence (AI) has also accelerated drug development in general. Key desirable features of AI that support a rapid and sustained response along the pandemic timeline include technical flexibility and efficiency (i.e. speed, resource-efficiency, algorithm adaptability), and clinical applicability and acceptability (i.e. scientific rigor, physiological applicability and practical implementation of proposed drugs). This chapter reviews a selection of AI-based applications used in drug development targeting COVID-19, including IDentif.AI-a small data platform for a rapid identification of optimal drug combinations, to illustrate the potential of AI in drug repurposing. The benefits and limitations of using Real-World Data are also discussed. The response to the COVID-19 pandemic has offered multiple learnings which highlight the need to strengthen both short- and long-term strategies in developing AI technologies, scientific and regulatory frameworks as well as worldwide collaborations to enable effective preparedness for future epidemic and pandemic risks. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

A comprehensive review on technological advances in alternate drug discovery process:Drug repurposing

The traditional de novo drug discovery is time consuming, costly and in some instances the drugs will fail to treat the disease which result in a huge loss to the organization. Drug repurposing is an alternative drug discovery process to overcome the limitations of the De novo drug discovery process. Ithelps for the identification of drugs to the rare diseases as well as in the pandemic situationwithin short span of time in a cost-effective way. The underlying principle of drug repurposing is that most of the drugs identified on a primary purpose have shown to treat other diseases also. One such example is Tocilizumab is primarily used for rheumatoid arthritis and it is repurposed to treat cancer and COVID-19. At present, nearly30% of the FDA approved drugs to treat various diseases are repurposed drugs. The drug repurposing is either drug-centric or disease centric and can be studied by using both experimental and in silico studies. The in silico repurpose drug discovery process is more efficient as it screens thousands of compounds from the diverse libraries within few days by various computational methods like Virtual screening, Docking, MD simulations,Machine Learning, Artificial Intelligence, Genome Wide Association Studies (GWAS), etc. with certain limitations.These limitationscan be addressed by effective integration of advanced technologies to identify a novel multi-purpose drug.Copyright © 2023, Association of Biotechnology and Pharmacy. All rights reserved.

Rational Repurposing of Drugs, Clinical Trial Candidates, and Natural Products for SARS-CoV-2 Therapy

In the last 20 years, the world has been threatened with coronavirus (CoV) pandemic threats from severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002, Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 and finally COVID-19 due to SARS-CoV-2 in 2019. These viruses posed serious global pandemic threats, with estimated case fatality rates of 15% for SARS-CoV, 34% for MERS-CoV, and 1-3% for SARS-CoV-2. With the current pandemic still far from over there is an urgent need to find new drug treatments for COVID-19. We can assume that this will not be the last coronavirus to threaten humanity, so we need better tools to identify drugs active against past but also future coronavirus threats. In this Chapter we describe in silico computer modeling and screening approaches that can rapidly identify drugs from existing drug libraries that could be repurposed to treat COVID-19 infections. We also describe how this computational screening pipeline can be expanded in the future to identify drugs with broad spectrum activity against a wide diversity of coronaviruses. A significant concern is that the protection against CoVs provided by single drugs protection may be short-lived because viruses rapidly mutate to develop drug resistance. We know from other viruses such as HIV that drugs hitting multiple targets within the virus provide better protection against the development of resistance. This Chapter describes the current state of development of in silico CoV drug repurposing, the challenges and pitfalls of these approaches, and our predictions of how these methods could be used to develop drugs for future pandemics before they occur. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Drug Repurposing for, ENT and Head and Neck, Infectious and Oncologic Diseases: Current Practices and Future Possibilities

The specialty of otolaryngology and head and neck surgery involves various subspecialties, encompassing clinical conditions ranging from medical to surgical issues in infections, noninfectious benign conditions and various benign and malignant tumors. Drug repurposing has proven to be significant in multiple fields and is still investigational in many promising possible solutions to different clinical challenges in this specialty. We discuss some classes of drugs that have been successfully repurposed for ENT pathologies. We also discuss the novel research goals that are being pursued in our department in the context of drug repurposing for airway infectious diseases including COVID-10 and mucormycosis. There has been a silent and underappreciated rise in drug-resistant invasive fungal infections (IFIs). Emerging Mucorales are difficult to diagnose and tolerant to many of the frontline antifungal therapies. There is an urgent need to combat these emerging pathogens and investigate the molecular mechanisms underlying their potentiated virulence traits to identify potential therapeutic targets susceptible to anti-fungal compounds. The drug development process for IFIs remains largely expensive, and is inherently risky. These challenges declare an urgent need for discovery of new antifungal drugs and encourage drug repurposing as alternative approach to fungal control. The understanding of molecular underpinnings behind fungi and human host continue to grow, however, further research endeavors are underway to fully explore the fungal pathogenesis, (including the role of iron) to gather new insights to achieve improved therapeutics. Above all, creative screening tools and out-of-the-box ideas aimed at increasing the possibility of identifying potential first-in-class antifungals are highly encouraged. The recently emerging fungal co-infections in the COVID-19 disease patients has revived the interest in the pathophysiology and clinical management of the IFIs, and identification of potential druggable nodes in olfactory niche to inhibit the spread of COVID-19 and associated co-infections by leveraging in vitro-disease models of host-pathogen interaction. We employed our recently established COVID-19 disease model to decipher potential anti-metabolic molecules that can be repurposed as novel bilateral drugs having anti-fungal and host-directed features with extended applicability in diabetes, COVID-19, and mucormycosis with and without COVID-19. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Drug Repurposing of the Antiviral Drug Acyclovir: New Pharmaceutical Salts

Drug repurposing is becoming interesting in terms of offering advantages over the traditional drug development, once drug discovery is a costly, time-consuming, and highly risky process. In particular, with the coronavirus disease (COVID-19) declared by World Health Organization as a global pandemic, there has emerged a considerable need to develop therapeutic agents capable of preventing viral outbreaks. Concomitantly, well-known and long-used drugs such as acyclovir (Acv) have been tested against COVID-19. Acv is a guanosine analogue that acts as an antiviral drug, commonly used to treat herpes simplex virus (HSV), genital herpes, and varicella zoster virus (VZV). Acv showed to inhibit viral proteases, multiple viral genes expression, and RNA-Dependent RNA Polymerase, helping to recover COVID-19 patients. However, ACV is a BCS class III/IV drug, with low permeability and/or slight water solubility (concentration-dependent). Given the repurposing eligibility of Acv, in this work, two new salts of this drug are presented (nitrate and sulfate), with the aim of improving its pharmacokinetic properties. The new salts were evaluated by X-ray diffraction, and thermal and spectroscopic analyses. A third salt, a chloride one, was also characterized and used for comparison.

Pharmacovigilance-Based Drug Repurposing

Pharmacovigilance involves evaluation of adverse effects of drugs in the interest of patient safety. Large-scale application of pharmacovigilance generates big datasets that are mined to identify previously unknown drug–event combinations, and, as an extension, may help in identifying new indications for old drugs. The therapeutic potential of a drug using pharmacovigilance-based drug repurposing can be assessed in one of the four ways—serendipity, mechanistic profiling, signature matching, and inverse signaling. Serendipity is the phenomenon of discovery of some valuable information for an already known drug, by chance, like minoxidil. Mechanistic profiling proposed the use of sulfonylureas for diabetes mellitus, based on the observation of their hypoglycemic effect. Signature matching is puzzling out new indications of drugs based on similarity of characteristics in a network of other drugs which are already approved for any condition. Inverse signaling approach takes cues from data mining approaches, applied to pharmacovigilance databases. Currently, this approach is being tried to evaluate existing compounds for Raynaud's phenomenon, COVID-19, Alzheimer' disease, etc. In this chapter, we discuss these pharmacovigilance-based methods as they have immense translational potential for drug repurposing. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Repurposing of reception shaft, Mumbai Coastal Road Project – Case study

As part of Mumbai Coastal Road Project-the connection between Nariman Point and Bandra Worli, a total length of 10.58 km-Package IV (MCRP4) includes submarine twin tube tunnels. Current Package's total length is 4,480 m, of which 2,008 m are excavated by means of one slurry shield and supported/lined by precast segments. Each tube will accommodate a three-lane carriageway, for an internal diameter of 11 m and an excavation diameter 12.19 m. To enable the launching and receiving of the TBM, two shafts were constructed at North end and South end of the package. The reception shaft is 42m long and 30m wide with a depth of 26m below the ground formation level at +3.0 msl. The intention was to disassemble the TBM after the first drive to reassemble and relaunch it from the original shaft – the "launch-ing shaft”. However, due to logistical constraints, given the project location in a dense urban setting, and due to time delays, because of stoppage of works during Covid lockdown, the Contractor of the project decided to relaunch the TBM from the reception shaft itself by rotating the TBM and save approx. 60-75 days. Due to this dynamic need of the project, reception shaft was repurposed for relaunching with additional ancillary structures (like Heavy weight modular gantry crane foundations, TBM reaction frame, Slurry treatment plant on surface etc.,) in and around the shaft which weren't foreseen during the excavation of shaft. This paper discusses design aspects with special focus on challenges which were needed for this repurposing of shaft. © 2023 The Author(s).

2-Deoxy-D-Glucose: A Repurposed Drug for COVID-19 Treatment

Coronaviruses is a broad group of viruses that has the potential to cause mild or severe respiratory infections. Currently, there is no specific treatment for the treatment of COVID-19. The symptomatic treatment is generally given on case-to-case basis along with basic life supportive measures for management of COVID-19. There is an acute urgency of evaluating the pre-existing drugs to develop a convincing treatment for COVID-19 or at least to reduce its severity. 2-DG being inhibitor of both glycolysis and glycosylation appears as a promising therapeutic option. In the present chapter, the rationale of repurposing of 2-DG as a potential treatment option for the management of COVID-19 has been discussed. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

SARS-CoV-2 main protease targeting potent fluorescent inhibitors: Repurposing thioxanthones

The coronavirus disease, COVID-19, is the major focus of the whole world due to insufficient treatment options. It has spread all around the world and is responsible for the death of numerous human beings. The future consequences for the disease survivors are still unknown. Hence, all contributions to understand the disease and effectively inhibit the effects of the disease have great importance. In this study, different thioxanthone based molecules, which are known to be fluorescent compounds, were selectively chosen to study if they can inhibit the main protease of SARS-CoV-2 using various computational tools. All candidate ligands were optimized, molecular docking and adsorption, distribution, metabolism, excretion, and toxicity (ADMET) studies were conducted and subsequently, some were subjected to 100 ns molecular dynamics simulations in conjunction with the known antiviral drugs, favipiravir, and hydroxychlo-roquine. It was found that different functional groups containing thioxanthone based molecules are capable of different intermolecular interactions. Even though most of the studied ligands showed stable interactions with the main protease, para-oxygen-di-acetic acid functional group containing thioxanthone was found to be a more effective inhibitor due to the higher number of intermolecular inter-actions and higher stability during the simulations.

Drug Repurposing in COVID-19 and Cancer: How Far Have We Come?

Drug repurposing is a strategy for ascertaining new implications for already approved drugs. Historically, this field started with the serendipitous and inadvertent findings of a drug that was found to have an effect other than its original indication that was previously unrecognized and that had potential application in an entirely different disease. The fact that the rate of failure associated with the development of new drugs is high and the funds needed are enormous, it has compelled the scientific fraternity to look for alternatives and thus the drug repurposing approach has gained traction in the scientific community. The havoc that COVID-19 wreaked is unprecedented and till date it has led to the death of around 5.7 million people worldwide. The scientific fraternity, the world over, has embarked on the journey of getting a sure shot treatment for this deadly disease and till date many studies have been published discussing the role of various repurposed drug candidates in COVID-19 treatment. A majority of these studies have been carried out using structural bioinformatics and have not been validated by in vitro experiments. There is a pressing need for the treatment of COVID-19 disease using repurposed drugs by experimental validation and clinical testing, and augmented by the modern Machine Learning (ML)-and Artificial Intelligence (AI)-based approaches. A number of drug candidates have been investigated for their potential applications in cancer therapy, however the conundrum about the utility of either repurposed drug candidates or only active anti-cancer drugs for cancer therapy is to be pursued thoroughly so that mankind gets the most out of whatever potential the drug candidates, whether old or new, have in store for us. This chapter discusses the utility of drug repurposing approach as an alternative strategy for drug discovery that is intended to find treatment for new and emerging infectious diseases, viz. COVID-19 and cancer. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Accelerating drug repurposing for COVID-19 treatment by modeling mechanisms of action using cell image features and machine learning.

The novel coronavirus disease, COVID-19, has rapidly spread worldwide. Developing methods to identify the therapeutic activity of drugs based on phenotypic data can improve the efficiency of drug development. Here, a state-of-the-art machine-learning method was used to identify drug mechanism of actions (MoAs) based on the cell image features of 1105 drugs in the  LINCS database. As the multi-dimensional features of cell images are affected by non-experimental factors, the characteristics of similar drugs vary considerably, and it is difficult to effectively identify the MoA of drugs as there is substantial noise. By applying the supervised information theoretic metric-learning (ITML) algorithm, a linear transformation made drugs with the same MoA aggregate. By clustering drugs to communities and performing enrichment analysis, we found that transferred image features were more conducive to the recognition of drug MoAs. Image features analysis showed that different features play important roles in identifying different drug functions. Drugs that significantly affect cell survival or proliferation, such as cyclin-dependent kinase inhibitors, were more likely to be enriched in communities, whereas other drugs might be decentralized. Chloroquine and clomiphene, which block the entry of virus, were clustered into the same community, indicating that similar MoA could be reflected by the cell image. Overall, the findings of the present study laid the foundation for the discovery of MoAs of new drugs, based on image data. In addition, it provided a new method of drug repurposing for COVID-19. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11571-021-09727-5.

High-Throughput SARS-CoV-2 Antiviral Testing Method Using the Celigo Image Cytometer.

The COVID-19 pandemic has created a worldwide public health crisis that has since resulted in 6.8 million reported deaths. The pandemic prompted the immediate response of researchers around the world to engage in rapid vaccine development, surveillance programs, and antiviral testing, which resulted in the delivery of multiple vaccines and repurposed antiviral drug candidates. However, the emergence of new highly transmissible SARS-CoV-2 variants has renewed the desire for discovering new antiviral drug candidates with high efficacy against the emerging variants of concern. Traditional antiviral testing methods employ the plaque-reduction neutralization tests (PRNTs), plaque assays, or RT-PCR analysis, but each assay can be tedious and time-consuming, requiring 2-3 days to complete the initial antiviral assay in biologically relevant cells, and then 3-4 days to visualize and count plaques in Vero cells, or to complete cell extractions and PCR analysis. In recent years, plate-based image cytometers have demonstrated high-throughput vaccine screening methods, which can be adopted for screening potential antiviral drug candidates. In this work, we developed a high-throughput antiviral testing method employing the Celigo Image Cytometer to investigate the efficacy of antiviral drug candidates on SARS-CoV-2 infectivity using a fluorescent reporter virus and their safety by measuring the cytotoxicity effects on the healthy host cell line using fluorescent viability stains. Compared to traditional methods, the assays defined here eliminated on average 3-4 days from our standard processing time for antiviral testing. Moreover, we were able to utilize human cell lines directly that are not typically amenable to PRNT or plaque assays. The Celigo Image Cytometer can provide an efficient and robust method to rapidly identify potential antiviral drugs to effectively combat the rapidly spreading SARS-CoV-2 virus and its variants during the pandemic.

Looking for SARS-CoV-2 therapeutics through computational approaches.

BACKGROUND: In the last few years in silico tools, including drug repurposing coupled with structure-based virtual screening, have been extensively employed to look for anti-COVID-19 agents. OBJECTIVE: The present review aims to provide readers with a portrayal of computational approaches that could conduct more quickly and cheaply to novel anti-viral agents. Particular attention is given to docking-based virtual screening. METHOD: The World Health Organization website was consulted to gain the latest information on SARS-CoV-2, its novel variants and their interplay with COVID-19 severity and treatment options. The Protein Data Bank was explored to look for 3D coordinates of SARS-CoV-2 proteins in their free and bound states, in the wild-types and mutated forms. Recent literature related to in silico studies focused on SARS-CoV-2 proteins was searched through PubMed. RESULTS: A large amount of work has been devoted thus far to computationally targeting viral entry and searching for inhibitors of the S-protein/ACE2 receptor complex. Another large area of investigation is linked to in silico identification of molecules able to block viral proteases -including Mpro- thus avoiding maturation of proteins crucial for virus life cycle. Such computational studies have explored the inhibitory potential of the most diverse molecule databases (including plant extracts, dietary compounds, FDA approved drugs). CONCLUSION: More efforts need to be dedicated in the close future to experimentally validate the therapeutic power of in silico identified compounds in order to catch, among the wide ensemble of computational hits, novel therapeutics to prevent and/or treat COVID-19.

Transcription Factor Driven Gene Regulation in COVID-19 Patients.

SARS-CoV-2 and its many variants have caused a worldwide emergency. Host cells colonised by SARS-CoV-2 present a significantly different gene expression landscape. As expected, this is particularly true for genes that directly interact with virus proteins. Thus, understanding the role that transcription factors can play in driving differential regulation in patients affected by COVID-19 is a focal point to unveil virus infection. In this regard, we have identified 19 transcription factors which are predicted to target human proteins interacting with Spike glycoprotein of SARS-CoV-2. Transcriptomics RNA-Seq data derived from 13 human organs are used to analyse expression correlation between identified transcription factors and related target genes in both COVID-19 patients and healthy individuals. This resulted in the identification of transcription factors showing the most relevant impact in terms of most evident differential correlation between COVID-19 patients and healthy individuals. This analysis has also identified five organs such as the blood, heart, lung, nasopharynx and respiratory tract in which a major effect of differential regulation mediated by transcription factors is observed. These organs are also known to be affected by COVID-19, thereby providing consistency to our analysis. Furthermore, 31 key human genes differentially regulated by the transcription factors in the five organs are identified and the corresponding KEGG pathways and GO enrichment are also reported. Finally, the drugs targeting those 31 genes are also put forth. This in silico study explores the effects of transcription factors on human genes interacting with Spike glycoprotein of SARS-CoV-2 and intends to provide new insights to inhibit the virus infection.

Identification of core therapeutic targets for Monkeypox virus and repurposing potential of drugs against them: An in silico approach.

Monkeypox virus (mpox virus) outbreak has rapidly spread to 82 non-endemic countries. Although it primarily causes skin lesions, secondary complications and high mortality (1-10%) in vulnerable populations have made it an emerging threat. Since there is no specific vaccine/antiviral, it is desirable to repurpose existing drugs against mpox virus. With little knowledge about the lifecycle of mpox virus, identifying potential inhibitors is a challenge. Nevertheless, the available genomes of mpox virus in public databases represent a goldmine of untapped possibilities to identify druggable targets for the structure-based identification of inhibitors. Leveraging this resource, we combined genomics and subtractive proteomics to identify highly druggable core proteins of mpox virus. This was followed by virtual screening to identify inhibitors with affinities for multiple targets. 125 publicly available genomes of mpox virus were mined to identify 69 highly conserved proteins. These proteins were then curated manually. These curated proteins were funnelled through a subtractive proteomics pipeline to identify 4 highly druggable, non-host homologous targets namely; A20R, I7L, Top1B and VETFS. High-throughput virtual screening of 5893 highly curated approved/investigational drugs led to the identification of common as well as unique potential inhibitors with high binding affinities. The common inhibitors, i.e., batefenterol, burixafor and eluxadoline were further validated by molecular dynamics simulation to identify their best potential binding modes. The affinity of these inhibitors suggests their repurposing potential. This work can encourage further experimental validation for possible therapeutic management of mpox.

ß-Cyclodextrins as affordable antivirals to treat coronavirus infection.

The SARS-CoV-2 pandemic made evident that there are only a few drugs against coronavirus. Here we aimed to identify a cost-effective antiviral with broad spectrum activity and high safety profile. Starting from a list of 116 drug candidates, we used molecular modelling tools to rank the 44 most promising inhibitors. Next, we tested their efficacy as antivirals against α and ß coronaviruses, such as the HCoV-229E and SARS-CoV-2 variants. Four drugs, OSW-1, U18666A, hydroxypropyl-ß-cyclodextrin (HßCD) and phytol, showed in vitro antiviral activity against HCoV-229E and SARS-CoV-2. The mechanism of action of these compounds was studied by transmission electron microscopy and by fusion assays measuring SARS-CoV-2 pseudoviral entry into target cells. Entry was inhibited by HßCD and U18666A, yet only HßCD inhibited SARS-CoV-2 replication in the pulmonary Calu-3 cells. Compared to the other cyclodextrins, ß-cyclodextrins were the most potent inhibitors, which interfered with viral fusion via cholesterol depletion. ß-cyclodextrins also prevented infection in a human nasal epithelium model ex vivo and had a prophylactic effect in the nasal epithelium of hamsters in vivo. All accumulated data point to ß-cyclodextrins as promising broad-spectrum antivirals against different SARS-CoV-2 variants and distant alphacoronaviruses. Given the wide use of ß-cyclodextrins for drug encapsulation and their high safety profile in humans, our results support their clinical testing as prophylactic antivirals.

RNA Therapeutics: A Healthcare Paradigm Shift.

COVID-19 brought about the mRNA vaccine and a paradigm shift to a new mode of treating and preventing diseases. Synthetic RNA products are a low-cost solution based on a novel method of using nucleosides to act as an innate medicine factory with unlimited therapeutic possibilities. In addition to the common perception of vaccines preventing infections, the newer applications of RNA therapies include preventing autoimmune disorders, such as diabetes, Parkinson's disease, Alzheimer's disease, and Down syndrome; now, we can deliver monoclonal antibodies, hormones, cytokines, and other complex proteins, reducing the manufacturing hurdles associated with these products. Newer PCR technology removes the need for the bacterial expression of DNA, making mRNA a truly synthetic product. AI-driven product design expands the applications of mRNA technology to repurpose therapeutic proteins and test their safety and efficacy quickly. As the industry focuses on mRNA, many novel opportunities will arise, as hundreds of products under development will bring new perspectives based on this significant paradigm shift-finding newer solutions to existing challenges in healthcare.