Ribavirin: Past, present and future

Cyclin-Dependent Kinase 8 Represents a Positive Regulator of Cytomegalovirus Replication and a Novel Host Target for Antiviral Strategies

Background. Cyclin-dependent kinase 8 (CDK8) is a multifaceted regulator and represents a catalytic component of the transcriptional Mediator complex. CDK8 activity, on the one hand, increases transcriptional elongation by the recruitment of Mediator/super elongation complexes, but, on the other hand, negatively regulates CDK7-controlled transcriptional initiation through inactivating cyclin H phosphorylation. Recently, these combined properties of CDK8 have also suggested its rate-limiting importance for herpesviral replication. Objectives. In this paper, we focused on human cytomegalovirus (HCMV) and addressed the question of whether the pharmacological inhibition or knock-down of CDK8 may affect viral replication efficiency in cell culture models. Methods. A number of human and animal herpesviruses, as well as non-herpesviruses, were used to analyze the importance of CDK8 for viral replication in cell culture models, and to assess the antiviral efficacy of CDK8 inhibitors. Results. Using clinically relevant CDK8 inhibitors (CCT-251921, MSC-2530818, and BI-1347), HCMV replication was found strongly reduced even at nanomolar drug concentrations. The EC50 values were consistent for three different HCMV strains (i.e., AD169, TB40, and Merlin) analyzed in two human cell types (i.e., primary fibroblasts and astrocytoma cells), and the drugs comprised a low level of cytotoxicity. The findings highlighted the following: (i) the pronounced in vitro SI values of anti-HCMV activity obtained with CDK8 inhibitors; (ii) a confirmation of the anti-HCMV efficacy by CDK8-siRNA knock-down; (iii) a CDK8-dependent reduction in viral immediate early, early, and late protein levels; (iv) a main importance of CDK8 for viral late-stage replication; (v) several mechanistic aspects, which point to a strong impact on viral progeny production and release, but a lack of CDK8 relevance for viral entry or nuclear egress; (vi) a significant anti-HCMV drug synergy for combinations of inhibitors against host CDK8 and the viral kinase vCDK/pUL97 (maribavir); (vii) finally, a broad-spectrum antiviral activity, as seen for the comparison of selected α-, β-, γ-, and non-herpesviruses. Conclusions. In summary, these novel data provide evidence for the importance of CDK8 as a positive regulator of herpesviral replication efficiency, and moreover, suggest its exploitability as an antiviral target for novel strategies of host-directed drug development.

An updated review on 1,2,3-/1,2,4-triazoles: synthesis and diverse range of biological potential

The synthesis of triazoles has attracted a lot of interest in the field of organic chemistry because of its versatile chemical characteristics and possible biological uses. This review offers an extensive overview of the different pathways used in the production of triazoles. A detailed analysis of recent research indicates that triazole compounds have a potential range of pharmacological activities, including the ability to inhibit enzymes, and have antibacterial, anticancer, and antifungal activities. The integration of computational and experimental methods provides a thorough understanding of the structure-activity connection, promoting sensible drug design and optimization. By including triazoles as essential components in drug discovery, researchers can further explore and innovate in the synthesis, biological assessment, and computational studies of triazoles as drugs, exploring the potential therapeutic significance of triazoles.

Addressing bottlenecks in Lassa fever treatment: overcoming the ribavirin parenteral formulation challenge

Ribavirin ampoule formulation remains a major challenge in managing Lassa fever disease. Lassa fever is an endemic viral hemorrhagic fever in the West Africa subregion, which has high-dose ribavirin as the standard of care. The high-dose therapy required makes the 200 mg/ml ampoule dosing of ribavirin a daunting task to administer, especially during disease outbreaks. This commentary highlights the challenges and makes a passionate call for vial dosage adjustment to fit the high-dose requirement of Lassa fever disease.

An Antiherpesviral Host-Directed Strategy Based on CDK7 Covalently Binding Drugs: Target-Selective, Picomolar-Dose, Cross-Virus Reactivity

The repertoire of currently available antiviral drugs spans therapeutic applications against a number of important human pathogens distributed worldwide. These include cases of the pandemic severe acute respiratory coronavirus type 2 (SARS-CoV-2 or COVID-19), human immunodeficiency virus type 1 (HIV-1 or AIDS), and the pregnancy- and posttransplant-relevant human cytomegalovirus (HCMV). In almost all cases, approved therapies are based on direct-acting antivirals (DAAs), but their benefit, particularly in long-term applications, is often limited by the induction of viral drug resistance or side effects. These issues might be addressed by the additional use of host-directed antivirals (HDAs). As a strong input from long-term experiences with cancer therapies, host protein kinases may serve as HDA targets of mechanistically new antiviral drugs. The study demonstrates such a novel antiviral strategy by targeting the major virus-supportive host kinase CDK7. Importantly, this strategy focuses on highly selective, 3D structure-derived CDK7 inhibitors carrying a warhead moiety that mediates covalent target binding. In summary, the main experimental findings of this study are as follows: (1) the in vitro verification of CDK7 inhibition and selectivity that confirms the warhead covalent-binding principle (by CDK-specific kinase assays), (2) the highly pronounced antiviral efficacies of the hit compounds (in cultured cell-based infection models) with half-maximal effective concentrations that reach down to picomolar levels, (3) a particularly strong potency of compounds against strains and reporter-expressing recombinants of HCMV (using infection assays in primary human fibroblasts), (4) additional activity against further herpesviruses such as animal CMVs and VZV, (5) unique mechanistic properties that include an immediate block of HCMV replication directed early (determined by Western blot detection of viral marker proteins), (6) a substantial drug synergism in combination with MBV (measured by a Loewe additivity fixed-dose assay), and (7) a strong sensitivity of clinically relevant HCMV mutants carrying MBV or ganciclovir resistance markers. Combined, the data highlight the huge developmental potential of this host-directed antiviral targeting concept utilizing covalently binding CDK7 inhibitors.

Validation of nuclear receptor RORγ isoform 1 as a novel host-directed antiviral target based on the modulation of cholesterol levels

Currently, the clinically approved repertoire of antiviral drugs predominantly comprises direct-acting antivirals (DAAs). However, the use of DAAs is frequently limited by adverse effects, restriction to individual virus species, or the induction of viral drug resistance. These issues will likely be resolved by the introduction of host-directed antivirals (HDAs) targeting cellular proteins crucial for viral replication. However, experiences with the development of antiviral HDAs and clinical applications are still in their infancy. With the present study, we explored the human nuclear receptor and transcription factor RORγ isoform 1 (RORγ1), a member of the retinoic acid receptor-related orphan receptor (ROR) family, as a putative target of antiviral HDAs. To this end, cell culture models were used to investigate major viral human pathogens, i.e. the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human cytomegalovirus (HCMV), varicella zoster virus (VZV) and human immunodeficiency virus 1 (HIV-1). Our results demonstrated (i) an antiviral activity of the clinically relevant RORγ modulators cedirogant and others, (ii) that isoform RORγ1 acts as the responsible determinant and drug target in the analyzed cell culture-based models, (iii) a selectivity of the antiviral effect for RORγ1 over related receptors RORα and RORβ, (iv) a late-phase inhibition exerted by cedirogant in HCMV replication and (v) a mechanistic link to the cellular cholesterol biosynthesis. Combined, the data highlight this novel RORγ-specific antiviral targeting concept and the developmental potential of RORγ-directed small molecules.

Triple in silico targeting of IMPDH enzyme and RNA-dependent RNA polymerase of both SARS-CoV-2 and Rhizopus oryzae

Aim: Mucormycosis has been associated with SARS-CoV-2 infections during the last year. The aim of this study was to triple-hit viral and fungal RNA-dependent RNA polymerases (RdRps) and human inosine monophosphate dehydrogenase (IMPDH). Materials & methods: Molecular docking and molecular dynamics simulation were used to test nucleotide inhibitors (NIs) against the RdRps of SARS-CoV-2 and Rhizopus oryzae RdRp. These same inhibitors targeted IMPDH. Results: Four NIs revealed a comparable binding affinity to the two drugs, remdesivir and sofosbuvir. Binding energies were calculated using the most abundant conformations of the RdRps after 100-ns molecular dynamics simulation. Conclusion: We suggest the triple-inhibition potential of four NIs against pathogenic RdRps and IMPDH, which is worth experimental validation.

Hepatitis E infection: A review

Hepatitis E virus (HEV) is a small non-enveloped virus that is transmitted via the fecal-oral route. It is a highly common cause of acute hepatitis, particularly in low to middle income regions of Asia, Africa, and Central America. Most cases are self-limited, and symptomatic patients usually present with acute icteric hepatitis. A subset of patients including pregnant women, older men, those with pre-existing liver disease and immunocompromised patients however, may develop severe disease and hepatic failure. Immunocompromised patients are also at risk for chronic infection, and their immunosuppression should be decreased in order to facilitate viral clearance. HEV can also present with a variety of extra-intestinal manifestations including neurological, renal, hematological, and pancreatic derangements. The gold standard of diagnosis is HEV ribonucleic acid detection via nucleic acid amplification testing. Currently, there are no approved treatments for Hepatitis E, though ribavirin is the most commonly used agent to reduce viral load. Studies assessing the safety and efficacy of other antiviral agents for HEV are currently underway. HEV vaccination has been approved in China, and is currently being investigated in other regions as well. This review article aims to discuss the epidemiology, pathogenesis, presentation, diagnosis, complications, and treatment of Hepatitis E infection.

Severe COVID-19: Drugs and Clinical Trials

By January of 2023, the COVID-19 pandemic had led to a reported total of 6,700,883 deaths and 662,631,114 cases worldwide. To date, there have been no effective therapies or standardized treatment schemes for this disease; therefore, the search for effective prophylactic and therapeutic strategies is a primary goal that must be addressed. This review aims to provide an analysis of the most efficient and promising therapies and drugs for the prevention and treatment of severe COVID-19, comparing their degree of success, scope, and limitations, with the aim of providing support to health professionals in choosing the best pharmacological approach. An investigation of the most promising and effective treatments against COVID-19 that are currently available was carried out by employing search terms including "Convalescent plasma therapy in COVID-19" or "Viral polymerase inhibitors" and "COVID-19" in the Clinicaltrials.gov and PubMed databases. From the current perspective and with the information available from the various clinical trials assessing the efficacy of different therapeutic options, we conclude that it is necessary to standardize certain variables-such as the viral clearance time, biomarkers associated with severity, hospital stay, requirement of invasive mechanical ventilation, and mortality rate-in order to facilitate verification of the efficacy of such treatments and to better assess the repeatability of the most effective and promising results.

Intralesional application of ribavirin in two American flamingos (Phoenicopterus ruber) with poxvirus infection

We report the successful treatment of poxvirus lesions in two juvenile American flamingos (Phoenicopterus ruber) with experimental low-dose intralesional ribavirin injection. In the first flamingo, the size and location of a beak verrucosity interfered with feeding, and after multiple surgical interventions, an experimental therapy of low-dose intralesional ribavirin was implemented with close blood parameter monitoring to minimize any potential side effects due to systemic antiviral administration. The second flamingo had a poxvirus lesion on the tibiotarsus, which recurred after unsuccessful conservative medical treatment and surgical intervention and a course of intralesional ribavirin therapy was implemented. Regression of the lesions in both flamingos commenced within 3 days of ribavirin treatment resulting in complete resolution within 6 weeks of onset of ribavirin treatment.

Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery

Lung diseases continue to draw considerable attention from biomedical and public health care agencies. The lung with the largest epithelial surface area is continuously exposed to the external environment during exchanging gas. Therefore, the chances of respiratory disorders and lung infections are overgrowing. This review has covered promising and opportunistic etiologic agents responsible for lung infections. These pathogens infect the lungs either directly or indirectly. However, it is difficult to intervene in lung diseases using available oral or parenteral antimicrobial formulations. Many pieces of research have been done in the last two decades to improve inhalable antimicrobial formulations. However, very few have been approved for human use. This review article discusses the approved inhalable antimicrobial agents (AMAs) and identifies why pulmonary delivery is explored. Additionally, the basic anatomy of the respiratory system linked with barriers to AMA delivery has been discussed here. This review opens several new scopes for researchers to work on pulmonary medicines for specific diseases and bring more respiratory medication to market.

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infections in infants. Currently, ribavirin, a nucleoside analog containing a 1,2,4-triazole-3-carboxamide moiety, is a first-line drug for its treatment, however, its clinical use has been limited due to its side effects. Here, we designed two new nitroaryl-1,2,3-triazole triterpene derivatives as novel anti-RSV drugs. Their anti-RSV and cytotoxic activity were evaluated in vitro, RSV protein F gene effects by RT-PCR and molecular modeling with inosine monophosphate dehydrogenase (IMPDH) were performed. Compound 8 was the best performing compound, with an EC50 value of 0.053 μM, a TI of 11160.37 and it inhibited hRSV protein F gene expression by approximately 65%. Molecular docking showed a top-ranked solution located in the same region occupied by crystallographic ligands in their complex with IMPDH. The results obtained in this study suggest that compound 8 might be a new anti-RSV candidate.

Potential common mechanism of four Chinese patent medicines recommended by diagnosis and treatment protocol for COVID-19 in medical observation period

The global epidemic has been controlled to some extent, while sporadic outbreaks still occur in some places. It is essential to summarize the successful experience and promote the development of new drugs. This study aimed to explore the common mechanism of action of the four Chinese patent medicine (CPMs) recommended in the Medical Observation Period COVID-19 Diagnostic and Treatment Protocol and to accelerate the new drug development process. Firstly, the active ingredients and targets of the four CPMs were obtained by the Chinese medicine composition database (TCMSP, TCMID) and related literature, and the common action targets of the four TCMs were sorted out. Secondly, the targets of COVID-19 were obtained through the gene-disease database (GeneCards, NCBI). Then the Venn diagram was used to intersect the common drug targets with the disease targets. And GO and KEGG pathway functional enrichment analysis was performed on the intersected targets with the help of the R package. Finally, the results were further validated by molecular docking and molecular dynamics analysis. As a result, a total of 101 common active ingredients and 21 key active ingredients of four CPMs were obtained, including quercetin, luteolin, acacetin, kaempferol, baicalein, naringenin, artemisinin, aloe-emodin, which might be medicinal substances for the treatment of COVID-19. TNF, IL6, IL1B, CXCL8, CCL2, IL2, IL4, ICAM1, IFNG, and IL10 has been predicted as key targets. 397 GO biological functions and 166 KEGG signaling pathways were obtained. The former was mainly enriched in regulating apoptosis, inflammatory response, and T cell activation. The latter, with 92 entries related to COVID-19, was mainly enriched to signaling pathways such as Coronavirus disease-COVID-19, Cytokine-cytokine receptor interaction, IL-17 signaling pathway, and Toll-like receptor signaling pathway. Molecular docking results showed that 19/21 of key active ingredients exhibited strong binding activity to recognized COVID-19-related targets (3CL of SARS-CoV-2, ACE2, and S protein), even better than one of these four antiviral drugs. Among them, shinflavanone had better affinity to 3CL, ACE2, and S protein of SARS-CoV-2 than these four antiviral drugs. In summary, the four CPMs may play a role in the treatment of COVID-19 by binding flavonoids such as quercetin, luteolin, and acacetin to target proteins such as ACE2, 3CLpro, and S protein and acting on TNF, IL6, IL1B, CXCL8, and other targets to participate in broad-spectrum antiviral, immunomodulatory and inflammatory responses.

Estimating the causal effect of treatment with direct-acting antivirals on kidney function among individuals with hepatitis C virus infection

Background

Direct-acting antivirals (DAA) are highly effective at treating Hepatitis C virus (HCV) infection, with a cure rate >95%. However, the effect of DAAs on kidney function remains debated.

Methods

We analyzed electronic health record data for DAA-naive patients with chronic HCV infection engaged in HCV care at Boston Medical Center between 2014 and 2018. We compared the following hypothetical interventions using causal inference methods: 1) initiation of DAA and 2) no DAA initiation. For patients with normal kidney function at baseline (eGFR>90 ml/min/1.73m²), we estimated and compared the risk for reaching Stage 3 chronic kidney disease (CKD) (eGFR≤60 ml/min/1.73m²) under each intervention. For patients with baseline CKD Stages 2–4 (15<eGFR≤90 ml/min/1.73m²), we estimated and compared the mean change in eGFR at 2 years after baseline under each intervention. We used the parametric g-formula to adjust our estimates for baseline and time-varying confounders.

Results

First, among 1390 patients with normal kidney function at baseline the estimated 2-year risk difference (95% CI) of reaching Stage 3 CKD for DAA initiation versus no DAA was -1% (-3, 2). Second, among 733 patients with CKD Stage 2–4 at baseline the estimated 2-year mean difference in change in eGFR for DAA initiation versus no DAA therapy was -3 ml/min/1.73m² (-8, 2).

Conclusions

We found no effect of DAA initiation on kidney function, independent of baseline renal status. This suggests that DAAs may not be nephrotoxic; furthermore, in the short-term, HCV clearance may not improve CKD.

Investigation of Selective Ribavirin Extraction from Serum Samples Using a Monolithic Silica Disk-Packed Spin Column

Ribavirin, a nucleoside analog, is used to treat chronic hepatitis C (HCV) infections. Therapeutic drug monitoring for ribavirin is useful for predicting the effect of treatment. In this study, the selective extraction of ribavirin from serum samples and the HPLC-UV detection method were investigated using a monolithic silica disk-packed spin column with phenylboronate moieties. In this study, 0.6% ammonia and 1% formic acid solutions were used as the conditioning and elution solutions, respectively, and recoveries of >90% were obtained. Ribavirin was separated on an InertSustain AQ-C18 column by isocratic elution. The mobile phase consisted of a mixture of 7 mM Na2SO4 and 60 mM H3PO4 in H2O. Linear regression curves were observed for calibrations over a concentration range of 0.25–25 µg/mL. The lower limit of detection was 0.05 µg/mL, and the lower limit of quantification was 0.1 µg/mL. The intra- and inter-day precisions were below 3.2 and 3.1%, respectively. This method can be applied to quantify ribavirin levels in human serum and may be useful for pharmacokinetic studies.

A Review: PI3K/AKT/mTOR Signaling Pathway and Its Regulated Eukaryotic Translation Initiation Factors May Be a Potential Therapeutic Target in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor developing from the esophageal squamous epithelium, and is the most common histological subtype of esophageal cancer (EC). EC ranks 10th in morbidity and sixth in mortality worldwide. The morbidity and mortality rates in China are both higher than the world average. Current treatments of ESCC are surgical treatment, radiotherapy, and chemotherapy. Neoadjuvant chemoradiotherapy plus surgical resection is recommended for advanced patients. However, it does not work in the significant promotion of overall survival (OS) after such therapy. Research on targeted therapy in ESCC mainly focus on EGFR and PD-1, but neither of the targeted drugs can significantly improve the 3-year and 5-year survival rates of disease. Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is an important survival pathway in tumor cells, associated with its aggressive growth and malignant progression. Specifically, proliferation, apoptosis, autophagy, and so on. Related genetic alterations of this pathway have been investigated in ESCC, such as PI3K, AKT and mTOR-rpS6K. Therefore, the PI3K/AKT/mTOR pathway seems to have the capability to serve as research hotspot in the future. Currently, various inhibitors are being tested in cells, animals, and clinical trials, which targeting at different parts of this pathway. In this work, we reviewed the research progress on the PI3K/AKT/mTOR pathway how to influence biological behaviors in ESCC, and discussed the interaction between signals downstream of this pathway, especially eukaryotic translation initiation factors (eIFs) and the development and progression of ESCC, to provide reference for the identification of new therapeutic targets in ESCC.

Reprofiling of approved drugs against SARS-CoV-2 main protease: an in-silico study

Given the COVID-19 pandemic, currently, there are many drugs in clinical trials against this virus. Among the excellent drug targets of SARS-CoV-2 are its proteases (Nsp3 and Nsp5) that plays vital role in polyprotein processing giving rise to functional nonstructural proteins, essential for viral replication and survival. Nsp5 (also known as Mpro) hydrolyzes replicase polyprotein (1ab) at eleven different sites. For targeting Mpro, we have employed drug repurposing approach to identify potential inhibitors of SARS-CoV-2 in a shorter time span. Screening of approved drugs through docking reveals Hyaluronic acid and Acarbose among the top hits which are showing strong interactions with catalytic site residues of Mpro. We have also performed docking of drugs Lopinavir, Ribavirin, and Azithromycin on SARS-CoV-2 Mpro. Further, binding of these compounds (Hyaluronic acid, Acarbose, and Lopinavir) is validated by extensive molecular dynamics simulation of 500 ns where these drugs show stable binding with Mpro. We believe that the high-affinity binding of these compounds will help in designing novel strategies for structure-based drug discovery against SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Synthesis of novel C-nucleoside analogues bearing an anomeric cyano and a 1,2,3-triazole nucleobase as potential antiviral agents

A linear sequence to access a novel series of C-nucleosides bearing a quaternary carbon at the anomeric position tethered to a 4-substituted 1,2,3-triazole ring is described. Most of the compounds were obtained from a C-1 alkynyl furanoside, by a tandem or two-step CuAAC/functionalisation sequence, along with a diastereoselective cyanation of the furanoside derivatives in acidic conditions.

Improved HPLC method for the determination of ribavirin concentration in red blood cells and its application in patients with COVID-19

Ribavirin is a synthetic, broad‐spectrum antiviral drug. Ribavirin is recommended as an antiviral drug in the Interim Guidance for Diagnosis and Treatment (the seventh edition) of COVID‐19. The ribavirin levels in red blood cells may be closely related to both its efficacy and adverse drug reactions. In this study, a simple and fast HPLC–UV method was established to determine the concentrations of total ribavirin in the red blood cells of 13 patients with COVID‐19. Phosphorylated ribavirin was dephosphorylated by phosphatase incubation to obtain the total amount of ribavirin in red blood cells. The chromatographic column was an Atlantis C₁₈. The recoveries were 85.45–89.05% at three levels. A good linear response was from 1 to 200 μg/ml, with a correlation coefficient of r² = 0.9991. The concentration of total ribavirin in the red blood cells of the patients ranged from 30.83 to 133.34 μg/ml. The same samples without phosphatase incubation ranged from 4.07 to 20.84 μg/ml. About 85% of ribavirin was phosphorylated in red blood cells. In addition, we observed changes in these patients' hematological parameters and found that the erythrocyte, hemoglobin and hematocrit declined to the lowest levels on the fifth day after discontinuation of ribavirin (p < 0.05).

In Silico Pesticide Discovery for New Anti-Tobacco Mosaic Virus Agents: Reactivity, Molecular Docking, and Molecular Dynamics Simulations

Considerable data are available regarding the molecular genetics of the tobacco mosaic virus. The disease caused by the tobacco mosaic virus is still out of control due to the lack of an efficient functional antagonist chemical molecule. Extensive research was carried out to try to find effective new anti-tobacco mosaic virus agents, however no study could find an effective agent which could completely inhibit the disease caused by the virus. In recent years, molecular docking, combined with molecular dynamics, which is considered to be one of the most important methods of drug discovery and design, were used to evaluate the type of binding between the ligand and its protein enzyme. The aim of the current work was to assess the in silico anti-tobacco mosaic virus activity for a selection of 41 new and 2 reference standard compounds. These compounds were chosen to examine their reactivity and binding efficiency with the tobacco mosaic virus coat protein (PDB ID: 2OM3). A comparison was made between the activity of the selected compounds and that for ningnanmycin and ribavirin, which are common inhibitors of plant viruses. The simulation results obtained from the molecular docking and molecular dynamics showed that two compounds of the antofine analogues could bind with the tobacco mosaic virus coat protein receptor better than ningnanmycin and ribavirin.

Favipiravir in the Battle with Respiratory Viruses

Abstract:

Among antiviral drugs, the vast majority targets only one or two related viruses. The conventional model, one virus - one drug, significantly limits therapeutic options. Therefore, in the strategy of controlling viral infections, there is a necessity to develop compounds with pleiotropic effects. Favipiravir (FPV) emerged as a strong candidate to become such a drug. The aim of the study is to present up-to-date information on the role of favipiravir in the treatment of viral respiratory infections. The anti-influenza activity of favipiravir has been confirmed in cell culture experiments, animal models and clinical trials. Thoroughly different - from the previously registered drugs - mechanism of action suggests that FVP can be used as a countermeasure for the novel or re-emerging influenza virus infections. In recent months, favipiravir has been broadly investigated due to its potential efficacy in the treatment of Covid-19. Based on preclinical and clinical studies and a recently published meta-analysis it seems that favipiravir may be a promising antiviral drug in the treatment of patients with Covid-19. FPV is also effective against other RNA respiratory viruses and may be a candidate for the treatment of serious infections caused by human rhinovirus, respiratory syncytial virus, metapneumovirus, parainfluenza viruses and hantavirus pulmonary syndrome.

The “Invisible Enemy” SARS-CoV-2: Viral Spread and Drug Treatment

Nowadays, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has become the main subject of the scientific medical world and all World Organizations, causing millions of deaths worldwide. In this review, we have highlighted the context of the Coronavirus disease 2019 (COVID-19) pandemic, how the virus spreads, the symptoms and complications that may occur, and, especially, the drug treatment of viral infection, with emphasis on monoclonal antibodies. While well-known strains such as Alpha, Beta, Gamma, and, especially, Delta have shown an accelerated transmission among the population, the new Omicron variant (discovered on 24 November 2021) indicates more significant infectiousness and the poor efficacy of monoclonal antibody therapy due to mutations on the spike protein receptor-binding domain. With these discoveries, the experiments began, the first being in silico and in vitro, but these are not enough, and in vivo experiments are needed to see exactly the cause of neutralization of the action of these drugs. Following the documentation of the latest medical and scientific research, it has been concluded that there are many chemical molecules that have the potential to treat SARS-CoV-2 infection, but more detailed clinical trials are needed for their use in therapy. In addition, it is important to consider the structure of the viral strain in the administration of treatment.

In-line treatments and clinical initiatives to fight against COVID-19 outbreak

In December 2019, when the whole world is waiting for Christmas and New Year, the physicians of Wuhan, China, are astounded by clusters of patients suffering from pneumonia from unknown causes. The pathogen isolated from the respiratory epithelium of the patients is similar to previously known coronaviruses with some distinct features. The disease was initially called nCoV-2019 or SARS-nCoV-2 and later termed as COVID-19 by WHO. The infection is rapidly propagating from the day of emergence, spread throughout the globe and now became a pandemic which challenged the competencies of developed nations in terms of health care management. As per WHO report, 216 countries are affected with SARS-CoV-19 by August 5, 2020 with 18, 142, 718 confirmed cases and 691,013 deaths reports. Such huge mortality and morbidity rates are truly threatening and calls for some aggressive and effective measures to slow down the disease transmission. The scientists are constantly engaged in finding a potential solution to diagnose and treat the pandemic. Various FDA approved drugs with the previous history of antiviral potency are repurposed for COVID-19 treatment. Different drugs and vaccines are under clinical trials and some rapid and effective diagnostic tools are also under development. In this review, we have highlighted the current epidemiology through infographics, disease transmission and progression, clinical features and diagnosis and possible therapeutic approaches for COVID-19. The article mainly focused on the development and possible application of various FDA approved drugs, including chloroquine, remdesivir, favipiravir, nefamostate mesylate, penciclovir, nitazoxanide, ribavirin etc., vaccines under development and various registered clinical trials exploring different therapeutic measures for the treatment of COVID-19. This information will definitely help the researchers to understand the in-line scientific progress by various clinical agencies and regulatory bodies against COVID-19.

Synthesis of trans N-Substituted Pyrrolidine Derivatives Bearing 1,2,4-triazole Ring

BACKGROUND

1,2,4-triazoles scaffolds display significant biological activities due to hydrogen bonding, solubility, dipole character, and rigidity.

OBJECTIVE

The core motif of 1,2,4-triazoles plays a vital role in clinical drugs such as Rizatriptan (anti-migraine), Ribavirin (antiviral), anastrozole (anticancer), etizolam (anxiolytic), estazolam (anticonvulsant), alprazolam (anti-hypnotic), letrozole (aromatase inhibitor), loreclezole (anticonvulsant), trazadone (antidepressant) etc. Method: Epoxide ring opening of tert-butyl 6-oxa-3-azabicyclo [3.1.0] hexane-3-carboxylate followed by methylation under basic conditions and de-protection gave the corresponding trans 1-(4-methoxypyrrolidin-3-yl)-1H-1,2,4-triazole hydrochloride salt as the precursor. This precursor on reaction with substituted benzoyl chlorides and benzyl bromides gave the desired amide and amine products.

RESULTS

A library of 14 N-substituted pyrrolidine derivatives i.e. trans3-methoxy-4-(1H-1,2,4-triazol-1-yl) pyrrolidin-1-yl) (phenyl)methanone and trans 1-benzyl-4-methoxypyrrolidin-3-yl)-1H-1,2,4-triazole were prepared.

CONCLUSION

Eight novel amides (6a-h) and six amines (8a-f) derivatives were synthesized using 1-(4-methoxypyrrolidin-3-yl)-1H-1,2,4-triazole 4 salt with substituted benzoyl chlorides and benzyl bromides.

Interferon-Induced Crohn's Disease: An Unusual Side Effect of Interferon Therapy in a Patient With Chronic Hepatitis C Virus Infection

Gastrointestinal side effects of interferon (IFN) therapy for chronic hepatitis C virus (HCV) infection are non-specific. Rarely, this therapy has been reported to induce ischemic colitis and even ulcerative colitis. However, IFN-induced Crohn's disease (CD) has previously been reported in only two individuals. We share our own experience of a patient treated for chronic HCV infection who developed CD after IFN therapy for chronic HCV infection. A 28-year-old asymptomatic man with a history only of chronic HCV infection was treated with IFN and ribavirin, which he tolerated for 18 months and achieved sustained viral response (SVR). Halfway through the IFN regimen, he noticed infrequent painful bowel movements and bloody diarrhea. Following treatment, his symptoms resolved. Six months after therapy, colonoscopy showed a normal terminal ileum and colitis with skipped lesions and rectal sparing. Pathology demonstrated spotty chronic active colitis, with diffuse cryptitis, crypt distortion, and abundant abscesses, compatible with CD. The patient declined treatment and remained asymptomatic for two years. Labs including C-​reactive protein (CRP), erythrocyte sedimentation rate (ESR), fecal calprotectin, and celiac panel were normal. Upper GI endoscopy and capsule endoscopy were normal. Repeat colonoscopy showed normal terminal ileum and normal colonic mucosa, and biopsies of the terminal ileum and all segments of the colon were unremarkable. The patient was observed off treatment and has continued to remain asymptomatic, with a resolution of symptoms and disease continuing away from IFN exposure. This is a rare case of CD induced by IFN, exhibiting significant importance regarding the evaluation of new cases of inflammatory bowel disease (IBD). Gastroenterologists need to keep in mind that INF therapy can be an uncommon cause of IBD.

Classification, structure and mechanism of antiviral polysaccharides derived from edible and medicinal fungus

The deficiency of chemical-synthesized antiviral drugs when applied in clinical therapy, such as drug resistance, and the lack of effective antiviral drugs to treat some newly emerging virus infections, such as COVID-19, promote the demand of novelty and safety anti-virus drug candidate from natural functional ingredient. Numerous studies have shown that some polysaccharides sourcing from edible and medicinal fungus (EMFs) exert direct or indirect anti-viral capacities. However, the internal connection of fungus type, polysaccharides structural characteristics, action mechanism was still unclear. Herein, our review focus on the two aspects, on the one hand, we discussed the type of anti-viral EMFs and the structural characteristics of polysaccharides to clarify the structure-activity relationship, on the other hand, the directly or indirectly antiviral mechanism of EMFs polysaccharides, including virus function suppression, immune-modulatory activity, anti-inflammatory activity, regulation of population balance of gut microbiota have been concluded to provide a comprehensive theory basis for better clinical utilization of EMFs polysaccharides as anti-viral agents.

Lassa Virus Treatment Options

Lassa fever causes an approximate 5000 to 10,000 deaths annually in West Africa and cases have been imported into Europe and the Americas, challenging public health. Although Lassa virus was first described over 5 decades ago in 1969, no treatments or vaccines have been approved to treat or prevent infection. In this review, we discuss current therapeutics in the development pipeline for the treatment of Lassa fever, focusing on those that have been evaluated in humans or animal models. Several treatments, including the antiviral favipiravir and a human monoclonal antibody cocktail, have shown efficacy in preclinical rodent and non-human primate animal models and have potential for use in clinical settings. Movement of the promising preclinical treatment options for Lassa fever into clinical trials is critical to continue addressing this neglected tropical disease.

Ribavirin inhibits colorectal cancer growth by downregulating PRMT5 expression and H3R8me2s and H4R3me2s accumulation

Eukaryotic translation initiation factor 4E (eIF4E) and protein arginine methyltransferase 5 (PRMT5) are frequently overexpressed in colorectal cancer (CRC) tissues and associated with poor prognosis. Ribavirin, the only clinically approved drug known to target eIF4E, is an anti-viral molecule currently used in hepatitis C therapy. The potential of ribavirin to treat CRC remains largely unknown. Ribavirin treatment in CRC cell lines drastically inhibited cell proliferation and colony formation, induced S phase arrest and reduced cyclin D1, cyclin A/E and proliferating cell nuclear antigen (PCNA) levels in vitro, and suppressed tumorigenesis in mouse model of colitis-associated CRC. Mechanistically, ribavirin treatment significantly reduced PRMT5 and eIF4E protein levels and the accumulation of symmetric dimethylation of histone 3 at arginine 8 (H3R8me2s) and that of histone 4 at arginine 3 (H4R3me2s). Importantly, inhibition of PRMT5 by ribavirin resulted in promoted H3R8 methylation in eIF4E promoter region. Our results demonstrate the anti-cancer efficacy of ribavirin in CRC and suggest that the anti-cancer efficacy of ribavirin may be mediated by downregulating PRMT5 levels but not its enzymatic activity.

EDP-938, a novel nucleoprotein inhibitor of respiratory syncytial virus, demonstrates potent antiviral activities in vitro and in a non-human primate model

EDP-938 is a novel non-fusion replication inhibitor of respiratory syncytial virus (RSV). It is highly active against all RSV-A and B laboratory strains and clinical isolates tested in vitro in various cell lines and assays, with half-maximal effective concentrations (EC₅₀s) of 21, 23 and 64 nM against Long (A), M37 (A) and VR-955 (B) strains, respectively, in the primary human bronchial epithelial cells (HBECs). EDP-938 inhibits RSV at a post-entry replication step of the viral life cycle as confirmed by time-of-addition study, and the activity appears to be mediated by viral nucleoprotein (N). In vitro resistance studies suggest that EDP-938 presents a higher barrier to resistance compared to viral fusion or non-nucleoside L polymerase inhibitors with no cross-resistance observed. Combinations of EDP-938 with other classes of RSV inhibitors lead to synergistic antiviral activity in vitro. Finally, EDP-938 has also been shown to be efficacious in vivo in a non-human primate model of RSV infection.

Respiratory syncytial virus (RSV) is a ubiquitous viral pathogen which inflicts a significant healthcare burden and is responsible for thousands of deaths annually. Currently no vaccine or targeted therapeutic exists. This work characterizes a newly discovered small molecule inhibitor of the virus, EDP-938, whose activity is mediated through the viral nucleoprotein. EDP-938 has potent in vitro activities against laboratory strains and clinical isolates of the virus, presents a high-barrier to resistance, can work synergistically with other known fusion or L protein inhibitors, and displays strong in vivo efficacy in a non-human primate model for RSV infection. EDP-938 is currently under evaluation in Phase 2 clinical studies.

Denovo designing, retro-combinatorial synthesis, and molecular dynamics analysis identify novel antiviral VTRM1.1 against RNA-dependent RNA polymerase of SARS CoV2 virus

A novel coronavirus disease (COVID-19) caused by SARS-CoV2 has now spread globally. Replication/transcription machinery of this virus consists of RNA-dependent RNA polymerase (nsp12 or RdRp) and its two cofactors nsp7 and nsp8 proteins. Hence, RdRp has emerged as a promising target to control COVID-19. In the present study, we are reporting a novel inhibitor VTRM1.1 against the RdRp protein of SARS CoV2. A series of antivirals were tested for binding to the catalytic residues of the active site of RdRp protein. In-silico screening, molecular mechanics, molecular dynamics simulation (MDS) analysis suggest ribavirin, and remdesivir have good interaction with the binding site of the RdRp protein as compared to other antiviral investigated. Hence, ribavirin and remdesivir were used for the denovo fragments based antiviral design. This design, along with docking and MDS analysis, identified a novel inhibitor VTRM1 that has better interaction with RdRp as compared to their parent molecules. Further, to produce a lead-like compound, retrosynthetic analysis, and combinatorial synthesis were performed, which produces 1000 analogs of VTRM1. These analogs were analysed by docking and MDS analysis that identified VTRM1.1 as a possible lead to inhibit RdRp protein. This lead has a good docking score, favourable binding energy and bind at catalytic residues of the active site of RdRp. The VTRM1.1 also interacts with RdRp in the presence of RNA primer and other cofactors. It was also seen that, VTRM1.1 do not have off-target in human. Therefore, the present study suggests a hybrid inhibitor VTRM1.1 for the RNA-dependent RNA polymerase of SARS CoV2 that may be useful to control infection caused by COVID-19.

Important Pharmacogenetic Information for Drugs Prescribed During the SARS-CoV-2 Infection (COVID-19)

In December 2019, the severe acute respiratory syndrome virus-2 pandemic began, causing the coronavirus disease 2019. A vast variety of drugs is being used off-label as potential therapies. Many of the repurposed drugs have clinical pharmacogenetic guidelines available with therapeutic recommendations when prescribed as indicated on the drug label. The aim of this review is to provide a comprehensive summary of pharmacogenetic biomarkers available for these drugs, which may help to prescribe them more safely.

Disseminated inflammation of the central nervous system associated with acute hepatitis E: a case report

BACKGROUND

Hepatitis E infection affects over 20 million people worldwide. Reports of neurological manifestations are largely limited to the peripheral nervous system. We report a middle-aged genotype 3c male patient with acute hepatitis E virus (HEV) infection and severe neurological deficits with evidence of multiple disseminated inflammatory lesions of the central nervous system.

CASE PRESENTATION

A 42-year-old male patient presented to our emergency department with musculoskeletal weakness, bladder and bowel retention, blurred vision and ascending hypoesthesia up to the level of T8. Serology showed elevated liver enzymes and positive IgM-titers of hepatitis E. Analysis of cerebrospinal fluid (CSF) showed mild pleocytosis and normal levels of glucose, lactate and protein. HEV-RNA-copies were detected in the CSF and stool. Within 3 days after admission the patient became paraplegic, had complete visual loss and absent pupillary reflexes. MRI showed inflammatory demyelination of the optic nerve sheaths, multiple subcortical brain regions and the spinal cord. Electrophysiology revealed axonal damage of the peroneal nerve on both sides with absent F-waves. Treatment was performed with methylprednisolone, two cycles of plasma exchange (PLEX), one cycle of intravenous immunoglobulins (IVIG) and ribavirin which was used off-label. Liver enzymes normalized after 1 week and serology was negative for HEV-RNA after 3 weeks. Follow-up MRI showed progressive demyelination and new leptomeningeal enhancement at the thoracic spine and cauda equina 4 weeks after admission. Four months later, after rehabilitation was completed, repeated MRI showed gliotic transformation of the spinal cord without signs of an active inflammation. Treatment with rituximab was initiated. The patient remained paraplegic and hypoesthesia had ascended up to T5. Nevertheless, he regained full vision.

CONCLUSIONS

Our case indicates a possible association of acute HEV infection with widespread disseminated central nervous system inflammation. Up to now, no specific drugs have been approved for the treatment of acute HEV infection. We treated our patient off-label with ribavirin and escalated immunomodulatory therapy considering clinical progression and the possibility of an autoimmune response targeting nerve cell structures. While response to treatment was rather limited in our case, detection of HEV in patients with acute neurological deficits might help optimize individual treatment strategies.

Emerging Molecular Prospective of SARS-CoV-2: Feasible Nanotechnology Based Detection and Inhibition

The rapid dissemination of SARS-CoV-2 demonstrates how vulnerable it can make communities and is why it has attained the status of global pandemic. According to the estimation from Worldometer, the SARS-CoV-2 affected cases and deaths are exponentially increasing worldwide, marking the mortality rate as ∼3.8% with no probability of its cessation till now. Despite massive attempts and races among scientific communities in search of proper therapeutic options, the termination of this breakneck outbreak of COVID-19 has still not been made possible. Therefore, this review highlights the diverse molecular events induced by a viral infection, such as autophagy, unfolded protein response (UPR), and inflammasome, illustrating the intracellular cascades regulating viral replication inside the host cell. The SARS-CoV-2-mediated endoplasmic reticulum stress and apoptosis are also emphasized in the review. Additionally, host's immune response associated with SARS-CoV-2 infection, as well as the genetic and epigenetic changes, have been demonstrated, which altogether impart a better understanding of its epidemiology. Considering the drawbacks of available diagnostics and medications, herein we have presented the most sensitive nano-based biosensors for the rapid detection of viral components. Moreover, conceptualizing the viral-induced molecular changes inside its target cells, nano-based antiviral systems have also been proposed in this review.

De novo design, retrosynthetic analysis and combinatorial synthesis of a hybrid antiviral (VTAR-01) to inhibit the interaction of SARS-CoV2 spike glycoprotein with human angiotensin-converting enzyme 2

SARS-like coronavirus (SARS-CoV2) has emerged as a global threat to humankind and is rapidly spreading. The infectivity, pathogenesis and infection of this virus are dependent on the interaction of SARS-CoV2 spike protein with human angiotensin converting enzyme 2 (hACE2). Spike protein contains a receptor-binding domain (RBD) that recognizes hACE-2. In the present study, we are reporting a de novo designed novel hybrid antiviral ‘VTAR-01’ molecule that binds at the interface of RBD-hACE2 interaction. A series of antiviral molecules were tested for binding at the interface of RBD-hACE2 interaction. In silico screening, molecular mechanics and molecular dynamics simulation (MDS) analysis suggest ribavirin, ascorbate, lopinavir and hydroxychloroquine have strong interaction at the RBD-hACE2 interface. These four molecules were used for de novo fragment-based antiviral design. De novo designing, docking and MDS analysis identified a ‘VTAR’ hybrid molecule that has better interaction with this interface than all of the antivirals used to design it. We have further used retrosynthetic analysis and combinatorial synthesis to design 100 variants of VTAR molecules. Retrosynthetic analysis and combinatorial synthesis, along with docking and MDS, identified that VTAR-01 interacts with the interface of the RBD-ACE2 complex. MDS analysis confirmed its interaction with the RBD-ACE2 interface by involving Glu35 and Lys353 of ACE2, as well as Gln493 and Ser494 of RBD. Interaction of spike protein with ACE2 is essential for pathogenesis and infection of this virus; hence, this in silico designed hybrid antiviral molecule (VTAR-01) that binds at the interface of RBD-hACE2 may be further developed to control the infection of SARS-CoV2.

Summary: SARS-CoV2 has caused an outbreak globally and is responsible for high mortality and morbidity. Interaction of the receptor-binding domain of spike protein of this virus with human angiotensin converting enzyme (ACE2) is vital for the infection. Hence, a de novo designed hybrid antiviral molecule (VTAR-01) targeting RBD-ACE2 interaction may play a very significant role in controlling the COVID-19 disease.

The Current and Future State of Vaccines, Antivirals and Gene Therapies Against Emerging Coronaviruses

Emerging coronaviruses (CoV) are constant global public health threats to society. Multiple ongoing clinical trials for vaccines and antivirals against CoVs showcase the availability of medical interventions to both prevent and treat the future emergence of highly pathogenic CoVs in human. However, given the diverse nature of CoVs and our close interactions with wild, domestic and companion animals, the next epidemic zoonotic CoV could resist the existing vaccines and antivirals developed, which are primarily focused on Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS CoV). In late 2019, the novel CoV (SARS-CoV-2) emerged in Wuhan, China, causing global public health concern. In this review, we will summarize the key advancements of current vaccines and antivirals against SARS-CoV and MERS-CoV as well as discuss the challenge and opportunity in the current SARS-CoV-2 crisis. At the end, we advocate the development of a "plug-and-play" platform technologies that could allow quick manufacturing and administration of broad-spectrum countermeasures in an outbreak setting. We will discuss the potential of AAV-based gene therapy technology for in vivo therapeutic antibody delivery to combat SARS-CoV-2 outbreak and the future emergence of severe CoVs.

In Silico Analysis, Synthesis, and Biological Evaluation of Triazole Derivatives as H1 Receptor Antagonist

INTRODUCTION

Histamine, a biological amine, is considered as a principal mediator of many pathological processes regulating several essential events in allergies and autoimmune diseases. Numerous derivatives have been developed that strive with histamine at the H1 receptor and prevent binding of histamine at the H1 receptor, thereby preventing allergic reactions. Molecules containing a triazole ring fused with six-membered ring systems are found to possess broad applications in the field of medicine and industry. The present study is an attempt to characterize the impact of the nature of the substituent introduced at 5 positions of the-4H-1,2,4-triazole-3-thiol on their capacities to bind with the H1 receptor.

METHODS

Molecular docking (PDB ID: 3RZE) revealed that synthesized derivatives and target proteins were actively involved in binding with Tyr-108, Thr-112, Ala-216, and Phe-432 subunits. A pharmacophore model, new 5-(4-substituted phenyl)-4-(phenylamino)-4-H-1,2,4-triazole-3- thiols (5a-5h) were designed and evaluated for H1-blocking activity using isolated segments from the guinea pig ileum.

RESULTS

According to in silico analysis, all the compounds have a topological polar surface area (TPSA) less than 140 Å squared, so they tend to easily penetrate cell membranes. The results show that most of the compounds are non-inhibitors of CYP450 substrates that play a fundamental role in drug metabolism. Compounds 5d (50.53±12.03), 5h (50.62±12.33) and 7a (55.07±12.41) are more active than others.

CONCLUSION

Finally, these derivatives were screened for H1 receptor antagonist activity using guinea pig ileum, taking chlorpheniramine maleate as a standard. Most of the compounds were found to possess better antihistamine activity.

Combined small molecule and loss-of-function screen uncovers estrogen receptor alpha and CAD as host factors for HDV infection and antiviral targets

OBJECTIVE

Hepatitis D virus (HDV) is a circular RNA virus coinfecting hepatocytes with hepatitis B virus. Chronic hepatitis D results in severe liver disease and an increased risk of liver cancer. Efficient therapeutic approaches against HDV are absent.

DESIGN

Here, we combined an RNAi loss-of-function and small molecule screen to uncover host-dependency factors for HDV infection.

RESULTS

Functional screening unravelled the hypoxia-inducible factor (HIF)-signalling and insulin-resistance pathways, RNA polymerase II, glycosaminoglycan biosynthesis and the pyrimidine metabolism as virus-hepatocyte dependency networks. Validation studies in primary human hepatocytes identified the carbamoyl-phosphatesynthetase 2, aspartate transcarbamylase and dihydroorotase (CAD) enzyme and estrogen receptor alpha (encoded by ESR1) as key host factors for HDV life cycle. Mechanistic studies revealed that the two host factors are required for viral replication. Inhibition studies using N-(phosphonoacetyl)-L-aspartic acid and fulvestrant, specific CAD and ESR1 inhibitors, respectively, uncovered their impact as antiviral targets.

CONCLUSION

The discovery of HDV host-dependency factors elucidates the pathogenesis of viral disease biology and opens therapeutic strategies for HDV cure.

Approaches for the Treatment of SARS-CoV-2 Infection: A Pharmacologic View and Literature Review

The emergence of a novel Coronavirus disease (COVID-19) inducing acute respiratory distress syndrome (ARDS) was identified in Hubei province of China in December 2019 and rapidly spread worldwide as pandemic and became a public health concern. COVID-19 disease is caused by a new virus known as SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), which has recently offered many challenges and efforts to identify effective drugs for its prevention and treatment. Currently, there is no proven effective approach and medication against this virus. Quickly expanding clinical trials and studies on Coronavirus disease 2019 increase our knowledge regarding SARS-CoV-2 virus and introduce several potential drugs targeting virus moiety or host cell elements. Overall, 3 stages were suggested for SARS-CoV-2 infection according to the disease severity, clinical manifestations, and treatment outcomes, including mild, moderate, and severe. This review aimed to classify and summarize several medications and potential therapies according to the disease 3 stages; however, it is worth noting that no medication and therapy has been effective so far.

Ribavirin sensitizes nasopharyngeal carcinoma to 5-fluorouracil through suppressing 5-fluorouracil-induced ERK-dependent-eIF4E activation

Although overexpression of eukaryotic translation initiation factor 4E (eIF4E) is associated with enhanced growth and poor prognosis in nasopharyngeal carcinoma (NPC), the function of eIF4E in NPC response to chemotherapy has not been revealed. In this work, we demonstrate that eIF4E inhibition using both ribavirin and siRNA targets NPC cells and enhances the efficacy of 5-fluorouracil (5-FU). Mechanism studies indicate that 5-FU treatment increases phosphorylation of eIF4E in NPC cells, and this is dependent on ERK activation. eIF4E inhibition thus significantly sensitizes NPC cell response to 5-FU. Of note, ribavirin is a clinically available anti-viral drug. We show that ribavirin exhibits preferential toxicity to NPC with normal nasopharyngeal epithelial cells largely unaffected. Ribavirin acts on NPC cells via inhibiting eIF4E/Akt signaling, and the suppression of eIF4E by ribavirin are not the consequence of inhibition of eIF4E upstream signaling: Mnk and mTOR. In two independent NPC xenograft mouse models, ribavirin at well-tolerated dose that significantly inhibited NPC growth as single drug alone and its combination with 5-FU completely arrests tumor growth throughout the whole duration of treatment, without causing toxicity in mice. Our findings provide the better understanding on the role of eIF4E in NPC in response to 5-FU and preclinical rationale to explore ribavirin as a sensitizing strategy to treat NPC, particularly in those who develop 5-FU resistance.

Targeting eIF4E signaling with ribavirin as a sensitizing strategy for ovarian cancer

The essential roles of eukaryotic translation initiation factor 4E (eIF4E) have been shown in various cancers, including ovarian cancer. In this work, we demonstrate that eIF4E inhibition in ovarian cancer can be achieved by ribavirin, a FDA-approved antiviral drug. We show that ribavirin at clinically relevant doses significantly inhibits growth and survival in multiple ovarian cancer cell lines, regardless of morphological and molecular subtypes. Mechanistically, ribavirin suppresses Akt/mTOR and eIF4E/p70S6K signaling pathways in ovarian cancer cells. We confirm that eIF4E is the critical molecular target of ribavirin, and furthermore that this is dependent on phosphorylation at S209. Notably, using both in vitro cell culture system and in vivo xenograft mouse model, we show that the combination of ribavirin with cisplatin (standard of care for patients with ovarian cancer) results in significantly greater efficacy than cisplatin alone in ovarian cancer. Interestingly, the sensitivity to ribavirin varies among a panel of ovarian cancer cell lines, mostly likely due to their differential expression level of eIF4E and dependency to eIF4E inhibition. The differential expression level is further observed in ovarian cancer tissues, with the higher level of eIF4E in the majority of ovarian cancer tissues compared to normal ovary tissues. Our work suggests that eIF4E expression varies among ovarian cancer. Additionally, ribavirin is a useful addition to ovarian cancer treatment, particularly to those with high dependency on eIF4E.

Clinically relevant concentration of anti-viral drug ribavirin selectively targets pediatric osteosarcoma and increases chemosensitivity

Ribavirin is an anti-viral drug but has recently gained attention as a potential candidate for cancer treatment. In line with these efforts, our work is the first to demonstrate that ribavirin, at clinically relevant concentration, selectively targets pediatric osteosarcoma and increases chemosensitivity. Using preclinical osteosarcoma cell and xenograft models, we found that ribavirin is active against osteosarcoma bulk and subpopulations with highly proliferative and invasive properties via inhibiting growth, inducing apoptosis and suppressing colony formation. At the same concentrations, ribavirin either did not or affected human normal osteoblastic cell and fibroblast cells in a less extent than osteosarcoma cells. Notably, the combination of ribavirin with doxorubicin resulted in greater efficacy than single drug alone. The combination completely arrested the osteosarcoma growth in vivo throughout the whole duration of drug treatment. We further showed that ribavirin acted on osteosarcoma largely via targeting eIF4E. In addition to eIF4E, ribavirin also modulated phosphorylation of Erk and expression of EZH2 and Snail without affecting Akt and mTOR. Lastly, we found that eIF4E expression and phosphorylation were elevated in osteosarcoma compared to normal cells, which might explain the selective anti-osteosarcoma activity of ribavirin. eIF4E depletion mimics the inhibitory effects of ribavirin, further confirm that eIF4E is the essential target of ribavirin in osteosarcoma. Our work provides fundamental evidence of repurposing ribavirin for the treatment of osteosarcoma. Our findings also highlight the therapeutic value of inhibiting eIF4E in osteosarcoma.

Genetic and pharmacological inhibition of eIF4E effectively targets esophageal cancer cells and augments 5-FU's efficacy

Background

Aberrant activation of eIF4E is critically involved in the progression and chemoresistance of various cancers. Elevated expression of eIF4E has also been documented in human cancerous esophageal tissues. However, the role of eIF4E in esophageal cancer is unclear.

Methods

We analysed the levels of eIF4E expression and eIF4E function in a number of normal and cancerous esophageal cancer cell lines, and studied its underlying mechanism.

Results

We observed that eIF4E expression varies in different esophageal cancer cell lines but was significantly elevated in all tested esophageal cell lines as compared to the control cell lines. We demonstrated that eIF4E inhibition via genetic and pharmacological approaches inhibits cancer cell growth and survival. This inhibition also augments 5-flurouracil's (5-FU's) efficacy as demonstrated with both the in vitro esophageal cancer culture system and our in vivo xenograft mouse model. Of note, the sensitivity of esophageal cancer cells to ribavirin or eIF4E knockdown correlates well with the expression levels of eIF4E, demonstrating that esophageal cells with higher eIF4E expression are more sensitive to eIF4E inhibition. We further confirmed that the mechanism of action of ribavirin on esophageal cancer cells was through suppressing the Akt/mTOR/eIF4E and eIF4E-regulated pathways.

Conclusions

To our knowledge, our work is the first to demonstrate the multiple roles of eIF4E in esophageal cancer. eIF4E was shown to promote cancer cell growth and survival, and protected the cells from chemotherapy. Our work also demonstrated that ribavirin is an attractive candidate for the treatment of esophageal cancer.

Ribavirin as a potential therapeutic for atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive, malignant tumors and are the most common malignant brain tumor in children under 6 months of age. Currently, there is no standard treatment for AT/RT. Recent studies have reported potential anti-tumoral properties of ribavirin, a guanosine analog and anti-viral molecule approved by the Food and Drug Administration for treatment of hepatitis C. We previously demonstrated that ribavirin inhibited glioma cell growth in vitro and in vivo. Based on these results and the fact that no pre-clinical model of ribavirin in AT/RT exists, we decided to investigate the effect of ribavirin on several human AT/RT cell lines (BT12, BT16, and BT37) both in vitro and in vivo. We provide evidence that ribavirin has a significant impact on AT/RT cell growth and increases cell cycle arrest and cell death, potentially through modulation of the eIF4E and/or EZH2 pathways. Interestingly, using scratch wound and transwell Boyden chamber assays, we observed that ribavirin also impairs AT/RT cell migration, invasion, and adhesion. Finally, we demonstrate that ribavirin significantly improves the survival of mice orthotopically implanted with BT12 cells. Our work establishes that ribavirin is effective against AT/RT by decreasing tumoral cell growth and dissemination and could represent a new therapeutic option for children with this deadly disease.

Liver decompensation predicts ribavirin overexposure in hepatitis C virus patients treated with direct-acting antivirals

AIM

To determine whether ribavirin (RBV) concentrations differ according to cirrhosis stage among cirrhotic patients treated with interferon-free regimens.

METHODS

We included patients with hepatitis C virus and cirrhosis [Child-Pugh (CP) A or B], Glomerular Filtration Rate ≥ 60 mL/min, who started therapy with DAAs and weight-based RBV between October 2014 and February 2016. RBV plasma levels were assessed during the treatment. We focused our analysis on the first 8 wk of therapy.

RESULTS

We studied 68 patients: 54 with compensated (CP-B) and 14 with decompensated (CP-A) cirrhosis. Patients with decompensated cirrhosis displayed significantly higher RBV concentrations than those with compensated cirrhosis at week 1, 2, 4 and 8 (P < 0.035). RBV levels were positively correlated with Hb loss over the treatment (P < 0.04). Majority (71%) of CP-B patients required a RBV dosage reduction during the treatment. After adjustment for confounders, Child-Pugh class remained significantly associated (95%CI: 35, 348, P = 0.017) to RBV levels, independently from baseline per-Kg RBV dosage.

CONCLUSION

Liver decompensation might affect RBV clearance leading to an overexposure and increased related toxicities in decompensated cirrhosis. Our findings underscore the importance of an early ribavirin therapeutic drug monitoring and suggest that an initial lower RBV dose, rather than weight-based, might be considered in those with advanced liver disease (CP-B) treated with direct-acting antivirals.

Chromosomal instability and cytotoxicity induced by ribavirin: comparative analysis in cell lines with different drug-metabolizing profiles

Ribavirin is an important component of the treatment for hepatitis C virus (HCV) infection and, in combination with the new direct-acting antiviral (DAA) agents, comprises the major current therapeutic regimens. This study evaluated the cytotoxicity and chromosomal instability induced by ribavirin using the in vitro cytokinesis-block micronucleus cytome (CBMN-Cyt) assay in two cell lines with different expression levels of drug-metabolizing enzymes: human hepatocellular carcinoma cells (HepG2) and Chinese hamster ovary (CHO-K1) cells. HepG2 cells were treated with nine concentrations (from 15.3 μg/ml to 3.9 mg/ml) and CHO-K1 cells were exposed to eight concentrations (from 15.3 μg/ml to 1.9 mg/ml) of ribavirin for 24 h. Ribavirin inhibited cell proliferation in both cell lines, but at different concentrations: 3.9 mg/ml in HepG2 and 244.2 μg/ml in CHO-K1 cells. No significant differences were observed regarding aspects of cell death in HepG2 and CHO-K1 cells, reflecting the absence of cytotoxic effects associated to ribavirin. Ribavirin did not increase the frequency of nucleoplasmic bridges (NPBs) and nuclear bud (NBUD). However, when compared to the negative control, a significant increase in micronuclei (MNi) frequency was observed in both cell lines. However, chromosomal instability was induced by higher concentrations of ribavirin in HepG2 cells (from 61.1 to 976.8 μg/ml), compared with CHO-K1 cells (15.3 and 30.5 μg/ml). These results demonstrate the potential of ribavirin to promote chromosomal instability, and suggest that cells with different expressions of drug-metabolizing enzymes show different susceptibility to ribavirin effects.

The role of ITPA and ribavirin transporter genes polymorphisms in prediction of ribavirin-induced anaemia in chronic hepatitis C Egyptian patients

Few data are available concerning the roles of polymorphisms of inosine triphosphatase (ITPA) gene and ribavirin (RBV) transporter genes in the prediction of RBV-induced anaemia among Egyptians with chronic hepatitis C (CHC). Genotyping of three ITPA gene variants and two variants of RBV transporter genes has been performed in 123 patients under pegylated interferon-α/ribavirin treatment. The baseline haemoglobin and ITPA rs1127354 CA/AA have been found as predictors of anaemia at 4, 8 and 12 weeks of RBV therapy. In addition, ITPA rs7270101 AC/CC and age predicted anaemia after 12 weeks of therapy. In conclusion, the ITPA variant rs1127354C>A significantly predict RBV-induced anaemia during the first 3 months of treatment and it is recommended to be assessed before RBV administration.