Ribavirin in the treatment of chronic hepatitis C

Antivirals in COVID-19: A Focus on Pediatric Cardiac Patients

The COVID-19 pandemic created an unprecedented public health crisis, driven by its rapid global spread and the urgent need for worldwide collaborative interventions to contain it. This urgency spurred the search for therapeutic agents to prevent or manage the infection. Among these, various types of antivirals emerged as a prominent treatment option, supported by a wealth of observational studies and randomized controlled trials. The results from such studies conflict, with some concluding efficacy and others the lack thereof, with variability also occurring depending on the severity of COVID-19 in the studied population. In addition, many agents have been explored using randomized controlled trials-the gold standard in evaluating the efficacy of an intervention-to only a limited degree, with most of the evidence behind their use concluded using observational studies. Thus, the sheer volume of data has made it challenging to resolve inconsistencies and determine true efficacy. Furthermore, there is a paucity in the literature regarding the use of antivirals in the pediatric population infected with COVID-19, with their use being extrapolated from the results of studies done on adult patients. As such, additional trials are needed to solidify the effectiveness of antivirals in managing COVID-19, particularly in the underexplored and especially vulnerable pediatric cardiac patients. Therefore, utilizing the results from randomized controlled trials, this narrative review evaluates the rationale behind the use of antivirals, summarizes the findings from the literature, and concludes with a focused discussion on their application in pediatric cardiac patients.

Anti-Butterfly Effect in Ribavirin Studied by Combined Experiment (PXRD/1H-14N NQR Cross-Relaxation Spectroscopy), Quantum Chemical Calculations, Molecular Docking, Molecular Dynamics Simulations, and Novel Structure-Binding Strength and Quadrupolar Indices

Ribavirin, 1-(β-D-Ribofuranosyl)-1H-1,2,4-triazole-3-carboxamide, which is included in the list of drugs recommended in the guidelines for the diagnosis and treatment of SARS-CoV-2 infection, has been the subject of experimental and theoretical investigation. The most thermodynamically stable polymorphic form was studied using 1H-14N NQR cross-relaxation, periodic DFT/QTAIM/RDS/3D Hirshfeld surfaces, and molecular docking. For the first time, a 1H-14N cross-relaxation spectrum of ribavirin was recorded and interpreted. Twelve resonance frequencies were assigned to four inequivalent nitrogen positions in the molecule using combined experimental techniques and solid-state quantum chemical calculations. The influence of the structural alteration on the NQR parameters was modeled using GGA/RPBE. The differences in the binding pattern of ribavirin, acadesine, inosine, guanosine, and favipiravir-ribofuranosyl in the solid state and the protein-ligand complex were assessed to elucidate the differences in the binding mechanism at the molecular level due to aglycone modification. The replacement of the carbon adjacent to the ribose with nitrogen, in conjunction with the absence of oxygen at the 2-position of the ring, resulted in an increased flexibility of the RBV structure in comparison to the favipiravir-ribofuranosyl structure. The present study identified the intramolecular hydrogen bond NH···N in RBV as playing a crucial role in the formation of a quasi-five-membered ring. However, this bond was proven to be too weak to force positioning of the amide group in the ring plane. The ribofuranosyl in RBV inhibits tautomerism and freezes the conformation of the amide group. The results of the molecular dynamics simulations demonstrated that RBV and favipiravir-ribofuranosyl incorporated into the RNA primer exhibited comparable stability within the protein binding region. The titular anti-butterfly (inverted butterfly) effect is associated with the consequences of both the changes in aglycone moiety and the neighborhood alteration. Seven structure-binding strength indices and six novel quadrupolar indices defined in this study have been proven to facilitate the evaluation of the similarity of binding motifs in the solid state and protein-ligand complex.

Combination therapy synergism prediction for virus treatment using machine learning models

Combining different drugs synergistically is an essential aspect of developing effective treatments. Although there is a plethora of research on computational prediction for new combination therapies, there is limited to no research on combination therapies in the treatment of viral diseases. This paper proposes AI-based models for predicting novel antiviral combinations to treat virus diseases synergistically. To do this, we assembled a comprehensive dataset comprising information on viral strains, drug compounds, and their known interactions. As far as we know, this is the first dataset and learning model on combination therapy for viruses. Our proposal includes using a random forest model, an SVM model, and a deep model to train viral combination therapy. The machine learning models showed the highest performance, and the predicted values were validated by a t-test, indicating the effectiveness of the proposed methods. One of the predicted combinations of acyclovir and ribavirin has been experimentally confirmed to have a synergistic antiviral effect against herpes simplex type-1 virus, as described in the literature.

Cutaneous granulomas associated with rubella virus: A clinical review

Since the initial identification of vaccine-derived rubella virus (RuV) in the cutaneous granulomas of pediatric patients with inborn errors of immunity in 2014, more than 80 cases of RuV granulomas have been reported implicating both vaccine-derived and wild type RuV. Previously thought to arise exclusively in patients with significant immunocompromise, the identification of RuV granulomas in clinically immunocompetent patients adds nuance to our understanding of the interplay between host environment, immune dysregulation, and RuV granuloma formation. This review summarizes the literature on RuV granulomas including clinical and histopathologic features, proposed pathomechanisms supporting granuloma development, and potential therapeutic options. There is no standardized algorithm to guide the workup and diagnosis of suspected RuV granulomas. We highlight the importance of contributing RuV granuloma cases to ongoing Centers for Disease Control and Prevention surveillance efforts to monitor wild type and vaccine-derived RuV transmission. Studies advancing our understanding of RuV granulomas may provide insights into the role of viral infectious agents in granulomatous disease pathogenesis and guide the development of improved therapeutic options.

Synthetic approaches and application of clinically approved small-molecule drugs to treat hepatitis

Hepatitis, a global public health concern, presents a significant burden on healthcare systems worldwide. Particularly, hepatitis B and C are viral infections that can lead to severe liver damage, cirrhosis, and even hepatocellular carcinoma (HCC). The urgency to combat these diseases has driven researchers to explore existing small-molecule drugs as potential therapeutics. This comprehensive review provides a systematic overview of synthetic routes to key antiviral agents used to manage hepatitis. Furthermore, it elucidates the mechanisms of action of these drugs, shedding light on their interference with viral replication and liver disease progression. The review also discusses the clinical applications of these drugs, including their use in combination therapies and various patient populations. By evaluating the synthetic pathways and clinical utility of these drugs, this review not only consolidates current knowledge but also highlights potential future directions for research and drug development in the fight against hepatitis, ultimately contributing to improved patient outcomes and reduced global disease burden.

Potential treatments of COVID-19: Drug repurposing and therapeutic interventions

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection is caused when Spike-protein (S-protein) present on the surface of SARS-CoV-2 interacts with human cell surface receptor, Angiotensin-converting enzyme 2 (ACE2). This binding facilitates SARS-CoV-2 genome entry into the human cells, which in turn causes infection. Since the beginning of the pandemic, many different therapies have been developed to combat COVID-19, including treatment and prevention. This review is focused on the currently adapted and certain other potential therapies for COVID-19 treatment, which include drug repurposing, vaccines and drug-free therapies. The efficacy of various treatment options is constantly being tested through clinical trials and in vivo studies before they are made medically available to the public.

Plantaricin NC8 αβ rapidly and efficiently inhibits flaviviruses and SARS-CoV-2 by disrupting their envelopes

Potent broad-spectrum antiviral agents are urgently needed to combat existing and emerging viral infections. This is particularly important considering that vaccine development is a costly and time consuming process and that viruses constantly mutate and render the vaccine ineffective. Antimicrobial peptides (AMP), such as bacteriocins, are attractive candidates as antiviral agents against enveloped viruses. One of these bacteriocins is PLNC8 αβ, which consists of amphipathic peptides with positive net charges that display high affinity for negatively charged pathogen membrane structures, including phosphatidylserine rich lipid membranes of viral envelopes. Due to the morphological and physiological differences between viral envelopes and host cell plasma membranes, PLNC8 αβ is thought to have high safety profile by specifically targeting viral envelopes without effecting host cell membranes. In this study, we have tested the antiviral effects of PLNC8 αβ against the flaviviruses Langat and Kunjin, coronavirus SARS-CoV-2, influenza A virus (IAV), and human immunodeficiency virus-1 (HIV-1). The concentration of PLNC8 αβ that is required to eliminate all the infective virus particles is in the range of nanomolar (nM) to micromolar (μM), which is surprisingly efficient considering the high content of cholesterol (8-35%) in their lipid envelopes. We found that viruses replicating in the endoplasmic reticulum (ER)/Golgi complex, e.g. SARS-CoV-2 and flaviviruses, are considerably more susceptible to PLNC8 αβ, compared to viruses that acquire their lipid envelope from the plasma membrane, such as IAV and HIV-1. Development of novel broad-spectrum antiviral agents can significantly benefit human health by rapidly and efficiently eliminating infectious virions and thereby limit virus dissemination and spreading between individuals. PLNC8 αβ can potentially be developed into an effective and safe antiviral agent that targets the lipid compartments of viral envelopes of extracellular virions, more or less independent of virus antigenic mutations, which faces many antiviral drugs and vaccines.

Expanding the chemical space of 3(5)-functionalized 1,2,4-triazoles

An efficient approach to the gram-scale synthesis of 3(5)-substituted, 1,3- and 1,5-disubstituted 1,2,4-triazole-derived building blocks is described. The key synthetic precursors - 1,2,4-triazole-3(5)-carboxylates (20 examples, 35-89% yield) were prepared from readily available acyl hydrazides and ethyl 2-ethoxy-2-iminoacetate hydrochloride. Further transformations were performed following the convergent synthetic strategy and allowed the preparation of 1,3- and 1,5-disubstituted 1,2,4-triazole-derived esters (16 examples, 25-75% yield), 3(5)-substituted, 1,3- and 1,5-disubstituted carboxylate salts (18 examples, 78-93% yield), amides (5 examples, 82-93% yield), nitriles (5 examples, 30-85% yield), hydrazides (6 examples, 84-89% yield), and hydroxamic acids (3 examples, 73-78% yield). Considering wide applications of the 1,2,4-triazole motif in medicinal chemistry, these compounds are valuable building blocks for lead-oriented synthesis; they have also great potential for coordination chemistry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10593-022-03064-z.

Clinical features and mechanistic insights into drug repurposing for combating COVID-19

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged from Wuhan in China before it spread to the entire globe. It causes coronavirus disease of 2019 (COVID-19) where mostly individuals present mild symptoms, some remain asymptomatic and some show severe lung inflammation and pneumonia in the host through the induction of a marked inflammatory 'cytokine storm'. New and efficacious vaccines have been developed and put into clinical practice in record time, however, there is a still a need for effective treatments for those who are not vaccinated or remain susceptible to emerging SARS-CoV-2 variant strains. Despite this, effective therapeutic interventions against COVID-19 remain elusive. Here, we have reviewed potential drugs for COVID-19 classified on the basis of their mode of action. The mechanisms of action of each are discussed in detail to highlight the therapeutic targets that may help in reducing the global pandemic. The review was done up to July 2021 and the data was assessed through the official websites of WHO and CDC for collecting the information on the clinical trials. Moreover, the recent research papers were also assessed for the relevant data. The search was mainly based on keywords like Coronavirus, SARS-CoV-2, drugs (specific name of the drugs), COVID-19, clinical efficiency, safety profile, side-effects etc.This review outlines potential areas for future research into COVID-19 treatment strategies.

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.

In Silico Identification of a Potent Arsenic Based Approved Drug Darinaparsin against SARS-CoV-2: Inhibitor of RNA Dependent RNA polymerase (RdRp) and Essential Proteases

BACKGROUND

COVID-19 is a life-threatening novel corona viral infection to our civilization and spreading rapidly. Tremendousefforts have been made by the researchers to search for a drug to control SARS-CoV-2.

METHODS

Here, a series of arsenical derivatives were optimized and analyzed with in silico study to search the inhibitor of RNA dependent RNA polymerase (RdRp), the major replication factor of SARS-CoV-2. All the optimized derivatives were blindly docked with RdRp of SARS-CoV-2 using iGEMDOCK v2.1.

RESULTS

Based on the lower idock score in the catalytic pocket of RdRp, darinaparsin (-82.52 kcal/- mol) was revealed to be the most effective among them. Darinaparsin strongly binds with both Nsp9 replicase protein (-8.77 kcal/mol) and Nsp15 endoribonuclease (-8.3 kcal/mol) of SARS-- CoV-2 as confirmed from the AutoDock analysis. During infection, the ssRNA of SARS-CoV-2 is translated into large polyproteins forming viral replication complex by specific proteases like 3CL protease and papain protease. This is also another target to control the virus infection where darinaparsin also performs the inhibitory role to proteases of 3CL protease (-7.69 kcal/mol) and papain protease (-8.43 kcal/mol).

CONCLUSION

In the host cell, the furin protease serves as a gateway to the viral entry and darinaparsin docked with furin protease, which revealed a strong binding affinity. Thus, screening of potential arsenic drugs would help in providing the fast in-vitro to in-vivo analysis towards the development of therapeutics against SARS-CoV-2.

Synthesis of α-substituted 2-(1H-1,2,4-triazol-3-yl)acetates and 5-amino-2,4-dihydro-3H-pyrazol-3-ones via the Pinner strategy

A series of 2-(1H-1,2,4-triazol-3-yl)acetates, as well as 4-mono- and 4,4-disubstituted 5-amino-2,4-dihydro-3H-pyrazol-3-ones (including spirocyclic derivatives) have been synthesized using the Pinner reaction strategy. α-Mono- and α,α-disubstituted ethyl cyanoacetates were converted into the corresponding carboxyimidate salts that served as the key intermediates. Their further reaction with formylhydrazide or hydrazine hydrate provided triazolylacetates or aminopyrazolones (including spirocyclic derivatives), depending on the structure of the starting Pinner salt and the nature of the nucleophile. The scope and limitations of the developed synthetic method have been established.

The situation of small molecules targeting key proteins to combat SARS-CoV-2: Synthesis, metabolic pathway, mechanism of action, and potential therapeutic applications

Due to the global epidemic and high mortality of 2019 coronavirus disease (COVID-19), there is an immediate need to discover drugs that can help before a vaccine becomes available. Given that the process of producing new drugs is so long, the strategy of repurposing existing drugs is one of the promising options for the urgent treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19 disease. Although FDA has approved Remdesivir for the use in hospitalized adults and pediatric patients suffering from COVID-19, no fully effective and reliable drug has been yet identified worldwide to treat COVID-19 specifically. Thus, scientists are still trying to find antivirals specific to COVID-19. This work reviews the chemical structure, metabolic pathway, mechanism of action of existing drugs with potential therapeutic applications for COVID-19. Further, we summarized the molecular docking stimulation of the medications related to key protein targets. These already drugs could be developed for further clinical trials to supply suitable therapeutic options for patients suffering from COVID-19.

Den molekularen Wirtszellveränderungen durch SARS-CoV-2 auf der Spur

Upon infection with SARS-CoV-2, a variety of changes happen inside the host cell. The virus hijacks host cell pathways for driving its own replication, while the host counteracts with response mechanisms. To gain a comprehensive understanding of COVID-19, caused by SARS-CoV-2 infection, and develop therapeutic strategies, it is crucial to observe these systematic changes in their entirety. In our recent studies, we followed the effects of SARS-CoV-2 infection on the human proteome, which led to the identification of several drugs that abolished viral proliferation in cells.

Discontinuation of new hepatitis C drugs among Medicare patients

OBJECTIVES

To examine factors associated with discontinuation of new hepatitis C drugs-second-generation direct-acting antivirals (DAAs)-among Medicare beneficiaries with chronic hepatitis C.

STUDY DESIGN

A retrospective analysis using 2014-2016 Medicare claims.

METHODS

The study population was patients with chronic hepatitis C in fee-for-service Medicare with Part D who initiated a DAA therapy between January 1, 2014, and September 1, 2016. We defined discontinuation of DAA therapy as filling prescriptions for fewer weeks than the expected duration of the DAA identified. We estimated adjusted odds ratios (aORs) of DAA discontinuation by patient characteristics using multivariable logistic regression. We estimated the model separately for patients with a Part D low-income subsidy (LIS) and those without an LIS.

RESULTS

Of 82,056 patients who initiated a DAA therapy during the study period, 5171 (6.3%) did not complete the therapy. Discontinuation rates varied across DAAs, ranging from 4.7% (elbasvir/grazoprevir) to 11.8% (ombitasvir/paritaprevir/ritonavir/dasabuvir). Women with an LIS were more likely to discontinue DAA therapy than men with an LIS (aOR, 1.16; 95% CI, 1.08-1.25; P <.01). Non-LIS black and Hispanic patients had higher odds of discontinuation than non-LIS white patients (black: aOR, 1.49; 95% CI, 1.28-1.73; P <.01; Hispanic: aOR, 1.56; 95% CI, 1.01-2.44; P <.05). High comorbidity index score increased the odds of DAA discontinuation among patients with an LIS.

CONCLUSIONS

Real-world discontinuation of DAA therapy was low, but it was 3 times more likely than in clinical trials and varied by patient characteristics. Efforts to increase DAA adherence would help lower patients' risk of developing resistance to future treatments and reduce potential waste of resources.

Emerging strategies on in silico drug development against COVID-19: challenges and opportunities

The importance of coronaviruses as human pathogen has been highlighted by the recent outbreak of SARS-CoV-2 leading to the search of suitable drugs to overcome respiratory infections caused by the virus. Due to the lack of specific drugs against coronavirus, the existing antiviral and antimalarial drugs are currently being administered to the patients infected with SARS-CoV-2. The scientists are also considering repurposing of some of the existing drugs as a suitable option in search of effective drugs against coronavirus till the establishment of a potent drug and/or vaccine. Computer-aided drug discovery provides a promising attempt to enable scientists to develop new and target specific drugs to combat any disease. The discovery of novel targets for COVID-19 using computer-aided drug discovery tools requires knowledge of the structure of coronavirus and various target proteins present in the virus. Targeting viral proteins will make the drug specific against the virus, thereby, increasing the chances of viral mortality. Hence, this review provides the structure of SARS-CoV-2 virus along with the important viral components involved in causing infection. It also focuses on the role of various target proteins in disease, the mechanism by which currently administered drugs act against the virus and the repurposing of few drugs. The gap arising from the absence of specific drugs is addressed by proposing potential antiviral drug targets which might provide insights into structure-based drug development against SARS-CoV-2.

Evaluation of the potency of FDA-approved drugs on wild type and mutant SARS-CoV-2 helicase (Nsp13)

SARS-CoV-2 has caused COVID-19 outbreak with nearly 2 M infected people and over 100K death worldwide, until middle of April 2020. There is no confirmed drug for the treatment of COVID-19 yet. As the disease spread fast and threaten human life, repositioning of FDA approved drugs may provide fast options for treatment. In this aspect, structure-based drug design could be applied as a powerful approach in distinguishing the viral drug target regions from the host. Evaluation of variations in SARS-CoV-2 genome may ease finding specific drug targets in the viral genome. In this study, 3458 SARS-CoV-2 genome sequences isolated from all around the world were analyzed. Incidence of C17747T and A17858G mutations were observed to be much higher than others and they were on Nsp13, a vital enzyme of SARS-CoV-2. Effect of these mutations was evaluated on protein-drug interactions using in silico methods. The most potent drugs were found to interact with the key and neighbor residues of the active site responsible from ATP hydrolysis. As result, cangrelor, fludarabine, folic acid and polydatin were determined to be the most potent drugs which have potency to inhibit both the wild type and mutant SARS-CoV-2 helicase. Clinical data supporting these findings would be important towards overcoming COVID-19.

Current approaches used in treating COVID-19 from a molecular mechanisms and immune response perspective

Coronavirus disease 2019 (COVID-19), which is caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared by the World Health Organization (WHO) as a global pandemic on March 11, 2020. SARS-CoV-2 targets the respiratory system, resulting in symptoms such as fever, headache, dry cough, dyspnea, and dizziness. These symptoms vary from person to person, ranging from mild to hypoxia with acute respiratory distress syndrome (ARDS) and sometimes death. Although not confirmed, phylogenetic analysis suggests that SARS-CoV-2 may have originated from bats; the intermediary facilitating its transfer from bats to humans is unknown. Owing to the rapid spread of infection and high number of deaths caused by SARS-CoV-2, most countries have enacted strict curfews and the practice of social distancing while awaiting the availability of effective U.S. Food and Drug Administration (FDA)-approved medications and/or vaccines. This review offers an overview of the various types of coronaviruses (CoVs), their targeted hosts and cellular receptors, a timeline of their emergence, and the roles of key elements of the immune system in fighting pathogen attacks, while focusing on SARS-CoV-2 and its genomic structure and pathogenesis. Furthermore, we review drugs targeting COVID-19 that are under investigation and in clinical trials, in addition to progress using mesenchymal stem cells to treat COVID-19. We conclude by reviewing the latest updates on COVID-19 vaccine development. Understanding the molecular mechanisms of how SARS-CoV-2 interacts with host cells and stimulates the immune response is extremely important, especially as scientists look for new strategies to guide their development of specific COVID-19 therapies and vaccines.

Potential Anti-SARS-CoV-2 Therapeutics That Target the Post-Entry Stages of the Viral Life Cycle: A Comprehensive Review

The coronavirus disease-2019 (COVID-19) pandemic continues to challenge health care systems around the world. Scientists and pharmaceutical companies have promptly responded by advancing potential therapeutics into clinical trials at an exponential rate. Initial encouraging results have been realized using remdesivir and dexamethasone. Yet, the research continues so as to identify better clinically relevant therapeutics that act either as prophylactics to prevent the infection or as treatments to limit the severity of COVID-19 and substantially decrease the mortality rate. Previously, we reviewed the potential therapeutics in clinical trials that block the early stage of the viral life cycle. In this review, we summarize potential anti-COVID-19 therapeutics that block/inhibit the post-entry stages of the viral life cycle. The review presents not only the chemical structures and mechanisms of the potential therapeutics under clinical investigation, i.e., listed in clinicaltrials.gov, but it also describes the relevant results of clinical trials. Their anti-inflammatory/immune-modulatory effects are also described. The reviewed therapeutics include small molecules, polypeptides, and monoclonal antibodies. At the molecular level, the therapeutics target viral proteins or processes that facilitate the post-entry stages of the viral infection. Frequent targets are the viral RNA-dependent RNA polymerase (RdRp) and the viral proteases such as papain-like protease (PLpro) and main protease (Mpro). Overall, we aim at presenting up-to-date details of anti-COVID-19 therapeutics so as to catalyze their potential effective use in fighting the pandemic.

Covid-19 Pandemic and Current Medical Interventions

First humanoid coronavirus was discovered in the middle of 1960s, the class of viruses are considered to be a huge threat. The first onset of human coronavirus, SARS (SARS-CoV) appeared in 2003 which spanned five continents having lethal effects on human population accompanied by The Middle East Respiratory Syndrome Coronavirus in 2012 with a death rate of 35%. The viruses remain a threat till date and are of serious concern since no vaccine or specified drug therapy has been approbated for treating human coronaviruses. The viruses became a pandemic worldwide with the emergence of Wuhan coronavirus (2019-nCoV). SARS-CoV2 viral manifestation poses a serious human life risk by causing acute lung injury and various respiratory outcomes and has become a global concern. High pathogenicity and transmission rate of the viral strain has become the spotlight of research community throughout the world. With the ongoing studies on viral structure and host interactions, the intricacy of the viral proteome structure and replication cycle proposes a need to explore our understanding of host factors playing role in viral multiplication cycle. This review provides insight into our prevalent perception of coronavirus-host interactions, structure of SARS-CoV2, receptor mediated entry of virus inside the human cells, ongoing clinical trials, drug therapies and treatments that are being used to combat COVID-19 targeting viral fusion, replication and its multiplication.

Proteomics of SARS-CoV-2-infected host cells reveals therapy targets

A new coronavirus was recently discovered and named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infection with SARS-CoV-2 in humans causes coronavirus disease 2019 (COVID-19) and has been rapidly spreading around the globe1,2. SARS-CoV-2 shows some similarities to other coronaviruses; however, treatment options and an understanding of how SARS-CoV-2 infects cells are lacking. Here we identify the host cell pathways that are modulated by SARS-CoV-2 and show that inhibition of these pathways prevents viral replication in human cells. We established a human cell-culture model for infection with a clinical isolate of SARS-CoV-2. Using this cell-culture system, we determined the infection profile of SARS-CoV-2 by translatome3 and proteome proteomics at different times after infection. These analyses revealed that SARS-CoV-2 reshapes central cellular pathways such as translation, splicing, carbon metabolism, protein homeostasis (proteostasis) and nucleic acid metabolism. Small-molecule inhibitors that target these pathways prevented viral replication in cells. Our results reveal the cellular infection profile of SARS-CoV-2 and have enabled the identification of drugs that inhibit viral replication. We anticipate that our results will guide efforts to understand the molecular mechanisms that underlie the modulation of host cells after infection with SARS-CoV-2. Furthermore, our findings provide insights for the development of therapies for the treatment of COVID-19.

Inhibitions of human parainfluenza virus type 2 replication by ribavirin and mycophenolate mofetil are restored by guanosine and S-(4-nitrobenzyl)-6-thioinosine

The antiviral activities of a nucleoside analog antiviral drug (ribavirin) and a non-nucleoside drug (mycophenolate mofetil) against human parainfluenza virus type 2 (hPIV-2) were investigated, and the restoration of the inhibition by guanosine and S-(4-nitrobenzyl)-6-thioinosine (NBTI: equilibrative nucleoside transporter 1 inhibitor) were also investigated. Ribavirin (RBV) and mycophenolate mofetil (MMF) inhibited cell fusion induced by hPIV-2. Both RBV and MMF considerably reduced the number of viruses released from the cells. Virus genome synthesis was inhibited by RBV and MMF as determined by polymerase chain reaction (PCR) and real time PCR. mRNA syntheses were also reduced. An indirect immunofluorescence study showed that RBV and MMF largely inhibited viral protein syntheses. Using a recombinant green fluorescence protein (GFP)-expressing hPIV-2 without matrix protein (rhPIV-2ΔMGFP), it was found that virus entry into the cells and multinucleated giant cell formation were almost completely blocked by RBV and MMF. RBV and MMF did not disrupt actin microfilaments or microtubules. Both guanosine and NBTI completely or partially reversed the inhibition by RBV and MMF in the viral replication, syntheses of genome RNA, mRNA and protein, and multinucleated giant cell formation. NBTI caused a little damage in actin microfilaments, but had no effect on microtubules. Both RBV and MMF inhibited the replication of hPIV-2, mainly by inhibiting viral genome RNA, mRNA and protein syntheses. The inhibition was almost completely recovered by guanosine. These results indicate that the major mechanism of the inhibition is the depletion of intracellular GTP pools.

Feasibility of Known RNA Polymerase Inhibitors as Anti-SARS-CoV-2 Drugs

Coronaviruses (CoVs) are positive-stranded RNA viruses that infect humans and animals. Infection by CoVs such as HCoV-229E, -NL63, -OC43 and -HKU1 leads to the common cold, short lasting rhinitis, cough, sore throat and fever. However, CoVs such as Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and the newest SARS-CoV-2 (the causative agent of COVID-19) lead to severe and deadly diseases with mortality rates ranging between ~1 to 35% depending on factors such as age and pre-existing conditions. Despite continuous global health threats to humans, there are no approved vaccines or drugs targeting human CoVs, and the recent outbreak of COVID-19 emphasizes an urgent need for therapeutic interventions. Using computational and bioinformatics tools, here we present the feasibility of reported broad-spectrum RNA polymerase inhibitors as anti- SARS-CoV-2 drugs targeting its main RNA polymerase, suggesting that investigational and approved nucleoside RNA polymerase inhibitors have potential as anti-SARS-CoV-2 drugs. However, we note that it is also possible for SARS-CoV-2 to evolve and acquire drug resistance mutations against these nucleoside inhibitors.

2-Hydroxyimino-6-aza-pyrimidine nucleosides: synthesis, DFT calculations, and antiviral evaluations

Synthesis, DFT calculations, and antiviral evaluation of a series of novel 2-hydroxyimino-6-aza-pyrimidine ribonucleosides is reported. The hydrogen bonding between the C²N–OH moiety and N³–H and/or N³ moieties shapes the pyrimidine nucleoside as purine.

Impact of treatment with direct-acting antivirals on anxiety and depression in chronic hepatitis C

BACKGROUND AND AIM

Treatment of hepatitis C with direct-acting antiviral agents (DAA) has few side effects. Although pivotal studies suggested that DAA were safe in patients with psychiatric diseases who could not be treated with previous antiviral therapies, their effects on anxiety and depression have not yet been analysed in clinical practice. The aim of our study was to analyse anxiety and depression in the setting of DAA treatment in a clinical practice series.

METHODS

All patients starting DAA treatment between November 1, 2014 and October 31, 2015 were eligible. Patients completed the Hospital Anxiety and Depression scale at different times during treatment. The results were plotted on line graphs and evaluated using a linear regression model with repeated measures.

RESULTS

One hundred and forty-five patients were included (11% with major psychiatric disorders; 32% on psychiatric treatment). Sustained virologic response (SVR) was achieved in 97.3% of cases. Anxiety and depression measures did not differ between time points. No differences between patients on psychiatric treatment or with advanced fibrosis or cirrhosis were found at any time point analysed.

CONCLUSION

DAA treatment had no impact on anxiety or depression during or after chronic hepatitis C infection treatment, even in high-risk patients with major psychiatric disorders.

Ribavirin inhibits human parainfluenza virus type 2 replication in vitro

The antiviral activities of eight nucleoside analog antiviral drugs (ribavirin, acyclovir, lamivudine, 3'-azido-3'-deoxythymidine, emtricitabine, tenofovir, penciclovir and ganciclovir) against human parainfluenza virus type 2 (hPIV-2) were investigated. Only ribavirin (RBV) inhibited both cell fusion and hemadsorption induced by hPIV-2. RBV considerably reduced the number of viruses released from the cells. Virus genome synthesis was inhibited by RBV, as determined by real time PCR. An indirect immunofluorescence study showed that RBV largely inhibited viral protein synthesis. mRNAs of the proteins were not detected, indicating that inhibition of protein synthesis was caused by transcription inhibition by RBV. Using a recombinant green fluorescence protein-expressing hPIV-2 without matrix protein, it was found that RBV did not completely inhibit virus entry into the cells; however, it almost completely blocked multinucleated giant cell formation. RBV did not disrupt actin microfilaments and microtubules. These results indicate that the inhibitory effect of RBV is caused by inhibition of both virus genome and mRNA synthesis, resulting in inhibition of virus protein synthesis, viral replication and multinucleated giant cell formation (extensive cell-to-cell spreading of the virus).

Ribavirin Inhibits Parrot Bornavirus 4 Replication in Cell Culture

Parrot bornavirus 4 is an etiological agent of proventricular dilatation disease, a fatal neurologic and gastrointestinal disease of psittacines and other birds. We tested the ability of ribavirin, an antiviral nucleoside analog with antiviral activity against a range of RNA and DNA viruses, to inhibit parrot bornavirus 4 replication in duck embryonic fibroblast cells. Two analytical methods that evaluate different products of viral replication, indirect immunocytochemistry for viral specific nucleoprotein and qRT-PCR for viral specific phosphoprotein gene mRNA, were used. Ribavirin at concentrations between 2.5 and 25 μg/mL inhibited parrot bornavirus 4 replication, decreasing viral mRNA and viral protein load, in infected duck embryonic fibroblast cells. The addition of guanosine diminished the antiviral activity of ribavirin suggesting that one possible mechanism of action against parrot bornavirus 4 may likely be through inosine monophosphate dehydrogenase inhibition. This study demonstrates parrot bornavirus 4 susceptibility to ribavirin in cell culture.

Discovery of 4'-chloromethyl-2'-deoxy-3',5'-di-O-isobutyryl-2'-fluorocytidine (ALS-8176), a first-in-class RSV polymerase inhibitor for treatment of human respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a leading pathogen of childhood and is associated with significant morbidity and mortality. To date, ribavirin is the only approved small molecule drug, which has limited use. The only other RSV drug is palivizumab, a monoclonal antibody, which is used for RSV prophylaxis. Clearly, there is an urgent need for small molecule RSV drugs. This article reports the design, synthesis, anti-RSV activity, metabolism, and pharmacokinetics of a series of 4'-substituted cytidine nucleosides. Among tested compounds 4'-chloromethyl-2'-deoxy-2'-fluorocytidine (2c) exhibited the most promising activity in the RSV replicon assay with an EC50 of 0.15 μM. The 5'-triphosphate of 2c (2c-TP) inhibited RSV polymerase with an IC50 of 0.02 μM without appreciable inhibition of human DNA and RNA polymerases at 100 μM. ALS-8176 (71), the 3',5'-di-O-isobutyryl prodrug of 2c, demonstrated good oral bioavailability and a high level of 2c-TP in vivo. Compound 71 is a first-in-class nucleoside RSV polymerase inhibitor that demonstrated excellent anti-RSV efficacy and safety in a phase 2 clinical RSV challenge study.

Peginterferon alfa-2a with or without low-dose ribavirin for treatment-naive patients with hepatitis C virus genotype 2 receiving haemodialysis: a randomised trial

OBJECTIVE

Data comparing the efficacy and safety of combination therapy with peginterferon plus low-dose ribavirin and peginterferon monotherapy in treatment-naive haemodialysis patients with hepatitis C virus genotype 2 (HCV-2) infection are limited.

DESIGN

In this randomised trial, 172 patients received 24 weeks of peginterferon alfa-2a 135 μg/week plus ribavirin 200 mg/day (n=86) or peginterferon alfa-2a 135 μg/week (n=86). The efficacy and safety endpoints were sustained virological response (SVR) rate and adverse event (AE)-related withdrawal rate.

RESULTS

Compared with monotherapy, combination therapy had a greater SVR rate (74% vs 44%, relative risk (RR): 1.68 [95% CI 1.29 to 2.20]; p<0.001). The beneficial effect of combination therapy was more pronounced in patients with baseline viral load ≥800,000 IU/mL than those with baseline viral load <800,000 IU/mL (RR: 3.08 [95% CI 1.80 to 5.29] vs. RR: 1.11 [95% CI 0.83 to 1.45]; interaction p=0.001). Patients receiving combination therapy were more likely to have a haemoglobin level of <8.5 g/dL (70% vs. 8%, risk difference (RD): 62% [95% CI 50% to 73%]; p<0.001) and required a higher dosage [mean: 13,417 vs. 6667 IU/week, p=0.027] of epoetin β to manage anaemia than those receiving monotherapy. The AE-related withdrawal rates were 6% and 3% in combination therapy and monotherapy groups, respectively (RD: 2% [95% CI -4% to 9%]).

CONCLUSIONS

In treatment-naive haemodialysis patients with HCV-2 infection, combination therapy with peginterferon plus low-dose ribavirin achieved a greater SVR rate than peginterferon monotherapy. Most haemodialysis patients can tolerate combination therapy.

TRIAL REGISTRATION NUMBER

ClinicalTrial.gov number, NCT00491244.

The impact of the new antiviral regimens on patient reported outcomes and health economics of patients with chronic hepatitis C

Hepatitis C is an important cause of chronic liver disease worldwide with an estimated 170 million people infected. Hepatitis C virus (HCV)-infected patients are physically and mentally impacted by fatigue, depression and anxiety causing an impairment of health related quality of life (HRQOL), lower worker productivity and other patient reported outcomes (PROs). Although anti-HCV regimens containing first generation direct acting antiviral agents (DAAs) were associated with significant side effects, the second generation DAAs, sofosbuvir (SOF) and simeprevir (SMV), are associated with fewer side effects, better tolerability and high cure rates. Despite these advantages, key stakeholders are currently trying to find ways to best integrate these new therapeutic regimens into the management of patients with chronic hepatitis C for the benefit of all. The purpose of this article is to offer insight into the other key and equally important outcomes (PRO's, HRQOL and cost) which should be considered when assessing the applicability of these new regimens for the care of patients infected with HCV. Our review provides evidence that the new treatment regimens for HCV not only have high efficacy rates but are also associated with better patient reported outcomes and cost per case of HCV cured. Additionally, compared to other medical interventions, these new regimens are cost-effective from a societal perspective.

Antiviral therapy for human rabies

Human rabies is virtually always fatal despite numerous attempts at aggressive therapy. Most survivors received one or more doses of rabies vaccine prior to the onset of the disease. The Milwaukee Protocol has proved to be ineffective for rabies and should no longer be used. New approaches are needed and an improved understanding of basic mechanisms responsible for the clinical disease in rabies may prove to be useful for the development of novel therapeutic approaches. Antiviral therapy is thought to be an important component of combination therapy for the management of human rabies, and immunotherapy and neuroprotective therapy should also be strongly considered. There are many important issues for consideration regarding drug delivery to the central nervous system in rabies, which are in part related to the presence of the blood-brain barrier and also the blood-spinal cord barrier. Ribavirin and interferon-α have proved to be disappointing agents for the therapy of rabies. There is insufficient evidence to support the continued use of ketamine or amantadine for the therapy of rabies. Minocycline or corticosteroids should not be used because of concerns about aggravating the disease. A variety of new antiviral agents are under development and evaluation, including favipiravir, RNA interference (for example, small interfering [si]RNAs) and novel targeted approaches, including interference with viral capsid assembly and viral egress.

Hepatitis C virus genotype 6: virology, epidemiology, genetic variation and clinical implication

Hepatitis C virus (HCV) is a serious public health problem affecting 170 million carriers worldwide. It is a leading cause of chronic hepatitis, cirrhosis, and liver cancer and is the primary cause for liver transplantation worldwide. HCV genotype 6 (HCV-6) is restricted to South China, South-East Asia, and it is also occasionally found in migrant patients from endemic countries. HCV-6 has considerable genetic diversity with 23 subtypes (a to w). Although direct sequencing followed by phylogenetic analysis is the gold standard for HCV-6 genotyping and subtyping, there are also now rapid genotyping tests available such as the reverse hybridization line probe assay (INNO-LiPA II; Innogenetics, Zwijnaarde, Belgium). HCV-6 patients present with similar clinical manifestations as patients infected with other genotypes. Based on current evidence, the optimal treatment duration of HCV-6 with pegylated interferon/ribavirin should be 48 wk, although a shortened treatment duration of 24 wk could be sufficient in patients with low pretreatment viral load who achieve rapid virological response. In addition, the development of direct-acting antiviral agents is ongoing, and they give high response rate when combined with standard therapy. Herein, we review the epidemiology, classification, diagnosis and treatment as it pertain to HCV-6.

Asymmetric synthesis of host-directed inhibitors of myxoviruses

High-throughput screening (HTS) previously identified benzimidazole 1 (JMN3-003) as a compound with broad antiviral activity against different influenza viruses and paramyxovirus strains. In pursuit of a lead compound from this series for development, we sought to increase both the potency and the aqueous solubility of 1. Lead optimization has achieved compounds with potent antiviral activity against a panel of myxovirus family members (EC₅₀ values in the low nanomolar range) and much improved aqueous solubilities relative to that of 1. Additionally, we have devised a robust synthetic strategy for preparing 1 and congeners in an enantio-enriched fashion, which has allowed us to demonstrate that the (S)-enantiomers are generally 7- to 110-fold more potent than the corresponding (R)-isomers.

Utility of high-resolution accurate MS to eliminate interferences in the bioanalysis of ribavirin and its phosphate metabolites

BACKGROUND

The polar nucleoside drug ribavirin (RBV) combined with IFN-α is a front-line treatment for chronic hepatitis C virus infection. RBV acts as a prodrug and exerts its broad antiviral activity primarily through its active phosphorylated metabolite ribavirin 5´-triphosphate (RTP), and also possibly through ribavirin 5´-monophosphate (RMP). To study RBV transport, diffusion, metabolic clearance and its impact on drug-metabolizing enzymes, a LC-MS method is needed to simultaneously quantify RBV and its phosphorylated metabolites (RTP, ribavirin 5´-diphosphate and RMP). In a recombinant human UGT1A1 assay, the assay buffer components uridine and its phosphorylated derivatives are isobaric with RBV and its phosphorylated metabolites, leading to significant interference when analyzed by LC-MS with the nominal mass resolution mode.

RESULTS

Presented here is a LC-MS method employing LC coupled with full-scan high-resolution accurate MS analysis for the simultaneous quantitative determination of RBV, RMP, ribavirin 5´-diphosphate and RTP by differentiating RBV and its phosphorylated metabolites from uridine and its phosphorylated derivatives by accurate mass, thus avoiding interference.

CONCLUSION

The developed LC-high-resolution accurate MS method allows for quantitation of RBV and its phosphorylated metabolites, eliminating the interferences from uridine and its phosphorylated derivatives in recombinant human UGT1A1 assays.

Negative predictive value of IL28B, SLC28A2, and CYP27B1 SNPs and low RBV plasma exposure for therapeutic response to PEG/IFN-RBV treatment

OBJECTIVES

The response rate to treatment of chronic hepatitis C virus-genotype 1 and 4 infections was recently found to be strongly influenced by many polymorphisms. The aim of our study was to carry out an integrated analysis of the effects of polymorphisms and ribavirin (RBV) plasma exposure on outcome.

METHODS

The retrospective analysis included 174 patients. IL28B, CYP27B1, SLC29A1, SLC28A3, and SLC28A2 polymorphisms were genotyped and tested for association with sustained virological response. The impact of RBV plasma exposure during the first 3 months of therapy on outcome was also investigated.

RESULTS

Considering patients infected by hepatitis C virus-1/4, 3 polymorphisms (IL28B rs8099917TT, CYP27B1 rs4646536TT, and CNT2 rs11854484TT) were associated with sustained virological response. The number of negative variant allele and low RBV exposure were correlated to percentage increasing to therapy failure, suggesting some degree of cumulative effect of the 4 factors. A cutoff of 2.5 μg/mL of RBV was found to be associated with outcome (area under ROC [AUROC] curve = 0.64, sensitivity = 55.0%, and specificity = 71.2%, P = 0.020). In multivariate logistic regression analyses, each variant allele and RBV plasma exposure cutoff were independently associated with outcome.

CONCLUSIONS

In this study, we found that additional polymorphisms and RBV plasma exposure are also able to influence the achievement of response. Regardless of the magnitude of RBV pharmacokinetic exposure, the negative predictive value of the polymorphisms here investigated is much stronger than the positive one.

Association of hepatitis C virus NS5B variants with resistance to new antiviral drugs among untreated patients

Mutations located in the 109-amino acid fragment of NS5B are typically associated with resistance to interferon (IFN) and ribavirin (RIB) and to new antiviral drugs. The prevalence of these mutations was examined in 69 drug-naïve individuals with hepatitis C virus (HCV) infections in Rio de Janeiro, Brazil. Mutations related to non-response to IFN/RIB were observed in all subtypes studied (1a, 1b, 2b, 3a and 4). The most common mutation was Q309R, present in all subtypes, except subtype 2b with frequency above 20%. D244N was detected only in subtype 3a and A333E was detected only in subtype 2b. We did not detect the S282T, S326G or T329I mutations in any of the samples analysed. Of note, the C316N mutation, previously related to a new non-nucleoside compound (HCV796 and AG-021541), was observed in only eight of 33 (24%) samples from subtype 1b. Site 316 was under positive selection in this HCV variant. Our data highlight the presence of previously described resistance mutations in HCV genotypes from drug-naïve patients.

Response-guided therapy for patients with hepatitis C virus genotype 6 infection: a pilot study

The optimal duration of treatment with pegylated interferon (PEG-IFN) plus ribavirin (RBV) in patients with hepatitis C virus (HCV) genotype 6 is unknown. This study was aimed at determining treatment response on the basis of rapid virological response (RVR) of HCV genotype 6 in comparison with genotypes 1 and 3. Sixty-six treatment naïve patients were treated with PEG-IFN-α2a (180 μg/week) plus weight-based RBV (1000-1200 mg/day). Patients with genotype 1 n = 16) and genotype 3 (n = 16) were treated for a fixed duration of 48 and 24 weeks, respectively. Patients with genotype 6 (n = 34) who achieved RVR were treated for 24 weeks (response-guided therapy) and the remaining patients were treated for 48 weeks (standard therapy). The mean baseline HCV RNA levels were not statistically different between groups (6.4 ± 0.8, 6.0 ± 1.0 and 6.5 ± 0.8 Log(10) IU/mL for genotypes 1, 3 and 6, respectively). Patients with genotypes 1, 3 and 6 achieved RVR in 43.8%, 87.5% and 73.5% of cases, respectively. One patient with genotype 1 and 3 with genotype 6 were considered nonresponders and discontinued therapy. Sustained virological response (SVR) was achieved in 62.5%, 81.3% and 76.5% of patients with genotypes 1, 3 and 6, respectively. The SVR rate in patients with genotype 6 who underwent response-guided therapy was 88%. This pilot study suggested that the SVR rate of HCV genotype 6 was at an intermediate level between those of genotypes 3 and 1. Treatment with PEG-IFN plus RBV for 24 weeks may be sufficient for patients with genotype 6 who achieve RVR. Prospective randomized trials are required to evaluate this response-guided strategy in a larger number of patients with genotype 6.

Ribavirin downmodulates inducible costimulator on CD4+ T cells and their interleukin-10 secretion to assist in hepatitis C virus clearance

BACKGROUND AND AIM

The immunological mechanism by which ribavirin (RBV) polarizes the T-helper (Th) 1/2 balance toward Th1 predominancy is not fully understood. We therefore examined whether RBV affects costimulatory signaling, which is known to be essential for regulating the Th1/2 balance.

METHODS

The expression of costimulatory molecules and their ligands, and levels of various cytokines, released from CD4(+) T cells obtained from healthy individuals or patients with chronic hepatitis C virus (HCV) infection were analyzed.

RESULTS

In CD4(+) T cells, RBV selectively downmodulates the expression of inducible costimulator (ICOS), a ligand for B7-H2 on dendritic cells, which mainly differentiates Th0 into Th2 cells. Moreover, the levels of interleukin-10 (IL-10) released from RBV-stimulated CD4(+) T cells also decreased, indicating that the downmodulation of ICOS induced by RBV might be correlated with the decrease in IL-10 released from Th cells, leading to the inhibition of Th2 activity. An analysis of the association between ICOS kinetics and hepatitis C virus (HCV) elimination in hepatitis C patients receiving combined pegylated interferon and RBV indicated that HCV elimination tended to occur more frequently in patients showing ICOS downmodulation with RBV treatment. A decrease in IL-10 production by CD4(+) T cells was also observed in association with ICOS downregulation in patients who succeeded in HCV elimination.

CONCLUSIONS

The downmodulation of ICOS in correlation with a reduction in IL-10 produced by CD4(+) T cells is possibly the immunological mechanism of action of RBV, which polarizes the Th1/2 balance toward a Th1 cytokine profile, thus contributing to the elimination of cells chronically infected with HCV.

Host-directed Inhibitors of Myxoviruses: Synthesis and in vitro Biochemical Evaluation

Drugs targeted to viral proteins are highly vulnerable to the development of viral resistance. One little explored approach to the treatment of viral diseases is the development of agents that target host factors required for virus replication. Myxoviruses are predominantly associated with acute disease and, thus, ideally suited for this approach since the necessary treatment time is anticipated to be limited. High-throughput screening previously identified benzimidazole 22407448 with broad anti-viral activity against different influenza virus and paramyxovirus strains. Hit to lead chemistry has generated 6p (JMN3-003) with potent antiviral activity against a panel of myxovirus family members exhibiting EC(50) values in the low nanomolar range.

Immune-mediated complications of the graft in interferon-treated hepatitis C positive liver transplant recipients

Hepatitis C virus (HCV) re-infection of the graft is universal and interferon based antiviral therapy remains at present the treatment of choice in HCV liver transplant recipients. Apart from the antiviral effects, interferon and ribavirin have both potent immunomodulatory properties resulting in a broad range of immune-related disorders including acute cellular rejection and chronic ductopenic rejection as well as de novo autoimmune hepatitis. Further complicating the picture, HCV infection per se is associated with a variety of autoimmune phenomena. We discuss here the immune-mediated complications and their relationship to chronic HCV and interferon based antiviral therapy.

Should ribavirin be used to treat hepatitis C in dialysis patients?

Hepatitis C virus infection adversely affects outcomes in patients with chronic kidney disease undergoing maintenance dialysis. Pegylated interferon and ribavirin, the standard-of-care treatment in patients with intact renal function, is associated with severe side effects, toxicity, and high dropout rates in this population. Ribavirin has an important role in maintaining antiviral response following completion of therapy and increases sustained viral response (SVR) rates. However, the use of ribavirin in dialysis patients has been limited by the high frequency of severe hemolytic anemia and is currently reserved for study protocols and highly selected candidates treated at experienced centers. Encouraging data from small trials have shown a significant increase in SVR rates with the use of different dosing regimens of ribavirin in addition to interferon-based therapy and aggressive erythroid-stimulating agent support in dialysis patients. Use of ribavirin in selected dialysis patients, particularly renal transplant candidates, by experienced clinicians is appropriate.

Pegylated interferon-α monotherapy leads to low response rates in HIV-infected patients with acute hepatitis C

BACKGROUND

Despite a rising incidence of acute HCV in patients infected with HIV, the optimal therapeutic strategy (pegylated interferon-α [PEG-IFN-α] monotherapy or in combination with ribavirin) is still under debate.

METHODS

A total of 23 HIV-infected patients were prospectively diagnosed with acute HCV and treated with PEG-IFN-α2a monotherapy (180 μg/week) for 24 or 48 weeks. Add-on ribavirin was allowed from week 4 of therapy onwards. There were three patients who were not included for different reasons. Blood samples were routinely drawn for viral load measurement and IL28B polymorphism analysis.

RESULTS

Spontaneous viral clearance occurred in 1 (4%) patient. Nineteen patients (13 genotype 1 and 6 genotype 4) received treatment with PEG-IFN-α monotherapy (3 with add-on ribavirin) resulting in a rapid virological response (HCV RNA<50 IU/ml at week 4) in 7 (37%) patients. A sustained virological response (SVR) was reached in 7 (37%) patients, whereas 9 (47%) patients were null-responders to treatment (that is, <2 log₁₀ drop in HCV RNA at week 12 of therapy). The unfavourable G allele of the IL28B polymorphism rs8099917 was detected in 66% of the non-responders. In case of re-emergence of HCV viraemia after treatment discontinuation, sequence analysis of quasispecies confirmed an HCV relapse in 3 patients while 2 patients were re-infected by their previously non-responding partner.

CONCLUSIONS

PEG-IFN-α monotherapy resulted in a low SVR rate and a high percentage of null-response, whereas non-SVR was associated with a polymorphism in the IL28B gene (rs8099917).

Plasma/erythrocyte ribavirin x100 ratio as an indicator of sustained virological response in HCV genotype 1 patients with early virological response

BACKGROUND

On-treatment predictors during antiviral therapy of HCV are useful because they allow discontinuation of an unnecessary treatment in non-responders. Our aim was to evaluate the usefulness of plasma and erythrocyte ribavirin levels in predicting sustained virological response (SVR) in HCV genotype 1 patients undergoing antiviral treatment.

METHODS

A total of 40 HCV genotype 1 patients treated with pegylated interferon-alpha2a 180 microg weekly plus ribavirin 1,000 or 1,200 mg daily (according to body weight) were included in the study. Plasma and erythrocyte ribavirin levels were evaluated in all patients at week 12 by HPLC. At week 24, ribavirin levels were reassessed in those achieving early virological response (EVR).

RESULTS

A total of 27 patients achieved EVR, whereas 17 achieved SVR. There was no difference among EVR and non-EVR patients in terms of plasma and erythrocyte ribavirin concentrations at week 12. At week 24, EVR patients obtaining SVR exhibited higher mean +/-sd levels of ribavirin in plasma and lower levels in erythrocytes compared with non-SVR patients (in plasma 12.8 +/-10 versus 5.8 +/-4 microM [P<0.02] and in erythrocytes 1,053 +/-504 versus 1,613 +/-589 microM [P<0.03]). When the plasma ribavirin/erythrocyte ribavirin x100 ratio was compared, the difference was enhanced (1.5 +/-1.3 versus 0.4 +/-0.3 microM; P<0.01). Receiver operating characteristic curve analysis identified a cutoff for plasma ribavirin/erythrocyte ribavirin x100 ratio in predicting SVR of 0.71 with a negative predictive value of 0.8 and a positive predictive value of 0.9, whereas those related to EVR were 1 and 0.6, respectively.

CONCLUSIONS

Plasma ribavirin/erythrocyte ribavirin x100 ratio at week 24 seems to be a good indicator of SVR in HCV genotype 1 patients achieving EVR.

Comparison of adverse effects related to pegylated interferon-based therapy for patients with chronic hepatitis B and chronic hepatitis C in Taiwan

PURPOSE

Pegylated interferon (Peg-IFN)-based therapy is effective in treating chronic hepatitis B (CHB) and C (CHC) but frequently induces adverse events (AEs). This study was conducted to compare the incidence of Peg-IFN-based therapy-associated AEs in Taiwanese patients with CHB and CHC.

METHODS

Fifty-six patients with CHB and 103 age-, sex- and treatment duration-matched patients with CHC were enrolled. Patients with CHB were treated with Peg-IFN-α-2a 180 μg/week for 24 weeks (HBeAg(+), n = 31) or 48 weeks (HBeAg(-), n = 25); patients with CHC were treated with Peg-IFN-α-2a 180 μg/week plus ribavirin 1,000-1,200 mg/day for 24 weeks (genotype 2/3, n = 57) or 48 weeks (genotype 1, n = 46).

RESULTS

Significantly higher incidences of Peg-IFN-related AEs, especially neuropsychiatric symptoms, and ribavirin-associated skin manifestations were observed in patients with CHC compared with those with CHB, with either the 24- or 48-week regimen. Frequencies of laboratory abnormalities, except for anemia, were comparable in both groups. Neither group showed overt hepatic decompensation. Frequency of dose reduction was similar between the groups. Substantially higher rates of early termination and severe AEs were observed in patients with CHC.

CONCLUSIONS

Patients with CHB treated with Peg-IFN had fewer AEs than patients with CHC treated with Peg-IFN/ribavirin. All patients were treated safely.