A critical review on phytochemicals as antiviral medications for SARS-CoV-2 virus infection.

A pandemic of acute respiratory infection, which was specified as coronavirus disease 2019, was instigated by a different strain of the virulent coronavirus SARS-CoV-2 that first appeared in late 2019. Since viral infections spread fast and there is presently no effective treatment, the use of plants with a long history of use in treating these infections has been explored regularly. The pandemic of coronavirus disease 2019 (COVID-19) has brought to light the dearth of medications with approval to treat acute viral illnesses. Because of this, the illness had a high fatality rate. The mortality rate was initially quite high and varied according to the patient's geographic location. For instance, among Chinese patients, the rate was 3·6%, whereas 1·5% of COVID-19-related deaths were documented outside of China. As of 2020, India has a 1.4% case fatality rate (CFR) of COVID-19 mortality, compared to 2.8% in Brazil and 1.8% in the USA. Many studies are being conducted to create pharmaceutical compounds specifically targeting important SARS-CoV-2 proteins. Several drug discovery initiatives are being undertaken to find powerful inhibitors by combining biochemical assay and computer-aided drug design techniques. Although plant-derived compounds have not had much success in the dominion of antivirals, plants are, however, believed to be a limitless supply of medications for a variety of diseases and clinical conditions. The scientific foundation required for developing novel natural source medications is provided by the chemical characterization and analysis of plant components. Most viral infections treated by ethnobotanical applications and historical literature on ayurveda, and traditional medicine are generally attributed to phytochemicals, which are compounds derived from medicinal plants. In this review, we have described the application of vascular plant-derived chemicals, such as tannins, polyphenols, alkaloids, and flavonoids, as antivirals, especially for managing COVID-19. This article discusses novel bioactive compounds and their molecular structures that target the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as prospective candidates for anti-coronavirus disease drugs. Moreover, to confirm the effectiveness of the phytochemicals that have demonstrated antiviral activity, clinical trials would need to be conducted in addition to the preclinical research that has already been done. To ensure spectacular findings, more applications of the compound would need to be studied to fully understand the effects of those phytochemicals whose clinical usefulness has already been established.

Comprehensive eco-geno-toxicity and environmental risk of common antiviral drugs in aquatic environments post-pandemic.

The eco-geno-toxicological impacts of the most widely used antiviral drugs against SARS-CoV2 - ribavirin, ritonavir, nirmatrelvir and tenofovir - were investigated in freshwater organisms. Ribavirin and tenofovir exhibited the highest acute toxicity in the rotifer Brachionus calyciflorus at concentrations of a few mg/L while ritonavir and nirmatrelvir showed similar effects at tens of mg/L; acute toxicity of ribavirin was also observed in the crustacean Ceriodaphnia dubia at similar concentrations. In contrast, the crustacean Thamnocephalus platyurus showed the lowest sensitivity to the antiviral drugs tested with no sublethal effects. Chronic toxicity tests revelead that these antivirals induced effects in consumers at concentrations of environmental concern (ng-µg/L). Ribavirin showed the highest toxicity to the alga Raphidocelis subcapitata, while ritonavir showed the highest toxicity to B. calyciflorus and C. dubia. DNA damage and oxidative stress were observed in C. dubia at 0.001 µg/L and 0.1 µg/L when exposed to ritonavir and nirmatrelvir respectively, and at 1 µg/L when exposed to ribavirin and tenofovir. Toxic and genotoxic environmental risks were assessed with risk quotients for ritonavir, tenofovir and ribavirin exceeding the threshold of 1, indicating significant environmental concern.

Management of Kidney Transplant Outpatients With COVID-19: A Single Center Experience.

Patients undergoing kidney transplant are at risk of severe COVID-19. Our single-center retrospective analysis evaluated the outcomes of kidney transplant outpatients with COVID-19 who were managed with reduced immunosuppression and treatment with molnupiravir. Between January 2022 and May 2023, we included 93 patients (62 men, average age 56 years), serum creatinine 127 (101-153) µmol/L. Molnupiravir was administered, and immunosuppressive therapy was reduced immediately following the confirmation of SARS-CoV-2 infection by PCR, which was 2 (1-3) days after the onset of symptoms. Only three (3.2%) patients required hospitalization, and one patient died. Acute kidney injury was observed in two patients. During the follow-up period of 19 (15-22) months, there was no significant increase in proteinuria, no acute or new chronic graft rejection, and kidney graft function remained stable; serum creatinine was 124 (106-159) µmol/L post-COVID-19 infection and 128 (101-161) µmol/L at the end of the follow-up period. Our results demonstrate that early initiation of molnupiravir treatment combined with a temporary reduction in immunosuppressive therapy results in favorable clinical outcomes in patients with COVID-19, with preservation of good graft function and no episodes of graft rejection.

Evaluation of inhibition effect and interaction mechanism of antiviral drugs on main protease of novel coronavirus: Molecular docking and molecular dynamics studies.

The outbreak of pneumonia caused by the novel coronavirus (SARS-CoV-2) has presented a challenge to public health. The identification and development of effective antiviral drugs is essential. The main protease (3CLpro) plays an important role in the viral replication of SARS-CoV-2 and is considered to be an effective therapeutic target. In this study, according to the principle of drug repurposing, a variety of antiviral drugs commonly used were studied by molecular docking and molecular dynamics (MD) simulations to obtain potential inhibitors of main proteases. 24 antiviral drugs were docked with 5 potential action sites of 3CLpro, and the drugs with high binding strength were further simulated by MD and the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy calculations. The results showed that the drugs with high flexibility could bind to 3CLpro better than those with low flexibility. The interaction mechanism between antiviral drugs and main protease was analyzed in detail by calculating the root mean square displacement (RMSD), root mean square fluctuation (RMSF) and interaction residues properties. The results showed that the six drugs with high flexibility (Remdesivir, Simnotrelvir, Sofosbuvir, Ledipasvir, Indinavir and Raltegravir) had strong binding strength with 3CLpro, and the last four antiviral drugs can be used as potential candidates for main protease inhibitors.

Myrtus communis L. Essential Oil Exhibits Antiviral Activity against Coronaviruses.

Human coronaviruses are a continuous threat to the human population and have limited antiviral treatments, and the recent COVID-19 pandemic sparked interest in finding new antiviral strategies, such as natural products, to combat emerging coronaviruses. Rapid efforts in the scientific community to identify effective antiviral agents for coronaviruses remain a focus to minimize mortalities and global setbacks. In this study, an essential oil derived from Myrtus communis L. (MEO) is effective against HCoV-229E and HCoV-OC43 virus infections in comparison to two FDA-approved drugs, Remdesivir and Nirmatrelvir. Gas-chromatography and mass spectrometry were used to identify the chemical composition of MEO. Slight antioxidant activity was observed in MEO, indicating a role in oxidative stress. A dose-response curve measuring the EC50 indicates a high potency against HCoV-229E and HCoV-OC43 virus infections on Huh7.5 cells with low cytotoxicity using a PrestoBlue cell viability assay. Our findings demonstrate that MEO exhibits potent antiviral activity against HCoV-229E and HCoV-OC43 on Huh7.5 cells within a low-cytotoxicity range, but not on SARS-CoV-2. Artificial bacterial chromosome plasmids that expressed SARS-CoV-2 used for replicon-to determine viral replication and viral assembly/egress on HEK293T/17 cells-and virus-like particles on Huh7.5-AT cells-to determine viral entry and assembly/egress-showed no antiviral activity with MEO in comparison to Remdesivir. This study reveals the potential effectiveness of MEO as an alternative natural remedy to treat human coronaviruses and a potential antiviral agent for future coronavirus infections.

Transport and retention of COVID-19-related antiviral drugs in saturated porous media under various hydrochemical conditions.

Antiviral drugs have garnered considerable attention, particularly in the global battle against the COVID-19 pandemic, amid heightened concerns regarding environmentally acquired antiviral resistance. A comprehensive understanding of their transport in subsurface environments is imperative for accurately predicting their environmental fate and risks. This study investigated the mobility and retention characteristics of six COVID-19 antiviral drugs in saturated quartz sand columns. Results showed that the mobility of the drugs was primarily contingent on their hydrophobicity, with ribavirin and favipiravir exhibiting the highest transportability, while arbidol displaying the greatest retention. The transport characteristics of ribavirin and favipiravir remained largely unaffected by pH, whereas the retention of the other four antivirals remained consistently minimal under alkaline conditions. Elevating ionic strength marginally facilitated the transport of these antivirals, while the presence of Ca2+ notably enhanced their retention in quartz sand compared to Na+. Ribavirin and remdesivir warrant particular attention due to their relatively high transportability and propensity for environmentally acquired antiviral resistance. These findings contribute to an enhanced understanding of the leachate potential and transport of COVID-19-related antivirals in sandy porous media, furnishing fundamental data for predicting their environmental fate and associated risks.

Mechanistic exploration of COVlD-19 antiviral drug ritonavir on anaerobic digestion through experimental validation coupled with metagenomics analysis.

Aggregation of antiviral drugs (ATVs) in waste activated sludge (WAS) poses considerable environmental risk, so it is crucial to understand the behavior of these agents during WAS treatment. This study investigated the effects of ritonavir (RIT), an ATV used to treat human immunodeficiency virus infection and coronavirus disease 2019, on anaerobic digestion (AD) of WAS to reveal the mechanisms by which it interferes with anaerobic flora. The dosage influence results showed that methane production in AD of WAS decreased by 46.56 % when RIT concentration was increased to 1000 µg/kg total suspended solids (TSS). The AD staging test revealed that RIT mainly stimulated microbial synthesis of the extracellular polymeric substance (EPS), limiting organic matter solubilization. At 500 µg/kg TSS, RIT decreased CHO and CHON levels in dissolved organic matter by 23.12 % and 56.68 %, respectively, significantly reducing substrate availability to microorganisms. Metagenomic analysis of microbial functional gene sets revealed that RIT had greater inhibitory effects on protein and amino acid metabolism than on carbohydrate metabolism. Under RIT stress, methanogens switched from hydrogenotrophic and acetotrophic methanogenesis to methylotrophic and acetotrophic methanogenesis.

Antiviral drugs in animal-derived matrices: A review.

The ban of antiviral drugs in food-producing animals in several parts of the world, latest by Commission Delegated Regulation (EU) 2022/1644, has increased the need for food control laboratories to develop analytical methods and perform official controls. However, little is known about antiviral drugs, their use, and its analysis in food-producing animals in the EU. This review aims to provide insights into relevant viruses, antiviral drugs, and animal-derived matrices for analytical method development and monitoring purposes to implement in food control laboratories. For years, animal viruses, such as African swine fever and avian influenza, have caused many outbreaks. Besides, they led to large economic losses due to the applied control measures and a lack of available treatments. Considering these losses and the known effectiveness of authorized human antiviral drugs in different organisms, medicines such as amantadine in Chinese poultry have been misused. Various analytical methods, including screening assays and sensors (published 2016-2023), and mass spectrometry methods (published 2012-2023) have been outlined in this review for the monitoring of antiviral drugs in animal-derived matrices. However, pharmacokinetics information on metabolite formation and distribution of these substances in different animal-derived matrices is incomplete. Additionally, apart from a few countries, there is a lack of available data on the potential misuse of different antiviral drugs in animal-derived matrices. Although a handful of important antiviral drugs, such as influenza, broad-spectrum, antiretroviral, and herpes drugs, and animal-derived matrices, such as chicken muscle, are identified, the priority of the scope should be further specified by closing the aforementioned gaps.

Electrochemical removal of antiretroviral drug - raltegravir from aquatic media: Multivariate optimization, degradation studies and transformation products characterization.

Electrochemical degradation of the antiretroviral drug raltegravir was investigated using different electrode materials (platinum, glassy carbon and boron-doped diamond). After preliminary studies with the use of multivariate chemometric method, electrochemical degradation was conducted with a boron-doped diamond electrode and phosphate buffer at pH 9. To assess the role of different variable in degradation kinetics, final experiments were conducted with varying applied current densities, chloride and humic acid concentrations, and using a natural river water sample. The results showed that raltegravir degradation generally followed pseudo-first-order kinetics. The degradation rate was inhibited by the presence of humic acid, while increasing the applied current density or chloride concentration enhanced the removal of raltegravir. Degradation process performed in the river water sample followed second-order kinetics and led to almost complete degradation of raltegravir within 30 min, highlighting the impact of natural matrices on reaction kinetics. Total organic carbon analysis was utilized, showing that even rapid degradation of the parent compound did not ensure total mineralization. Additionally, the energy consumption analysis revealed that the presence of chloride ions significantly improves efficiency of the organic carbon elimination. With the use of high-resolution mass spectrometry fourteen transformation products were elucidated, and their aquatic toxicity was predicted using in silico approach. Half of the identified transformation products were found to possess higher aquatic toxic potential than the parent compound, emphasizing the necessity of the mineralization assessment.

Impact of patient's financial burden of COVID-19 treatment on antiviral prescription rates and clinical and economic outcomes.

BACKGROUND: In Japan, medical expenses for COVID-19 treatment transitioned from full public funding support to out-of-pocket (OOP) payment by patients plus partial public support in October 2023, and public support fully ended in March 2024. This study evaluated the clinical and economic impacts of initiating OOP payments. RESEARCH DESIGN AND METHODS: To assess the impact on prescription rates, we compared the prescription rates of antivirals from the 4-month pre- to post-OOP payment initiation period using a claims database. Subsequently, a budget impact model assessed the impacts of a hypothetical decline in the prescription rates on COVID-19-related hospitalizations, deaths, and direct medical costs for antiviral prescription and hospitalization. RESULTS: The antiviral prescription rate per 100 patients decreased from 17.5 for the pre-OOP payment initiation period to 11.5 for the post-OOP payment initiation period, that is, a change of - 34.3%. With prescription rate decreases of 40%, 60%, and 80%, the hospitalizations would increase annually by 22,533 (3.3%), 33800 (5.0%), and 45,066 (6.6%), respectively. The total costs would increase by JPY9.5 billion (USD67.3 million; 0.7%), JPY14.3 billion (USD100.9 million; 1.0%), and JPY19.0 billion (USD134.5 million; 1.3%), respectively. CONCLUSIONS: Higher OOP payment decreased the antiviral prescription rate, potentially leading to clinical and economic loss.

Hydroxyl radical-induced C1'-H abstraction reaction of different artificial nucleotides.

CONTEXT: Recently, a few antiviral drugs viz Molnupiravir (EIDD-1931), Favipiravir, Ribavirin, Sofosbuvir, Galidesivir, and Remdesivir are shown to be beneficial against COVID-19 disease. These drugs bind to the viral RNA single strand to inhibit the virus genome replication. Similarly, recently, some artificial nucleotides, such as P, J, B, X, Z, V, S, and K were proposed to behave as potent antiviral candidates. However, their activity in the presence of the most reactive hydroxyl (OH) radical is not yet known. Here, the possibility of RNA strand break due to the OH radical-induced C1'-hydrogen (H) abstraction reaction of the above molecules (except Remdesivir) is studied in detail by considering their nucleotide conformation. The results are compared with those of the natural RNA nucleotides (G, C, A, and U). Due to low Gibbs barrier-free energy and high exothermicity, all these nucleotides (except Remdesivir) are prone to OH radical-induced C1'-H abstraction reaction. As Remdesivir contains a C1'-CN bond, the OH radical substitution reactions at the CN and C1' sites would likely liberate the catalytically important CN group, thereby downgrading its activity. METHOD: Initially, the B3LYP-D3 dispersion-corrected density functional theory method and 6-31 + G* basis set were used to optimize all reactant, transition state, and product complexes in the implicit aqueous medium. Subsequently, the structures of these complexes were further optimized by using the ωB97X-D dispersion-corrected density functional theory method and cc-PVTZ basis set in the aqueous medium. The IEFPCM method was used to model the aqueous medium.

Inhibition of influenza virus infection in mice by pulmonary administration of a spray dried antiviral.

Increasing resistance to antiviral drugs approved for the treatment of influenza urges the development of novel compounds. Ideally, this should be complemented by a careful consideration of the administration route. 6'siallyllactosamine-functionalized ß-cyclodextrin (CD-6'SLN) is a novel entry inhibitor that acts as a mimic of the primary attachment receptor of influenza, sialic acid. In this study, we aimed to develop a dry powder formulation of CD-6'SLN to assess its in vivo antiviral activity after administration via the pulmonary route. By means of spray drying the compound together with trileucine, a dispersion enhancer, we created a powder that retained the antiviral effect of the drug, remained stable under elevated temperature conditions and performed well in a dry powder inhaler. To test the efficacy of the dry powder drug against influenza infection in vivo, infected mice were treated with CD-6'SLN using an aerosol generator that allowed for the controlled administration of powder formulations to the lungs of mice. CD-6'SLN was effective in mitigating the course of the disease compared to the control groups, reflected by lower disease activity scores and by the prevention of virus-induced IL-6 production. Our data show that CD-6'SLN can be formulated as a stable dry powder that is suitable for use in a dry powder inhaler and is effective when administered via the pulmonary route to influenza-infected mice.

Epstein-Barr Virus-Associated Aggressive Natural Killer Cell Leukemia: Challenges and Emerging Therapies.

A 24-year-old Ecuadorian female, previously diagnosed with acute fatty liver (AFL) during pregnancy, developed constitutional symptoms, jaundice, and abdominal pain in a subsequent pregnancy, prompting investigations that suggested a recurrence of AFL. She underwent an elective abortion, which resulted in the resolution of her abdominal pain, and a liver biopsy, which showed granulomatous inflammation and lymphocytic infiltration. She later presented with abdominal distention, productive cough, and persistent constitutional symptoms and jaundice. Extensive laboratory and imaging studies indicated sepsis, acute liver injury, and disseminated intravascular coagulopathy. Her serum Epstein-Barr virus (EBV) level was elevated. Special staining of her previous liver biopsy revealed EBV-positive natural killer (NK) cells. A bone marrow biopsy also revealed EBV-positive NK cells. She was diagnosed with aggressive NK cell leukemia (ANKL) with or without chronic active EBV (CAEBV). Treatment included dexamethasone, atovaquone, bortezomib, and ganciclovir, with plans for a stem cell transplant. However, her course was complicated by infections and multi-organ failure, resulting in her passing. This case highlights the rarity and challenges in managing EBV-associated ANKL, emphasizing the need for early detection and improved treatment options, with stem cell transplantation offering the best prognosis.

Cardiovascular adverse effects of antiviral therapies for COVID-19: Evidence and plausible mechanisms.

Antiviral therapeutics have made a critical contribution in mitigating the symptoms and clinical outcomes of the coronavirus disease of 2019 (COVID-19), in which a single-stranded RNA viral pathogen, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causes multi-organ injuries. Several antivirals were widely prescribed to treat COVID-19, either through the emergency use authorization (EUA) by the governmental regulatory agencies (i.e., remdesivir, paxlovid, molnupiravir, and the SARS-CoV-2-targeted monoclonal antibodies - tixagevimab and cilgavimab), as well as the repurposed use of the existing antiviral or antimalarial drugs (e.g., hydroxychloroquine, chloroquine, and ivermectin). Despite their efficacy in ameliorating COVID-19 symptoms, some adverse side-effects of the antivirals were also reported during the COVID-19 pandemic. Our current review has aimed to gather and extrapolate the recently published information concerning cardiovascular adverse effects caused by each of the antivirals. We also provide further discussion on the potential cellular mechanisms underlying the cardiovascular adverse effects of the selected antiviral drugs, which should be carefully considered when evaluating risk factors in managing patients with COVID-19 or similar infectious diseases. It is foreseeable that future antiviral drug development assisted with the newest artificial intelligence platform may improve the accuracy to predict the structures of biomolecules of antivirals and therefore to mitigate their associated cardiovascular adversities.

Computational exploration and molecular dynamic simulation for the discovery of antiviral agents targeting Newcastle disease virus.

Newcastle disease virus (NDV) is a highly infectious viral disease that impacts birds globally, especially domestic poultry. NDV is a type of avian paramyxovirus which poses a major threat to the poultry industry due to its ability to inflict significant economic damage. The membrane protein, Hemagglutinin-Neuraminidase (HN) of NDV is an attractive therapeutic candidate. It contributes to pathogenicity through various functions, such as promoting fusion and preventing viral self-agglutination, which allows for viral spread. In this study, we used pharmacophore modeling to identify natural molecules that can inhibit the HN protein of NDV. Physicochemical characteristics and phylogenetic analysis were determined to elucidate structural information and phylogeny of target protein across different species as well as members of the virus family. For structural analysis, the missing residues of HN target protein were filled and the structure was evaluated by PROCHECK and VERIFY 3D. Moreover, shape and feature-based pharmacophore model was employed to screen natural compounds' library through numerous scoring schemes. Top 48 hits with 0.8860 pharmacophore fit score were subjected towards structure-based molecular docking. Top 9 compounds were observed witihin the range of -8.9 to -7.5 kcal/mol binding score. Five best-fitting compounds in complex with HN receptor were subjected to predict biological activity and further analysis. Top two hits were selected for MD simulations to validate binding modes and structural stability. Finally, upon scrutinization, A1 (ZINC05223166) emerges as potential HN inhibitor to treat NDV, necessitating further validation via clinical trials.

Knowledge of, and attitude towards, the treatment of hepatitis C in people who inject drugs.

BACKGROUND: Direct acting antivirals (DAAs) as a curative treatment of hepatitis C have been available for several years and have replaced interferon-containing therapies. However, treatment rates of people who inject drugs (PWID) are declining in Germany, putting the elimination of hepatitis C by 2030 at risk. This study aimed at elucidating the knowledge of, and attitude towards, hepatitis C treatment in a clinical sample of PWID. METHODS: Participants were recruited between February 2019 and October 2020 at two opioid agonist therapy (OAT) clinics and two in-patient drug detoxification wards. Based on the European Addiction Severity Index (Europ-ASI), a standardized interview focusing on: sociodemographic data, drug history, risky behavior, infection with hepatitis C virus (HCV) and HIV, and previous experience with HCV treatment was carried out. In addition, participants filled in a questionnaire evaluating 13 statements relating to HCV treatment (right/wrong) and 15 statements on their personal 'pros and cons' views to start such a treatment assessed with the means of a 6-point Likert scale. RESULTS: A total of 153 patients (average age 45 years, male 78%; 106 (69.3%) currently in opioid maintenance treatment, 47 (30.7%) currently admitted to an inpatient detoxification) with an opioid use disorder were investigated. All of them reported having injected drugs at least once in their lives; 97 participants (63.3%) stated that they had been previously diagnosed with HCV infection. Among them, 27/97 patients (27.8%) reported a previous treatment with interferon; 27/97 (27.8%) with DAAs; and 32/97 (33.0%) reported a currently active hepatitis C. Most patients knew about the availability and efficacy of DAAs. However, DAAs' low rate of side effects, their short treatment duration, and their replacement of interferon, were not correctly evaluated by up to 50.3% of patients. 25-40% of 32 patients with currently active hepatitis C prioritized handling of social and other medical issues, e.g., reduction of heroin use, over treatment of hepatitis C. CONCLUSIONS: Although current levels of risky behavior have reportedly been reduced by active PWID over the past few years, educational and motivational interventions to increase hepatitis C treatment uptake should address the gaps in patients' knowledge.

4-(3-Phenylsulfonylindol-2-yl)-1-(pyridin-2-yl)piperazinyl-methanones as Potent Inhibitors of both SARS-CoV-2 and HCoV-OC43 Viruses.

SARS-CoV-2 and HCoV-OC43 belong to the same ß genus of the Coronaviridae family. SARS-CoV-2 was responsible for the recent COVID-19 pandemic, and HCoV-OC43 is the etiological agent of mild upper respiratory tract infections. SARS-COV-2 and HCoV-OC43 co-infections were found in children with respiratory symptoms during the COVID-19 pandemic. The two ß-coronaviruses share a high degree of homology between the 3CLpro active sites, so much so that the safer HCoV-OC43 has been suggested as a tool for the identification of new anti-SARS-COV-2 agents. Compounds 5 and 24 inhibited effectively both Wuhan and British SARS-CoV-2 patient isolates in Vero E6 cells and the HCoV-OC43 in MRC-5 cells at low micromolar concentrations. The inhibition was apparently exerted via targeting the 3CLpro active sites of both viruses. Compounds 5 and 24 at 100 µM inhibited the SARS-CoV-2 3CLpro activity of 61.78 and 67.30%, respectively. These findings highlight 5 and 24 as lead compounds of a novel class of antiviral agents with the potential to treat SARS-COV-2 and HCoV-OC43 infections.

SARS-CoV-2 Mpro inhibitor identification using a cellular gain-of-signal assay for high-throughput screening.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2, SARS2) is responsible for the COVID-19 pandemic and infections that continue to affect the lives of millions of people worldwide, especially those who are older and/or immunocompromised. The SARS2 main protease enzyme, Mpro (also called 3C-like protease, 3CLpro), is a bona fide drug target as evidenced by potent inhibition with nirmatrelvir and ensitrelvir, the active components of the drugs Paxlovid and Xocova, respectively. However, the existence of nirmatrelvir and ensitrelvir-resistant isolates underscores the need to develop next-generation drugs with different resistance profiles and/or distinct mechanisms of action. Here, we report the results of a high-throughput screen of 649,568 compounds using a cellular gain-of-signal assay. In this assay, Mpro inhibits expression of a luciferase reporter, and 8,777 small molecules were considered hits by causing a gain in luciferase activity 3x SD above the sample field activity (6.8% gain-of-signal relative to 100 µM GC376). Single concentration and dose-response gain-of-signal experiments confirmed 3,522/8,762 compounds as candidate inhibitors. In parallel, all initial high-throughput screening hits were tested in a peptide cleavage assay with purified Mpro and only 39/8,762 showed inhibition. Importantly, 19/39 compounds (49%) re-tested positive in both SARS2 assays, including two previously reported Mpro inhibitors, demonstrating the efficacy of the overall screening strategy. This approach led to the rediscovery of known Mpro inhibitors such as calpain inhibitor II, as well as to the discovery of novel compounds that provide chemical information for future drug development efforts.

Viral replication organelles: the highly complex and programmed replication machinery.

Viral infections usually induce the rearrangement of cellular cytoskeletal proteins and organelle membrane structures, thus creating independent compartments [termed replication organelles (ROs)] to facilitate viral genome replication. Within the ROs, viral replicases, including polymerases, helicases, and ligases, play functional roles during viral replication. These viral replicases are pivotal in the virus life cycle, and numerous studies have demonstrated that the viral replicases could be the potential targets for drugs development. Here, we summarize primarily the key replicases within viral ROs and emphasize the advancements of antiviral drugs targeting crucial viral replicases, providing novel insights into the future development of antiviral strategies.

Surveillance for Hepatocellular Carcinoma in Patients with Successfully Treated Viral Disease of the Liver: A Systematic Review.

Background: Surveillance for hepatocellular carcinoma (HCC) has been proven to increase the proportion of tumors detected at early stages and the chance of receiving curative therapies, reducing mortality by about 30%. Summary: Current recommendations consist of a semi-annual abdominal ultrasound with or without serum alpha-fetoprotein measurement in patients with cirrhosis and specific subgroups of populations with chronic viral hepatitis. Antiviral therapies, such as nucleot(s)ide analogs that efficiently suppress the replication of hepatitis B virus (HBV) and direct-acting antiviral drugs able to eliminate the hepatitis C virus (HCV) in >90% of patients, have radically changed the outcomes of viral liver disease and decreased, but not eliminated, the risk of HCC in both cirrhotic and non-cirrhotic patients. HCC risk is a key starting point for implementing a cost-effective surveillance and should also guide the decision-making process concerning its modality. As the global number of effectively treated viral patients continues to rise, there is a pressing need to identify those for whom the benefit-to-harm ratio of surveillance is favorable and to determine how to conduct cost-effective screening on such patients. Key Messages: This article addresses this topic and attempts to determine which patients should continue HCC surveillance after HBV suppression or HCV eradication, based on cost-effectiveness principles and the fact that HCC risk declines over time. We also formulate a proposal for a surveillance algorithm that switches the use of surveillance for HCC from the "one-size-fits-all" approach to individualized programs based on oncologic risk (precision surveillance).