Antiviral Compounds Research Articles

Understanding the stability and dynamics of influenza a H5N1 polymerase PB2 CAP-Binding domain in complex with natural compounds for antiviral drug discovery

Influenza A virus, particularly the H5N1 strain, poses a significant threat to public health due to its ability to cause severe respiratory illness and its high mortality rate. Traditional antiviral drugs targeting influenza A virus have faced challenges such as drug resistance and limited efficacy. Therefore, new antiviral compounds are needed to be discovered and developed. This study concentrated on examining the stability and behavior of the H5N1 polymerase PB2 CAP-binding domain when interacting with natural compounds, aiming to identify potential candidates for antiviral drug discovery. Through the virtual screening process, four lead compounds, ZINC000096095464, ZINC000044404209, ZINC000001562130, and ZINC000059779788, were selected, and these compounds showed binding energies −9.6, −9.4, −9.3, and −9.2 kcal/mol, respectively. When complexed with PB2, the ligand showed acceptable binding stability due to significant bond formation. However, during the 200ns MD simulation analysis, three (ZINC000096095464, ZINC000044404209, and ZINC000059779788) showed significant stability, which was proven by the trajectory analysis. The Rg-RMSD-based FEL plot showed significant structural stability due to stable conformers. The free-binding energy calculation also validates the stability of these complexes. This study offers valuable insights into the stability and dynamics of the H5N1 polymerase PB2 CAP-binding domain in complexes with natural compounds. These findings highlight the potential of these natural compounds as antiviral agents against the H5N1 influenza virus. Furthermore, this research contributes to the broader field of influenza virus treatment by demonstrating the effectiveness of computational methods in predicting and evaluating the stability and dynamics of potential drug candidates.

Anticipating Viral Challenges: A Perspective on Phytochemicals Against Existing and Emerging Viruses

Abstract: Viral infections impact millions of individuals annually and in 2018, the WHO called for global preparedness to address potential high-mortality pathogens, referred to as "Pathogen X," which can include fungi, viruses, parasites, or prions. The constant evolution of RNA viruses leads to continually changing variants, challenging the effectiveness of vac-cines and drugs. In underserved healthcare regions, plant-based phytochemicals offer prom-ise in combating viral diseases due to their ready availability, proven effectiveness, and low toxicity. Amidst the evolving virus variants and recurring fatal outbreaks, especially in re-source-constrained regions, phytochemicals hold promise as potential anti-infective agents. This review delves into plant-based antivirals, aiming to update plant-derived antiviral com-pounds' status against existing and emerging viruses from 2019 to 2023. The study aimed to identify active components from medicinal plants with IC50 and EC50 values against human-infecting viruses. It utilized in vitro and in vivo methods to predict phytochemical mechanisms and enhance bioavailability. Among the phytochemicals studied as antivirals, Emodin, Quercetin, Myricetin, Resveratrol, and Silymarin demonstrated efficacy against multiple viruses. Notably, certain plant compounds were effective against multiple viruses and could serve as potential antiviral treatments. Overall, the review illustrates that harness-ing plant-derived compounds shows promise in combating current and evolving infectious threats.

New Highly Selective Antivirals for Chikungunya Virus identified from the Screening of a Drug-Like Compound Library.

Chikungunya fever is a mosquito-borne disease caused by Chikungunya virus (CHIKV). Treatment of CHIKV infections is currently supportive and does not limit viral replication or symptoms of persistent chronic arthritis. Although there are multiple compounds reported as antivirals active against CHIKV in vitro, there are still no effective and safe antivirals. Thus, active research aims at the identification of new chemical structures with antiviral activity. Here, we report the screen of the Pandemic Response Box library of small molecules against a fully infectious CHIKV reporter virus. Our screening approach successfully identified previously reported CHIKV antiviral compounds within this library and further expanded potentially active hits, supporting the use of reporter-virus-based assays in high-throughput screening format as a reliable tool for antiviral drug discovery. Four molecules were identified as potential drug candidates against CHIKV: MMV1634402 (Brilacidin) and MMV102270 (Diphyllin), which were previously shown to present broad-spectrum antiviral activities, in addition to MMV1578574 (Eravacycline), and the antifungal MMV689401 (Fluopicolide), for which their antiviral potential is uncovered here.

A Literature Review Focusing on the Antiviral Activity of [1,2,4] and [1,2,3]-triazoles.

Out of a variety of heterocycles, triazole scaffolds have been shown to play a significant part in a wide array of biological functions. Many drug compounds containing a triazole moiety with important antimicrobial, anticancer and antidepressant properties have been commercialized. In addition, the triazole scaffold exhibits remarkable antiviral activity either incorporated into nucleoside analogs or non-nucleosides. Many synthetic techniques have been produced by scientists around the world as a result of their wide-ranging biological function. In this review, we have tried to summarize new synthetic methods produced by diverse research groups as well as provide a comprehensive description of the function of [1,2,4] and [1,2,3]-triazole derivatives as antiviral agents. Antiviral triazole compounds have been shown to target a wide variety of molecular proteins. In addition, several strains of viruses, including the human immunodeficiency virus, SARS virus, hepatitis B and C viruses, influenza virus, Hantavirus, and herpes virus, were discovered to be susceptible to triazole derivatives. This review article covered the reports for antiviral activity of both 1,2,3- and 1,2,4-triazole moieties up to 2022.

Drug library screening for putative antiviral compounds' discovery against equine arteritis virus

Drug library screening for putative antiviral compounds' discovery against equine arteritis virus

A novel live DNA tagging system for African swine fever virus shows that bisbenzimide Hoechst 33342 can effectively block its replication

African swine fever virus (ASFV) infection causes a frequently fatal disease in domestic swine that has affected more than 50 countries worldwide since 2021, with a major impact on animal welfare and economy. The development of effective vaccines or antivirals against this disease are urgently required for its effective control. Live detection of viral replication has been used as a tool for the screening and characterization of antiviral compounds in other dsDNA genome containing viruses. Here, we have adapted the ANCHOR fluorescent DNA labelling system to ASFV by constructing and characterizing a novel recombinant virus. We show that this virus is viable and effectively tags viral DNA replication sites, which can be detected and quantified in real time. Further, we have used high content cell microscopy to test the antiviral activity of bisbenzimide compounds and show that Hoechst 33342 has specific anti-ASFV activity. We expect this novel tool to be useful both in the further study of ASFV replication as in the screening of new specific antiviral compounds.

Synthetic Naphthoquinone Inhibits Herpes Simplex Virus Type-1 Replication Targeting Na+, K+ ATPase.

Since 1970 acyclovir (ACV) has been the reference drug in treating herpes simplex virus (HSV) infections. However, resistant herpes simplex virus type 1 (HSV-1) strains have emerged, narrowing the treatment efficacy. The antiviral activity of classical Na+, K+ ATPase enzyme (NKA) inhibitors linked the viral replication to the NKA's activity. Herein, we evaluated the anti-HSV-1 activity of synthetic naphthoquinones, correlating their antiviral activity with NKA inhibition. We tested seven synthetic naphthoquinones initially at 50 μM on HSV-1-infected African green monkey kidney cells (VERO cells). Only one compound, 2-hydroxy-3-(2-thienyl)-1,4-naphthoquinone (AN-06), exhibited higher antiviral activity with a low cytotoxicity. AN-06 reduced the viral titer of 9 (log10) to 1.32 (log10) and decreased the steps of attachment and penetration. The addition of AN-06 up to 20 h postinfection (hpi) interfered with the viral cycle. The viral infection alone increases NKA activity 3 h postinfection (hpi), scaling up to 6 hpi. The addition of AN-06 in a culture infected with HSV-1 decreased NKA activity, suggesting that its antiviral action is linked to NKA inhibition. Also, docking results showed that this compound binds at the same site of NKA in which adenosine triphosphate (ATP) binds. AN-06 exhibited promising pharmacokinetic and toxicology properties. Thus, we postulate that AN-06 may be a good candidate for antiviral compounds with a mechanism of action targeting NKA activity.

Nonpeptidic Irreversible Inhibitors of SARS-CoV-2 Main Protease with Potent Antiviral Activity.

SARS-CoV-2 infections pose a high risk for vulnerable patients. In this study, we designed benzoic acid halopyridyl esters bearing a variety of substituents as irreversible inhibitors of the main viral protease (Mpro). Altogether, 55 benzoyl chloro/bromo-pyridyl esters were synthesized, with broad variation of the substitution pattern on the benzoyl moiety. A workflow was employed for multiparametric optimization, including Mpro inhibition assays of SARS-CoV-2 and related pathogenic coronaviruses, the duration of enzyme inhibition, the compounds' stability versus glutathione, cytotoxicity, and antiviral activity. Several compounds showed IC50 values in the low nanomolar range, kinact/Ki values of >100,000 M-1 s-1 and high antiviral activity. High-resolution X-ray cocrystal structures indicated an important role of ortho-fluorobenzoyl substitution, forming a water network that stabilizes the inhibitor-bound enzyme. The most potent antiviral compound was the p-ethoxy-o-fluorobenzoyl chloropyridyl ester (PSB-21110, 29b, MW 296 g/mol; EC50 2.68 nM), which may serve as a lead structure for broad-spectrum anticoronaviral therapeutics.

Chemically Tagging Cargo for Specific Packaging inside and on the Surface of Virus-like Particles.

Virus-like particles (VLPs) have untapped potential for packaging and delivery of macromolecular cargo. To be a broadly useful platform, there needs to be a strategy for attaching macromolecules to the inside or the outside of the VLP with minimal modification of the platform or cargo. Here, we repurpose antiviral compounds that bind to hepatitis B virus (HBV) capsids to create a chemical tag to noncovalently attach cargo to the VLP. Our tag consists of a capsid assembly modulator, HAP13, connected to a linker terminating in maleimide. Our cargo is a green fluorescent protein (GFP) with a single addressable cysteine, a feature that can be engineered in many proteins. The HAP-GFP construct maintained HAP's intrinsic ability to bind HBV capsids and accelerate assembly. We investigated the capacity of HAP-GFP to coassemble with HBV capsid protein and bind to preassembled capsids. HAP-GFP binding was concentration-dependent, sensitive to capsid stability, and dependent on linker length. Long linkers had the greatest activity to bind capsids, while short linkers impeded assembly and damaged intact capsids. In coassembly reactions, >20 HAP-GFP molecules were presented on the outside and inside of the capsid, concentrating the cargo by more than 100-fold compared to bulk solution. We also tested an HAP-GFP with a cleavable linker so that external GFP molecules could be removed, resulting in exclusive internal packaging. These results demonstrate a generalizable strategy for attaching cargo to a VLP, supporting development of HBV as a modular VLP platform.

Screening a neurotransmitter-receptor-related inhibitor library identifies clomipramine HCl as a potential antiviral compound against Japanese encephalitis virus

BackgroundJapanese encephalitis virus (JEV) is a leading cause of viral encephalitis worldwide. JEV exhibits significant neuroinvasiveness and neurotoxicity, resulting in considerable damage to the nervous system. Japanese encephalitis is associated with high morbidity and mortality rate, seriously harming both human health and livestock production. The current lack of specific antiviral drugs means that the development of new therapeutic agents for JEV has become urgent. MethodsAnti-JEV drugs were screened from 111 inhibitors of neurotransmitter receptor-related molecules by high content technology. The antiviral effects of clomipramine HCl were evaluated through plaque assay, real-time quantitative PCR, immunofluorescence assay and western blotting assay. Bioinformatic tools were utilized to cluster the altered signaling pathway members after clomipramine HCl treatment. Finally, the anti-JEV mechanism was deeply resolved in vivo via such molecular biology and virological detection techniques. ResultsIn this study, we screened nine compounds with significant anti-JEV activity, of which clomipramine HCl demonstrated the most potent antiviral effect and exhibited dose-dependent activity. Mechanistically, clomipramine HCl may activate endoplasmic reticulum stress and modulate the unfolded protein response, thus inhibiting the assembly stage of JEV infection. ConclusionThis study highlights the importance of clomipramine HCl as a promising approach for JEV infection protection, which may lead to new host-directed antiviral approaches to such mosquito-borne viruses.

Predicting Clinical Outcomes of SARS-CoV-2 Drug Efficacy with a High-Throughput Human Airway Microphysiological System.

The average cost to bring a new drug from its initial discovery to a patient's bedside is estimated to surpass $2 billion and requires over a decade of research and development. There is a need for new drug screening technologies that can parse drug candidates with increased likelihood of clinical utility early in development in order to increase the cost-effectiveness of this pipeline. For example, during the COVID-19 pandemic, resources were rapidly mobilized to identify effective therapeutic treatments but many lead antiviral compounds failed to demonstrate efficacy when progressed to human trials. To address the lack of predictive preclinical drug screening tools, PREDICT96-ALI, a high-throughput (n = 96) microphysiological system (MPS) that recapitulates primary human tracheobronchial tissue,is adapted for the evaluation of differential antiviral efficacy of native SARS-CoV-2 variants of concern. Here, PREDICT96-ALI resolves both the differential viral kinetics between variants and the efficacy of antiviral compounds over a range of drug doses. PREDICT96-ALI is able to distinguish clinically efficacious antiviral therapies like remdesivir and nirmatrelvir from promising lead compounds that do not show clinical efficacy. Importantly, results from this proof-of-concept study track with known clinical outcomes, demonstrate the feasibility of this technology as a prognostic drug discovery tool.

Pharmaco-phytochemistry of esters isolated from leaf extracts of Spondias mombin as potential antiviral agents

The present work reports on the isolation and characterisation of two novel antiviral ester compounds from dichloromethane leaf extracts of Spondias mombin (SM). The characterisation and structural elucidation were established from spectroscopic evidence of nuclear magnetic resonance, Fourier transform infrared and mass spectroscopy. The compounds identified were 6-methylheptyl pentadecanoate and 6-methylheptyl-15-(1,2,3,4,4a,8a-hexahydronaphthalen-1-yl)pentadecanoate. The novel isolated ester compounds were reported to have anti-rhino virus activity in silico against a known biological target (HsNMT1) that plays a key role in developing therapeutics against the common cold. Molecular docking analysis revealed the binding affinity across all targets within the range of −4.6 to −8.2 kcal/mol, whilst molecular dynamic simulation showed that systems attained good stability due to the maintenance of mean root-mean-square deviation values within the acceptable range of 1.5−2.5 Å. It can be concluded that the novel compounds are potential inhibitory candidates against rhinovirus protein target HsNMT1. However, in vitro and in vivo experiments are further required to validate the possible inhibitory candidates against rhinovirus disease (common cold).

Establishment of a Luciferase-Based Reporter System to Study Aspects of Human Cytomegalovirus Infection, Replication Characteristics, and Antiviral Drug Efficacy.

Human cytomegalovirus (HCMV) represents a highly medically important pathogen which has constantly been the subject of both molecular and clinical investigations. HCMV infections, especially those in high-risk patients, still raise many unanswered questions, so current investigations are focused on viral pathogenesis, vaccine development, and options for antiviral drug targeting. To this end, the use of suitable viral strains as well as recombinant reporter constructs in cultured cells and model systems has specific significance. We previously reported on the application of various herpesviruses that express green, red, or related fluorescent proteins, especially in the fields of virus-host interaction and antiviral research. Here, we characterized a recombinant version of the clinically relevant and cell type-adaptable HCMV strain TB40, which expresses firefly luciferase as a quantitative reporter of viral replication (TB40-FLuc). The data provide evidence for five main conclusions. First, HCMV TB40-FLuc is employable in multiple settings in primary human cells. Second, viral reporter signals are easily quantifiable, even at early time points within viral replication. Third, the FLuc reporter reflects the kinetics of viral intracellular replication, cascade-like viral IE-E-L protein production, and progeny release. Fourth, as relates to specific applications of the TB40-FLuc system, we demonstrated the reliability of quantitative antiviral compound determination in multi-well formats and its independence from fluorescence-based measurements in the case of autofluorescent inhibitors. Finally, we illustrated increased reporter sensitivity in comparison to other recombinant HCMVs. In essence, recombinant HCMV TB40-FLuc combines several molecular properties that are considered beneficial in studies on viral host tropism, replication efficiency, and antiviral drug assessment.

Longitudinal Monitoring of the Effects of Anti-Adenoviral Treatment Regimens in a Permissive In Vivo Model.

Adenovirus infections of immunocompromised patients can cause life-threatening disseminated disease. While there are presently no drugs specifically approved to treat these infections, there are several compounds that showed efficacy against adenovirus in preclinical studies. For any such compound, low toxicity is an essential requirement. As cumulative drug effects can accentuate pathology, especially in patients with other morbidities, it is important to limit antiviral exposure to what is absolutely necessary. This is achievable by monitoring the virus burden of the patients and administering antivirals to suppress virus replication to a non-pathogenic level. We modeled such a system using Syrian hamsters infected with a replication-competent adenovirus vector, in which luciferase expression is coupled to virus replication. We found that virus replication could be followed in vivo in the same animal by repeated measurement of luciferase expression. To test the utility of an interrupted treatment regimen, we used NPP-669 and valganciclovir, two antiviral compounds with high and moderate anti-adenoviral efficacy, respectively. We found that short-term treatment of adenovirus-infected hamsters at times of peak virus replication can prevent virus-associated pathology. Thus, we believe that this animal model can be used to model different treatment regimens for anti-adenoviral compounds.

Insight into the Potential Antiviral Properties of the Genus Clerodendrum: Bioactive compounds with Mechanism of Action

Abstract: Antiviral compounds from plant origin have been the focus of researchers throughout the world for a long time as the potential alternative to classical antiviral therapies. The search for antiviral phytochemicals comes into the limelight amidst the recent COVID-19 pandemic. This tremendous surge in the hunt for effective and alternative treatment from the plant source is mainly due to the toxicity and inadequate responses of synthetic antiviral drugs to resistant viral strains. A comprehensive literature survey on the antiviral activity of bioactive compounds from the genus Clerodendrum was conducted using known and widely acknowledged scientific databases. This in-depth review is prepared to shed light on the promising effect of the bioactive phytochemicals isolated from different Clerodendrum spp. against some of the most pathogenically relevant viruses such as Severe Acute Respiratory Syndrome-Corona Virus-2 (SARS-CoV-2), Human Immunodeficiency Virus (HIV), Influenza Virus, Hepatitis C Virus (HCV), Herpes Simplex Virus (HSV), Japanese Encephalitis Virus (JEV), Dengue Virus (DENV), and Chikungunya Virus (CHIKV). Bioactive compounds such as ursolic acid, sugiol, and quercetin are reported to prevent virus-host cell adhesion. Harpagide is found to reduce intracellular Ca2+ and mitochondrial stress in infected cells, preventing viral infection. Researchers reported the efficacy of β- sitosterol in inhibiting immune responses via RIG-I signalling and IFN production. Rengyolone is found to mitigate viral infection by preventing acute inflammation. Betulinic acid, tricin, and oleanolic acid are found to prevent IAV and HIV replication. Evidence has also suggested the possible action of kaempferol, acacetin and apigenin to inhibit mRNA and protein production in virus-infected cells. Future research should be oriented towards the isolation and quantitation of these bioactive compounds from Clerodendrum spp., along with their efficacy both in vitro and in vivo prior to their clinical applications in combating a variety of viral infections.

Exploring the therapeutic potential of Thai medicinal plants: in vitro screening and in silico docking of phytoconstituents for novel anti-SARS-CoV-2 agents

BackgroundThe high virulence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for coronavirus disease 2019 (COVID-19), has triggered global health and economic concerns. The absence of specific antiviral treatments and the side effects of repurposed drugs present persistent challenges. This study explored a promising antiviral herbal extract against SARS-CoV-2 from selected Thai medicinal plants based on in vitro efficacy and evaluated its antiviral lead compounds by molecular docking.MethodsTwenty-two different ethanolic-aqueous crude extracts (CEs) were rapidly screened for their potential activity against porcine epidemic diarrhea virus (PEDV) as a surrogate using a plaque reduction assay. Extracts achieving ≥ 70% anti-PEDV efficacy proceeded to the anti-SARS-CoV-2 activity test using a 50% tissue culture infectious dose method in Vero E6 cells. Molnupiravir and extract-free media served as positive and negative controls, respectively. Potent CEs underwent water/ethyl acetate fractionation to enhance antiviral efficacy, and the fractions were tested for anti-SARS-CoV-2 performance. The fraction with the highest antiviral potency was identified using liquid chromatography–high-resolution mass spectrometry (LC–HRMS). Molecular docking analyses of these compounds against the main protease (Mpro) of SARS-CoV-2 (6LU7) were performed to identify antiviral lead molecules. The top three hits were further evaluated for their conformational stability in the docked complex using molecular dynamics (MD) simulation.ResultsThe water fraction of mulberry (Morus alba Linn.) leaf CE (WF-MLCE) exhibited the most potent anti-SARS-CoV-2 efficacy with low cytotoxicity profile (CC50 of ~ 0.7 mg/mL), achieving 99.92% in pre-entry mode and 99.88% in postinfection treatment mode at 0.25 mg/mL. Flavonoids and conjugates were the predominant compounds identified in WF-MLCE. Molecular docking scores of several flavonoids against SARS-CoV-2 Mpro demonstrated their superior antiviral potency compared to molnupiravir. Remarkably, myricetin-3-O-β-D-galactopyranoside, maragrol B, and quercetin 3-O-robinobioside exhibited binding energies of ~ − 9 kcal/mol. The stability of each ligand–protein complex of these compounds with the Mpro system showed stability during MD simulation. These three molecules were pronounced as antiviral leads of WF-MLCE. Given the low cytotoxicity and high antiviral potency of WF-MLCE, it holds promise as a candidate for future therapeutic development for COVID-19 treatment, especially considering its economic and pharmacological advantages.

Investigating the antiviral activity of Erigeron annuus (L.) pers extract against RSV and examining its active components

Ethnopharmacological relevanceThe plants in the genus Erigeron are known to exhibit antiviral activities, including those against the respiratory syncytial virus (RSV). In traditional medicine Erigeron annuus (L.) Pers (EA) has been used in the treatment of pulmonary diseases and acute infectious hepatitis. Aim of this studyThe aim of this study is to determine the optimum extraction method to produce the most potent anti-RSV extract, elucidate its mode and mechanisms of antiviral activity in both in vitro and in vivo models, and identify the chemical structures of the bioactive compounds. Materials and methodsThe whole plant of EA was extracted with ethyl acetate, methanol, ethanol, water, aqueous methanol (60, 80% and 100%) and aqueous ethanol (50, 75% and 95%) using maceration, reflux, and ultrasound-assisted extraction methods. The antiviral activities of the extracts were determined in vitro. The in vitro antiviral activities of the extracts were determined using Hep-2 cells. Four in vitro experiments were performed to determine the mode of antiviral activity of the most active extract, ethyl acetate fraction (EAE) of Erigeron annuus whole plant extract prepared by refluxing with 50% ethanol, by examining its ability to inactivate the virus directly, inhibit viral adsorption and penetration, inhibit viral replication and preventive effect. The effect of temperature and duration of treatment on these modes of action was also determined. The antiviral activity of the EAE was also assessed in vivo in a mouse model. The lung index, viral load, and lung tissue histology were measured. qRT-PCR and ELISA studies were performed to determine the expression of key genes (TLR-3 and TLR-4) and proteins (IL-2, IFN-γ, and TNF-α) related to RSV infection. The most active antiviral compound was isolated using chromatography techniques, and its chemical structure was identified through electrospray triple quadrupole mass spectroscopy and nuclear magnetic resonance spectroscopy. ResultsThe EAE was the most active on RSV. In vitro experiments showed that the antiviral activity of EAE is via direct inactivation, inhibition of entry, and inhibition of the proliferation of the virus. In vivo experiments showed that the EAE effectively inhibited the proliferation of RSV in the lungs and alleviated the lung tissue lesions in RSV-infected mice. The antiviral activity of the EAE is mediated by downregulating the expression of TLR3 and TLR4 in the lung, upregulating the expression of IL-2 and IFN-γ, and downregulating the expression of TNF-α. Apigenin 7-O-methylglucuronide was found to be a major bioactive compound in EAE. ConclusionsThe results of this study confirmed the antiviral activity of EA by inactivating, inhibiting the entry, and inhibiting the proliferation of RSV. The activity is mediated by regulating the immunity and inflammatory mediators. Apigenin 7-O-methylglucuronide is the bioactive compound present in EA.

Development of robust antiviral assays using relevant apical-out human airway organoids.

While breakthroughs with organoids have emerged as next-generation in vitro tools, standardization for drug discovery remains a challenge. This work introduces human airway organoids with reversed biopolarity (AORBs), cultured and analyzed in a high-throughput, single-organoid-per-well format, enabling milestones towards standardization. AORBs exhibit a spatio-temporally stable apical-out morphology, facilitating high-yield direct intact-organoid virus infection. Single-cell RNA sequencing and immunohistochemistry confirm the physiologically relevant recapitulation of differentiated human airway epithelia. The cellular tropism of five severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains along with host response differences between Delta, Washington, and Omicron variants, as observed in transcriptomic profiles, also suggest clinical relevance. Dose-response analysis of three well-studied SARS-CoV-2 antiviral compounds (remdesivir, bemnifosbuvir, and nirmatrelvir) demonstrates that AORBs efficiently predict human efficacy, comparable to gold-standard air-liquid interface cultures, but with higher throughput (~10-fold) and fewer cells (~100-fold). This combination of throughput and relevance allows AORBs to robustly detect false negative results in efficacy, preventing irretrievable loss of promising lead compounds. While this work leverages the SARS-CoV-2 study as a proof-of-concept application, the standardization capacity of AORB holds broader implications in line with regulatory efforts to push alternatives to animal studies.

Inhibition of early RNA replication in Chikungunya and Dengue virus by lycorine: In vitro and in silico studies

Arboviruses such as chikungunya virus (CHIKV) and dengue virus (DENV) collectively afflict millions of individuals worldwide particularly in endemic countries like India, leading to substantial morbidity and mortality. With the lack of effective vaccines for both CHIKV and DENV in India, the search for antiviral compounds becomes paramount to control these viral infections. In line with this, our investigation was focused on screening natural compounds for their potential antiviral activity against CHIKV and DENV. Using different assays, including plaque assay, immunofluorescence, and reverse transcription-quantitative real-time PCR (qRT-PCR), out of 109 natural compounds tested, we confirmed lycorine's in vitro antiviral activity against CHIKV and DENV at low micromolar concentrations in different cell types. Time of addition assays indicated that lycorine does not impede viral entry. Additionally, qRT-PCR results along with time of addition assay suggested that lycorine interferes with the synthesis of negative strand viral RNA. Molecular docking analysis was done to understand the mode of inhibition of viral replication. The results revealed that the most likely binding site with the highest binding affinity of lycorine, was at the palm and finger domains, in the vicinity of the catalytic site of CHIKV and DENV RNA-dependent RNA polymerase (RdRp). Collectively, our data underscores the potential of lycorine to be developed as a direct acting inhibitor for DENV and CHIKV, addressing the critical need of requirement of an antiviral in regions where these viruses pose significant public health threats.

A novel nitrogenous coumarin: The promising antiviral therapy against white spot syndrome virus in the culture of shrimp seedlings

White spot disease (WSD), attributed to the white spot syndrome virus (WSSV), represents a substantial danger to the international shrimp sector, resulting in considerable losses in both production and economic terms. Nevertheless, there are currently no approved therapeutic measures to control the outbreak. This study involved the synthesis of 15 new compounds for the assessment of their anti-WSSV efficacy in Litopenaeus vannamei post-larvae. Among these compounds, N-(4-methyl-2-oxo-2H-chromen-7-yl)acetamide (P13) exhibited a maximum antiviral response of > 90 %, with a median effective concentration (EC50) < 12 mg/L, making P13 the most promising antiviral compound. In the cases where the larvae were simultaneously incubated with WSSV and P13, as well as where the larvae were first infected with WSSV and then treated with P13, the replication of WSSV was significantly inhibited. However, pre-treatment with P13 had minimal impact on WSSV multiplication, suggesting a potential therapeutic effect. Simultaneously, the cumulative mortality rate of WSSV-infected post-larvae decreased in the presence of P13. After the shrimp larvae were infected with WSSV, continuously changing the aquacultural water containing DMSO resulted in a mortality rate of 80 % at 120 hours post-infection (hpi); whereas continuously changing the aquaculture water containing P13 resulted in a mortality rate of 45 %. Given that P13 remains stable in farmed water for up to two days, it is recommended to regularly replace the medication to eliminate the virus threat. In conclusion, P13 demonstrates a positive anti-WSSV activity and holds potential for further development as an antiviral therapy against WSSV infection.