Anti-Coronavirus Potential of Polyether Ionophores: The New Application of Veterinary Antibiotics in Livestock.

Coronaviruses have consistently posed a major global concern in the field of livestock industry and public health. However, there is currently a lack of efficient drugs with broad-spectrum antiviral activity to address the challenges presented by emerging mutated strains or drug resistance. Additionally, the method for identifying multitarget drugs is also insufficient. Aminopeptidase N (APN) and 3C-like proteinase (3CLpro) represent promising targets for host-directed and virus-directed strategies, respectively, in the development of effective drugs against various coronaviruses. In this study, maduramycin ammonium demonstrated a broad-spectrum antiviral effect by targeting both of the proteins. The binding domains 4 Å from the ligand of both target proteins shared a structural similarity, suggesting that screening and designing drugs based on these domains might exhibit broad-spectrum and highly effective antiviral activity. Furthermore, it was identified that the polyether ionophores' ability to carry zinc ion might be one of the reasons why they were able to target APN and exhibit antiviral effect. The findings of this experiment provide novel perspectives for future drug screening and design, while also offering valuable references for the utilization of polyether ionophores in the management of livestock health.

2-Bromopalmitate depletes lipid droplets to inhibit viral replication.

The global impact of emerging viral infections emphasizes the urgent need for effective broad-spectrum antivirals. The cellular organelle, lipid droplet (LD), is utilized by many types of viruses for replication, but its reduction does not affect cell survival. Therefore, LD is a potential target for developing broad-spectrum antivirals. In this study, we found that 2-bromopalmitate (2 BP), a previously defined palmitoylation inhibitor, depletes LD across all studied cell lines and exerts remarkable antiviral effects on different coronaviruses. We comprehensively utilized 2 BP, alongside other palmitoylation inhibitors such as cerulenin and 2-fluoro palmitic acid (2-FPA), as well as the enhancer palmostatin B and evaluated their impact on LD and the replication of human coronaviruses (hCoV-229E, hCoV-Oc43) and murine hepatitis virus (MHV-A59) at non-cytotoxic concentrations. While cerulenin and 2-FPA exhibited moderate inhibition of viral replication, 2 BP exhibited a much stronger suppressive effect on MHV-A59 replication, although they share similar inhibitory effects on palmitoylation. As expected, palmostatin B significantly enhanced viral replication, it failed to rescue the inhibitory effects of 2 BP, whereas it effectively counteracted the effects of cerulenin and 2-FPA. This suggests that the mechanism that 2 BP used to inhibit viral replication is beyond palmitoylation inhibition. Further investigations unveil that 2 BP uniquely depletes LDs, a phenomenon not exhibited by 2-FPA and cerulenin. Importantly, the depletion of LDs was closely associated with the inhibition of viral replication because the addition of oleic acid to 2 BP significantly rescued LD depletion and its inhibitory effects on MHV-A59. Our findings indicate that the inhibitory effects of 2 BP on viral replication primarily stem from LD disruption rather than palmitoylation inhibition. Intriguingly, fatty acid (FA) assays demonstrated that 2 BP reduces the FA level in mitochondria while concurrently increasing FA levels in the cytoplasm. These results highlight the crucial role of LDs in viral replication and uncover a novel biological activity of 2 BP. These insights contribute to the development of broad-spectrum antiviral strategies. IMPORTANCE: In our study, we conducted a comparative investigation into the antiviral effects of palmitoylation inhibitors including 2-bromopalmitate (2-BP), 2-fluoro palmitic acid (2-FPA), and cerulenin. Surprisingly, we discovered that 2-BP has superior inhibitory effects on viral replication compared to 2-FPA and cerulenin. However, their inhibitory effects on palmitoylation were the same. Intrigued by this finding, we delved deeper into the underlying mechanism of 2-BP's potent antiviral activity, and we unveiled a novel biological activity of 2-BP: depletion of lipid droplets (LDs). Importantly, we also highlighted the crucial role of LDs in viral replication. Our insights shed new light on the antiviral mechanism of LD depletion paving the way for the development of broad-spectrum antiviral strategies by targeting LDs.

Structural Basis for Coronaviral Main Proteases Inhibition by the 3CLpro Inhibitor GC376.

The main protease (Mpro) of coronaviruses participates in viral replication, serving as a hot target for drug design. GC376 is able to effectively inhibit the activity of Mpro, which is due to nucleophilic addition of GC376 by binding covalently with Cys145 in Mpro active site. Here, we used fluorescence resonance energy transfer (FRET) assay to analyze the IC50 values of GC376 against Mpros from six different coronaviruses (SARS-CoV-2, HCoV-229E, HCoV-HUK1, MERS-CoV, SARS-CoV, HCoV-NL63) and five Mpro mutants (G15S, M49I, K90R, P132H, S46F) from SARS-CoV-2 variants. The results showed that GC376 displays effective inhibition to various coronaviral Mpros and SARS-CoV-2 Mpro mutants. In addition, the crystal structures of SARS-CoV-2 Mpro (wide type)-GC376, SARS-CoV Mpro-GC376, MERS-CoV Mpro-GC376, and SARS-CoV-2 Mpro mutants (G15S, M49I, S46F, K90R, and P132H)-GC376 complexes were solved. We found that GC376 is able to fit into the active site of Mpros from different coronaviruses and different SARS-CoV-2 variants properly. Detailed structural analysis revealed key molecular determinants necessary for inhibition and illustrated the binding patterns of GC376 to these different Mpros. In conclusion, we not only proved the inhibitory activity of GC376 against different Mpros including SARS-CoV-2 Mpro mutants, but also revealed the molecular mechanism of inhibition by GC376, which will provide scientific guidance for the development of broad-spectrum drugs against SARS-CoV-2 as well as other coronaviruses.

On a path toward a broad-spectrum anti-viral: inhibition of HIV-1 and coronavirus replication by SR kinase inhibitor harmine.

IMPORTANCE: This study highlights the crucial role RNA processing plays in regulating viral gene expression and replication. By targeting SR kinases, we identified harmine as a potent inhibitor of HIV-1 as well as coronavirus (HCoV-229E and multiple SARS-CoV-2 variants) replication. Harmine inhibits HIV-1 protein expression and reduces accumulation of HIV-1 RNAs in both cell lines and primary CD4+ T cells. Harmine also suppresses coronavirus replication post-viral entry by preferentially reducing coronavirus sub-genomic RNA accumulation. By focusing on host factors rather than viral targets, our study offers a novel approach to combating viral infections that is effective against a range of unrelated viruses. Moreover, at doses required to inhibit virus replication, harmine had limited toxicity and minimal effect on the host transcriptome. These findings support the viability of targeting host cellular processes as a means of developing broad-spectrum anti-virals.

Cruciferous vegetable-derived indole-3-carbinol prevents coronavirus cell egression mechanisms in tracheal and intestinal 3D in vitro models.

The potential antiviral effects of indole-3-carbinol (I3C), a phytochemical found in Cruciferous vegetables, were investigated. Fibroblasts and epithelial cells were co-cultured on Alvetex® scaffolds, to obtain ad hoc 3D in vitro platforms able to mimic the trachea and intestinal mucosae, which represent the primary structures involved in the coronavirus pathogenesis. The two barriers generated in vitro were treated with various concentrations of I3C for different incubation periods. A protective effect of I3C on both intestinal and trachea models was demonstrated. A significant reduction in the transcription of the two main genes belonging to the Homologous to E6AP C-terminus (HECT)-E3 ligase family members, namely NEDD4 E3 Ubiquitin Protein Ligase (NEDD4) and WW Domain Containing E3 Ubiquitin Protein Ligase 1 (WWP1), which promote virus matrix protein ubiquitination and inhibit viral egression, were detected. These findings indicate I3C potential effect in preventing coronavirus cell egression processes that inhibit viral production. Although further studies are needed to clarify the molecular mechanisms whereby HECT family members control virus life cycle, this work paves the way to the possible therapeutic use of new natural compounds that may reduce the clinical severity of future pandemics.

Antimalarials and macrolides: a review of off-label pharmacotherapies during the first wave of the SARS-CoV-2 pandemic

Abstract We critically analyzed clinical trials performed with chloroquine (CQ) and hydroxychloroquine (HCQ) with or without macrolides during the first wave of COVID-19 and discussed the design and limitations of peer-reviewed studies from January to July 2020. Seventeen studies were eligible for the discussion. CQ and HCQ did not demonstrate clinical advantages that justified their inclusion in therapeutic regimens of free prescription for treatment or prophylactic purposes, as suggested by health authorities, including in Brazil, during the first wave. Around August 2020, robust data had already indicated that pharmacological effects of CQ, HCQ and macrolides as anti-SARS-CoV-2 molecules were limited to in vitro conditions and largely based on retrospective trials with low quality and weak internal validity, which made evidence superficial for decision-making. Up to that point, most randomized and nonrandomized clinical trials did not reveal beneficial effects of CQ or HCQ with or without macrolides to reduce lethality, rate of intubation, days of hospitalization, respiratory support/mechanical ventilation requirements, duration, type and number of symptoms, and death and were unsuccessful in increasing virus elimination and/or days alive in hospitalized or ambulatory patients with COVID-19. In addition, many studies have demonstrated that side effects are more common in CQ-or HCQ-treated patients.

Influencia del tratamiento con estatinas en una cohorte de pacientes ingresados por COVID-19 / Influence of statin treatment in a cohort of patients admitted for COVID-19

Antecedentes y objetivos:Se ha especulado que las estatinas pueden ser de utilidad en el tratamiento de pacientes con COVID-19, pero no existen evidencias clínicas sólidas. El objetivo de este trabajo es conocer su utilidad en una cohorte de gran tamaño de pacientes hospitalizados por COVID-19, así como si su retirada se asocia con un peor pronóstico.Material y métodos:Estudio retrospectivo observacional. Se incluyeron 2.191 pacientes hospitalizados con infección confirmada con SARS-CoV-2.Resultados:La edad media fue de 68,0 ± 17,8 años y fallecieron un total de 597 (27,3%) pacientes. Un total de 827 pacientes (37,7% de la muestra) estaban tratados previamente con estatinas. Aunque precisaron con mayor frecuencia de ingreso en camas de críticos, dicho grupo terapéutico no resultó un factor predictor independiente de muerte en el seguimiento [HR 0,95 (0,72-1,25)]. Un total de 371 pacientes (16,9%) recibió al menos una dosis de estatina durante el ingreso. A pesar de ser una población con un perfil clínico más desfavorable, tanto su uso [HR 1,03 (0,78-1,35)] como la suspensión durante el ingreso en pacientes que las recibían crónicamente [HR 1,01 (0,78-1,30)] presentaron un efecto neutro en la mortalidad. No obstante, el grupo con estatinas desarrolló con mayor frecuencia datos de citolisis hepática, rabdomiolisis y más eventos trombóticos y hemorrágicos.Conclusiones:En nuestra muestra, las estatinas no se asociaron de forma independiente a una menor mortalidad en pacientes con COVID-19. En aquellos pacientes que tengan indicación de recibirlas por su patología previa es necesario monitorizar estrechamente sus potenciales efectos adversos durante el ingreso hospitalario. (AU)

Aims and objectives:Statins have been proposed as potentially useful agents for modulating the host response in COVID-19. However, solid evidence-based recommendations are still lacking. Our aim was to study the association between statin use and clinical outcomes in a large cohort of hospitalized patients with SARS-CoV-2 infection, as well as the specific consequences of chronic treatment withdrawal during hospital admission.Material and methods:Retrospective observational study including 2191 hospitalized patients with confirmed SARS-CoV-2 infection.Results:Mean age was 68.0±17.8 years and 597 (27.3%) patients died during follow-up. A total of 827 patients (37.7% of the whole sample), received chronic treatment with statins. Even though they underwent more frequent admissions in critical care units, chronic treatment with statins was not independently associated with all-cause mortality [HR 0.95 (0.72-1.25)]. During the whole hospital admission, 371 patients (16.9%) received at least one dose of statin. Although these patients had a significantly worse clinical profile, both treatment with statins during admission [HR 1.03 (0.78-1.35)] and withdrawal of chronic statin treatment [HR 1.01 (0.78-1.30)] showed a neutral effect in mortality. However, patients treated with statins presented more frequently hepatic cytolysis, rhabdomyolysis and thrombotic/hemorrhagic events.Conclusions:In this large cohort of hospitalized COVID-19 patients, statins were not independently associated with all-cause mortality during follow-up. Clinically relevant statin-associated adverse effects should be carefully monitored during hospital admission. (AU)

Effect of tocilizumab versus standard of care in adults hospitalized with moderate-severe COVID-19 pneumonia / Efecto de tocilizumab frente a cuidado estándar en pacientes adultos hospitalizados con neumonía COVID-19 moderada-grave

Introduction and objectives:Tocilizumab is an interleukin-6 receptor-blocking agent proposed for the treatment of severe COVID-19; however, limited data are available on their efficacy. The aim of this study was to assess the effect of tocilizumab on the outcomes of patients with COVID-19 pneumonia by using propensity-score-matching (PSM) analysis.Methods:A retrospective observational analysis of hospitalized COVID-19 adult patients admitted to the Vall d’Hebron Hospital was performed between March and April 2020. We used the logistic regression to analyze the effect of tocilizumab on mortality, as main outcome, and PSM analysis to further validate their effect. Secondary outcomes were length-of-stay (LOS) and intensive-care-unit (ICU) stay. Same outcomes were also assessed for early tocilizumab administration, within 72h after admission. Patients were selected by matching their individual propensity for receiving therapy with tocilizumab, conditional on their demographic and clinical variables.Results:A total of 544 COVID-19 patients were included, 197 (36.2%) were treated with tocilizumab of whom 147 were treated within the first 72h after admission; and 347 were included in the control group. After PSM analyses, the results showed no association between tocilizumab use and overall mortality (OR=1.03, 95%CI: 0.63–1.68). However, shorter ICU-stay in the tocilizumab group was found compared to the control group (Coefficient −4.27 95%CI: −6.63 to −1.92). Similar results were found in the early tocilizumab cohort.Conclusions:The administration of tocilizumab in patients with moderate to severe COVID-19 did not reduce the risk of mortality in our cohort of patients, regardless of the time of administration. (AU)

Introducción y objetivos:El tocilizumab es un agente bloqueador del receptor de la interleucina 6 propuesto para el tratamiento de la COVID-19 grave; sin embargo, se dispone de datos limitados sobre su eficacia. El objetivo de este estudio fue evaluar el efecto de tocilizumab en los resultados de los pacientes con neumonía por COVID-19 mediante un análisis de emparejamiento por propensity-score-matching (PSM, «puntuación de propensión»).Métodos:Se realizó un análisis observacional retrospectivo de los pacientes adultos con COVID-19 ingresados en el Hospital Vall d’Hebron entre marzo y abril de 2020. Se utilizó la regresión logística para analizar el efecto de tocilizumab en la mortalidad, como resultado principal, y el análisis PSM para validar aún más su efecto. Los resultados secundarios fueron la duración de la estancia y la estancia en la unidad de cuidados intensivos (UCI). También se evaluaron los mismos resultados para la administración temprana de tocilizumab, dentro de las 72h posteriores al ingreso. Los pacientes se seleccionaron mediante el emparejamiento de su propensión individual a recibir tratamiento con tocilizumab, condicionado a sus variables demográficas y clínicas.Resultados:Se incluyeron 544 pacientes de COVID-19, 197 (36,2%) fueron tratados con tocilizumab, de los cuales 147 fueron tratados dentro de las primeras 72h tras el ingreso; y 347 fueron incluidos en el grupo control. Tras los análisis PSM, los resultados no mostraron ninguna asociación entre el uso de tocilizumab y la mortalidad global (OR=1,03; IC del 95%: 0,63-1,68). Sin embargo, se encontró una menor estancia en la UCI en el grupo de tocilizumab en comparación con el grupo de control (coeficiente −4,27; IC del 95%: −6,63−−1,92). Se encontraron resultados similares en la cohorte de tocilizumab temprano. (AU)

Consumo de antibióticos en atención primaria en población adulta de Asturias durante el periodo 2014-2020 / Antibiotic consumption in primary care in the adult population of Asturias during 2014–2020 period

Objetivo: Estudiar la evolución del consumo de antibióticos en población adulta en el ámbito de Atención Primaria (AP) del Servicio de Salud del Principado de Asturias (SESPA) durante 2014-2020.DiseñoEstudio observacional retrospectivo.EmplazamientoAP del SESPA.ParticipantesPoblación de la base de datos de Tarjeta Sanitaria Individual.IntervencionesSe recogieron datos de prescripción de antibióticos, realizada en las consultas de medicina de familia, dispensados en las oficinas de farmacia con cargo al SESPA. Se analizaron variables de uso y consumo de antibióticos mediante modelos de regresión lineal.Mediciones principalesPrevalencia de uso de antibióticos (porcentaje población); tasa de consumo de antibióticos de uso sistémico (DTD), consumo relativo de antibióticos de espectro reducido (porcentaje DDD).ResultadosLa prevalencia media del uso de antibióticos del periodo 2014-2019 fue de 32,2% y 23,9% en 2020. La tasa de consumo de antibióticos de uso sistémico pasó de 21,4 DTD en 2014 a 12,7 DTD en 2020. El consumo de antibióticos de espectro reducido se mantuvo estable (19,4% DDD en 2014 y 19,3% DDD en 2020) (IC95: -0,10, 0,26). En el periodo de marzo a diciembre de 2020, el consumo de antibióticos se redujo un 28,6% respecto al mismo periodo de 2019.ConclusionesEn 2014-2020 el consumo de antibióticos disminuyó, especialmente a partir de la pandemia por COVID-19, con estabilización del consumo de antibióticos de espectro reducido respecto al total. Existe variabilidad en el consumo por subgrupos terapéuticos.

Trend study of the consumption of systemic antibiotics in the adult population in of Primary Care of the Health Service of the Principality of Asturias (SESPA) during the period 2014̶2020. Retrospective observational study. SESPA, Primary Care. Population from the Individual Health Card database. Data were collected on the prescription of antibiotics, carried out in the family medicine consultations, dispensed in the pharmacy offices with charge of SESPA. Antibiotic use and consumption variables were analyzed using linear regression models. Prevalence of antibiotic use (population percentage); consumption rate of systemic antibiotics (DTD), relative consumption of narrow-spectrum antibiotics (percentage DDD). The average prevalence of the use of antibiotics for the 2014̶2019 period was 32.2% and 23.9% in 2020. The rate of consumption of systemic antibiotics decreased from 21.4 DTD in 2014 to 12.7 DTD in 2020. The consumption of narrow-spectrum antibiotics remained stable (19.4% DDD in 2014 and 19.3% DDD in 2020) (CI95: −0.10, 0.26). In the period from March to December 2020, the consumption of antibiotics decreased by 28.6% compared to the same period in 2019. In 2014̶2020, the consumption of antibiotics decreased, especially since the COVID-19 pandemic, with stabilization of the consumption of narrow-spectrum antibiotics compared to the total. There is variability in consumption by therapeutic subgroups.

Identifying Inhibitors of -1 Programmed Ribosomal Frameshifting in a Broad Spectrum of Coronaviruses.

Recurrent outbreaks of novel zoonotic coronavirus (CoV) diseases in recent years have highlighted the importance of developing therapeutics with broad-spectrum activity against CoVs. Because all CoVs use -1 programmed ribosomal frameshifting (-1 PRF) to control expression of key viral proteins, the frameshift signal in viral mRNA that stimulates -1 PRF provides a promising potential target for such therapeutics. To test the viability of this strategy, we explored whether small-molecule inhibitors of -1 PRF in SARS-CoV-2 also inhibited -1 PRF in a range of bat CoVs-the most likely source of future zoonoses. Six inhibitors identified in new and previous screens against SARS-CoV-2 were evaluated against the frameshift signals from a panel of representative bat CoVs as well as MERS-CoV. Some drugs had strong activity against subsets of these CoV-derived frameshift signals, while having limited to no effect on -1 PRF caused by frameshift signals from other viruses used as negative controls. Notably, the serine protease inhibitor nafamostat suppressed -1 PRF significantly for multiple CoV-derived frameshift signals. These results suggest it is possible to find small-molecule ligands that inhibit -1 PRF specifically in a broad spectrum of CoVs, establishing frameshift signals as a viable target for developing pan-coronaviral therapeutics.

Naphthoquine: A Potent Broad-Spectrum Anti-Coronavirus Drug In Vitro.

COVID-19 has spread around the world and caused serious public health and social problems. Although several vaccines have been authorized for emergency use, new effective antiviral drugs are still needed. Some repurposed drugs including Chloroquine, Hydroxychloroquine and Remdesivir were immediately used to treat COVID-19 after the pandemic. However, the therapeutic effects of these drugs have not been fully demonstrated in clinical studies. In this paper, we found an antimalarial drug, Naphthoquine, showed good broad-spectrum anti-coronavirus activity. Naphthoquineinhibited HCoV-229E, HCoV-OC43 and SARS-CoV-2 replication in vitro, with IC50 = 2.05 ± 1.44 µM, 5.83 ± 0.74 µM, and 2.01 ± 0.38 µM, respectively. Time-of-addition assay was also performed to explore at which stage Naphthoquine functions during SARS-CoV-2 replication. The results suggested that Naphthoquine may influence virus entry and post-entry replication. Considering the safety of Naphthoquine was even better than that of Chloroquine, we think Naphthoquine has the potential to be used as a broad-spectrum drug for coronavirus infection.

Photodynamic Inactivation of Human Coronaviruses.

Photodynamic inactivation (PDI) employs a photosensitizer, light, and oxygen to create a local burst of reactive oxygen species (ROS) that can inactivate microorganisms. The botanical extract PhytoQuinTM is a powerful photosensitizer with antimicrobial properties. We previously demonstrated that photoactivated PhytoQuin also has antiviral properties against herpes simplex viruses and adenoviruses in a dose-dependent manner across a broad range of sub-cytotoxic concentrations. Here, we report that human coronaviruses (HCoVs) are also susceptible to photodynamic inactivation. Photoactivated-PhytoQuin inhibited the replication of the alphacoronavirus HCoV-229E and the betacoronavirus HCoV-OC43 in cultured cells across a range of sub-cytotoxic doses. This antiviral effect was light-dependent, as we observed minimal antiviral effect of PhytoQuin in the absence of photoactivation. Using RNase protection assays, we observed that PDI disrupted HCoV particle integrity allowing for the digestion of viral RNA by exogenous ribonucleases. Using lentiviruses pseudotyped with the SARS-CoV-2 Spike (S) protein, we once again observed a strong, light-dependent antiviral effect of PhytoQuin, which prevented S-mediated entry into human cells. We also observed that PhytoQuin PDI altered S protein electrophoretic mobility. The PhytoQuin constituent emodin displayed equivalent light-dependent antiviral activity to PhytoQuin in matched-dose experiments, indicating that it plays a central role in PhytoQuin PDI against CoVs. Together, these findings demonstrate that HCoV lipid envelopes and proteins are damaged by PhytoQuin PDI and expands the list of susceptible viruses.

Virtual Screening and Molecular Docking to Study the Mechanism of Chinese Medicines in the Treatment of Coronavirus Infection.

BACKGROUND Heat-clearing and detoxifying herbs (HDHs) play an important role in the prevention and treatment of coronavirus infection. However, their mechanism of action needs further study. This study aimed to explore the anti-coronavirus basis and mechanism of HDHs. MATERIAL AND METHODS Database mining was performed on 7 HDHs. Core ingredients and targets were screened according to ADME rules combined with Neighborhood, Co-occurrence, Co-expression, and other algorithms. GO enrichment and KEGG pathway analyses were performed using the R language. Finally, high-throughput molecular docking was used for verification. RESULTS HDHs mainly acts on NOS3, EGFR, IL-6, MAPK8, PTGS2, MAPK14, NFKB1, and CASP3 through quercetin, luteolin, wogonin, indirubin alkaloids, ß-sitosterol, and isolariciresinol. These targets are mainly involved in the regulation of biological processes such as inflammation, activation of MAPK activity, and positive regulation of NF-kappaB transcription factor activity. Pathway analysis further revealed that the pathways regulated by these targets mainly include: signaling pathways related to viral and bacterial infections such as tuberculosis, influenza A, Ras signaling pathways; inflammation-related pathways such as the TLR, TNF, MAPK, and HIF-1 signaling pathways; and immune-related pathways such as NOD receptor signaling pathways. These pathways play a synergistic role in inhibiting lung inflammation and regulating immunity and antiviral activity. CONCLUSIONS HDHs play a role in the treatment of coronavirus infection by regulating the body's immunity, fighting inflammation, and antiviral activities, suggesting a molecular basis and new strategies for the treatment of COVID-19 and a foundation for the screening of new antiviral drugs.

Coronaviral RNA-methyltransferases: function, structure and inhibition.

Coronaviral methyltransferases (MTases), nsp10/16 and nsp14, catalyze the last two steps of viral RNA-cap creation that takes place in cytoplasm. This cap is essential for the stability of viral RNA and, most importantly, for the evasion of innate immune system. Non-capped RNA is recognized by innate immunity which leads to its degradation and the activation of antiviral immunity. As a result, both coronaviral MTases are in the center of scientific scrutiny. Recently, X-ray and cryo-EM structures of both enzymes were solved even in complex with other parts of the viral replication complex. High-throughput screening as well as structure-guided inhibitor design have led to the discovery of their potent inhibitors. Here, we critically summarize the tremendous advancement of the coronaviral MTase field since the beginning of COVID pandemic.

Drug Combinations as a First Line of Defense against Coronaviruses and Other Emerging Viruses.

The world was unprepared for coronavirus disease 2019 (COVID-19) and remains ill-equipped for future pandemics. While unprecedented strides have been made developing vaccines and treatments for COVID-19, there remains a need for highly effective and widely available regimens for ambulatory use for novel coronaviruses and other viral pathogens. We posit that a priority is to develop pan-family drug cocktails to enhance potency, limit toxicity, and avoid drug resistance. We urge cocktail development for all viruses with pandemic potential both in the short term (<1 to 2 years) and longer term with pairs of drugs in advanced clinical testing or repurposed agents approved for other indications. While significant efforts were launched against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in vitro and in the clinic, many studies employed solo drugs and had disappointing results. Here, we review drug combination studies against SARS-CoV-2 and other viruses and introduce a model-driven approach to assess drug pairs with the highest likelihood of clinical efficacy. Where component agents lack sufficient potency, we advocate for synergistic combinations to achieve therapeutic levels. We also discuss issues that stymied therapeutic progress against COVID-19, including testing of agents with low likelihood of efficacy late in clinical disease and lack of focus on developing virologic surrogate endpoints. There is a need to expedite efficient clinical trials testing drug combinations that could be taken at home by recently infected individuals and exposed contacts as early as possible during the next pandemic, whether caused by a coronavirus or another viral pathogen. The approach herein represents a proactive plan for global viral pandemic preparedness.

mTOR kinase is a therapeutic target for respiratory syncytial virus and coronaviruses.

Therapeutic interventions targeting viral infections remain a significant challenge for both the medical and scientific communities. While specific antiviral agents have shown success as therapeutics, viral resistance inevitably develops, making many of these approaches ineffective. This inescapable obstacle warrants alternative approaches, such as the targeting of host cellular factors. Respiratory syncytial virus (RSV), the major respiratory pathogen of infants and children worldwide, causes respiratory tract infection ranging from mild upper respiratory tract symptoms to severe life-threatening lower respiratory tract disease. Despite the fact that the molecular biology of the virus, which was originally discovered in 1956, is well described, there is no vaccine or effective antiviral treatment against RSV infection. Here, we demonstrate that targeting host factors, specifically, mTOR signaling, reduces RSV protein production and generation of infectious progeny virus. Further, we show that this approach can be generalizable as inhibition of mTOR kinases reduces coronavirus gene expression, mRNA transcription and protein production. Overall, defining virus replication-dependent host functions may be an effective means to combat viral infections, particularly in the absence of antiviral drugs.

Multiscale interactome analysis coupled with off-target drug predictions reveals drug repurposing candidates for human coronavirus disease.

The COVID-19 pandemic has highlighted the urgent need for the identification of new antiviral drug therapies for a variety of diseases. COVID-19 is caused by infection with the human coronavirus SARS-CoV-2, while other related human coronaviruses cause diseases ranging from severe respiratory infections to the common cold. We developed a computational approach to identify new antiviral drug targets and repurpose clinically-relevant drug compounds for the treatment of a range of human coronavirus diseases. Our approach is based on graph convolutional networks (GCN) and involves multiscale host-virus interactome analysis coupled to off-target drug predictions. Cell-based experimental assessment reveals several clinically-relevant drug repurposing candidates predicted by the in silico analyses to have antiviral activity against human coronavirus infection. In particular, we identify the MET inhibitor capmatinib as having potent and broad antiviral activity against several coronaviruses in a MET-independent manner, as well as novel roles for host cell proteins such as IRAK1/4 in supporting human coronavirus infection, which can inform further drug discovery studies.

An oral SARS-CoV-2 Mpro inhibitor clinical candidate for the treatment of COVID-19.

The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.