The Conserved Macrodomain Is a Potential Therapeutic Target for Coronaviruses and Alphaviruses

Emerging and re-emerging viral diseases pose continuous public health threats, and effective control requires a combination of non-pharmacologic interventions, treatment with antivirals, and prevention with vaccines. The COVID-19 pandemic has demonstrated that the world was least prepared to provide effective treatments. This lack of preparedness has been due, in large part, to a lack of investment in developing a diverse portfolio of antiviral agents, particularly those ready to combat viruses of pandemic potential. Here, we focus on a drug target called macrodomain that is critical for the replication and pathogenesis of alphaviruses and coronaviruses. Some mutations in alphavirus and coronaviral macrodomains are not tolerated for virus replication. In addition, the coronavirus macrodomain suppresses host interferon responses. Therefore, macrodomain inhibitors have the potential to block virus replication and restore the host’s protective interferon response. Viral macrodomains offer an attractive antiviral target for developing direct acting antivirals because they are highly conserved and have a structurally well-defined (druggable) binding pocket. Given that this target is distinct from the existing RNA polymerase and protease targets, a macrodomain inhibitor may complement current approaches, pre-empt the threat of resistance and offer opportunities to develop combination therapies for combating COVID-19 and future viral threats.

The Broad-Spectrum Antiviral Potential of the Amphibian Peptide AR-23

Viral infections represent a serious threat to the world population and are becoming more frequent. The search and identification of broad-spectrum antiviral molecules is necessary to ensure new therapeutic options, since there is a limited availability of effective antiviral drugs able to eradicate viral infections, and consequently due to the increase of strains that are resistant to the most used drugs. Recently, several studies on antimicrobial peptides identified them as promising antiviral agents. In detail, amphibian skin secretions serve as a rich source of natural antimicrobial peptides. Their antibacterial and antifungal activities have been widely reported, but their exploitation as potential antiviral agents have yet to be fully investigated. In the present study, the antiviral activity of the peptide derived from the secretion of Rana tagoi, named AR-23, was evaluated against both DNA and RNA viruses, with or without envelope. Different assays were performed to identify in which step of the infectious cycle the peptide could act. AR-23 exhibited a greater inhibitory activity in the early stages of infection against both DNA (HSV-1) and RNA (MeV, HPIV-2, HCoV-229E, and SARS-CoV-2) enveloped viruses and, on the contrary, it was inactive against naked viruses (PV-1). Altogether, the results indicated AR-23 as a peptide with potential therapeutic effects against a wide variety of human viruses.

Virus Elimination by Direct-Acting Antiviral Agents Impacts Glucose Homeostasis in Chronic Hepatitis C Patients

Background and AimsChronic hepatitis C virus (HCV) infection is associated with dysregulation of glucose homeostasis, including insulin resistance (IR) and type 2 diabetes. However, independent risk factors associated with IR in chronic HCV-infected patients have not been detailly elucidated. Previous data regarding the impact of HCV elimination by direct-acting antiviral agents (DAAs) on glucose homeostasis is insufficient and controversial. This study aimed to analyze the independent factors associated with IR and to evaluate the changes in glucose homeostasis in chronic HCV-infected patients treated with DAAs therapies.MethodsWe screened 704 patients with chronic HCV infection who underwent treatment with interferon-free DAAs. Patients’ baseline characteristics, biochemical and virological data were collected. The outcome measurements were their IR and β-cell function assessed by the homeostasis model assessment (HOMA) method at baseline and 12-weeks post-treatment.ResultsHigh IR (HOMA-IR ≥ 2.5) was observed in 35.1% of the patients. Multivariable logistic regression analysis revealed that body mass index (BMI) >25 kg/m2, treatment experience, elevated baseline levels of alanine aminotransferase (ALT) and triglyceride, as well as Fibrosis-4 score >3.25 were independently associated with high IR. In patients who achieved sustained virological response (SVR), no significant change in mean HOMA-IR was observed from baseline to 12-weeks post-treatment (2.74 ± 2.78 to 2.54 ± 2.20, p = 0.128). We observed a significant improvement in β-cell secretion stress from 121.0 ± 110.1 to 107.6 ± 93.0 (p = 0.015). Subgroup analysis revealed that SVR was associated with a significant reduction in mean HOMA-IR in patients with baseline HOMA-IR ≥ 2.5 (5.31 ± 3.39 to 3.68 ± 2.57, p < 0.001), HCV genotype 1 (3.05 ± 3.11 to 2.62 ± 2.05, p = 0.027), and treatment experience (4.00 ± 3.37 to 3.01 ± 2.49, p = 0.039).ConclusionsThere were several independent factors associated with IR in patients with chronic HCV infection, including obesity, treatment experience, high serum ALT and triglyceride levels, as well as advanced hepatic fibrosis. After viral elimination by DAAs, we observed a significant reduction in mean HOMA-IR in patients with baseline high IR, HCV genotype 1, and treatment experience.

Herbal Medicine for the Treatmentof Viral Infections: A Systemic Review

The term “Antiviral agents” has been defined in very wide terms as substances other than a virus or virus containing vaccine or specific antibody which can build either a protective or therapeutic effect to the direct measurable advantage of the virus infected host. Viruses are simple in form which are very tiny germs. They comprise of genetic material inside of a protein coating. Viruses cause amicable infectious diseases like common cold, flu and warts. They also cause severe diseases such as HIV/AIDS, Ebola, avian influenzas, dengue virus and COVID-19. Viral diseases are very complex and are easily spread. Herbs and herbal medicines were the foremost in treating infections from centuries over the world in every civilization. Modern science has narrowed the importance of herbal medicine in the past two centuries. But, the side effects and new varieties of diseases creating challenges to modern science. So, usage of herbal medicines is again attaining interests these days. Herbal products for different treatments have achieved a lot of popularity in the last couple of decades. Thus, discovering novel antiviral drugs is of extremely important and natural products are an excellent source for such discoveries. There are many herbs which are excellent sources for the antiviral properties to treat viral infections. This review provides the verified data on the herbal substances with antiviral activity, and some of the herbal marketed antiviral agents like CORONIL TABLETS from Patanjali and different companies had made an attempt to treat viral infections in this pandemic situation. Therefore, herbal plants proved to be a major resort for the treatment of diseases and sickness by traditional healers in many societies.

Virtual Combinatorial Library Screening of Quinadoline B Derivatives against SARS-CoV-2 RNA-Dependent RNA Polymerase

The unprecedented global health threat of SARS-CoV-2 has sparked a continued interest in discovering novel anti-COVID-19 agents. To this end, we present here a computer-based protocol for identifying potential compounds targeting RNA-dependent RNA polymerase (RdRp). Starting from our previous study wherein, using a virtual screening campaign, we identified a fumiquinazolinone alkaloid quinadoline B (Q3), an antiviral fungal metabolite with significant activity against SARS-CoV-2 RdRp, we applied in silico combinatorial methodologies for generating and screening a library of anti-SARS-CoV-2 candidates with strong in silico affinity for RdRp. For this study, the quinadoline pharmacophore was subjected to structural iteration, obtaining a Q3-focused library of over 900,000 unique structures. This chemical library was explored to identify binders of RdRp with greater affinity with respect to the starting compound Q3. Coupling this approach with the evaluation of physchem profile, we found 26 compounds with significant affinities for the RdRp binding site. Moreover, top-ranked compounds were submitted to molecular dynamics to evaluate the stability of the systems during a selected time, and to deeply investigate the binding mode of the most promising derivatives. Among the generated structures, five compounds, obtained by inserting nucleotide-like scaffolds (1, 2, and 5), heterocyclic thiazolyl benzamide moiety (compound 3), and a peptide residue (compound 4), exhibited enhanced binding affinity for SARS-CoV-2 RdRp, deserving further investigation as possible antiviral agents. Remarkably, the presented in silico procedure provides a useful computational procedure for hit-to-lead optimization, having implications in anti-SARS-CoV-2 drug discovery and in general in the drug optimization process.

Regression of liver fibrosis and hepatocellular carcinoma development after HCV eradication with oral antiviral agents

We prospectively investigated the changes of liver stiffness (LS) and the occurrence of hepatocellular carcinoma (HCC) after hepatitis C virus (HCV) eradication using direct antiviral agents (DAA) over three years. LS measurement using transient elastography and serum fibrosis surrogate markers before treatment and at 48, 96, 144 weeks after starting direct-acting antivirals (DAA) according to the protocol were evaluated. Patients were also compared with historical cohort treated with pegylated interferon (peg-IFN). Sustained viral response (SVR) was observed in 95.8%. LS value in the patients achieving SVR significantly decreased over time (19.4 ± 12.9 kPa [baseline], 13.9 ± 9.1 kPa [48 weeks], 11.7 ± 8.2 kPa [96 weeks], 10.09 ± 6.23 [144 weeks], all p < 0.001). With matched analysis, the decrease in LS value was significantly larger in DAA group than peg-IFN group at both 48 weeks (29% vs. 9%) and 96 weeks (39% vs. 17%). The incidence of HCC was not significantly different between DAA and peg-IFN groups (5.5% vs. 5.4%) at 144 weeks. HCV eradication with DAA can lead to improvement of liver stiffness over time. The regression of fibrosis was greater in the group with DAA than peg-IFN.Clinical trials registration: ClinicalTrials.gov (NCT02865369).