Identification of the binding interactions of some novel antiviral compounds against Nsp1 protein from SARS-CoV-2 (COVID-19) through high throughput screening

Human coronaviruses (HCoVs), including severe acute respiratory syndrome coronavirus (SARS-CoV) and 2019 novel coronavirus (2019-nCoV), also known as SARS-CoV-2, have caused global epidemics with high morbidity and mortality. Active research on finding effective drugs against 2019-nCoV/SARS-CoV-2 is going on. In silico screening represents the best approach for hits identification and could shorten the time and reduce cost compared to de novo drug discovery. Recently, CoV2 mutations have been a big concern in India, particularly on non-structural proteins (NSPs) and Spike Protein (B.1.617) which are the key targets that play a pivotal role in mediating viral replication and transcription. Herein, this study analyzed the NSPs and spike’s structural aspects of mutant strains of SARS-CoV-2. The three-dimensional structures of NSPs and S Spike proteins were retrieved from the protein data bank or modeled. And a dataset of an antiviral compound library containing 490,000 drug-like ligands and structurally diverse biologically active scaffolds was used for our studies. Initially, the molecular alignment was performed for library compounds with the reference drug molecule to find targets that match the field points. Antiviral compounds having a similarity score >0.6; were selected for further docking studies with wild and mutant NSPs and S Spike protein of SARS-CoV-2 variant B.1.617. The docking studies identified a potent analog MA-11, which exhibited the highest binding affinity towards wild and mutant proteins. Further, molecular dynamics simulation studies of selected compounds confirmed their perfect fitting into NSP12 and spike active sites and offer direction for further lead optimization and rational drug design.

By the end of 2019, the sudden outbreak of the novel coronavirus disease (COVID-19) has become a global threat. It is called COVID-19 because it was caused by the novel coronavirus (SARS-COV-2) in 2019. A total of 1.9 M deaths and 87.9 M cases have been reported all over the world, where 49M cases have recovered so far. Scientists are working hard to find chemotherapeutics and vaccines for COVID-19. Mutations in SARS-CoV-2 have been observed in a combination of several hazardous stresses, making them more resistant and beneficial. So to break down the viral system, the disease targets are examined. In today's review, a comprehensive study of spike protein explains the main purpose of the novel coronavirus and how to prevent the spread of the disease virus cross-transmission from infected to a healthy person. Covid-19 has already been declared a pandemic by the World Health Organization (WHO) due to its result in causing death and severe illness globally. SARS-CoV-2 is highly contagious; however, the intermediate host of the novel coronavirus is not clear. To explore the mechanisms of disease, one of the viral targets, such as the spike protein that binds to human cells and causes the disease by altering its genetic structure which is considered along with potential inhibitors. It has been shown that the interaction of receptor-binding domain (RBD) protein of SARS- CoV-2 spike and the angiotensin-converting enzyme 2 (ACE2) host receptor and further replication of coronavirus spike protein causes its invasion in the host cell. The human Lymphocyte antigen 6 complex, Locus E (LY6E), inhibits the entry of CoV into host cells by interfering with the human gene, inducing spike protein-mediated membrane fusion. Some natural formulations have also been shown to prevent spike protein from binding to the host cell. With the development of the LY6E gene activator that can inhibit spike protein- ACE2-mediated membrane fusion, new opportunities for SARS-CoV-2 treatment may emerge. Existing antiviral fusion inhibitors and natural compounds targeting spike resistance can serve as a template for further SARS-CoV-2 drug formulation.

Background: Chloroquine and HydroxyChloroquine have been successfully used against the treatment of COVID 19 disease spread by a coronavirus (SARS-CoV-2)(1). However, the use of these drugs is still questionable especially because of their efficacy and side effects. We report the use of an in-silico approach for high throughput screening of FDA approved antiviral drugs and plant compounds having antiviral activities against coronavirus (SARS-CoV-2)[2]. Materials and Methods: Protein structures Experimental structures of Receptor binding domains (RBD) of spike proteins from Severe Acute Respiratory Syndrome (SARS CoV-19) are obtained from RCSB data bank with PDB code for spike protein (pdb id: 6VSB (chain A). All water molecules and heteroatoms were removed before submitting to docking simulations. Compound database FDA approved antiviral drugs were downloaded from the Drug Bank database ( https://www.drugbank.ca/ ). A total of 88 chemical drugs was obtained from the drug bank database in PDB format. Based on the available literature of natural antiviral compounds, a total of 191 compounds was downloaded from the PubChem database (Wang et al., 2009). Their Smiles strings (Weininger,1990) were obtained from the PubChem database and converted into the 3D structure via the Corina server. All files were saved in the PDB file format (http://www.molecular-networks.com/online_demos/corina_demo). Molecular docking of compounds with RBD proteins Molecular Docking of Plant antiviral compounds and FDA approved antiviral drugs are performed by Patchdock and Autodock software. Later, the top hits plant and chemical compounds are subjected to VEGA software to predict toxicity and carcinogenicity. Results: Plant compound Tocopheryl-curcumin produces more affinity for spike protein of SARS-CoV-2 as compare to FDA approved drugs. Tocopherylcurcumin binds at the binding site of RBD domain of spike protein (6VSB, chain A) with free energy (∆G) of binding of -11.2 kcal/mol and makes strong hydrogen bonds with amino acid residues of S366, V367, L368, S373, and K529 (Figure 1). Pibrentasvir obtains top rank among FDA approved drugs with free energy (∆G) of binding of -9.6 kcal/mol. Chloroquine (-6.87 kcal/mol) and Hydroxychloroquine (-7.24 kcal/mol) obtain lower rank in our docking study. Toxicity prediction by VEGA tool predicts that tocopherylcurcumin shows no toxicity as compared to FDA approved drugs. Therefore, tocopheryl-curcumin could be used as a potential antiviral (Non toxic) drug against COVID 19 disease as compared to chemical drugs.

The ongoing COVID-19 pandemic inspired exceptional efforts in vaccine development. By January 10, exactly 12 months after the sequence of SARS-CoV-2 was reported, there were eight vaccines cleared for use. Michael Gross reports.

Attacking the flu: New prospects for the rational design of antivirals

A major obstacle in the treatment of chronic hepatitis C virus (HCV) infection has been the lack of effective, well-tolerated therapeutics. Notably, the recent development of the HCV cell culture infection system now allows not only for the study of the entire viral life cycle, but also for the screening of inhibitors against all aspects of HCV infection. However, in order to screen libraries of potential antiviral compounds, it is necessary to develop a highly reproducible, accurate assay for HCV infection adaptable for high-throughput screening (HTS) automation. Using an internally quenched 5-FAM/QXL 520 fluorescence resonance energy transfer (FRET) substrate containing the HCV NS3 peptide cleavage sequence, we report the development of a simple, mix-and-measure, homogenous, cell-based HCV infection assay amendable for HTS. This assay makes use of synchronized, nondividing human hepatoma-derived Huh7 cells, which support more-reproducible long-term HCV infection and can be readily scaled down to a 96-well-plate format. We demonstrate that this stable cell culture method eliminates common problems associated with standard cell-based HTS, such as cell culture variability, poor reproducibility, and low signal intensity. Importantly, this HCV FRET assay not only can identify inhibitors that act throughout the viral life cycle as effectively as more-standard HCV assays, such as real-time quantitative PCR and Western blot analysis, but also exhibits a high degree of accuracy with limited signal variation (i.e., Z' > or = 0.6), providing the basis for a robust HTS campaign for screening compound libraries and identifying novel HCV antivirals.

Context: Mangosteen (Garcinia mangostana L.) is used in traditional medicine as an antibacterial, antioxidant, and anti-inflammatory. Aims: To determine the molecular mechanism and potential of garciniaxanthone derivate compounds from G. mangostana as SARS-CoV-2 antiviral and prevent cytokine storm through in silico approach. Methods: Ligand and protein samples were obtained from databases such as PubChem and Protein Databank, then drug-likeness analysis using Lipinski, Ghose, Veber, Egan, and Muege rules on SwissADME server, prediction of antiviral probability through PASSOnline server. Furthermore, molecular docking simulation with PyRx v1.0 software (Scripps Research, USA) with an academic license, identification of interactions and chemical bond positions of ligands on the target by PoseView server, 3D visualization of PyMOLv.2.5.2 software (Schrödinger, Inc., USA) with an academic license, molecular dynamics simulation for molecular stability prediction by CABS-flex v2.0 server, target prediction of antiviral candidate compounds by SwissTargetPrediction server, pathway analysis through STRING v11.5 database, and toxicity by ProTox-II server were used. Results: Garciniaxanthone C from G. mangostana was found to be a drug-like molecule with low toxicity. This can be a candidate for SARS-Cov-2 antiviral through inhibitor activity on two viral enzymes consisting of Mpro and replicase with a binding affinity value that is more negative than other garciniaxanthone derivates and is stable. Garciniaxanthone C is predicted to bind and inhibit pro-inflammatory proteins that trigger cytokine storms, such as NFKB1 and PTGS2. Conclusions: Garciniaxanthone derivative compounds from G. mangostana may be candidates for SARS-CoV-2 antiviral and preventing cytokine storm through garciniaxanthone C activity.

The XBB.1.5 sub-variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron now continues to spread rapidly due to the increased transmission rate as a result of increased affinity of the virus binding over the ACE-2 receptor - a gained property due to the mutation that occurred in spike protein. The protectivity of BNT162b2 antibodies produced in the serum of patients is an important parameter for preventing transmission. However, the affinity of the antibodies of patients vaccinated with BNT162b2 over the latest SARS-CoV-2 variant, XBB.1.5, is not well established. This study aimed to evaluate the efficacy of the BNT162b2 vaccine-induced antibody on XBB.1.5 by comparing the X-ray crystallographic structures and spike protein mutations of BA.5 and XBB.1.5 using in silico methods. Binding points and binding affinity values of the BNT162b2 antibody with BA.5 and XBB.1.5 spike protein were calculated using ClusPro 2.0 protein-protein docking and Discovery Studio 2021 Client software. Mutations in the genetic code of the spike protein for SARS-CoV-2 BA.5 and XBB.1.5 sub-variants were screened using the GISAID database. Binding affinity values showed that BNT162b2 had higher negative values in the XBB.1.5 sub-variant than BA.5 at the mutation sites at the binding region. The results suggested that BNT162b2 may retain its activity despite mutations and conformational changes in the binding site of the XBB.1.5. The findings of this study shed light on the importance and usability of the current BNT162b2 vaccine for XBB.1.5 and future variants of concern.

CORDITE: The Curated CORona Drug InTERactions Database for SARS-CoV-2.

In March 2020, the World Health Organization (WHO) declared COVID-19 a pandemic, and the spike protein has been reported to be an important drug target for anti-COVID-19 treatment. As such, in this study, we successfully developed a novel electrochemical receptor biosensor by immobilizing the SARS-CoV-2 spike protein and using AuNPs-HRP as an electrochemical signal amplification system. Moreover, the time-current method was used to quantify seven antiviral drug compounds, such as arbidol and chloroquine diphosphate. The results show that the spike protein and the drugs are linearly correlated within a certain concentration range and that the detection sensitivity of the sensor is extremely high. In the low concentration range of linear response, the kinetics of receptor–ligand interactions are similar to that of an enzymatic reaction. Among the investigated drug molecules, bromhexine exhibits the smallest Ka value, and thus, is most sensitively detected by the sensor. Hydroxychloroquine exhibits the largest Ka value. Molecular docking simulations of the spike protein with six small-molecule drugs show that residues of this protein, such as Asp, Trp, Asn, and Gln, form hydrogen bonds with the -OH or -NH2 groups on the branched chains of small-molecule drugs. The electrochemical receptor biosensor can directly quantify the interaction between the spike protein and drugs such as abidor and hydroxychloroquine and perform kinetic studies with a limit of detection 3.3 × 10−20 mol/L, which provides a new research method and idea for receptor–ligand interactions and pharmacodynamic evaluation.

Facing the challenge of viral mutations in the age of pandemic: Developing highly potent, broad-spectrum, and safe COVID-19 vaccines and therapeutics.

D614G mutation eventuates in all VOI and VOC in SARS-CoV-2: Is it part of the positive selection pioneered by Darwin?

Uncovering the impact of SARS-CoV2 spike protein variants on human receptors: A molecular dynamics docking and simulation approach

Identification of phytocompounds as newer antiviral drugs against COVID-19 through molecular docking and simulation based study

The world-wide COVID-19 pandemic has promoted a series of alternative vaccination strategies aiming to elicit neutralizing adaptive immunity in the human host. However, restricted efficacies of these vaccines targeting epitopes on the spike (S) protein that is involved in primary viral entry were observed and putatively assigned to viral glycosylation as an effective escape mechanism. Besides the well-recognized N-glycan shield covering SARS-CoV-2 spike (S) proteins, immunization strategies may be hampered by heavy O-glycosylation and variable O-glycosites fluctuating depending on the organ sites of primary infection and those involved in immunization. A further complication associated with viral glycosylation arises from the development of autoimmune antibodies to self-carbohydrates, including O-linked blood group antigens, as structural parts of viral proteins. This outline already emphasizes the importance of viral glycosylation in general and, in particular, highlights the impact of the site-specific O-glycosylation of virions, since this modification is independent of sequons and varies strongly in dependence on cell-specific repertoires of peptidyl-N-acetylgalactosaminyltransferases with their varying site preferences and of glycan core-specific glycosyltransferases. This review summarizes the current knowledge on the viral O-glycosylation of the SARS-CoV-2 spike protein and its impact on virulence and immune modulation in the host.