Drug repurposing of minocycline against dengue virus infection

Proteomic and phosphoproteomic analysis of responses to enterovirus A71 infection reveals novel targets for antiviral and viral replication

Hand, foot, and mouth disease (HFMD) is a common infectious disease in infants and children, especially those under five years of age. EV-A71 is a common pathogen that causes HFMD and the primary pathogen leading to severe or fatal HFMD, which is characterized by neurological complications. However, the underlying mechanisms of EV-A71 pathogenesis remain largely unknown. In this report, we used proteomic and phosphorylated proteomic methods to characterize the proteome and phosphoproteome profiles of EV-A71-infected human neuroblastoma SK-N-SH cells. More than 7744 host proteins and 10069 phosphorylation modification sites were successfully quantified. Among them, 974 proteins and 3648 phosphorylation modification sites were regulated significantly during EV-A71 infection. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis revealed that EV-A71 altered cell biological processes, including protein synthesis, RNA splicing and metabolism in SK-N-SH cells. Notably, based on the prediction of upregulated kinases during EV-A71 infection, we identified specific kinase inhibitors approved by the FDA, with ceralasertib, bosutinib, flavin mononucleotide, minocycline, pimasertib and acetylcysteine inhibiting EV-A71 infection. Finally, EV-A71 proteins were found to be phosphorylated during infection, with one site (S184 on 3D polymerase) observed to be crucial for viral replication because a S184A mutation knocked out viral replication. The results improve our understanding of the host response to EV-A71 infection of neuroblastoma cells and provide potential targets for developing anti-EV-A71 strategies.

Cepharanthine inhibits dengue virus production and cytokine secretion

Dengue virus (DENV) infection is a public health problem in tropical and subtropical regions. It can cause a spectrum of clinical manifestations ranging from mild dengue fever (DF) to severe dengue haemorrhagic fever (DHF) and potentially life-threatening disease including dengue shock syndrome (DSS). Severe DENV infection is caused by high viral load and cytokine storm in dengue-infected patients. Currently, there is no specific antiviral drug for DENV infection. An anti-DENV agent that demonstrates inhibitory effects on both DENV replication and cytokine secretion is urgently needed. In this study, cepharanthine (CEP), which is an anti-inflammatory, anti-HIV, and anti-tumor compound isolated from Stephania cepharantha Hayata, was tested for inhibition of DENV infection. We investigated the efficacy of CEP to inhibit DENV infection, replication, and cytokine production. The inhibitory effect of CEP treatment was studied in DENV-infected human chronic myeloid leukemia (K562) cells. The levels of DENV E protein and DENV production were determined by flow cytometry and FFU assay, respectively. CEP treatment significantly reduced viral E protein and viral production in all DENV-1, 2, 3, 4 serotypes. In addition, CEP treatment reduced the IL-6 proinflammatory cytokine production in DENV-infected A549 cells. Taken together, CEP has inhibitory effects on DENV infection specifically at the initial viral replication states and proinflammatory cytokine secretion, and is a promising candidate for further development as an anti-DENV treatment.

S-Adenosyl-l-Homocysteine Exhibits Potential Antiviral Activity Against Dengue Virus Serotype-3 (DENV-3) in Bangladesh: A Viroinformatics-Based Approach

Dengue outbreak is one of the concerning issues in Bangladesh due to the annual outbreak with the alarming number of death and infection. However, there is no effective antiviral drug available to treat dengue-infected patients. This study evaluated and screened antiviral drug candidates against dengue virus serotype 3 (DENV-3) through viroinformatics-based analyses. Since 2017, DENV-3 has been the predominant serotype in Bangladesh. We selected 3 non-structural proteins of DENV-3, named NS3, NS4A, and NS5, as antiviral targets. Protein modeling and validation were performed with VERIFY-3D, Ramachandran plotting, MolProbity, and PROCHECK. We found 4 drug-like compounds from DRUGBANK that can interact with these non-structural proteins of DENV-3. Then, the ADMET profile of these compounds was determined by admetSAR2, and molecular docking was performed with AutoDock, SWISSDOCK, PatchDock, and FireDock. Furthermore, they were subjected to molecular dynamics (MD) simulation study using the DESMOND module of MAESTRO academic version 2021-4 (force field OPLS_2005) to determine their solution's stability in a predefined body environment. Two drug-like compounds named Guanosine-5'-Triphosphate (DB04137) and S-adenosyl-l-homocysteine (DB01752) were found to have an effective binding with these 3 proteins (binding energy > 33.47 KJ/mole). We found NS5 protein was stable and equilibrated in a 100 ns simulation run along with a negligible (<3Å) root-mean-square fluctuation value. The root-mean-square deviation value of the S-adenosyl-l-homocysteine-NS5 complex was less than 3Å, indicating stable binding between them. The global binding energy of S-adenosyl-l-homocysteine with NS5 was -40.52 KJ/mole as ∆G. Moreover, these 2 compounds mentioned above are non-carcinogenic according to their ADMET (chemical absorption, distribution, metabolism, excretion, and toxicity) profile (in silico). These outcomes suggest the suitability of S-adenosyl-l-homocysteine as a potential drug candidate for dengue drug discovery research.

SARS-CoV-2 induces "cytokine storm" hyperinflammatory responses in RA patients through pyroptosis

Background

The coronavirus disease (COVID-19) is a pandemic disease that threatens worldwide public health, and rheumatoid arthritis (RA) is the most common autoimmune disease. COVID-19 and RA are each strong risk factors for the other, but their molecular mechanisms are unclear. This study aims to investigate the biomarkers between COVID-19 and RA from the mechanism of pyroptosis and find effective disease-targeting drugs.

Methods

We obtained the common gene shared by COVID-19, RA (GSE55235), and pyroptosis using bioinformatics analysis and then did the principal component analysis(PCA). The Co-genes were evaluated by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and ClueGO for functional enrichment, the protein-protein interaction (PPI) network was built by STRING, and the k-means machine learning algorithm was employed for cluster analysis. Modular analysis utilizing Cytoscape to identify hub genes, functional enrichment analysis with Metascape and GeneMANIA, and NetworkAnalyst for gene-drug prediction. Network pharmacology analysis was performed to identify target drug-related genes intersecting with COVID-19, RA, and pyroptosis to acquire Co-hub genes and construct transcription factor (TF)-hub genes and miRNA-hub genes networks by NetworkAnalyst. The Co-hub genes were validated using GSE55457 and GSE93272 to acquire the Key gene, and their efficacy was assessed using receiver operating curves (ROC); SPEED2 was then used to determine the upstream pathway. Immune cell infiltration was analyzed using CIBERSORT and validated by the HPA database. Molecular docking, molecular dynamics simulation, and molecular mechanics-generalized born surface area (MM-GBSA) were used to explore and validate drug-gene relationships through computer-aided drug design.

Results

COVID-19, RA, and pyroptosis-related genes were enriched in pyroptosis and pro-inflammatory pathways(the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex, death-inducing signaling complex, regulation of interleukin production), natural immune pathways (Network map of SARS-CoV-2 signaling pathway, activation of NLRP3 inflammasome by SARS-CoV-2) and COVID-19-and RA-related cytokine storm pathways (IL, nuclear factor-kappa B (NF-κB), TNF signaling pathway and regulation of cytokine-mediated signaling). Of these, CASP1 is the most involved pathway and is closely related to minocycline. YY1, hsa-mir-429, and hsa-mir-34a-5p play an important role in the expression of CASP1. Monocytes are high-caspase-1-expressing sentinel cells. Minocycline can generate a highly stable state for biochemical activity by docking closely with the active region of caspase-1.

Conclusions

Caspase-1 is a common biomarker for COVID-19, RA, and pyroptosis, and it may be an important mediator of the excessive inflammatory response induced by SARS-CoV-2 in RA patients through pyroptosis. Minocycline may counteract cytokine storm inflammation in patients with COVID-19 combined with RA by inhibiting caspase-1 expression.

Drug Repurposing: A Strategy for Discovering Inhibitors against Emerging Viral Infections

BACKGROUND

Viral diseases are responsible for several deaths around the world. Over the past few years, the world has seen several outbreaks caused by viral diseases that, for a long time, seemed to possess no risk. These are diseases that have been forgotten for a long time and, until nowadays, there are no approved drugs or vaccines, leading the pharmaceutical industry and several research groups to run out of time in the search for new pharmacological treatments or prevention methods. In this context, drug repurposing proves to be a fast and economically viable technique, considering the fact that it uses drugs that have a well-established safety profile. Thus, in this review, we present the main advances in drug repurposing and their benefit for searching new treatments against emerging viral diseases.

METHODS

We conducted a search in the bibliographic databases (Science Direct, Bentham Science, PubMed, Springer, ACS Publisher, Wiley, and NIH's COVID-19 Portfolio) using the keywords "drug repurposing", "emerging viral infections" and each of the diseases reported here (CoV; ZIKV; DENV; CHIKV; EBOV and MARV) as an inclusion/exclusion criterion. A subjective analysis was performed regarding the quality of the works for inclusion in this manuscript. Thus, the selected works were those that presented drugs repositioned against the emerging viral diseases presented here by means of computational, high-throughput screening or phenotype-based strategies, with no time limit and of relevant scientific value.

RESULTS

291 papers were selected, 24 of which were CHIKV; 52 for ZIKV; 43 for DENV; 35 for EBOV; 10 for MARV; and 56 for CoV and the rest (72 papers) related to the drugs repurposing and emerging viral diseases. Among CoV-related articles, most were published in 2020 (31 papers), updating the current topic. Besides, between the years 2003 - 2005, 10 articles were created, and from 2011 - 2015, there were 7 articles, portraying the outbreaks that occurred at that time. For ZIKV, similar to CoV, most publications were during the period of outbreaks between the years 2016 - 2017 (23 articles). Similarly, most CHIKV (13 papers) and DENV (14 papers) publications occur at the same time interval. For EBOV (13 papers) and MARV (4 papers), they were between the years 2015 - 2016. Through this review, several drugs were highlighted that can be evolved in vivo and clinical trials as possible used against these pathogens showed that remdesivir represent potential treatments against CoV. Furthermore, ribavirin may also be a potential treatment against CHIKV; sofosbuvir against ZIKV; celgosivir against DENV, and favipiravir against EBOV and MARV, representing new hopes against these pathogens.

CONCLUSION

The conclusions of this review manuscript show the potential of the drug repurposing strategy in the discovery of new pharmaceutical products, as from this approach, drugs could be used against emerging viral diseases. Thus, this strategy deserves more attention among research groups and is a promising approach to the discovery of new drugs against emerging viral diseases and also other diseases.

Minocycline prevents primary duck neurons from duck Tembusu virus-induced death

Duck Tembusu virus (DTMUV), a neurotropic flavivirus, is a causative agent of severe neurological diseases in different birds. No approved vaccines or antiviral therapeutic treatments are available to date. The poultry industry experiences significant economic losses due to DTMUV infections. Minocycline is a second-generation semi-synthetic tetracycline analogue that is commonly used as an antimicrobial treatment. Experimental studies have indicated the successful protective effects of minocycline against neuronal cell death from neurodegenerative diseases and viral encephalitis. The aim of this study was to investigate the effects of minocycline on DTMUV infection in neurons. Primary duck neurons were treated with minocycline, which exhibited neuroprotective effects via anti-apoptotic function rather than through viral replication inhibition. Minocycline might serve as a potential effective drug in DTMUV infection.

Dynamic blood single-cell immune responses in patients with COVID-19

The 2019 coronavirus disease (COVID-19) outbreak caused by the SARS-CoV-2 virus is an ongoing global health emergency. However, the virus’ pathogenesis remains unclear, and there is no cure for the disease. We investigated the dynamic changes of blood immune response in patients with COVID-19 at different stages by using 5’ gene expression, T cell receptor (TCR), and B cell receptors (BCR) V(D)J transcriptome analysis at a single-cell resolution. We obtained single-cell mRNA sequencing (scRNA-seq) data of 341,420 peripheral blood mononuclear cells (PBMCs) and 185,430 clonotypic T cells and 28,802 clonotypic B cells from 25 samples of 16 patients with COVID-19 for dynamic studies. In addition, we used three control samples. We found expansion of dendritic cells (DCs), CD14+ monocytes, and megakaryocytes progenitor cells (MP)/platelets and a reduction of naïve CD4+ T lymphocytes in patients with COVID-19, along with a significant decrease of CD8+ T lymphocytes, and natural killer cells (NKs) in patients in critical condition. The type I interferon (IFN-I), mitogen-activated protein kinase (MAPK), and ferroptosis pathways were activated while the disease was active, and recovered gradually after patient conditions improved. Consistent with this finding, the mRNA level of IFN-I signal-induced gene IFI27 was significantly increased in patients with COVID-19 compared with that of the controls in a validation cohort that included 38 patients and 35 controls. The concentration of interferon-α (IFN-α) in the serum of patients with COVID-19 increased significantly compared with that of the controls in an additional cohort of 215 patients with COVID-19 and 106 controls, further suggesting the important role of the IFN-I pathway in the immune response of COVID-19. TCR and BCR sequences analyses indicated that patients with COVID-19 developed specific immune responses against SARS-CoV-2 antigens. Our study reveals a dynamic landscape of human blood immune responses to SARS-CoV-2 infection, providing clues for therapeutic potentials in treating COVID-19.

Discovery of human coronaviruses pan-papain-like protease inhibitors using computational approaches

The papain-like protease (PLpro) is vital for the replication of coronaviruses (CoVs), as well as for escaping innate-immune responses of the host. Hence, it has emerged as an attractive antiviral drug-target. In this study, computational approaches were employed, mainly the structure-based virtual screening coupled with all-atom molecular dynamics (MD) simulations to computationally identify specific inhibitors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PLpro, which can be further developed as potential pan-PLpro based broad-spectrum antiviral drugs. The sequence, structure, and functional conserveness of most deadly human CoVs PLpro were explored, and it was revealed that functionally important catalytic triad residues are well conserved among SARS-CoV, SARS-CoV-2, and middle east respiratory syndrome coronavirus (MERS-CoV). The subsequent screening of a focused protease inhibitors database composed of ∼7,000 compounds resulted in the identification of three candidate compounds, ADM_13083841, LMG_15521745, and SYN_15517940. These three compounds established conserved interactions which were further explored through MD simulations, free energy calculations, and residual energy contribution estimated by MM-PB(GB)SA method. All these compounds showed stable conformation and interacted well with the active residues of SARS-CoV-2 PLpro, and showed consistent interaction profile with SARS-CoV PLpro and MERS-CoV PLpro as well. Conclusively, the reported SARS-CoV-2 PLpro specific compounds could serve as seeds for developing potent pan-PLpro based broad-spectrum antiviral drugs against deadly human coronaviruses. Moreover, the presented information related to binding site residual energy contribution could lead to further optimization of these compounds.

Identification of novel human USP2 inhibitor and its putative role in treatment of COVID-19 by inhibiting SARS-CoV-2 papain-like (PLpro) protease

Human ubiquitin carboxyl-terminal hydrolase-2 (USP2) inhibitors, such as thiopurine analogs, have been reported to inhibit SARS-CoV papain-like proteases (PLpro). The PLpro have significant functional implications in the innate immune response during SARS-CoV-2 infection and considered an important antiviral target. Both proteases share strikingly similar USP fold with right-handed thumb-palm-fingers structural scaffold and conserved catalytic triad Cys-His-Asp/Asn. In this urgency situation of COVID-19 outbreak, there is a lack of in-vitro facilities readily available to test SARS-CoV-2 inhibitors in whole-cell assays. Therefore, we adopted an alternate route to identify potential USP2 inhibitor through integrated in-silico efforts. After an extensive virtual screening protocol, the best compounds were selected and tested. The compound Z93 showed significant IC50 value against Jurkat (9.67 μM) and MOTL-4 cells (11.8 μM). The binding mode of Z93 was extensively analyzed through molecular docking, followed by MD simulations, and molecular interactions were compared with SARS-CoV-2. The relative binding poses of Z93 fitted well in the binding site of both proteases and showed consensus π-π stacking and H-bond interactions with histidine and aspartate/asparagine residues of the catalytic triad. These results led us to speculate that compound Z93 might be the first potential chemical lead against SARS-CoV-2 PLpro, which warrants in-vitro evaluations.

Oral disease-modifying antirheumatic drugs and immunosuppressants with antiviral potential, including SARS-CoV-2 infection: a review

There have been several episodes of viral infection evolving into epidemics in recent decades, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the latest example. Its high infectivity and moderate mortality have resulted in an urgent need to find an effective treatment modality. Although the category of immunosuppressive drugs usually poses a risk of infection due to interference of the immune system, some of them have been found to exert antiviral properties and are already used in daily practice. Recently, hydroxychloroquine and baricitinib have been proposed as potential drugs for SARS-CoV-2. In fact, there are other immunosuppressants known with antiviral activities, including cyclosporine A, hydroxyurea, minocycline, mycophenolic acid, mycophenolate mofetil, leflunomide, tofacitinib, and thalidomide. The inherent antiviral activity could be a treatment choice for patients with coexisting rheumatological disorders and infections. Clinical evidence, their possible mode of actions and spectrum of antiviral activities are included in this review article.

LAY SUMMARY

Immunosuppressants often raise the concern of infection risks, especially for patients with underlying immune disorders. However, some disease-modifying antirheumatic drugs (DMARDs) with inherent antiviral activity would be a reasonable choice in the situation of concomitant viral infections and flare up of autoimmune diseases. This review covers DMARDs of treatment potential for SARS-CoV-2 in part I, and antiviral mechanisms plus trial evidence for viruses other than SARS-CoV-2 in part II.

Recent advances in antiviral drug development towards dengue virus

Despite the high disease burden of dengue virus, there is no approved antiviral treatment or broadly applicable vaccine to treat or prevent dengue virus infection. In the last decade, many antiviral compounds have been identified but only few have been further evaluated in pre-clinical or clinical trials. This review will give an overview of the direct-acting and host-directed antivirals identified to date. Furthermore, important parameters for further development that is, drug properties including efficacy, specificity and stability, pre-clinical animal testing, and combinational drug therapy will be discussed.

A systematic review on use of aminoquinolines for the therapeutic management of COVID-19: Efficacy, safety and clinical trials

Recent global outbreak of the pandemic caused by coronavirus (COVID-19) emphasizes the urgent need for novel antiviral therapeutics. It can be supplemented by utilization of efficient and validated drug discovery approaches such as drug repurposing/repositioning. The well reported and clinically used anti-malarial aminoquinoline drugs (chloroquine and hydroxychloroquine) have shown potential to be repurposed to control the present pandemic by inhibition of COVID-19. The review elaborates the mechanism of action, safety (side effects, adverse effects, toxicity) and details of clinical trials for chloroquine and hydroxychloroquine to benefit the clinicians, medicinal chemist, pharmacologist actively involved in controlling the pandemic and to provide therapeutics for the treatment of COVID-19 infection.

Roles of Macrophage Migration Inhibitory Factor in Dengue Pathogenesis: From Pathogenic Factor to Therapeutic Target

Dengue virus (DENV) infection is the most prevalent mosquito-borne viral infection and can lead to severe dengue hemorrhagic fever (DHF) and even life-threatening dengue shock syndrome (DSS). Although the cytokine storm has been revealed as a critical factor in dengue disease, the limited understanding of dengue immunopathogenesis hinders the development of effective treatments. Macrophage migration inhibitory factor (MIF) is a pleiotropic proinflammatory cytokine that mediates diverse immune responses, and the serum level of MIF positively correlates with disease severity in patients with dengue. MIF is involved in DENV replication and many pathological changes, such as vascular leakage, during DENV infection. In this paper, the pathogenic roles of MIF and the regulation of MIF secretion during DENV infection are reviewed. Furthermore, whether MIF is a potential therapeutic target against DENV infection is also discussed.

Discovery of novel Hepatitis C virus inhibitor targeting multiple allosteric sites of NS5B polymerase

HCV is a viral infection posing a severe global threat when left untreated progress to end-stage liver disease, including cirrhosis and HCC. The NS5B polymerase of HCV is the most potent target that harbors four allosteric binding sites that could interfere with the HCV infection. We present the discovery of a novel synthetic compound that harbors the potential of NS5B polymerase inhibition. All eight compounds belonging to the benzothiazine family of heterocycles displayed no cellular cytotoxicity in HepG2 cells at nontoxic dose concentration (200 μM). Subsequently, among eight compounds of the series, merely compound 5b exhibited significant inhibition of the expression of the HCV NS5B gene as compared to DMSO control in semi-quantitative PCR. Based on our western blot result, 5b at the range of 50, 100 and 200 μM induced 20, 40, and 70% inhibition of NS5B protein respectively. To estimate the binding potential, 5b was docked at respective allosteric sites followed by molecular dynamics (MD) simulations for a period of 20 ns. In addition, binding free energy calculation by MM-GB/PBSA method revealed a conserved interaction profile of residues lining the allosteric sites in agreement with the reported NS5B co-crystallized inhibitors. The presented results provide important information about a novel compound 5b which may facilitate the the discovery of novel inhibitors that tends to target multiple sites on NS5B polymerase.

Suppression of µ1 subunit of the adaptor protein complex 2 reduces dengue virus release

Dengue virus (DENV) requires clathrin-mediated endocytosis for its entry into the cells where the adaptor protein complex (AP) is vital for the clathrin-coated vesicle formation. The role of AP-2 was previously examined in the early stages of DENV infection; however, the role of AP-2 in the late stage of DENV infection was not determined. The µ1 subunit of AP-2 (AP2M1) is one of the most important cytoplasmic carrier domains in clathrin-mediated endocytosis and the phosphorylation of this subunit by the kinase enzyme, AP-2 associated protein kinase 1 (AAK1), stimulates clathrin and supports the cell surface receptor incorporation. In the present study, we primarily aimed to investigate the role of AP2M1 by gene silencing approach as well as using naked DENV RNA transfection into AP2M1 knockdown cells. Secondarily, an inhibitor of AAK1, sunitinib was used to investigate whether AAK1 could influence the virus production in DENV-infected Huh7 cells. The knockdown of AP2M1 in the DENV-infected Huh7 cells displayed a reduction in the viral titer at 24 h post-infection. Furthermore, experiments were conducted to bypass the DENV internalization using a naked DENV RNA transfection into the AP2M1 knockdown cells. Higher intracellular DENV RNA, DENV E protein, and intracellular virion were observed, whereas the extracellular virion production was comparably less than that of control. Treatment with sunitinib in DENV-infected Huh7 cells was able to reduce extracellular virion production and was consistent with all four serotypes of DENV. Therefore, our findings demonstrate the role of AP2M1 in the exocytosis step of DENV replication leading to infectious DENV production and the efficacy of sunitinib in suppressing virus production during the infection with different serotypes of DENV.

Antibiotic Minocycline Prevents Respiratory Syncytial Virus Infection

Treatment drugs, besides their specific activity, often have multiple effects on the body. The undesired effect of the drug may be repurposed as therapeutics, saving significant investigative time and effort. Minocycline has anti-cancer, anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Presently, minocycline is also known to show anti-viral activity against Influenza virus, Japanese encephalitis virus, Simian immunodeficiency virus, Human immunodeficiency virus and West Nile virus. Here, we investigate the effect of minocycline on Respiratory syncytial virus (RSV), a common respiratory virus that causes severe mortality and morbidity in infants, children, and older adult populations. Currently, there is no effective vaccine or treatment for RSV infection; hence, there is a critical need for alternative and effective drug choices. Our study shows that minocycline reduces the RSV-mediated cytopathic effect and prevents RSV infection. This is the first study demonstrating the anti-viral activity of minocycline against RSV.

Insect anionic septapeptides suppress DENV replication by activating antiviral cytokines and miRNAs in primary human monocytes

Dengue viruses (DENVs) have threatened 2/3 of the world population for decades. Thus, combating DENV infection with either antiviral therapy or protective vaccination is an urgent goal. In the present study, we investigated the anti-DENV activity of insect cell-derived anionic septapeptides from C6/36 mosquito cell cultures persistently infected with DENV. These molecules were previously shown to protect C6/36 and Vero cells against DENV infection. We found that treatment with these septapeptides strongly and rapidly downregulated the multiplication of DENV-1 16007, DENV-3 16562, and DENV-4 1036 but not that of DENV-2 16681 in primary human monocytes. This inhibitory effect was likely mediated through various routes including the increased production of antiviral cytokines (IFN-I), activation of mononuclear cell migration, and upregulation of the expression of antiviral miRNAs (has-miR-30e*, has-miR-133a, and has-miR-223) and inflammation-related miRNAs (has-miR-146a and has-miR-147). In conclusion, anionic septapeptides exerted anti-DENV activity in human monocytes through the upregulation of innate immune responses and the activation of several previously reported antiviral and inflammation-related miRNAs.

In silico structural elucidation of RNA-dependent RNA polymerase towards the identification of potential Crimean-Congo Hemorrhagic Fever Virus inhibitors

The Crimean-Congo Hemorrhagic Fever virus (CCHFV) is a segmented negative single-stranded RNA virus (-ssRNA) which causes severe hemorrhagic fever in humans with a mortality rate of ~50%. To date, no vaccine has been approved. Treatment is limited to supportive care with few investigational drugs in practice. Previous studies have identified viral RNA dependent RNA Polymerase (RdRp) as a potential drug target due to its significant role in viral replication and transcription. Since no crystal structure is available yet, we report the structural elucidation of CCHFV-RdRp by in-depth homology modeling. Even with low sequence identity, the generated model suggests a similar overall structure as previously reported RdRps. More specifically, the model suggests the presence of structural/functional conserved RdRp motifs for polymerase function, the configuration of uniform spatial arrangement of core RdRp sub-domains, and predicted positively charged entry/exit tunnels, as seen in sNSV polymerases. Extensive pharmacophore modeling based on per-residue energy contribution with investigational drugs allowed the concise mapping of pharmacophoric features and identified potential hits. The combination of pharmacophoric features with interaction energy analysis revealed functionally important residues in the conserved motifs together with in silico predicted common inhibitory binding modes with highly potent reference compounds.

Drug repurposing for new, efficient, broad spectrum antivirals

Emerging viruses are a major threat to human health. Recent outbreaks have emphasized the urgent need for new antiviral treatments. For several pathogenic viruses, considerable efforts have focused on vaccine development. However, during epidemics infected individuals need to be treated urgently. High-throughput screening of clinically tested compounds provides a rapid means to identify undiscovered, antiviral functions for well-characterized therapeutics. Repurposed drugs can bypass part of the early cost and time needed for validation and authorization. In this review we describe recent efforts to find broad spectrum antivirals through drug repurposing. We have chosen several candidates and propose strategies to understand their mechanism of action and to determine how resistance to antivirals develops in infected cells.

Drug repurposing of N-acetyl cysteine as antiviral against dengue virus infection

Liver injury is one of the hallmark features of severe dengue virus (DENV) infection since DENV can replicate in the liver and induce hepatocytes to undergo apoptosis. N-acetyl cysteine (NAC), which is a clinically-used drug for treating acetaminophen toxicity, was found to benefit patients with DENV-induced liver injury; however, its mechanism of action remains unclear. Accordingly, our aim was to repurpose NAC in the preclinical studies to investigate its mechanism of action. Time of addition experiments in HepG2 cells elucidated effectiveness of NAC to reduce infectious virion at pre-, during- and post infection. In DENV-infected mice, NAC improved DENV-associated clinical manifestations, including leucopenia and thrombocytopenia, and reduced liver injury and hepatocyte apoptosis. Interestingly, we discovered that NAC significantly reduced DENV production in HepG2 cells and in liver of DENV-infected mice by induction of antiviral responses via interferon signaling. NAC treatment in DENV-infected mice helped to maintain antioxidant enzymes and redox balance in the liver. Therefore, NAC reduces DENV production and oxidative damage to ameliorate DENV-induced liver injury. Taken together, these findings suggest the novel therapeutic potential of NAC in DENV-induced liver injury and recommend evaluating its efficacy and safety in humans with DENV-induced liver injury.

Drug repositioning for dengue haemorrhagic fever by integrating multiple omics analyses

To detect drug candidates for dengue haemorrhagic fever (DHF), we employed a computational drug repositioning method to perform an integrated multiple omics analysis based on transcriptomic, proteomic, and interactomic data. We identified 3,892 significant genes, 389 proteins, and 221 human proteins by transcriptomic analysis, proteomic analysis, and human–dengue virus protein–protein interactions, respectively. The drug candidates were selected using gene expression profiles for inverse drug–disease relationships compared with DHF patients and healthy controls as well as interactomic relationships between the signature proteins and chemical compounds. Integrating the results of the multiple omics analysis, we identified eight candidates for drug repositioning to treat DHF that targeted five proteins (ACTG1, CALR, ERC1, HSPA5, SYNE2) involved in human–dengue virus protein–protein interactions, and the signature proteins in the proteomic analysis mapped to significant pathways. Interestingly, five of these drug candidates, valparoic acid, sirolimus, resveratrol, vorinostat, and Y-27632, have been reported previously as effective treatments for flavivirus-induced diseases. The computational approach using multiple omics data for drug repositioning described in this study can be used effectively to identify novel drug candidates.

Dengue virus non-structural protein 1: a pathogenic factor, therapeutic target, and vaccine candidate

Dengue virus (DENV) infection is the most common mosquito-transmitted viral infection. DENV infection can cause mild dengue fever or severe dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Hemorrhage and vascular leakage are two characteristic symptoms of DHF/DSS. However, due to the limited understanding of dengue pathogenesis, no satisfactory therapies to treat nor vaccine to prevent dengue infection are available, and the mortality of DHF/DSS is still high. DENV nonstructural protein 1 (NS1), which can be secreted in patients’ sera, has been used as an early diagnostic marker for dengue infection for many years. However, the roles of NS1 in dengue-induced vascular leakage were described only recently. In this article, the pathogenic roles of DENV NS1 in hemorrhage and vascular leakage are reviewed, and the possibility of using NS1 as a therapeutic target and vaccine candidate is discussed.

The program of antiviral agents inhibits virus infection

Virus infections are the root cause of epidemics in the world. Vaccines and antiviral agents have been the two important methods to control viral diseases; in recent times, RNA-mediated therapeutics and prevention have received much attention. In this review, we provide an overview of the current information regarding the use of vaccines, antiviral agents, and RNA-mediated methods in controlling or preventing viral infections. We stress specifically on the potential of existing RNA-mediated methods in clinical applications.

Role of mitogen-activated protein kinase signaling in the pathogenesis of dengue virus infection

Dengue virus (DENV) infection is a disease that is endemic to many parts of the world, and its increasing prevalence ranks it among the diseases considered to be a significant threat to public health. The clinical manifestations of DENV infection range from mild dengue fever (DF) to more severe dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Increased proinflammatory cytokines and vascular permeability, both of which cause organ injury, are the hallmarks of severe dengue disease. Signs of liver injury were observed in studies using hepatic cell lines, mouse models, and autopsy specimens from DENV-infected patients, and these signs substantiated the effects of inflammatory responses and hepatic cell apoptosis. Mitogen-activated protein kinases (MAPK) are involved in inflammatory responses and cellular stress during viral infections. The roles of MAPK signaling in DENV infection were reviewed, and published data indicate MAPK signaling to be involved in inflammatory responses and hepatic cell apoptosis in both in vitro cultures and in vivo models. Modulation of MAPK signaling ameliorates the inflammatory responses and hepatic cell apoptosis in DENV infection. This accumulation of published data relative to the role of MAPK signaling in inflammatory responses and cell apoptosis in DENV infection is elucidatory, and may help to accelerate the development of novel or repositioned therapies to treat this unpredictable and often debilitating disease.

Novel activities of safe-in-human broad-spectrum antiviral agents

According to the WHO, there is an urgent need for better control of viral diseases. Re-positioning existing safe-in-human antiviral agents from one viral disease to another could play a pivotal role in this process. Here, we reviewed all approved, investigational and experimental antiviral agents, which are safe in man, and identified 59 compounds that target at least three viral diseases. We tested 55 of these compounds against eight different RNA and DNA viruses. We found novel activities for dalbavancin against echovirus 1, ezetimibe against human immunodeficiency virus 1 and Zika virus, as well as azacitidine, cyclosporine, minocycline, oritavancin and ritonavir against Rift valley fever virus. Thus, the spectrum of antiviral activities of existing antiviral agents could be expanded towards other viral diseases.

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339 approved, investigational and experimental safe-in-human antivirals were identified.

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59 compounds, which target ≥3 viral diseases, were selected.

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55 of the 59 compounds were tested against 8 RNA and DNA viruses.

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7 compounds were found to possess novel antiviral activities.

Vivo-morpholino oligomers strongly inhibit dengue virus replication and production

Dengue virus (DENV) infection is a worldwide public health problem, which can cause severe dengue hemorrhagic fever (DHF) and life-threatening dengue shock syndrome (DSS). There are currently no anti-DENV drugs available, and there has been an intensive search for effective anti-DENV agents that can inhibit all four DENV serotypes. In this study, we tested whether vivo-morpholino oligomers (vivo-MOs), whose effect on DENV infection has not previously been studied, can inhibit DENV infection. Vivo-MOs were designed to target the top of 3' stem-loop (3' SL) in the 3' UTR of the DENV genome and tested for inhibition of DENV infection in monkey kidney epithelial (Vero) cells and human lung epithelial carcinoma (A549) cells. The results showed that vivo-MOs could bind to a DENV RNA sequence and markedly reduce DENV-RNA, protein, and virus production in infected Vero and A549 cells. Vivo-MOs at a concentration of 4 µM could inhibit DENV production by more than 10⁴-fold when compared to that of an untreated control. In addition, vivo-MOs also inhibited DENV production in U937 cells and primary human monocytes. Therefore, vivo-MOs targeting to the 3' SL in the 3' UTR of DENV genomes are effective and have the potential to be developed as anti-DENV agents.

JNK1/2 inhibitor reduces dengue virus-induced liver injury

High viral load with liver injury is exhibited in severe dengue virus (DENV) infection. Mitogen activated protein kinases (MAPKs) including ERK1/2 and p38 MAPK were previously found to be involved in the animal models of DENV-induced liver injury. However, the role of JNK1/2 signaling in DENV-induced liver injury has never been investigated. JNK1/2 inhibitor, SP600125, was used to investigate the role of JNK1/2 signaling in the BALB/c mouse model of DENV-induced liver injury. SP600125-treated DENV-infected mice ameliorated leucopenia, thrombocytopenia, hemoconcentration, liver transaminases and liver histopathology. DENV-induced liver injury exhibited induced phosphorylation of JNK1/2, whereas SP600125 reduced this phosphorylation. An apoptotic real-time PCR array profiler was used to screen how SP600125 affects the expression of 84 cell death-associated genes to minimize DENV-induced liver injury. Modulation of caspase-3, caspase-8 and caspase-9 expressions by SP600125 in DENV-infected mice suggests its efficiency in restricting apoptosis via both extrinsic and intrinsic pathways. Reduced expressions of TNF-α and TRAIL are suggestive to modulate the extrinsic apoptotic signals, where reduced p53 phosphorylation and induced anti-apoptotic Bcl-2 expression indicate the involvement of the intrinsic apoptotic pathway. This study thus demonstrates the pivotal role of JNK1/2 signaling in DENV-induced liver injury and how SP600125 modulates this pathogenesis.