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1.
Viruses ; 13(12)2021 12 14.
Article in English | MEDLINE | ID: covidwho-1572668

ABSTRACT

Broad-spectrum antiviral therapies hold promise as a first-line defense against emerging viruses by blunting illness severity and spread until vaccines and virus-specific antivirals are developed. The nucleobase favipiravir, often discussed as a broad-spectrum inhibitor, was not effective in recent clinical trials involving patients infected with Ebola virus or SARS-CoV-2. A drawback of favipiravir use is its rapid clearance before conversion to its active nucleoside-5'-triphosphate form. In this work, we report a synergistic reduction of flavivirus (dengue, Zika), orthomyxovirus (influenza A), and coronavirus (HCoV-OC43 and SARS-CoV-2) replication when the nucleobases favipiravir or T-1105 were combined with the antimetabolite 6-methylmercaptopurine riboside (6MMPr). The 6MMPr/T-1105 combination increased the C-U and G-A mutation frequency compared to treatment with T-1105 or 6MMPr alone. A further analysis revealed that the 6MMPr/T-1105 co-treatment reduced cellular purine nucleotide triphosphate synthesis and increased conversion of the antiviral nucleobase to its nucleoside-5'-monophosphate, -diphosphate, and -triphosphate forms. The 6MMPr co-treatment specifically increased production of the active antiviral form of the nucleobases (but not corresponding nucleosides) while also reducing levels of competing cellular NTPs to produce the synergistic effect. This in-depth work establishes a foundation for development of small molecules as possible co-treatments with nucleobases like favipiravir in response to emerging RNA virus infections.


Subject(s)
Antimetabolites/pharmacology , Antiviral Agents/pharmacology , RNA Viruses/drug effects , Adenosine Triphosphate/metabolism , Amides/pharmacology , Animals , Cell Line , Drug Synergism , Guanosine Triphosphate/metabolism , Humans , Methylthioinosine/pharmacology , Mutation/drug effects , Phosphoribosyl Pyrophosphate/metabolism , Pyrazines/pharmacology , RNA Viruses/classification , RNA Viruses/genetics , RNA, Viral/drug effects , RNA, Viral/genetics , Virus Replication/drug effects
2.
PLoS Pathog ; 17(10): e1009726, 2021 10.
Article in English | MEDLINE | ID: covidwho-1484867

ABSTRACT

The zinc finger antiviral protein (ZAP) is a broad inhibitor of virus replication. Its best-characterized function is to bind CpG dinucleotides present in viral RNAs and, through the recruitment of TRIM25, KHNYN and other cofactors, target them for degradation or prevent their translation. The long and short isoforms of ZAP (ZAP-L and ZAP-S) have different intracellular localization and it is unclear how this regulates their antiviral activity against viruses with different sites of replication. Using ZAP-sensitive and ZAP-insensitive human immunodeficiency virus type I (HIV-1), which transcribe the viral RNA in the nucleus and assemble virions at the plasma membrane, we show that the catalytically inactive poly-ADP-ribose polymerase (PARP) domain in ZAP-L is essential for CpG-specific viral restriction. Mutation of a crucial cysteine in the C-terminal CaaX box that mediates S-farnesylation and, to a lesser extent, the residues in place of the catalytic site triad within the PARP domain, disrupted the activity of ZAP-L. Addition of the CaaX box to ZAP-S partly restored antiviral activity, explaining why ZAP-S lacks antiviral activity for CpG-enriched HIV-1 despite conservation of the RNA-binding domain. Confocal microscopy confirmed the CaaX motif mediated localization of ZAP-L to vesicular structures and enhanced physical association with intracellular membranes. Importantly, the PARP domain and CaaX box together jointly modulate the interaction between ZAP-L and its cofactors TRIM25 and KHNYN, implying that its proper subcellular localisation is required to establish an antiviral complex. The essential contribution of the PARP domain and CaaX box to ZAP-L antiviral activity was further confirmed by inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication, which replicates in double-membrane vesicles derived from the endoplasmic reticulum. Thus, compartmentalization of ZAP-L on intracellular membranes provides an essential effector function in ZAP-L-mediated antiviral activity against divergent viruses with different subcellular replication sites.


Subject(s)
Prenylation/physiology , RNA Viruses/drug effects , RNA-Binding Proteins/pharmacology , Virus Replication/physiology , CpG Islands/physiology , HEK293 Cells , HIV-1/physiology , HeLa Cells , Humans , RNA Viruses/physiology , RNA, Viral/chemistry , RNA, Viral/metabolism , RNA-Binding Motifs/physiology , RNA-Binding Proteins/chemistry , RNA-Binding Proteins/metabolism , SARS-CoV-2/physiology , Transfection , Virus Replication/drug effects
3.
Curr Res Transl Med ; 69(4): 103309, 2021 10.
Article in English | MEDLINE | ID: covidwho-1459004

ABSTRACT

PURPOSE OF THE STUDY: Currently no treatment has been proven to be efficacious for patients with early symptoms of COVID-19. Although most patients present mild or moderate symptoms, up to 5-10% may have a poor disease progression, so there is an urgent need for effective drugs, which can be administered even before the onset of severe symptoms, i.e. when the course of the disease is modifiable. Recently, promising results of several studies on oral ivermectin have been published, which has prompted us to conduct the present review of the scientific literature. METHODS: A narrative review has been carried out, focusing on the following four main topics: a) short-term efficacy in the treatment of the disease, b) long-term efficacy in the treatment of patients with post-acute symptoms of COVID-19, c) efficacy in the prophylaxis of the disease, and c) safety of ivermectin. RESULTS: The reviewed literature suggests that there seems to be sufficient evidence about the safety of oral ivermectin, as well as the efficacy of the drug in the early-treatment and the prophylaxis of COVID-19. CONCLUSIONS: In the view of the available evidence, the Frontline COVID-19 Critical Care Alliance (FLCCC) recommends the use of oral ivermectin for both prophylaxis and early-treatment of COVID-19. Further well-designed studies should be conducted in order to explore the efficacy and safety of invermectin at low and high doses, following different dosing schedules, in both, the short and long-term treatment.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/drug therapy , Drug Repositioning , Ivermectin/therapeutic use , SARS-CoV-2/drug effects , Antiviral Agents/adverse effects , COVID-19/prevention & control , Case-Control Studies , Dose-Response Relationship, Drug , Humans , Ivermectin/administration & dosage , Ivermectin/adverse effects , Ivermectin/pharmacology , Meta-Analysis as Topic , Multicenter Studies as Topic , Practice Guidelines as Topic , Protein Transport/drug effects , RNA Viruses/drug effects , Randomized Controlled Trials as Topic , Time Factors , Treatment Outcome
4.
Virol J ; 17(1): 136, 2020 09 09.
Article in English | MEDLINE | ID: covidwho-1435256

ABSTRACT

BACKGROUND: Coronaviruses (CoVs) were long thought to only cause mild respiratory and gastrointestinal symptoms in humans but outbreaks of Middle East Respiratory Syndrome (MERS)-CoV, Severe Acute Respiratory Syndrome (SARS)-CoV-1, and the recently identified SARS-CoV-2 have cemented their zoonotic potential and their capacity to cause serious morbidity and mortality, with case fatality rates ranging from 4 to 35%. Currently, no specific prophylaxis or treatment is available for CoV infections. Therefore we investigated the virucidal and antiviral potential of Echinacea purpurea (Echinaforce®) against human coronavirus (HCoV) 229E, highly pathogenic MERS- and SARS-CoVs, as well as the newly identified SARS-CoV-2, in vitro. METHODS: To evaluate the antiviral potential of the extract, we pre-treated virus particles and cells and evaluated remaining infectivity by limited dilution. Furthermore, we exposed cells to the extract after infection to further evaluate its potential as a prophylaxis and treatment against coronaviruses. We also determined the protective effect of Echinaforce® in re-constituted nasal epithelium. RESULTS: In the current study, we found that HCoV-229E was irreversibly inactivated when exposed to Echinaforce® at 3.2 µg/ml IC50. Pre-treatment of cell lines, however, did not inhibit infection with HCoV-229E and post-infection treatment had only a marginal effect on virus propagation at 50 µg/ml. However, we did observe a protective effect in an organotypic respiratory cell culture system by exposing pre-treated respiratory epithelium to droplets of HCoV-229E, imitating a natural infection. The observed virucidal activity of Echinaforce® was not restricted to common cold coronaviruses, as both SARS-CoV-1 and MERS-CoVs were inactivated at comparable concentrations. Finally, the causative agent of COVID-19, SARS-CoV-2 was also inactivated upon treatment with 50µg/ml Echinaforce®. CONCLUSIONS: These results show that Echinaforce® is virucidal against HCoV-229E, upon direct contact and in an organotypic cell culture model. Furthermore, MERS-CoV and both SARS-CoV-1 and SARS-CoV-2 were inactivated at similar concentrations of the extract. Therefore we hypothesize that Echinacea purpurea preparations, such as Echinaforce®, could be effective as prophylactic treatment for all CoVs due to their structural similarities.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Coronavirus 229E, Human/drug effects , Coronavirus Infections/drug therapy , Coronavirus/drug effects , Plant Extracts/pharmacology , Plant Extracts/therapeutic use , Animals , COVID-19 , Cell Line , Chlorocebus aethiops , Common Cold/drug therapy , Common Cold/virology , Coronavirus Infections/virology , Humans , Middle East Respiratory Syndrome Coronavirus/drug effects , Pandemics , Pneumonia, Viral/drug therapy , Pneumonia, Viral/virology , RNA Viruses/drug effects , Randomized Controlled Trials as Topic , SARS-CoV-2 , Severe Acute Respiratory Syndrome/drug therapy , Severe Acute Respiratory Syndrome/virology , Vero Cells
5.
Viruses ; 13(5)2021 05 04.
Article in English | MEDLINE | ID: covidwho-1383920

ABSTRACT

Viral infections are responsible for several chronic and acute diseases in both humans and animals. Despite the incredible progress in human medicine, several viral diseases, such as acquired immunodeficiency syndrome, respiratory syndromes, and hepatitis, are still associated with high morbidity and mortality rates in humans. Natural products from plants or other organisms are a rich source of structurally novel chemical compounds including antivirals. Indeed, in traditional medicine, many pathological conditions have been treated using plant-derived medicines. Thus, the identification of novel alternative antiviral agents is of critical importance. In this review, we summarize novel phytochemicals with antiviral activity against human viruses and their potential application in treating or preventing viral disease.


Subject(s)
Antiviral Agents/pharmacology , Biological Products/pharmacology , Drug Discovery , Animals , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , Biological Products/chemistry , Biological Products/therapeutic use , DNA Viruses/drug effects , DNA Viruses/physiology , Drug Development , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Host-Pathogen Interactions/immunology , Humans , RNA Viruses/drug effects , RNA Viruses/physiology , Virus Diseases/diagnosis , Virus Diseases/drug therapy , Virus Diseases/etiology , Virus Diseases/metabolism , Virus Replication/drug effects
6.
mBio ; 12(2)2021 04 13.
Article in English | MEDLINE | ID: covidwho-1388457

ABSTRACT

Mammalian cells detect microbial molecules known as pathogen-associated molecular patterns (PAMPs) as indicators of potential infection. Upon PAMP detection, diverse defensive responses are induced by the host, including those that promote inflammation and cell-intrinsic antimicrobial activities. Host-encoded molecules released from dying or damaged cells, known as damage-associated molecular patterns (DAMPs), also induce defensive responses. Both DAMPs and PAMPs are recognized for their inflammatory potential, but only the latter are well established to stimulate cell-intrinsic host defense. Here, we report a class of DAMPs that engender an antiviral state in human epithelial cells. These DAMPs include oxPAPC (oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine), PGPC (1-palmitoyl-2-glutaryl phosphatidylcholine), and POVPC [1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphatidylcholine], oxidized lipids that are naturally released from dead or dying cells. Exposing cells to these DAMPs prior to vesicular stomatitis virus (VSV) infection limits viral replication. Mechanistically, these DAMPs prevent viral entry, thereby limiting the percentage of cells that are productively infected and consequently restricting viral load. We found that the antiviral actions of oxidized lipids are distinct from those mediated by the PAMP Poly I:C, in that the former induces a more rapid antiviral response without the induction of the interferon response. These data support a model whereby interferon-independent defensive activities can be induced by DAMPs, which may limit viral replication before PAMP-mediated interferon responses are induced. This antiviral activity may impact viruses that disrupt interferon responses in the oxygenated environment of the lung, such as influenza virus and SARS-CoV-2.IMPORTANCE In this work, we explored how a class of oxidized lipids, spontaneously created during tissue damage and unprogrammed cell lysis, block the earliest events in RNA virus infection in the human epithelium. This gives us novel insight into the ways that we view infection models, unveiling a built-in mechanism to slow viral growth that neither engages the interferon response nor is subject to known viral antagonism. These oxidized phospholipids act prior to infection, allowing time for other, better-known innate immune mechanisms to take effect. This discovery broadens our understanding of host defenses, introducing a soluble factor that alters the cellular environment to protect from RNA virus infection.


Subject(s)
Alarmins/pharmacology , Antiviral Agents/pharmacology , RNA Viruses/drug effects , Virus Internalization/drug effects , Virus Replication/drug effects , A549 Cells , Cell Death/drug effects , Humans , Immunity, Innate , Interferons/genetics , Interferons/metabolism , Kinetics , Pathogen-Associated Molecular Pattern Molecules/pharmacology , Phosphatidylcholines/pharmacology , RNA Viruses/physiology , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Vesiculovirus/drug effects , Vesiculovirus/physiology , Viral Load
7.
Viruses ; 12(6)2020 05 30.
Article in English | MEDLINE | ID: covidwho-1389514

ABSTRACT

Single-stranded positive RNA ((+) ssRNA) viruses include several important human pathogens. Some members are responsible for large outbreaks, such as Zika virus, West Nile virus, SARS-CoV, and SARS-CoV-2, while others are endemic, causing an enormous global health burden. Since vaccines or specific treatments are not available for most viral infections, the discovery of direct-acting antivirals (DAA) is an urgent need. Still, the low-throughput nature of and biosafety concerns related to traditional antiviral assays hinders the discovery of new inhibitors. With the advances of reverse genetics, reporter replicon systems have become an alternative tool for the screening of DAAs. Herein, we review decades of the use of (+) ssRNA viruses replicon systems for the discovery of antiviral agents. We summarize different strategies used to develop those systems, as well as highlight some of the most promising inhibitors identified by the method. Despite the genetic alterations introduced, reporter replicons have been shown to be reliable systems for screening and identification of viral replication inhibitors and, therefore, an important tool for the discovery of new DAAs.


Subject(s)
Antiviral Agents/pharmacology , Drug Discovery/methods , Genes, Reporter/physiology , RNA Viruses/drug effects , Replicon/physiology , Animals , Antiviral Agents/chemistry , Cell Line , Chlorocebus aethiops , Cricetinae , Humans , RNA Viruses/genetics , Transfection , Vero Cells
8.
Viruses ; 13(7)2021 06 27.
Article in English | MEDLINE | ID: covidwho-1289026

ABSTRACT

Many viruses, especially RNA viruses, utilize programmed ribosomal frameshifting and/or stop codon readthrough in their expression, and in the decoding of a few a UGA is dynamically redefined to specify selenocysteine. This recoding can effectively increase viral coding capacity and generate a set ratio of products with the same N-terminal domain(s) but different C-terminal domains. Recoding can also be regulatory or generate a product with the non-universal 21st directly encoded amino acid. Selection for translation speed in the expression of many viruses at the expense of fidelity creates host immune defensive opportunities. In contrast to host opportunism, certain viruses, including some persistent viruses, utilize recoding or adventitious frameshifting as part of their strategy to evade an immune response or specific drugs. Several instances of recoding in small intensively studied viruses escaped detection for many years and their identification resolved dilemmas. The fundamental importance of ribosome ratcheting is consistent with the initial strong view of invariant triplet decoding which however did not foresee the possibility of transitory anticodon:codon dissociation. Deep level dynamics and structural understanding of recoding is underway, and a high level structure relevant to the frameshifting required for expression of the SARS CoV-2 genome has just been determined.


Subject(s)
DNA Viruses/genetics , DNA Viruses/immunology , Histocompatibility Antigens Class I/immunology , Immune Evasion , RNA Viruses/genetics , Antiviral Agents/pharmacology , Codon, Terminator , DNA Viruses/drug effects , Frameshifting, Ribosomal , Histocompatibility Antigens Class I/genetics , Nucleic Acid Conformation , Peptides/immunology , Protein Biosynthesis , RNA Viruses/drug effects , RNA Viruses/immunology
9.
Int J Mol Sci ; 22(8)2021 Apr 17.
Article in English | MEDLINE | ID: covidwho-1206368

ABSTRACT

Viral infections cause a host of fatal diseases and seriously affect every form of life from bacteria to humans. Although most viral infections can receive appropriate treatment thereby limiting damage to life and livelihood with modern medicine and early diagnosis, new types of viral infections are continuously emerging that need to be properly and timely treated. As time is the most important factor in the progress of many deadly viral diseases, early detection becomes of paramount importance for effective treatment. Aptamers are small oligonucleotide molecules made by the systematic evolution of ligands by exponential enrichment (SELEX). Aptamers are characterized by being able to specifically bind to a target, much like antibodies. However, unlike antibodies, aptamers are easily synthesized, modified, and are able to target a wider range of substances, including proteins and carbohydrates. With these advantages in mind, many studies on aptamer-based viral diagnosis and treatments are currently in progress. The use of aptamers for viral diagnosis requires a system that recognizes the binding of viral molecules to aptamers in samples of blood, serum, plasma, or in virus-infected cells. From a therapeutic perspective, aptamers target viral particles or host cell receptors to prevent the interaction between the virus and host cells or target intracellular viral proteins to interrupt the life cycle of the virus within infected cells. In this paper, we review recent attempts to use aptamers for the diagnosis and treatment of various viral infections.


Subject(s)
Antiviral Agents/therapeutic use , Aptamers, Nucleotide/therapeutic use , Virus Diseases/diagnosis , Virus Diseases/drug therapy , Animals , DNA Viruses/drug effects , Humans , RNA Viruses/drug effects , Viral Proteins/drug effects , Virion/drug effects
10.
FEBS Open Bio ; 11(5): 1452-1464, 2021 05.
Article in English | MEDLINE | ID: covidwho-1168813

ABSTRACT

Human pathogenic RNA viruses are threats to public health because they are prone to escaping the human immune system through mutations of genomic RNA, thereby causing local outbreaks and global pandemics of emerging or re-emerging viral diseases. While specific therapeutics and vaccines are being developed, a broad-spectrum therapeutic agent for RNA viruses would be beneficial for targeting newly emerging and mutated RNA viruses. In this study, we conducted a screen of repurposed drugs using Sendai virus (an RNA virus of the family Paramyxoviridae), with human-induced pluripotent stem cells (iPSCs) to explore existing drugs that may present anti-RNA viral activity. Selected hit compounds were evaluated for their efficacy against two important human pathogens: Ebola virus (EBOV) using Huh7 cells and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using Vero E6 cells. Selective estrogen receptor modulators (SERMs), including raloxifene, exhibited antiviral activities against EBOV and SARS-CoV-2. Pioglitazone, a PPARγ agonist, also exhibited antiviral activities against SARS-CoV-2, and both raloxifene and pioglitazone presented a synergistic antiviral effect. Finally, we demonstrated that SERMs blocked entry steps of SARS-CoV-2 into host cells. These findings suggest that the identified FDA-approved drugs can modulate host cell susceptibility against RNA viruses.


Subject(s)
Antiviral Agents/pharmacology , Drug Repositioning , RNA Viruses/drug effects , RNA, Viral/antagonists & inhibitors , SARS-CoV-2/drug effects , Animals , COVID-19/drug therapy , Cell Line , Chlorocebus aethiops , Drug Repositioning/methods , Ebolavirus/drug effects , Ebolavirus/physiology , Humans , Induced Pluripotent Stem Cells/virology , Microbial Sensitivity Tests/methods , Pioglitazone/pharmacology , RNA Viruses/physiology , Raloxifene Hydrochloride/pharmacology , SARS-CoV-2/physiology , Selective Estrogen Receptor Modulators/pharmacology , Sendai virus/drug effects , Sendai virus/physiology , Vero Cells
11.
Virus Res ; 297: 198384, 2021 05.
Article in English | MEDLINE | ID: covidwho-1127061

ABSTRACT

Bovine respiratory disease (BRD) complex is an important viral infection that causes huge economic losses in cattle herds worldwide. However, there is no directly effective antiviral drug application against respiratory viral pathogens; generally, the metaphylactic antibacterial drug applications are used for BRD. Ivermectin (IVM) is currently used as a broad-spectrum anti-parasitic agent both for veterinary and human medicine on some occasions. Moreover, since it is identified as an inhibitor for importin α/ß-mediated nuclear localization signal (NLS), IVM is also reported to have antiviral potential against several RNA and DNA viruses. Since therapeutic use of IVM in COVID-19 cases has recently been postulated, the potential antiviral activity of IVM against bovine respiratory viruses including BRSV, BPIV-3, BoHV-1, BCoV and BVDV are evaluated in this study. For these purposes, virus titration assay was used to evaluate titers in viral harvest from infected cells treated with non-cytotoxic IVM concentrations (1, 2.5 and 5 µM) and compared to titers from non-treated infected cells. This study indicated that IVM inhibits the replication of BCoV, BVDV, BRSV, BPIV-3 and BoHV-1 in a dose-dependent manner in vitro as well as number of extracellular infectious virions. In addition, it was demonstrated that IVM has no clear effect on the attachment and penetration steps of the replication of the studied viruses. Finally, this study shows for the first time that IVM can inhibit infection of BRD-related viral agents namely BCoV, BPIV-3, BVDV, BRSV and BoHV-1 at the concentrations of 2.5 and 5 µM. Consequently, IVM, which is licensed for antiparasitic indications, also deserves to be evaluated as a broad-spectrum antiviral in BRD cases caused by viral pathogens.


Subject(s)
Antiviral Agents/pharmacology , Ivermectin/pharmacology , RNA Viruses/drug effects , Virus Replication/drug effects , Animals , Bovine Respiratory Disease Complex/drug therapy , Cattle , Dogs , Drug Evaluation, Preclinical , Madin Darby Canine Kidney Cells , RNA Viruses/physiology , Virus Attachment/drug effects
12.
ACS Infect Dis ; 7(2): 471-478, 2021 02 12.
Article in English | MEDLINE | ID: covidwho-1006383

ABSTRACT

A series of 7-deazaadenine ribonucleosides bearing alkyl, alkenyl, alkynyl, aryl, or hetaryl groups at position 7 as well as their 5'-O-triphosphates and two types of monophosphate prodrugs (phosphoramidates and S-acylthioethanol esters) were prepared and tested for antiviral activity against selected RNA viruses (Dengue, Zika, tick-borne encephalitis, West Nile, and SARS-CoV-2). The modified triphosphates inhibited the viral RNA-dependent RNA polymerases at micromolar concentrations through the incorporation of the modified nucleotide and stopping a further extension of the RNA chain. 7-Deazaadenosine nucleosides bearing ethynyl or small hetaryl groups at position 7 showed (sub)micromolar antiviral activities but significant cytotoxicity, whereas the nucleosides bearing bulkier heterocycles were still active but less toxic. Unexpectedly, the monophosphate prodrugs were similarly or less active than the corresponding nucleosides in the in vitro antiviral assays, although the bis(S-acylthioethanol) prodrug 14h was transported to the Huh7 cells and efficiently released the nucleoside monophosphate.


Subject(s)
Antiviral Agents/pharmacology , Prodrugs/pharmacology , Purines/pharmacology , RNA Viruses/drug effects , Ribonucleosides/pharmacology , COVID-19/drug therapy , COVID-19/virology , Cell Line, Tumor , Dengue Virus/drug effects , Encephalitis Viruses, Tick-Borne/drug effects , Humans , Phosphates/pharmacology , Purine Nucleosides , RNA-Dependent RNA Polymerase/metabolism , SARS-CoV-2/drug effects , West Nile virus/drug effects , Zika Virus/drug effects
13.
J Nat Prod ; 84(1): 161-182, 2021 01 22.
Article in English | MEDLINE | ID: covidwho-989652

ABSTRACT

Three families of RNA viruses, the Coronaviridae, Flaviviridae, and Filoviridae, collectively have great potential to cause epidemic disease in human populations. The current SARS-CoV-2 (Coronaviridae) responsible for the COVID-19 pandemic underscores the lack of effective medications currently available to treat these classes of viral pathogens. Similarly, the Flaviviridae, which includes such viruses as Dengue, West Nile, and Zika, and the Filoviridae, with the Ebola-type viruses, as examples, all lack effective therapeutics. In this review, we present fundamental information concerning the biology of these three virus families, including their genomic makeup, mode of infection of human cells, and key proteins that may offer targeted therapies. Further, we present the natural products and their derivatives that have documented activities to these viral and host proteins, offering hope for future mechanism-based antiviral therapeutics. By arranging these potential protein targets and their natural product inhibitors by target type across these three families of virus, new insights are developed, and crossover treatment strategies are suggested. Hence, natural products, as is the case for other therapeutic areas, continue to be a promising source of structurally diverse new anti-RNA virus therapeutics.


Subject(s)
Antiviral Agents/therapeutic use , Biological Products/therapeutic use , COVID-19/drug therapy , RNA Virus Infections/drug therapy , Animals , Drug Development , Genome, Viral , Humans , RNA Viruses/drug effects , RNA Viruses/enzymology , RNA Viruses/physiology , Virus Replication
14.
Viruses ; 12(12)2020 12 10.
Article in English | MEDLINE | ID: covidwho-969583

ABSTRACT

Recent RNA virus outbreaks such as Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Ebola virus (EBOV) have caused worldwide health emergencies highlighting the urgent need for new antiviral strategies. Targeting host cell pathways supporting viral replication is an attractive approach for development of antiviral compounds, especially with new, unexplored viruses where knowledge of virus biology is limited. Here, we present a strategy to identify host-targeted small molecule inhibitors using an image-based phenotypic antiviral screening assay followed by extensive target identification efforts revealing altered cellular pathways upon antiviral compound treatment. The newly discovered antiviral compounds showed broad-range antiviral activity against pathogenic RNA viruses such as SARS-CoV-2, EBOV and Crimean-Congo hemorrhagic fever virus (CCHFV). Target identification of the antiviral compounds by thermal protein profiling revealed major effects on proteostasis pathways and disturbance in interactions between cellular HSP70 complex and viral proteins, illustrating the supportive role of HSP70 on many RNA viruses across virus families. Collectively, this strategy identifies new small molecule inhibitors with broad antiviral activity against pathogenic RNA viruses, but also uncovers novel virus biology urgently needed for design of new antiviral therapies.


Subject(s)
Antiviral Agents/pharmacology , Host-Pathogen Interactions/drug effects , RNA Viruses/drug effects , Virus Replication/drug effects , Animals , Cell Line , Ebolavirus/drug effects , Ebolavirus/physiology , HSP70 Heat-Shock Proteins/metabolism , Hemorrhagic Fever Virus, Crimean-Congo/drug effects , Hemorrhagic Fever Virus, Crimean-Congo/physiology , Humans , Protein Binding/drug effects , Protein Stability , Proteome/drug effects , Proteostasis/drug effects , RNA Virus Infections/metabolism , RNA Virus Infections/virology , RNA Viruses/physiology , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Small Molecule Libraries/pharmacology , Viral Proteins/metabolism
15.
Molecules ; 25(23)2020 Dec 03.
Article in English | MEDLINE | ID: covidwho-963646

ABSTRACT

The RNA-dependent RNA polymerase (RdRp) is an essential enzyme for the viral replication process, catalyzing the viral RNA synthesis using a metal ion-dependent mechanism. In recent years, RdRp has emerged as an optimal target for the development of antiviral drugs, as demonstrated by recent approvals of sofosbuvir and remdesivir against Hepatitis C virus (HCV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respectively. In this work, we overview the main sequence and structural features of the RdRp of emerging RNA viruses such as Coronaviruses, Flaviviruses, and HCV, as well as inhibition strategies implemented so far. While analyzing the structural information available on the RdRp of emerging RNA viruses, we provide examples of success stories such as for HCV and SARS-CoV-2. In contrast, Flaviviruses' story has raised attention about how the lack of structural details on catalytically-competent or ligand-bound RdRp strongly hampers the application of structure-based drug design, either in repurposing and conventional approaches.


Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , RNA Viruses/enzymology , RNA-Dependent RNA Polymerase/chemistry , Amides/chemistry , Amides/pharmacology , Coronavirus/drug effects , Coronavirus/enzymology , Coronavirus/genetics , Drug Design , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Flavivirus/drug effects , Flavivirus/enzymology , Flavivirus/genetics , Hepacivirus/drug effects , Hepacivirus/enzymology , Hepacivirus/genetics , Humans , Pyrazines/chemistry , Pyrazines/pharmacology , RNA Virus Infections/epidemiology , RNA Viruses/drug effects , RNA-Dependent RNA Polymerase/antagonists & inhibitors , RNA-Dependent RNA Polymerase/metabolism , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology
16.
J Med Chem ; 63(24): 15371-15388, 2020 12 24.
Article in English | MEDLINE | ID: covidwho-929526

ABSTRACT

Fatal infectious diseases caused by HIV-1, influenza A virus, Ebola virus, and currently pandemic coronavirus highlight the great need for the discovery of antiviral agents in mechanisms different from current viral replication-targeted approaches. Given the critical role of virus-host interactions in the viral life cycle, the development of entry or shedding inhibitors may expand the current repertoire of antiviral agents; the combination of antireplication inhibitors and entry or shedding inhibitors would create a multifaceted drug cocktail with a tandem antiviral mechanism. Therefore, we provide critical information about triterpenoids as potential antiviral agents targeting entry and release, focusing specifically on the emerging aspect of triterpenoid-mediated inhibition of a variety of virus-host membrane fusion mechanisms via a trimer-of-hairpin motif. These properties of triterpenoids supply their host an evolutionary advantage for chemical defense and may protect against an increasingly diverse array of viruses infecting mammals, providing a direction for antiviral drug discovery.


Subject(s)
Antiviral Agents/therapeutic use , RNA Viruses/drug effects , Triterpenes/therapeutic use , Virus Internalization/drug effects , Virus Release/drug effects , Animals , Cell Line, Tumor , Humans , Molecular Structure , SARS-CoV-2/drug effects , Structure-Activity Relationship , Virus Shedding/drug effects
17.
Eur J Pharmacol ; 887: 173553, 2020 Nov 15.
Article in English | MEDLINE | ID: covidwho-764566

ABSTRACT

In 2020 the whole world focused on antivirus drugs towards SARS-CoV-2. Most of the researchers focused on drugs used in other viral infections or malaria. We have not seen such mobilization towards one topic in this century. The whole situation makes clear that progress needs to be made in antiviral drug development. The first step to do it is to characterize the potential antiviral activity of new or already existed drugs on the market. Phenothiazines are antipsychotic agents used previously as antiseptics, anthelminthics, and antimalarials. Up to date, they are tested for a number of other disorders including the broad spectrum of viruses. The goal of this paper was to summarize the current literature on activity toward RNA-viruses of such drugs like chlorpromazine, fluphenazine, perphenazine, prochlorperazine, and thioridazine. We identified 49 papers, where the use of the phenothiazines for 23 viruses from different families were tested. Chlorpromazine, fluphenazine, perphenazine, prochlorperazine, and thioridazine possess anti-viral activity towards different types of viruses. These drugs inhibit clathrin-dependent endocytosis, cell-cell fusion, infection, replication of the virus, decrease viral invasion as well as suppress entry into the host cells. Additionally, since the drugs display activity at nontoxic concentrations they have therapeutic potential for some viruses, still, further research on animal and human subjects are needed in this field to verify cell base research.


Subject(s)
Antipsychotic Agents/pharmacology , Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Phenothiazines/pharmacology , Pneumonia, Viral/drug therapy , RNA Viruses/drug effects , Animals , Antipsychotic Agents/therapeutic use , Antiviral Agents/therapeutic use , COVID-19 , Chlorpromazine/pharmacology , Chlorpromazine/therapeutic use , Fluphenazine/pharmacology , Fluphenazine/therapeutic use , Humans , Pandemics , Perphenazine/pharmacology , Perphenazine/therapeutic use , Phenothiazines/therapeutic use , Prochlorperazine/pharmacology , Prochlorperazine/therapeutic use , SARS-CoV-2 , Thioridazine/pharmacology , Thioridazine/therapeutic use
18.
Sci Rep ; 10(1): 4746, 2020 03 16.
Article in English | MEDLINE | ID: covidwho-740043

ABSTRACT

Ginkgolic acids (GA) are alkylphenol constituents of the leaves and fruits of Ginkgo biloba. GA has shown pleiotropic effects in vitro, including: antitumor effects through inhibition of lipogenesis; decreased expression of invasion associated proteins through AMPK activation; and potential rescue of amyloid-ß (Aß) induced synaptic impairment. GA was also reported to have activity against Escherichia coli and Staphylococcus aureus. Several mechanisms for this activity have been suggested including: SUMOylation inhibition; blocking formation of the E1-SUMO intermediate; inhibition of fatty acid synthase; non-specific SIRT inhibition; and activation of protein phosphatase type-2C. Here we report that GA inhibits Herpes simplex virus type 1 (HSV-1) by inhibition of both fusion and viral protein synthesis. Additionally, we report that GA inhibits human cytomegalovirus (HCMV) genome replication and Zika virus (ZIKV) infection of normal human astrocytes (NHA). We show a broad spectrum of fusion inhibition by GA of all three classes of fusion proteins including HIV, Ebola virus (EBOV), influenza A virus (IAV) and Epstein Barr virus (EBV). In addition, we show inhibition of a non-enveloped adenovirus. Our experiments suggest that GA inhibits virion entry by blocking the initial fusion event. Data showing inhibition of HSV-1 and CMV replication, when GA is administered post-infection, suggest a possible secondary mechanism targeting protein and DNA synthesis. Thus, in light of the strong effect of GA on viral infection, even after the infection begins, it may potentially be used to treat acute infections (e.g. Coronavirus, EBOV, ZIKV, IAV and measles), and also topically for the successful treatment of active lesions (e.g. HSV-1, HSV-2 and varicella-zoster virus (VZV)).


Subject(s)
Antiviral Agents/pharmacology , DNA Virus Infections/metabolism , DNA Viruses/drug effects , RNA Virus Infections/metabolism , RNA Viruses/drug effects , Salicylates/pharmacology , Viral Envelope Proteins/antagonists & inhibitors , Viral Fusion Proteins/antagonists & inhibitors , Animals , Astrocytes/metabolism , Chlorocebus aethiops , DNA Replication/drug effects , DNA Virus Infections/virology , DNA Viruses/genetics , DNA, Viral/genetics , HEK293 Cells , Humans , RNA Virus Infections/virology , RNA Viruses/genetics , Vero Cells , Viral Envelope Proteins/biosynthesis , Viral Fusion Proteins/biosynthesis , Virion/drug effects , Virus Internalization/drug effects , Virus Replication/drug effects
19.
J Cell Biol ; 219(10)2020 10 05.
Article in English | MEDLINE | ID: covidwho-713813

ABSTRACT

With the rapid global spread of SARS-CoV-2, we have become acutely aware of the inadequacies of our ability to respond to viral epidemics. Although disrupting the viral life cycle is critical for limiting viral spread and disease, it has proven challenging to develop targeted and selective therapeutics. Synthetic lethality offers a promising but largely unexploited strategy against infectious viral disease; as viruses infect cells, they abnormally alter the cell state, unwittingly exposing new vulnerabilities in the infected cell. Therefore, we propose that effective therapies can be developed to selectively target the virally reconfigured host cell networks that accompany altered cellular states to cripple the host cell that has been converted into a virus factory, thus disrupting the viral life cycle.


Subject(s)
Antiviral Agents/pharmacology , Host Microbial Interactions/drug effects , Virus Diseases/drug therapy , Virus Replication/drug effects , Drug Discovery , Humans , Immunologic Factors/pharmacology , Metabolic Networks and Pathways/drug effects , Protein Interaction Maps , Proteolysis , RNA Viruses/drug effects , RNA Viruses/physiology , Virus Diseases/genetics
20.
Protein Cell ; 11(10): 723-739, 2020 10.
Article in English | MEDLINE | ID: covidwho-697126

ABSTRACT

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC50 of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.


Subject(s)
Antiviral Agents/pharmacology , Coronavirus Infections/drug therapy , Oxidoreductases/antagonists & inhibitors , Pandemics , Pneumonia, Viral/drug therapy , RNA Viruses/drug effects , Thiazoles/pharmacology , Animals , Antiviral Agents/therapeutic use , Betacoronavirus/drug effects , Betacoronavirus/physiology , Binding Sites/drug effects , COVID-19 , Cell Line , Coronavirus Infections/virology , Crotonates/pharmacology , Cytokine Release Syndrome/drug therapy , Drug Evaluation, Preclinical , Gene Knockout Techniques , Humans , Hydroxybutyrates , Influenza A virus/drug effects , Leflunomide/pharmacology , Mice , Mice, Inbred BALB C , Nitriles , Orthomyxoviridae Infections/drug therapy , Oseltamivir/therapeutic use , Oxidoreductases/metabolism , Oxidoreductases Acting on CH-CH Group Donors , Pneumonia, Viral/virology , Protein Binding/drug effects , Pyrimidines/biosynthesis , RNA Viruses/physiology , SARS-CoV-2 , Structure-Activity Relationship , Thiazoles/therapeutic use , Toluidines/pharmacology , Ubiquinone/metabolism , Virus Replication/drug effects
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