1
|
Sinha S, Singh K, Ravi Kumar YS, Roy R, Phadnis S, Meena V, Bhattacharyya S, Verma B. Dengue virus pathogenesis and host molecular machineries. J Biomed Sci 2024; 31:43. [PMID: 38649998 PMCID: PMC11036733 DOI: 10.1186/s12929-024-01030-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 04/14/2024] [Indexed: 04/25/2024] Open
Abstract
Dengue viruses (DENV) are positive-stranded RNA viruses belonging to the Flaviviridae family. DENV is the causative agent of dengue, the most rapidly spreading viral disease transmitted by mosquitoes. Each year, millions of people contract the virus through bites from infected female mosquitoes of the Aedes species. In the majority of individuals, the infection is asymptomatic, and the immune system successfully manages to control virus replication within a few days. Symptomatic individuals may present with a mild fever (Dengue fever or DF) that may or may not progress to a more critical disease termed Dengue hemorrhagic fever (DHF) or the fatal Dengue shock syndrome (DSS). In the absence of a universally accepted prophylactic vaccine or therapeutic drug, treatment is mostly restricted to supportive measures. Similar to many other viruses that induce acute illness, DENV has developed several ways to modulate host metabolism to create an environment conducive to genome replication and the dissemination of viral progeny. To search for new therapeutic options, understanding the underlying host-virus regulatory system involved in various biological processes of the viral life cycle is essential. This review aims to summarize the complex interaction between DENV and the host cellular machinery, comprising regulatory mechanisms at various molecular levels such as epigenetic modulation of the host genome, transcription of host genes, translation of viral and host mRNAs, post-transcriptional regulation of the host transcriptome, post-translational regulation of viral proteins, and pathways involved in protein degradation.
Collapse
Affiliation(s)
- Saumya Sinha
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Kinjal Singh
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Y S Ravi Kumar
- Department of Biotechnology, M. S. Ramaiah Institute of Technology, MSR Nagar, Bengaluru, India
| | - Riya Roy
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Sushant Phadnis
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Varsha Meena
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Sankar Bhattacharyya
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, India
| | - Bhupendra Verma
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
| |
Collapse
|
2
|
Akram M, Hameed S, Hassan A, Khan KM. Development in the Inhibition of Dengue Proteases as Drug Targets. Curr Med Chem 2024; 31:2195-2233. [PMID: 37723635 DOI: 10.2174/0929867331666230918110144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/24/2023] [Accepted: 08/04/2023] [Indexed: 09/20/2023]
Abstract
BACKGROUND Viral infections continue to increase morbidity and mortality severely. The flavivirus genus has fifty different species, including the dengue, Zika, and West Nile viruses that can infect 40% of individuals globally, who reside in at least a hundred different countries. Dengue, one of the oldest and most dangerous human infections, was initially documented by the Chinese Medical Encyclopedia in the Jin period. It was referred to as "water poison," connected to flying insects, i.e., Aedes aegypti and Aedes albopictus. DENV causes some medical expressions like dengue hemorrhagic fever, acute febrile illness, and dengue shock syndrome. OBJECTIVE According to the World Health Organization report of 2012, 2500 million people are in danger of contracting dengue fever worldwide. According to a recent study, 96 million of the 390 million dengue infections yearly show some clinical or subclinical severity. There is no antiviral drug or vaccine to treat this severe infection. It can be controlled by getting enough rest, drinking plenty of water, and using painkillers. The first dengue vaccine created by Sanofi, called Dengvaxia, was previously approved by the USFDA in 2019. All four serotypes of the DENV1-4 have shown re-infection in vaccine recipients. However, the usage of Dengvaxia has been constrained by its adverse effects. CONCLUSION Different classes of compounds have been reported against DENV, such as nitrogen-containing heterocycles (i.e., imidazole, pyridine, triazoles quinazolines, quinoline, and indole), oxygen-containing heterocycles (i.e., coumarins), and some are mixed heterocyclic compounds of S, N (thiazole, benzothiazine, and thiazolidinediones), and N, O (i.e., oxadiazole). There have been reports of computationally designed compounds to impede the molecular functions of specific structural and non-structural proteins as potential therapeutic targets. This review summarized the current progress in developing dengue protease inhibitors.
Collapse
Affiliation(s)
- Muhammad Akram
- Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Shehryar Hameed
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, 75720, Pakistan
| | - Abbas Hassan
- Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Khalid Mohammed Khan
- H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences, University of Karachi, Karachi, 75720, Pakistan
| |
Collapse
|
3
|
Diani E, Lagni A, Lotti V, Tonon E, Cecchetto R, Gibellini D. Vector-Transmitted Flaviviruses: An Antiviral Molecules Overview. Microorganisms 2023; 11:2427. [PMID: 37894085 PMCID: PMC10608811 DOI: 10.3390/microorganisms11102427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/18/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023] Open
Abstract
Flaviviruses cause numerous pathologies in humans across a broad clinical spectrum with potentially severe clinical manifestations, including hemorrhagic and neurological disorders. Among human flaviviruses, some viral proteins show high conservation and are good candidates as targets for drug design. From an epidemiological point of view, flaviviruses cause more than 400 million cases of infection worldwide each year. In particular, the Yellow Fever, dengue, West Nile, and Zika viruses have high morbidity and mortality-about an estimated 20,000 deaths per year. As they depend on human vectors, they have expanded their geographical range in recent years due to altered climatic and social conditions. Despite these epidemiological and clinical premises, there are limited antiviral treatments for these infections. In this review, we describe the major compounds that are currently under evaluation for the treatment of flavivirus infections and the challenges faced during clinical trials, outlining their mechanisms of action in order to present an overview of ongoing studies. According to our review, the absence of approved antivirals for flaviviruses led to in vitro and in vivo experiments aimed at identifying compounds that can interfere with one or more viral cycle steps. Still, the currently unavailability of approved antivirals poses a significant public health issue.
Collapse
Affiliation(s)
- Erica Diani
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, 37134 Verona, Italy; (A.L.); (V.L.); (R.C.)
| | - Anna Lagni
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, 37134 Verona, Italy; (A.L.); (V.L.); (R.C.)
| | - Virginia Lotti
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, 37134 Verona, Italy; (A.L.); (V.L.); (R.C.)
| | - Emil Tonon
- Unit of Microbiology, Azienda Ospedaliera Universitaria Integrata Verona, 37134 Verona, Italy;
| | - Riccardo Cecchetto
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, 37134 Verona, Italy; (A.L.); (V.L.); (R.C.)
- Unit of Microbiology, Azienda Ospedaliera Universitaria Integrata Verona, 37134 Verona, Italy;
| | - Davide Gibellini
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, 37134 Verona, Italy; (A.L.); (V.L.); (R.C.)
- Unit of Microbiology, Azienda Ospedaliera Universitaria Integrata Verona, 37134 Verona, Italy;
| |
Collapse
|
4
|
Delgado-Maldonado T, Moreno-Herrera A, Pujadas G, Vázquez-Jiménez LK, González-González A, Rivera G. Recent advances in the development of methyltransferase (MTase) inhibitors against (re)emerging arboviruses diseases dengue and Zika. Eur J Med Chem 2023; 252:115290. [PMID: 36958266 DOI: 10.1016/j.ejmech.2023.115290] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/14/2023] [Accepted: 03/14/2023] [Indexed: 03/22/2023]
Abstract
Emerging and/or re-emerging viral diseases such as dengue and Zika are a worldwide concern. Therefore, new antiviral therapeutics are necessary. In this sense, a non-structural protein with methyltransferase (MTase) activity is an attractive drug target because it plays a crucial role in dengue and Zika virus replication. Different drug strategies such as virtual screening, molecular docking, and molecular dynamics have identified new inhibitors that bind on the MTase active site. Therefore, in this review, we analyze MTase inhibitors, including S-adenosyl-L-methionine (SAM), S-adenosyl-l-homocysteine (SAH) and guanosine-5'-triphosphate (GTP) analogs, nitrogen-containing heterocycles (pyrimidine, adenosine, and pyridine), urea derivatives, and natural products. Advances in the design of MTase inhibitors could lead to the optimization of a possible single or broad-spectrum antiviral drug against dengue and Zika virus.
Collapse
Affiliation(s)
- Timoteo Delgado-Maldonado
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710, Reynosa, Mexico
| | - Antonio Moreno-Herrera
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710, Reynosa, Mexico
| | - Gerard Pujadas
- Departament de Bioquímica i Biotecnologia, Research group in Cheminformatics & Nutrition, Campus de Sescelades, Universitat Rovira i Virgili, 43007, Tarragona, Catalonia, Spain
| | - Lenci K Vázquez-Jiménez
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710, Reynosa, Mexico
| | - Alonzo González-González
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710, Reynosa, Mexico
| | - Gildardo Rivera
- Laboratorio de Biotecnología Farmacéutica, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, 88710, Reynosa, Mexico.
| |
Collapse
|
5
|
Lee MF, Wu YS, Poh CL. Molecular Mechanisms of Antiviral Agents against Dengue Virus. Viruses 2023; 15:v15030705. [PMID: 36992414 PMCID: PMC10056858 DOI: 10.3390/v15030705] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/07/2023] [Accepted: 03/07/2023] [Indexed: 03/11/2023] Open
Abstract
Dengue is a major global health threat causing 390 million dengue infections and 25,000 deaths annually. The lack of efficacy of the licensed Dengvaxia vaccine and the absence of a clinically approved antiviral against dengue virus (DENV) drive the urgent demand for the development of novel anti-DENV therapeutics. Various antiviral agents have been developed and investigated for their anti-DENV activities. This review discusses the mechanisms of action employed by various antiviral agents against DENV. The development of host-directed antivirals targeting host receptors and direct-acting antivirals targeting DENV structural and non-structural proteins are reviewed. In addition, the development of antivirals that target different stages during post-infection such as viral replication, viral maturation, and viral assembly are reviewed. Antiviral agents designed based on these molecular mechanisms of action could lead to the discovery and development of novel anti-DENV therapeutics for the treatment of dengue infections. Evaluations of combinations of antiviral drugs with different mechanisms of action could also lead to the development of synergistic drug combinations for the treatment of dengue at any stage of the infection.
Collapse
|
6
|
Abstract
Flaviviruses are vector-borne pathogens capable of causing devastating human diseases. The re-emergence of Zika in 2016 notoriously led to a widescale epidemic in the Americas. New daunting evidence suggests that a single mutation in Zika virus genome may increase transmission and pathogenesis, further highlighting the need to be prepared for flavivirus outbreaks. Dengue, in particular infects about 400 million people each year, leading to reoccurring local outbreaks. Public health efforts to mitigate flavivirus transmission is largely dependent on vector control strategies, as only a limited number of flavivirus vaccines have been developed thus far. There are currently no commercially available antivirals for flaviviruses, leaving supportive care as the primary treatment option. In this review, we will briefly paint a broad picture of the flavivirus landscape in terms of therapeutics, with particular focus on viral targets, promising novel compounds entering the drug discovery pipeline, as well as model systems for evaluating drug efficacy.
Collapse
|
7
|
De S, Aamna B, Sahu R, Parida S, Behera SK, Dan AK. Seeking heterocyclic scaffolds as antivirals against dengue virus. Eur J Med Chem 2022; 240:114576. [PMID: 35816877 PMCID: PMC9250831 DOI: 10.1016/j.ejmech.2022.114576] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 12/20/2022]
Abstract
Dengue is one of the most typical viral infection categorized in the Neglected Tropical Diseases (NTDs). It is transmitted via the female Aedes aegypti mosquito to humans and majorly puts risk to the lives of more than half of the world. Recent advancements in medicinal chemistry have led to the design and development of numerous potential heterocyclic scaffolds as antiviral drug candidates for the inhibition of the dengue virus (DENV). Thus, in this review, we have discussed the significance of inhibitory and antiviral activities of nitrogen, oxygen, and mixed (nitrogen-sulfur and nitrogen-oxygen) heterocyclic scaffolds that are published in the last seven years (2016–2022). Furthermore, we have also discussed the probable mechanisms of action and the diverse structure-activity relationships (SARs) of the heterocyclic scaffolds. In addition, this review has elaborately outlined the mechanism of viral infection and the life cycle of DENV in the host cells. The wide set of heterocycles and their SARs will aid in the development of pharmaceuticals that will allow the researchers to synthesize the promising anti-dengue drug candidate in the future.
Collapse
|
8
|
Sundar S, Piramanayagam S, Natarajan J. A review on structural genomics approach applied for drug discovery against three vector-borne viral diseases: Dengue, Chikungunya and Zika. Virus Genes 2022; 58:151-171. [PMID: 35394596 DOI: 10.1007/s11262-022-01898-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 03/22/2022] [Indexed: 12/22/2022]
Abstract
Structural genomics involves the advent of three-dimensional structures of the genome encoded proteins through various techniques available. Numerous structural genomics research groups have been developed across the globe and they contribute enormously to the identification of three-dimensional structures of various proteins. In this review, we have discussed the applications of the structural genomics approach towards the discovery of potential lead-like molecules against the genomic drug targets of three vector-borne diseases, namely, Dengue, Chikungunya and Zika. Currently, all these three diseases are associated with the most important global public health problems and significant economic burden in tropical countries. Structural genomics has accelerated the identification of novel drug targets and inhibitors for the treatment of these diseases. We start with the current development status of the drug targets and antiviral drugs against these three diseases and conclude by describing challenges that need to be addressed to overcome the shortcomings in the process of drug discovery.
Collapse
Affiliation(s)
- Shobana Sundar
- Computational Biology Lab, Department of Bioinformatics, Bharathiar University, Coimbatore, India
| | | | - Jeyakumar Natarajan
- Data Mining and Text Mining Laboratory, Department of Bioinformatics, Bharathiar University, Coimbatore, Tamil Nadu, India.
| |
Collapse
|
9
|
Targeting the Virus Capsid as a Tool to Fight RNA Viruses. Viruses 2022; 14:v14020174. [PMID: 35215767 PMCID: PMC8879806 DOI: 10.3390/v14020174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 12/10/2022] Open
Abstract
Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of efficient vaccines, to target the virus by developed antibodies, others focus on finding antiviral compounds with activities that inhibit selected virus replication steps. Currently, there is an increasing number of antiviral drugs on the market; however, some have unpleasant side effects, are toxic to cells, or the viruses quickly develop resistance to them. As the current situation shows, the combination of multiple antiviral strategies or the combination of the use of various compounds within one strategy is very important. The most desirable are combinations of drugs that inhibit different steps in the virus life cycle. This is an important issue especially for RNA viruses, which replicate their genomes using error-prone RNA polymerases and rapidly develop mutants resistant to applied antiviral compounds. Here, we focus on compounds targeting viral structural capsid proteins, thereby inhibiting virus assembly or disassembly, virus binding to cellular receptors, or acting by inhibiting other virus replication mechanisms. This review is an update of existing papers on a similar topic, by focusing on the most recent advances in the rapidly evolving research of compounds targeting capsid proteins of RNA viruses.
Collapse
|
10
|
Norshidah H, Vignesh R, Lai NS. Updates on Dengue Vaccine and Antiviral: Where Are We Heading? Molecules 2021; 26:molecules26226768. [PMID: 34833860 PMCID: PMC8620506 DOI: 10.3390/molecules26226768] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 12/23/2022] Open
Abstract
Approximately 100–400 million people from more than 100 countries in the tropical and subtropical world are affected by dengue infections. Recent scientific breakthroughs have brought new insights into novel strategies for the production of dengue antivirals and vaccines. The search for specific dengue inhibitors is expanding, and the mechanisms for evaluating the efficacy of novel drugs are currently established, allowing for expedited translation into human trials. Furthermore, in the aftermath of the only FDA-approved vaccine, Dengvaxia, a safer and more effective dengue vaccine candidate is making its way through the clinical trials. Until an effective antiviral therapy and licensed vaccine are available, disease monitoring and vector population control will be the mainstays of dengue prevention. In this article, we highlighted recent advances made in the perspectives of efforts made recently, in dengue vaccine development and dengue antiviral drug.
Collapse
Affiliation(s)
- Harun Norshidah
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Gelugor 11800, Penang, Malaysia;
- Faculty of Pharmacy and Health Sciences, Universiti Kuala Lumpur-Royal College of Medicine Perak, Ipoh 30450, Perak, Malaysia
| | - Ramachandran Vignesh
- Faculty of Medicine, Universiti Kuala Lumpur-Royal College of Medicine Perak, Ipoh 30450, Perak, Malaysia;
| | - Ngit Shin Lai
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Gelugor 11800, Penang, Malaysia;
- Correspondence:
| |
Collapse
|
11
|
Sangiambut S, Promphet N, Chaiyaloom S, Puttikhunt C, Avirutnan P, Kasinrerk W, Sittisombut N, Malasit P. Increased capsid oligomerization is deleterious to dengue virus particle production. J Gen Virol 2021; 102. [PMID: 34410905 DOI: 10.1099/jgv.0.001635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The capsid protein (C) of dengue virus is required for viral infectivity as it packages viral RNA genome into infectious particles. C exists as a homodimer that forms via hydrophobic interactions between the α2 and α4 helices of monomers. To identify C region(s) important for virus particle production, a complementation system was employed in which single-round infectious particles are generated by trans-encapsidation of a viral C-deleted genome by recombinant C expressed in mosquito cells. Mutants harbouring a complete α3 deletion, or a dual Ile65-/Trp69-to-Ala substitution in the α3 helix, exhibited reduced production of infectious virus. Unexpectedly, higher proportions of oligomeric C were detected in cells expressing both mutated forms as compared with the wild-type counterpart, indicating that the α3 helix, through its internal hydrophobic residues, may down-modulate oligomerization of C during particle formation. Compared with wild-type C, the double Ile65-/Trp69 to Ala mutations appeared to hamper viral infectivity but not C and genomic RNA incorporation into the pseudo-infectious virus particles, suggesting that increased C oligomerization may impair DENV replication at the cell entry step.
Collapse
Affiliation(s)
- Sutha Sangiambut
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Natcha Promphet
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Suwipa Chaiyaloom
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Chunya Puttikhunt
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Panisadee Avirutnan
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Watchara Kasinrerk
- Biomedical Technology Research Center National Center for Genetic Engineering and Biotechnology, National Sciences and Technology Development Agency at the Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.,Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Nopporn Sittisombut
- Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Prida Malasit
- Molecular Biology of Dengue and Flaviviruses Research Team, Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Luang, Pathum Thani 12120, Thailand.,Medical Biotechnology Research Unit, National Center for Genetic Engineering and Biotechnology National Science and Technology Development Agency, Bangkok 12120, Thailand.,Siriraj Center of Research Excellence in Dengue and Emerging Pathogens, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.,Division of Dengue Hemorrhagic Fever Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| |
Collapse
|
12
|
S AH, Pujar GV, Sethu AK, Bhagyalalitha M, Singh M. Dengue structural proteins as antiviral drug targets: Current status in the drug discovery & development. Eur J Med Chem 2021; 221:113527. [PMID: 34020338 DOI: 10.1016/j.ejmech.2021.113527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/30/2021] [Accepted: 04/20/2021] [Indexed: 01/04/2023]
Abstract
Dengue virus belongs to the class of RNA viruses and subclass of enveloped single-stranded positive-sense RNA virus. It causes dengue fever (DF), dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS), where DHF and DSS are life-threatening. Even though dengue is an age-old disease, it is still a mystery and continues to be a global threat. Numerous attempts have been carried out in the past few decades to eradicate the virus through vaccine and antiviral drugs, but still battle continues. In this review, the possible drug targets for discovery and development of potential antiviral drugs against structural proteins of dengue virus, the current development status of the antiviral drugs against dengue around the world, and challenges that need to be addressed to overcome the shortcomings in the process of drug discovery have been discussed.
Collapse
Affiliation(s)
- Akshatha H S
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Sri Shivarathreeshwara Nagara, Mysuru, 570015, India
| | - Gurubasavaraj V Pujar
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Sri Shivarathreeshwara Nagara, Mysuru, 570015, India.
| | - Arun Kumar Sethu
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Sri Shivarathreeshwara Nagara, Mysuru, 570015, India
| | - Meduri Bhagyalalitha
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Sri Shivarathreeshwara Nagara, Mysuru, 570015, India
| | - Manisha Singh
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Sri Shivarathreeshwara Nagara, Mysuru, 570015, India
| |
Collapse
|
13
|
Ahmed SK, Haese NN, Cowan JT, Pathak V, Moukha-Chafiq O, Smith VJ, Rodzinak KJ, Ahmad F, Zhang S, Bonin KM, Streblow AD, Streblow CE, Kreklywich CN, Morrison C, Sarkar S, Moorman N, Sander W, Allen R, DeFilippis V, Tekwani BL, Wu M, Hirsch AJ, Smith JL, Tower NA, Rasmussen L, Bostwick R, Maddry JA, Ananthan S, Gerdes JM, Augelli-Szafran CE, Suto MJ, Morrison TE, Heise MT, Streblow DN, Pathak AK. Targeting Chikungunya Virus Replication by Benzoannulene Inhibitors. J Med Chem 2021; 64:4762-4786. [PMID: 33835811 PMCID: PMC9774970 DOI: 10.1021/acs.jmedchem.0c02183] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A benzo[6]annulene, 4-(tert-butyl)-N-(3-methoxy-5,6,7,8-tetrahydronaphthalen-2-yl) benzamide (1a), was identified as an inhibitor against Chikungunya virus (CHIKV) with antiviral activity EC90 = 1.45 μM and viral titer reduction (VTR) of 2.5 log at 10 μM with no observed cytotoxicity (CC50 = 169 μM) in normal human dermal fibroblast cells. Chemistry efforts to improve potency, efficacy, and drug-like properties of 1a resulted in a novel lead compound 8q, which possessed excellent cellular antiviral activity (EC90 = 270 nM and VTR of 4.5 log at 10 μM) and improved liver microsomal stability. CHIKV resistance to an analog of 1a, compound 1c, tracked to a mutation in the nsP3 macrodomain. Further mechanism of action studies showed compounds working through inhibition of human dihydroorotate dehydrogenase in addition to CHIKV nsP3 macrodomain. Moderate efficacy was observed in an in vivo CHIKV challenge mouse model for compound 8q as viral replication was rescued from the pyrimidine salvage pathway.
Collapse
Affiliation(s)
| | | | - Jaden T. Cowan
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Vibha Pathak
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Omar Moukha-Chafiq
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Valerie J. Smith
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Kevin J. Rodzinak
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Fahim Ahmad
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Sixue Zhang
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Kiley M. Bonin
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Aaron D. Streblow
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Cassilyn E. Streblow
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Craig N. Kreklywich
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Clayton Morrison
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Sanjay Sarkar
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Nathaniel Moorman
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Wes Sander
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Robbie Allen
- Oregon Translational Research and Development Institute, Portland, Oregon 97239, United States
| | - Victor DeFilippis
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Babu L. Tekwani
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Mousheng Wu
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Alec J. Hirsch
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Jessica L. Smith
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Nichole A. Tower
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Lynn Rasmussen
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Robert Bostwick
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Joseph A. Maddry
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Subramaniam Ananthan
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - John M Gerdes
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | | | - Mark J. Suto
- Drug Discovery Division, Southern Research, Birmingham, Alabama 35205, United States
| | - Thomas E. Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Mark T. Heise
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Daniel N. Streblow
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, United States
| | - Ashish K. Pathak
- Drug Discovery Division, Southern, Research, Birmingham, Alabama 35205, United States
| |
Collapse
|
14
|
Ali F, Chorsiya A, Anjum V, Khasimbi S, Ali A. A systematic review on phytochemicals for the treatment of dengue. Phytother Res 2020; 35:1782-1816. [PMID: 33118251 DOI: 10.1002/ptr.6917] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/23/2020] [Accepted: 10/04/2020] [Indexed: 02/06/2023]
Abstract
Dengue fever is prevalent in subtopic regions, producing mortality and morbidity worldwide, which have been of major concern to different governments and World Health Organization. The search of new anti-dengue agents from phytochemicals was assumed to be highly emergent in past. The phytochemicals have been used in wide distribution of vector ailments such as malaria. The demand of the phytochemicals is based on the medicines which are mostly considered to be safer, less harmful than synthetic drugs and nontoxic. This review mentions majorly about the phytochemicals potentially inhibiting dengue fever around the world. The phytochemicals have been isolated from different species, have potential for the treatment of dengue. Different crude extracts and essential oils obtained from different species showed a broad activity against different phytochemicals. The current studies showed that natural products represent a rich source of medicines toward the dengue fever. Furthermore, ethnobotanical surveys and laboratory investigation established identified natural plants species in the development of drug discovery to control the dengue fever.
Collapse
Affiliation(s)
- Faraat Ali
- Department of Inspection and Licensing, Laboratory Services, Botswana Medicines Regulatory Authority, Gaborone, Botswana
| | - Anushma Chorsiya
- School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi, India
| | - Varisha Anjum
- Department of Pharmacognosy and Phytochemistry, Faculty of Pharmacy, Jamia Hamdard, New Delhi, India
| | - Shaik Khasimbi
- Department of Pharmaceutical Chemistry, Delhi Institute of Pharmaceutical Sciences and Research (DIPSAR), New Delhi, India
| | - Asad Ali
- Department of Chemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
| |
Collapse
|
15
|
Troost B, Smit JM. Recent advances in antiviral drug development towards dengue virus. Curr Opin Virol 2020; 43:9-21. [PMID: 32795907 DOI: 10.1016/j.coviro.2020.07.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 07/09/2020] [Indexed: 01/29/2023]
Abstract
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.
Collapse
Affiliation(s)
- Berit Troost
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jolanda M Smit
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
| |
Collapse
|
16
|
A cocrystal structure of dengue capsid protein in complex of inhibitor. Proc Natl Acad Sci U S A 2020; 117:17992-18001. [PMID: 32669438 DOI: 10.1073/pnas.2003056117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dengue virus (DENV) was designated as a top 10 public health threat by the World Health Organization in 2019. No clinically approved anti-DENV drug is currently available. Here we report the high-resolution cocrystal structure (1.5 Å) of the DENV-2 capsid protein in complex with an inhibitor that potently suppresses DENV-2 but not other DENV serotypes. The inhibitor induces a "kissing" interaction between two capsid dimers. The inhibitor-bound capsid tetramers are assembled inside virions, resulting in defective uncoating of nucleocapsid when infecting new cells. Resistant DENV-2 emerges through one mutation that abolishes hydrogen bonds in the capsid structure, leading to a loss of compound binding. Structure-based analysis has defined the amino acids responsible for the inhibitor's inefficacy against other DENV serotypes. The results have uncovered an antiviral mechanism through inhibitor-induced tetramerization of the viral capsid and provided essential structural and functional knowledge for rational design of panserotype DENV capsid inhibitors.
Collapse
|
17
|
Pierson TC, Diamond MS. The continued threat of emerging flaviviruses. Nat Microbiol 2020; 5:796-812. [PMID: 32367055 DOI: 10.1038/s41564-020-0714-0] [Citation(s) in RCA: 434] [Impact Index Per Article: 108.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/27/2020] [Indexed: 12/18/2022]
Abstract
Flaviviruses are vector-borne RNA viruses that can emerge unexpectedly in human populations and cause a spectrum of potentially severe diseases including hepatitis, vascular shock syndrome, encephalitis, acute flaccid paralysis, congenital abnormalities and fetal death. This epidemiological pattern has occurred numerous times during the last 70 years, including epidemics of dengue virus and West Nile virus, and the most recent explosive epidemic of Zika virus in the Americas. Flaviviruses are now globally distributed and infect up to 400 million people annually. Of significant concern, outbreaks of other less well-characterized flaviviruses have been reported in humans and animals in different regions of the world. The potential for these viruses to sustain epidemic transmission among humans is poorly understood. In this Review, we discuss the basic biology of flaviviruses, their infectious cycles, the diseases they cause and underlying host immune responses to infection. We describe flaviviruses that represent an established ongoing threat to global health and those that have recently emerged in new populations to cause significant disease. We also provide examples of lesser-known flaviviruses that circulate in restricted areas of the world but have the potential to emerge more broadly in human populations. Finally, we discuss how an understanding of the epidemiology, biology, structure and immunity of flaviviruses can inform the rapid development of countermeasures to treat or prevent human infections as they emerge.
Collapse
Affiliation(s)
- Theodore C Pierson
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, the National Institutes of Health, Bethesda, MD, USA.
| | - Michael S Diamond
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO, USA.
| |
Collapse
|
18
|
Yokokawa F. Recent progress on phenotype-based discovery of dengue inhibitors. RSC Med Chem 2020; 11:541-551. [PMID: 33479655 DOI: 10.1039/d0md00052c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 03/24/2020] [Indexed: 12/19/2022] Open
Abstract
Dengue fever is the world's most prevalent mosquito-borne viral disease caused by the four serotypes of dengue virus, which are widely spread throughout tropical and sub-tropical countries. There has been an urgent need to identify an effective and safe dengue inhibitor as a therapeutic and a prophylactic agent for dengue fever. Most clinically approved antiviral drugs for the treatment of human immunodeficiency syndrome-1 (HIV-1) and hepatitis C virus (HCV) target virally encoded enzymes such as protease or polymerase. Inhibitors of these enzymes were typically identified by target-based screening followed by optimization via structure-based design. However, due to the lack of success to date of research efforts to identify dengue protease and polymerase inhibitors, alternative strategies for anti-dengue drug discovery need to be considered. As a complementary approach to the target-based drug discovery, phenotypic screening is a strategy often used in identification of new chemical starting points with novel mechanisms of action in the area of infectious diseases such as antibiotics, antivirals, and anti-parasitic agents. This article is an overview of recent reports on dengue phenotypic screens and discusses phenotype-based hit-to-lead chemistry optimization. The challenges encountered and the outlook on dengue phenotype-based lead discovery are discussed at the end of this article.
Collapse
Affiliation(s)
- Fumiaki Yokokawa
- Novartis Institute for Tropical Diseases , Emeryville , CA 94608 , USA .
| |
Collapse
|
19
|
Dighe SN, Ekwudu O, Dua K, Chellappan DK, Katavic PL, Collet TA. Recent update on anti-dengue drug discovery. Eur J Med Chem 2019; 176:431-455. [PMID: 31128447 DOI: 10.1016/j.ejmech.2019.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/12/2019] [Accepted: 05/06/2019] [Indexed: 01/27/2023]
Abstract
Dengue is the most important arthropod-borne viral disease of humans, with more than half of the global population living in at-risk areas. Despite the negative impact on public health, there are no antiviral therapies available, and the only licensed vaccine, Dengvaxia®, has been contraindicated in children below nine years of age. In an effort to combat dengue, several small molecules have entered into human clinical trials. Here, we review anti-DENV molecules and their drug targets that have been published within the past five years (2014-2018). Further, we discuss their probable mechanisms of action and describe a role for classes of clinically approved drugs and also an unclassified class of anti-DENV agents. This review aims to enhance our understanding of novel agents and their cognate targets in furthering innovations in the use of small molecules for dengue drug therapies.
Collapse
Affiliation(s)
- Satish N Dighe
- Innovative Medicines Group, Institute of Health & Biomedical Innovation, School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia.
| | - O'mezie Ekwudu
- Innovative Medicines Group, Institute of Health & Biomedical Innovation, School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Kamal Dua
- Discipline of Pharmacy, Graduate School of Health, University of Technology Sydney, Ultimo, Australia
| | - Dinesh Kumar Chellappan
- Department of Life Sciences, School of Pharmacy, International Medical University (IMU), Bukit Jalil, Kuala Lumpur, 57000, Malaysia
| | - Peter L Katavic
- Innovative Medicines Group, Institute of Health & Biomedical Innovation, School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Trudi A Collet
- Innovative Medicines Group, Institute of Health & Biomedical Innovation, School of Clinical Sciences, Queensland University of Technology, Brisbane, Australia
| |
Collapse
|
20
|
Dengue drug discovery: Progress, challenges and outlook. Antiviral Res 2018; 163:156-178. [PMID: 30597183 DOI: 10.1016/j.antiviral.2018.12.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/22/2018] [Accepted: 12/25/2018] [Indexed: 12/14/2022]
Abstract
In the context of the only available vaccine (DENGVAXIA) that was marketed in several countries, but poses higher risks to unexposed individuals, the development of antivirals for dengue virus (DENV), whilst challenging, would bring significant benefits to public health. Here recent progress in the field of DENV drug discovery made in academic laboratories and industry is reviewed. Characteristics of an ideal DENV antiviral molecule, given the specific immunopathology provoked by this acute viral infection, are described. New chemical classes identified from biochemical, biophysical and phenotypic screens that target viral (especially NS4B) and host proteins, offer promising opportunities for further development. In particular, new methodologies ("omics") can accelerate the discovery of much awaited flavivirus specific inhibitors. Challenges and opportunities in lead identification activities as well as the path to clinical development of dengue drugs are discussed. To galvanize DENV drug discovery, collaborative public-public partnerships and open-access resources will greatly benefit both the DENV research community and DENV patients.
Collapse
|