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Krause M, Samolej J, Yakimovich A, Kriston-Vizi J, Huttunen M, Lara-Reyna S, Frickel EM, Mercer J. Vaccinia virus subverts xenophagy through phosphorylation and nuclear targeting of p62. J Cell Biol 2024; 223:e202104129. [PMID: 38709216 PMCID: PMC11076808 DOI: 10.1083/jcb.202104129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 11/13/2023] [Accepted: 02/12/2024] [Indexed: 05/07/2024] Open
Abstract
Autophagy is an essential degradation program required for cell homeostasis. Among its functions is the engulfment and destruction of cytosolic pathogens, termed xenophagy. Not surprisingly, many pathogens use various strategies to circumvent or co-opt autophagic degradation. For poxviruses, it is known that infection activates autophagy, which however is not required for successful replication. Even though these complex viruses replicate exclusively in the cytoplasm, autophagy-mediated control of poxvirus infection has not been extensively explored. Using the prototypic poxvirus, vaccinia virus (VACV), we show that overexpression of the xenophagy receptors p62, NDP52, and Tax1Bp1 restricts poxvirus infection. While NDP52 and Tax1Bp1 were degraded, p62 initially targeted cytoplasmic virions before being shunted to the nucleus. Nuclear translocation of p62 was dependent upon p62 NLS2 and correlated with VACV kinase mediated phosphorylation of p62 T269/S272. This suggests that VACV targets p62 during the early stages of infection to avoid destruction and further implies that poxviruses exhibit multi-layered control of autophagy to facilitate cytoplasmic replication.
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Affiliation(s)
- Melanie Krause
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jerzy Samolej
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Artur Yakimovich
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Janos Kriston-Vizi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Moona Huttunen
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Samuel Lara-Reyna
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Eva-Maria Frickel
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Jason Mercer
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
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2
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Rabaan AA, Alshahrani FS, Garout M, Alissa M, Mashraqi MM, Alshehri AA, Alsaleh AA, Alwarthan S, Sabour AA, Alfaraj AH, AlShehail BM, Alotaibi N, Abduljabbar WA, Aljeldah M, Alestad JH. Repositioning of anti-infective compounds against monkeypox virus core cysteine proteinase: a molecular dynamics study. Mol Divers 2024:10.1007/s11030-023-10802-8. [PMID: 38652365 DOI: 10.1007/s11030-023-10802-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/26/2023] [Indexed: 04/25/2024]
Abstract
Monkeypox virus (MPXV) core cysteine proteinase (CCP) is one of the major drug targets used to examine the inhibitory action of chemical moieties. In this study, an in silico technique was applied to screen 1395 anti-infective compounds to find out the potential molecules against the MPXV-CCP. The top five hits were selected after screening and processed for exhaustive docking based on the docked score of ≤ -9.5 kcal/mol. Later, the top three hits based on the exhaustive-docking score and interaction profile were selected to perform MD simulations. The overall RMSD suggested that two compounds, SC75741 and ammonium glycyrrhizinate, showed a highly stable complex with a standard deviation of 0.18 and 0.23 nm, respectively. Later, the MM/GBSA binding free energies of complexes showed significant binding strength with ΔGTOTAL from -21.59 to -15 kcal/mol. This report reported the potential inhibitory activity of SC75741 and ammonium glycyrrhizinate against MPXV-CCP by competitively inhibiting the binding of the native substrate.
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Affiliation(s)
- Ali A Rabaan
- Molecular Diagnostic Laboratory, Johns Hopkins Aramco Healthcare, 31311, Dhahran, Saudi Arabia.
- College of Medicine, Alfaisal University, 11533, Riyadh, Saudi Arabia.
- Department of Public Health and Nutrition, The University of Haripur, Haripur, 22610, Pakistan.
| | - Fatimah S Alshahrani
- Department of Internal Medicine, College of Medicine, King Saud University, 11362, Riyadh, Saudi Arabia
- Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, King Saud University and King Saud University Medical City, 11451, Riyadh, Saudi Arabia
| | - Mohammed Garout
- Department of Community Medicine and Health Care for Pilgrims, Faculty of Medicine, Umm Al-Qura University, 21955, Makkah, Saudi Arabia
| | - Mohammed Alissa
- Department of Medical Laboratory, College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, 11942, Al-Kharj, Saudi Arabia
| | - Mutaib M Mashraqi
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Najran University, 61441, Najra, Saudi Arabia
| | - Ahmad A Alshehri
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Najran University, 61441, Najra, Saudi Arabia
| | - Abdulmonem A Alsaleh
- Clinical Laboratory Science Department, Mohammed Al-Mana College for Medical Sciences, 34222, Dammam, Saudi Arabia
| | - Sara Alwarthan
- Department of Internal Medicine, College of Medicine, Imam Abdulrahman Bin Faisal University, 34212, Dammam, Saudi Arabia
| | - Amal A Sabour
- Department of Botany and Microbiology, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia
| | - Amal H Alfaraj
- Pediatric Department, Abqaiq General Hospital, First Eastern Health Cluster, 33261, Abqaiq, Saudi Arabia
| | - Bashayer M AlShehail
- Pharmacy Practice Department, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, 31441, Dammam, Saudi Arabia
| | - Nouf Alotaibi
- Clinical pharmacy Department, College of Pharmacy, Umm Al-Qura University, 21955, Makkah, Saudi Arabia
| | - Wesam A Abduljabbar
- Department of Medical laboratory sciences, Fakeeh College for Medical Science, 21134, Jeddah, Saudi Arabia
| | - Mohammed Aljeldah
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, University of Hafr Al Batin, 39831, Hafr Al Batin, Saudi Arabia
| | - Jeehan H Alestad
- Immunology and Infectious Microbiology Department, University of Glasgow, Glasgow, G1 1XQ, UK.
- Microbiology Department, Collage of Medicine, 46300, Jabriya, Kuwait.
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3
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Ghate SD, Pinto L, Alva S, Srinivasa MG, Vangala RK, Naik P, Revanasiddappa BC, Rao RSP. In silico identification of potential phytochemical inhibitors for mpox virus: molecular docking, MD simulation, and ADMET studies. Mol Divers 2024:10.1007/s11030-023-10797-2. [PMID: 38519803 DOI: 10.1007/s11030-023-10797-2] [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: 08/24/2023] [Accepted: 12/19/2023] [Indexed: 03/25/2024]
Abstract
The mpox virus (MPXV), a member of the Poxviridae family, which recently appeared outside of the African continent has emerged as a global threat to public health. Given the scarcity of antiviral treatments for mpox disease, there is a pressing need to identify and develop new therapeutics. We investigated 5715 phytochemicals from 266 species available in IMMPAT database as potential inhibitors for six MPXV targets namely thymidylate kinase (A48R), DNA ligase (A50R), rifampicin resistance protein (D13L), palmytilated EEV membrane protein (F13L), viral core cysteine proteinase (I7L), and DNA polymerase (E9L) using molecular docking. The best-performing phytochemicals were also subjected to molecular dynamics (MD) simulations and in silico ADMET analysis. The top phytochemicals were forsythiaside for A48R, ruberythric acid for A50R, theasinensin F for D13L, theasinensin A for F13L, isocinchophyllamine for I7L, and terchebin for E9L. Interestingly, the binding energies of these potential phytochemical inhibitors were far lower than brincidofovir and tecovirimat, the standard drugs used against MPXV, hinting at better binding properties of the former. These findings may pave the way for developing new MPXV inhibitors based on natural product scaffolds. However, they must be further studied to establish their inhibitory efficacy and toxicity in in vitro and in vivo models.
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Affiliation(s)
- Sudeep D Ghate
- Center for Bioinformatics, NITTE Deemed to be University, Mangaluru, 575018, India.
- Central Research Laboratory, KS Hegde Medical Academy, NITTE Deemed to be University, Mangaluru, 575018, India.
| | - Larina Pinto
- Center for Bioinformatics, NITTE Deemed to be University, Mangaluru, 575018, India
| | - Shivakiran Alva
- Center for Bioinformatics, NITTE Deemed to be University, Mangaluru, 575018, India
| | - Mahendra Gowdru Srinivasa
- Department of Pharmaceutical Chemistry, Nitte (Deemed to be University) NGSM Institute of Pharmaceutical Sciences (NGSMIPS), Mangaluru, 575018, India
| | - Rajani Kanth Vangala
- Institute for Applied Research and Innovation, Neuome Technologies Pvt. Ltd., Bangalore Bioinnovation Centre, IBAB Campus, Electronic City Phase 1, Bangalore, 560100, India
| | - Prashantha Naik
- Department of Biosciences, Mangalore University, Mangaluru, 574199, India
| | - B C Revanasiddappa
- Department of Pharmaceutical Chemistry, Nitte (Deemed to be University) NGSM Institute of Pharmaceutical Sciences (NGSMIPS), Mangaluru, 575018, India
| | - R Shyama Prasad Rao
- Center for Bioinformatics, NITTE Deemed to be University, Mangaluru, 575018, India.
- Central Research Laboratory, KS Hegde Medical Academy, NITTE Deemed to be University, Mangaluru, 575018, India.
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Hernandez-Gonzalez M, Calcraft T, Nans A, Rosenthal PB, Way M. Palisade structure in intact vaccinia virions. mBio 2024; 15:e0313423. [PMID: 38171004 PMCID: PMC10865856 DOI: 10.1128/mbio.03134-23] [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: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
Vaccinia virus assembly in the cytoplasm of infected cells involves the formation of a biconcave viral core inside the maturing viral particle. The boundary of the core is defined by a pseudohexagonal palisade layer, composed of trimers projecting from an inner wall. To understand the assembly of this complex core architecture, we obtained a subnanometer structure of the palisade trimer by cryo-electron tomography and subtomogram averaging of purified intact virions. Using AlphaFold2 structure predictions, we determined that the palisade is formed from trimers of the proteolytically processed form of the viral protein A10. In addition, we found that each A10 protomer associates with an α-helix (residues 24-66) of A4. Cellular localization assays outside the context of infection demonstrate that the A4 N-terminus is necessary and sufficient to interact with A10. The interaction between A4 and A10 provides insights into how the palisade layer might become tightly associated with the viral membrane during virion maturation. Reconstruction of the palisade layer reveals that, despite local hexagonal ordering, the A10/A4 trimers are widely spaced, suggesting that additional components organize the lattice. This spacing would, however, allow the adoption of the characteristic biconcave shape of the viral core. Finally, we also found that the palisade incorporates multiple copies of a hexameric portal structure. We suggest that these portals are formed by E6, a viral protein that is essential for virion assembly and required to release viral mRNA from the core early in infection.IMPORTANCEPoxviruses such as variola virus (smallpox) and monkeypox cause diseases in humans. Other poxviruses, including vaccinia and modified vaccinia Ankara, are used as vaccine vectors. Given their importance, a greater structural understanding of poxvirus virions is needed. We now performed cryo-electron tomography of purified intact vaccinia virions to study the structure of the palisade, a protein lattice that defines the viral core boundary. We identified the main viral proteins that form the palisade and their interaction surfaces and provided new insights into the organization of the viral core.
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Affiliation(s)
- Miguel Hernandez-Gonzalez
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Thomas Calcraft
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Peter B. Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Michael Way
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute, London, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
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5
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Imran M, Abida, Alotaibi NM, Thabet HK, Alruwaili JA, Eltaib L, Alshehri A, Alsaiari AA, Kamal M, Alshammari AMA. Repurposing Anti-Dengue Compounds against Monkeypox Virus Targeting Core Cysteine Protease. Biomedicines 2023; 11:2025. [PMID: 37509664 PMCID: PMC10377189 DOI: 10.3390/biomedicines11072025] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
The monkeypox virus (MPXV) is an enveloped, double-stranded DNA virus belonging to the genus Orthopox viruses. In recent years, the virus has spread to countries where it was previously unknown, turning it into a worldwide emergency for public health. This study employs a structural-based drug design approach to identify potential inhibitors for the core cysteine proteinase of MPXV. During the simulations, the study identified two potential inhibitors, compound CHEMBL32926 and compound CHEMBL4861364, demonstrating strong binding affinities and drug-like properties. Their docking scores with the target protein were -10.7 and -10.9 kcal/mol, respectively. This study used ensemble-based protein-ligand docking to account for the binding site conformation variability. By examining how the identified inhibitors interact with the protein, this research sheds light on the workings of the inhibitors' mechanisms of action. Molecular dynamic simulations of protein-ligand complexes showed fluctuations from the initial docked pose, but they confirmed their binding throughout the simulation. The MMGBSA binding free energy calculations for CHEMBL32926 showed a binding free energy range of (-9.25 to -9.65) kcal/mol, while CHEMBL4861364 exhibited a range of (-41.66 to -31.47) kcal/mol. Later, analogues were searched for these compounds with 70% similarity criteria, and their IC50 was predicted using pre-trained machine learning models. This resulted in identifying two similar compounds for each hit with comparable binding affinity for cysteine proteinase. This study's structure-based drug design approach provides a promising strategy for identifying new drugs for treating MPXV infections.
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Affiliation(s)
- Mohd Imran
- Department of Pharmaceutical Chemistry, College of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia;
| | - Abida
- Department of Pharmaceutical Chemistry, College of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia;
| | - Nawaf M. Alotaibi
- Department of Clinical Pharmacy, College of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia
| | - Hamdy Khamees Thabet
- Chemistry Department, College of Arts and Sciences, Northern Border University, Rafha 91911, Saudi Arabia
| | - Jamal Alhameedi Alruwaili
- Medical Lab Technology Department, College of Applied Medical Sciences, Northern Border University, Arar 91431, Saudi Arabia
| | - Lina Eltaib
- Department of Pharmaceutics, College of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia
| | - Ahmed Alshehri
- Department of Pharmacology and Toxicology, College of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia
- Department of Pharmacology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, King Faisal Road, Dammam 31441, Saudi Arabia
| | - Ahad Amer Alsaiari
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Mehnaz Kamal
- Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia;
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Ozhelvaci F, Steczkiewicz K. Identification and Classification of Papain-like Cysteine Proteinases. J Biol Chem 2023:104801. [PMID: 37164157 DOI: 10.1016/j.jbc.2023.104801] [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: 01/23/2023] [Revised: 04/11/2023] [Accepted: 05/05/2023] [Indexed: 05/12/2023] Open
Abstract
Papain-like cysteine peptidases form a big and highly diverse superfamily of proteins involved in many important biological functions, such as protein turnover, deubiquitination, tissue remodeling, blood clotting, virulence, defense, and cell wall remodeling. High sequence and structure diversity observed within these proteins hinders their comprehensive classification as well as the identification of new representatives. Moreover, in general protein databases, many families already classified as papain-like lack details regarding their mechanism of action or biological function. Here, we use transitive remote homology searches and 3D modeling to newly classify 21 families to the papain-like cysteine peptidase superfamily. We attempt to predict their biological function, and provide structural chacterization of 89 protein clusters defined based on sequence similarity altogether spanning 106 papain-like families. Moreover, we systematically discuss observed diversity in sequences, structures, and catalytic sites. Eventually, we expand the list of human papain-related proteins by seven representatives, including dopamine receptor-interacting protein (DRIP1) as potential deubiquitinase, and centriole duplication regulating CEP76 as retaining catalytically active peptidase-like domain. The presented results not only provide structure-based rationales to already existing peptidase databases but also may inspire further experimental research focused on peptidase-related biological processes.
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Affiliation(s)
- Fatih Ozhelvaci
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Kamil Steczkiewicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Sahu A, Gaur M, Mahanandia NC, Subudhi E, Swain RP, Subudhi BB. Identification of core therapeutic targets for Monkeypox virus and repurposing potential of drugs against them: An in silico approach. Comput Biol Med 2023; 161:106971. [PMID: 37211001 DOI: 10.1016/j.compbiomed.2023.106971] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 04/11/2023] [Accepted: 04/19/2023] [Indexed: 05/23/2023]
Abstract
Monkeypox virus (mpox virus) outbreak has rapidly spread to 82 non-endemic countries. Although it primarily causes skin lesions, secondary complications and high mortality (1-10%) in vulnerable populations have made it an emerging threat. Since there is no specific vaccine/antiviral, it is desirable to repurpose existing drugs against mpox virus. With little knowledge about the lifecycle of mpox virus, identifying potential inhibitors is a challenge. Nevertheless, the available genomes of mpox virus in public databases represent a goldmine of untapped possibilities to identify druggable targets for the structure-based identification of inhibitors. Leveraging this resource, we combined genomics and subtractive proteomics to identify highly druggable core proteins of mpox virus. This was followed by virtual screening to identify inhibitors with affinities for multiple targets. 125 publicly available genomes of mpox virus were mined to identify 69 highly conserved proteins. These proteins were then curated manually. These curated proteins were funnelled through a subtractive proteomics pipeline to identify 4 highly druggable, non-host homologous targets namely; A20R, I7L, Top1B and VETFS. High-throughput virtual screening of 5893 highly curated approved/investigational drugs led to the identification of common as well as unique potential inhibitors with high binding affinities. The common inhibitors, i.e., batefenterol, burixafor and eluxadoline were further validated by molecular dynamics simulation to identify their best potential binding modes. The affinity of these inhibitors suggests their repurposing potential. This work can encourage further experimental validation for possible therapeutic management of mpox.
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Affiliation(s)
- Anshuman Sahu
- Drug Development and Analysis Laboratory, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, 751030, India
| | - Mahendra Gaur
- Drug Development and Analysis Laboratory, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, 751030, India; Department of Biotechnology, Punjabi University, Patiala, 147002, India
| | - Nimai Charan Mahanandia
- Division of Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, Pusa, New Delhi, 110012, India
| | - Enketeswara Subudhi
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, 751030, India
| | - Ranjit Prasad Swain
- Department of Pharmaceutics, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, 751030, India
| | - Bharat Bhusan Subudhi
- Drug Development and Analysis Laboratory, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, 751030, India.
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8
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Dodaro A, Pavan M, Moro S. Targeting the I7L Protease: A Rational Design for Anti-Monkeypox Drugs? Int J Mol Sci 2023; 24:ijms24087119. [PMID: 37108279 PMCID: PMC10138331 DOI: 10.3390/ijms24087119] [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: 02/28/2023] [Revised: 03/29/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
The latest monkeypox virus outbreak in 2022 showcased the potential threat of this viral zoonosis to public health. The lack of specific treatments against this infection and the success of viral protease inhibitors-based treatments against HIV, Hepatitis C, and SARS-CoV-2, brought the monkeypox virus I7L protease under the spotlight as a potential target for the development of specific and compelling drugs against this emerging disease. In the present work, the structure of the monkeypox virus I7L protease was modeled and thoroughly characterized through a dedicated computational study. Furthermore, structural information gathered in the first part of the study was exploited to virtually screen the DrugBank database, consisting of drugs approved by the Food and Drug Administration (FDA) and clinical-stage drug candidates, in search for readily repurposable compounds with similar binding features as TTP-6171, the only non-covalent I7L protease inhibitor reported in the literature. The virtual screening resulted in the identification of 14 potential inhibitors of the monkeypox I7L protease. Finally, based on data collected within the present work, some considerations on developing allosteric modulators of the I7L protease are reported.
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Affiliation(s)
- Andrea Dodaro
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
| | - Matteo Pavan
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
| | - Stefano Moro
- Molecular Modeling Section (MMS), Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy
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9
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Wang J, Shahed-Ai-Mahmud M, Chen A, Li K, Tan H, Joyce R. An Overview of Antivirals against Monkeypox Virus and Other Orthopoxviruses. J Med Chem 2023; 66:4468-4490. [PMID: 36961984 DOI: 10.1021/acs.jmedchem.3c00069] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
The current monkeypox outbreaks during the COVID-19 pandemic have reignited interest in orthopoxvirus antivirals. Monkeypox belongs to the Orthopoxvirus genus of the Poxviridae family, which also includes the variola virus, vaccinia virus, and cowpox virus. Two orally bioavailable drugs, tecovirimat and brincidofovir, have been approved for treating smallpox infections. Given their human safety profiles and in vivo antiviral efficacy in animal models, both drugs have also been recommended to treat monkeypox infection. To facilitate the development of additional orthopoxvirus antivirals, we summarize the antiviral activity, mechanism of action, and mechanism of resistance of orthopoxvirus antivirals. This perspective covers both direct-acting and host-targeting antivirals with an emphasis on drug candidates showing in vivo antiviral efficacy in animal models. We hope to speed the orthopoxvirus antiviral drug discovery by providing medicinal chemists with insights into prioritizing proper drug targets and hits for further development.
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Affiliation(s)
- Jun Wang
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Md Shahed-Ai-Mahmud
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Angelo Chen
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Kan Li
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Haozhou Tan
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Ryan Joyce
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, United States
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10
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Jordan I, Horn D, Thiele K, Haag L, Fiddeke K, Sandig V. A Deleted Deletion Site in a New Vector Strain and Exceptional Genomic Stability of Plaque-Purified Modified Vaccinia Ankara (MVA). Virol Sin 2019; 35:212-226. [PMID: 31833037 PMCID: PMC7198643 DOI: 10.1007/s12250-019-00176-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/18/2019] [Indexed: 12/29/2022] Open
Abstract
Vectored vaccines based on highly attenuated modified vaccinia Ankara (MVA) are reported to be immunogenic, tolerant to pre-existing immunity, and able to accommodate and stably maintain very large transgenes. MVA is usually produced on primary chicken embryo fibroblasts, but production processes based on continuous cell lines emerge as increasingly robust and cost-effective alternatives. An isolate of a hitherto undescribed genotype was recovered by passage of a non-plaque-purified preparation of MVA in a continuous anatine suspension cell line (CR.pIX) in chemically defined medium. The novel isolate (MVA-CR19) replicated to higher infectious titers in the extracellular volume of suspension cultures and induced fewer syncytia in adherent cultures. We now extend previous studies with the investigation of the point mutations in structural genes of MVA-CR19 and describe an additional point mutation in a regulatory gene. We furthermore map and discuss an extensive rearrangement of the left telomer of MVA-CR19 that appears to have occurred by duplication of the right telomer. This event caused deletions and duplications of genes that may modulate immunologic properties of MVA-CR19 as a vaccine vector. Our characterizations also highlight the exceptional genetic stability of plaque-purified MVA: although the phenotype of MVA-CR19 appears to be advantageous for replication, we found that all genetic markers that differentiate wildtype and MVA-CR19 are stably maintained in passages of recombinant viruses based on either wildtype or MVA-CR.
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Affiliation(s)
- Ingo Jordan
- ProBioGen AG, Herbert-Bayer-Straße 8, 13086, Berlin, Germany.
| | - Deborah Horn
- ProBioGen AG, Herbert-Bayer-Straße 8, 13086, Berlin, Germany
| | - Kristin Thiele
- ProBioGen AG, Herbert-Bayer-Straße 8, 13086, Berlin, Germany.,Sartorius Stedim Cellca GmbH, Erwin-Rentschler-Str 21, 88471, Laupheim, Germany
| | - Lars Haag
- Vironova AB, Gävlegatan 22, 113 30, Stockholm, Sweden.,Department of Laboratory Medicine, Karolinska Universitetsjukhuset i Huddinge, 14152, Huddinge, Sweden
| | | | - Volker Sandig
- ProBioGen AG, Herbert-Bayer-Straße 8, 13086, Berlin, Germany
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Novy K, Kilcher S, Omasits U, Bleck CKE, Beerli C, Vowinckel J, Martin CK, Syedbasha M, Maiolica A, White I, Mercer J, Wollscheid B. Proteotype profiling unmasks a viral signalling network essential for poxvirus assembly and transcriptional competence. Nat Microbiol 2018; 3:588-599. [DOI: 10.1038/s41564-018-0142-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/07/2018] [Indexed: 11/09/2022]
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12
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Leite FGG, Bergthaler A, Skern T. Vaccinia virus G1 protein: absence of autocatalytic self-processing. Arch Virol 2017; 162:2803-2808. [PMID: 28523522 DOI: 10.1007/s00705-017-3409-y] [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: 12/30/2016] [Accepted: 05/08/2017] [Indexed: 11/30/2022]
Abstract
Vaccinia virus relies on a series of proteolytic cleavage events involving two viral proteins, I7 and G1, to complete its life cycle. Furthermore, G1 itself is cleaved during vaccinia virus infection. However, convincing evidence is lacking to show whether G1 participates in autoproteolysis or is a substrate of another protease. We employed both biochemical and cell-based approaches to investigate G1 cleavage. G1, when expressed in bacteria, rabbit reticulocyte lysates or HeLa cells, was not processed. Moreover, G1 was cleaved in infected cells, but only in the presence of virus late gene expression; cleavage was strongly inhibited by proteasome inhibitors. Thus, these results imply a more complex G1 cleavage reaction than previously envisaged.
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Affiliation(s)
- F G G Leite
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, 1030, Vienna, Austria. .,Cellular Signalling and Cytoskeletal Function, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
| | - A Bergthaler
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, 1090, Vienna, Austria
| | - T Skern
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9/3, 1030, Vienna, Austria
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13
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Wang H, Jiang J, Ding R, Wang X, Liao M, Shao J, Luo X, Luo S, Duan C. Identification and characterization of Orf virus 050 protein proteolysis. Virus Genes 2017; 53:400-409. [PMID: 28190135 DOI: 10.1007/s11262-017-1430-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 01/20/2017] [Indexed: 12/24/2022]
Abstract
The Orf virus 050 (ORFV050) gene is located in the core region of the ORFV genome. It is similar to Vaccinia virus (VV) Copenhagen L4R, and encodes the DNA-binding virion core protein VP8, which has structures similar to the VV P25K core protein and may undergo similar proteolytic processing during virus assembly. Three conserved Ala-Gly-X motifs at putative cleavage sites were identified in ORFV050. To investigate the proteolysis of ORFV050 and its participation in viral assembly, full-length and site-directed mutant ORFV050 recombinant proteins were constructed and expressed. Two distinct protein bands of 28.5 and 25 kDa were detected in the infected cells using anti-ORFV050 polyclonal antiserum. A potential cleavage site was identified at amino acids 30-32 of ORFV050. Mutation of AG/A to (R) in ORFV050 abolished the process of proteolysis. ORFV050 is a late gene synthesized during viral replication in the host cytoplasm. According to these results, we conclude that ORFV050 undergoes proteolysis and plays an important role in viral assembly.
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Affiliation(s)
- Han Wang
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China
| | - Junyi Jiang
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China
| | - Rui Ding
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China
| | - Xiaoping Wang
- Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, 510515, Guangdong, People's Republic of China.,Department of Laboratory Medicine, Nongken Centre Hospital of Guangdong Province, Zhanjiang, 524002, Guangdong, People's Republic of China
| | - Meiying Liao
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Department of Laboratory Medicine, Kiang Wu Hospital, Macau, 999078, People's Republic of China
| | - Jing Shao
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Medical Research Center, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China
| | - Xiaohong Luo
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China
| | - Shuhong Luo
- Department of Laboratory Medicine, School of Stomatology and Medicine, Foshan University, 5 Hebin Road, Foshan, 528000, Guangdong, People's Republic of China.
| | - Chaohui Duan
- Department of Laboratory Medicine, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China. .,Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, The Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, Guangdong, People's Republic of China.
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14
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Seo D, Kim NY, Lee JA, Han KR, Hur GH, Yang JM, Shin S. Protection against lethal vaccinia virus infection in mice using an siRNA targeting the A5R gene. Antivir Ther 2016; 21:397-404. [DOI: 10.3851/imp3022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
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15
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Vaccinia Virus B1 Kinase Is Required for Postreplicative Stages of the Viral Life Cycle in a BAF-Independent Manner in U2OS Cells. J Virol 2015. [PMID: 26223647 DOI: 10.1128/jvi.01252-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED The vaccinia virus B1R gene encodes a highly conserved protein kinase that is essential for the poxviral life cycle. As demonstrated in many cell types, B1 plays a critical role during viral DNA replication when it inactivates the cellular host defense effector barrier to autointegration factor (BAF or BANF1). To better understand the role of B1 during infection, we have characterized the growth of a B1-deficient temperature-sensitive mutant virus (Cts2 virus) in U2OS osteosarcoma cells. In contrast to all other cell lines tested to date, we found that in U2OS cells, Cts2 viral DNA replication is unimpaired at the nonpermissive temperature. However, the Cts2 viral yield in these cells was reduced more than 10-fold, thus indicating that B1 is required at another stage of the vaccinia virus life cycle. Our results further suggest that the host defense function of endogenous BAF may be absent in U2OS cells but can be recovered through either overexpression of BAF or fusion of U2OS cells with mouse cells in which the antiviral function of BAF is active. Interestingly, examination of late viral proteins during Cts2 virus infection demonstrated that B1 is required for optimal processing of the L4 protein. Finally, execution point analyses as well as electron microscopy studies uncovered a role for B1 during maturation of poxviral virions. Overall, this work demonstrates that U2OS cells are a novel model system for studying the cell type-specific regulation of BAF and reveals a role for B1 beyond DNA replication during the late stages of the viral life cycle. IMPORTANCE The most well characterized role for the vaccinia virus B1 kinase is to facilitate viral DNA replication by phosphorylating and inactivating BAF, a cellular host defense responsive to foreign DNA. Additional roles for B1 later in the viral life cycle have been postulated for decades but are difficult to examine directly due to the importance of B1 during DNA replication. Here, we demonstrate that in U2OS cells, a B1 mutant virus escapes the block in DNA replication observed in other cell types and, instead, this mutant virus exhibits impaired late protein accumulation and incomplete maturation of new virions. These data provide the clearest evidence to date that B1 is needed for multiple critical junctures in the poxviral life cycle in a manner that is both dependent on and independent of BAF.
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16
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Genetic Confirmation that the H5 Protein Is Required for Vaccinia Virus DNA Replication. J Virol 2015; 89:6312-27. [PMID: 25855734 DOI: 10.1128/jvi.00445-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/28/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The duplication of the poxvirus double-stranded DNA genome occurs in cytoplasmic membrane-delimited factories. This physical autonomy from the host nucleus suggests that poxvirus genomes encode the full repertoire of proteins committed for genome replication. Biochemical and genetic analyses have confirmed that six viral proteins are required for efficient DNA synthesis; indirect evidence has suggested that the multifunctional H5 protein may also have a role. Here we show that H5 localizes to replication factories, as visualized by immunofluorescence and immunoelectron microscopy, and can be retrieved upon purification of the viral polymerase holoenzyme complex. The temperature-sensitive (ts) mutant Dts57, which was generated by chemical mutagenesis and has a lesion in H5, exhibits defects in DNA replication and morphogenesis under nonpermissive conditions, depending upon the experimental protocol. The H5 variant encoded by the genome of this mutant is ts for function but not stability. For a more precise investigation of how H5 contributes to DNA synthesis, we placed the ts57 H5 allele in an otherwise wild-type viral background and also performed small interfering RNA-mediated depletion of H5. Finally, we generated a complementing cell line, CV-1-H5, which allowed us to generate a viral recombinant in which the H5 open reading frame was deleted and replaced with mCherry (vΔH5). Analysis of vΔH5 allowed us to demonstrate conclusively that viral DNA replication is abrogated in the absence of H5. The loss of H5 does not compromise the accumulation of other early viral replication proteins or the uncoating of the virion core, suggesting that H5 plays a direct and essential role in facilitating DNA synthesis. IMPORTANCE Variola virus, the causative agent of smallpox, is the most notorious member of the Poxviridae family. Poxviruses are unique among DNA viruses that infect mammalian cells, in that their replication is restricted to the cytoplasm of the cell. This physical autonomy from the nucleus has both cell biological and genetic ramifications. Poxviruses must establish cytoplasmic niches that support replication, and the genomes must encode the repertoire of proteins necessary for genome synthesis. Here we focus on H5, a multifunctional and abundant viral protein. We confirm that H5 associates with the DNA polymerase holoenzyme and localizes to the sites of DNA synthesis. By generating an H5-expressing cell line, we were able to isolate a deletion virus that lacks the H5 gene and show definitively that genome synthesis does not occur in the absence of H5. These data support the hypothesis that H5 is a crucial participant in cytoplasmic poxvirus genome replication.
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17
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Chen JS, Li HC, Lin SI, Yang CH, Chien WY, Syu CL, Lo SY. Cleavage of Dicer protein by I7 protease during vaccinia virus infection. PLoS One 2015; 10:e0120390. [PMID: 25815818 PMCID: PMC4376780 DOI: 10.1371/journal.pone.0120390] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 01/21/2015] [Indexed: 11/18/2022] Open
Abstract
Dicer is the key component in the miRNA pathway. Degradation of Dicer protein is facilitated during vaccinia virus (VV) infection. A C-terminal cleaved product of Dicer protein was detected in the presence of MG132 during VV infection. Thus, it is possible that Dicer protein is cleaved by a viral protease followed by proteasome degradation of the cleaved product. There is a potential I7 protease cleavage site in the C-terminus of Dicer protein. Indeed, reduction of Dicer protein was detected when Dicer was co-expressed with I7 protease but not with an I7 protease mutant protein lack of the protease activity. Mutation of the potential I7 cleavage site in the C-terminus of Dicer protein resisted its degradation during VV infection. Furthermore, Dicer protein was reduced dramatically by recombinant VV vI7Li after the induction of I7 protease. If VV could facilitate the degradation of Dicer protein, the process of miRNA should be affected by VV infection. Indeed, accumulation of precursor miR122 was detected after VV infection or I7 protease expression. Reduction of miR122 would result in the suppression of HCV sub-genomic RNA replication, and, in turn, the amount of viral proteins. As expected, significant reduction of HCVNS5A protein was detected after VV infection and I7 protease expression. Therefore, our results suggest that VV could cleave Dicer protein through I7 protease to facilitate Dicer degradation, and in turn, suppress the processing of miRNAs. Effect of Dicer protein on VV replication was also studied. Exogenous expression of Dicer protein suppresses VV replication slightly while knockdown of Dicer protein does not affect VV replication significantly.
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Affiliation(s)
- Jhih-Si Chen
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Hui-Chun Li
- Department of Biochemistry, Tzu Chi University, Hualien, Taiwan
| | - Shu-I Lin
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Chee-Hing Yang
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Wan-Yu Chien
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Ciao-Ling Syu
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Shih-Yen Lo
- Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan
- Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
- * E-mail:
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18
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Liu L, Cooper T, Howley PM, Hayball JD. From crescent to mature virion: vaccinia virus assembly and maturation. Viruses 2014; 6:3787-808. [PMID: 25296112 PMCID: PMC4213562 DOI: 10.3390/v6103787] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 01/22/2023] Open
Abstract
Vaccinia virus (VACV) has achieved unprecedented success as a live viral vaccine for smallpox which mitigated eradication of the disease. Vaccinia virus has a complex virion morphology and recent advances have been made to answer some of the key outstanding questions, in particular, the origin and biogenesis of the virion membrane, the transformation from immature virion (IV) to mature virus (MV), and the role of several novel genes, which were previously uncharacterized, but have now been shown to be essential for VACV virion formation. This new knowledge will undoubtedly contribute to the rational design of safe, immunogenic vaccine candidates, or effective antivirals in the future. This review endeavors to provide an update on our current knowledge of the VACV maturation processes with a specific focus on the initiation of VACV replication through to the formation of mature virions.
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Affiliation(s)
- Liang Liu
- Experimental Therapeutics Laboratory, Hanson Institute and Sansom Institute, Adelaide, 5000, SA, Australia.
| | - Tamara Cooper
- Experimental Therapeutics Laboratory, Hanson Institute and Sansom Institute, Adelaide, 5000, SA, Australia.
| | - Paul M Howley
- Experimental Therapeutics Laboratory, Hanson Institute and Sansom Institute, Adelaide, 5000, SA, Australia.
| | - John D Hayball
- Experimental Therapeutics Laboratory, Hanson Institute and Sansom Institute, Adelaide, 5000, SA, Australia.
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19
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20
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Jordan I, Lohr V, Genzel Y, Reichl U, Sandig V. Elements in the Development of a Production Process for Modified Vaccinia Virus Ankara. Microorganisms 2013; 1:100-121. [PMID: 27694766 PMCID: PMC5029493 DOI: 10.3390/microorganisms1010100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 11/16/2022] Open
Abstract
The production of several viral vaccines depends on chicken embryo fibroblasts or embryonated chicken eggs. To replace this logistically demanding substrate, we created continuous anatine suspension cell lines (CR and CR.pIX), developed chemically-defined media, and established production processes for different vaccine viruses. One of the processes investigated in greater detail was developed for modified vaccinia virus Ankara (MVA). MVA is highly attenuated for human recipients and an efficient vector for reactogenic expression of foreign genes. Because direct cell-to-cell spread is one important mechanism for vaccinia virus replication, cultivation of MVA in bioreactors is facilitated if cell aggregates are induced after infection. This dependency may be the mechanism behind our observation that a novel viral genotype (MVA-CR) accumulates with serial passage in suspension cultures. Sequencing of a major part of the genomic DNA of the new strain revealed point mutations in three genes. We hypothesize that these changes confer an advantage because they may allow a greater fraction of MVA-CR viruses to escape the host cells for infection of distant targets. Production and purification of MVA-based vaccines may be simplified by this combination of designed avian cell line, chemically defined media and the novel virus strain.
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Affiliation(s)
- Ingo Jordan
- ProBioGen AG, Goethestr. 54, 13086 Berlin, Germany.
| | - Verena Lohr
- ProBioGen AG, Goethestr. 54, 13086 Berlin, Germany.
| | - Yvonne Genzel
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106 Magdeburg, Germany.
| | - Udo Reichl
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106 Magdeburg, Germany.
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21
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Jordan I, Horn D, John K, Sandig V. A genotype of modified vaccinia Ankara (MVA) that facilitates replication in suspension cultures in chemically defined medium. Viruses 2013; 5:321-39. [PMID: 23337383 PMCID: PMC3564123 DOI: 10.3390/v5010321] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 01/11/2013] [Accepted: 01/17/2013] [Indexed: 11/16/2022] Open
Abstract
While vectored vaccines, based on hyperattenuated viruses, may lead to new treatment options against infectious diseases and certain cancers, they are also complex products and sometimes difficult to provide in sufficient amount and purity. To facilitate vaccine programs utilizing host-restricted poxviruses, we established avian suspension cell lines (CR and CR.pIX) and developed a robust, chemically defined, culturing process for production of this class of vectors. For one prominent member, modified vaccinia Ankara (MVA), we now describe a new strain that appears to replicate to greater yields of infectious units, especially in the cell-free supernatant of cultures in chemically defined media. The new strain was obtained by repeated passaging in CR suspension cultures and, consistent with reports on the exceptional genetic stability of MVA, sequencing of 135 kb of the viral genomic DNA revealed that only three structural proteins (A3L, A9L and A34R) each carry a single amino acid exchange (H639Y, K75E and D86Y, respectively). Host restriction in a plaque-purified isolate of the new genotype appears to be maintained in cell culture. Processing towards an injectable vaccine preparation may be simplified with this strain as a complete lysate, containing the main burden of host cell contaminants, may not be required anymore to obtain adequate yields.
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Affiliation(s)
- Ingo Jordan
- ProBioGen AG, Goethestr. 54, 13086 Berlin, Germany.
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22
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Aleshin AE, Drag M, Gombosuren N, Wei G, Mikolajczyk J, Satterthwait AC, Strongin AY, Liddington RC, Salvesen GS. Activity, specificity, and probe design for the smallpox virus protease K7L. J Biol Chem 2012; 287:39470-9. [PMID: 23012361 DOI: 10.1074/jbc.m112.388678] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The K7L gene product of the smallpox virus is a protease implicated in the maturation of viral proteins. K7L belongs to protease Clan CE, which includes distantly related cysteine proteases from eukaryotes, pathogenic bacteria, and viruses. Here, we describe its recombinant high level expression, biochemical mechanism, substrate preference, and regulation. Earlier studies inferred that the orthologous I7L vaccinia protease cleaves at an AG-X motif in six viral proteins. Our data for K7L suggest that the AG-X motif is necessary but not sufficient for optimal cleavage activity. Thus, K7L requires peptides extended into the P7 and P8 positions for efficient substrate cleavage. Catalytic activity of K7L is substantially enhanced by homodimerization, by the substrate protein P25K as well as by glycerol. RNA and DNA also enhance cleavage of the P25K protein but not of synthetic peptides, suggesting that nucleic acids augment the interaction of K7L with its protein substrate. Library-based peptide preference analyses enabled us to design an activity-based probe that covalently and selectively labels K7L in lysates of transfected and infected cells. Our study thus provides proof-of-concept for the design of inhibitors and probes that may contribute both to a better understanding of the role of K7L in the virus life cycle and the design of novel anti-virals.
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Affiliation(s)
- Alexander E Aleshin
- Program in Apoptosis and Cell Death Research, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA
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23
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Vaccinia virus virion membrane biogenesis protein A11 associates with viral membranes in a manner that requires the expression of another membrane biogenesis protein, A6. J Virol 2012; 86:11276-86. [PMID: 22875972 DOI: 10.1128/jvi.01502-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A group of vaccinia virus (VACV) proteins, including A11, L2, and A6, are required for biogenesis of the primary envelope of VACV, specifically, for the acquisition of viral membrane precursors. However, the interconnection among these proteins is unknown and, with the exception of L2, the connection of these proteins with membranes is also unknown. In this study, prompted by the findings that A6 coprecipitated A11 and that the cellular distribution of A11 was dramatically altered by repression of A6 expression, we studied the localization of A11 in cells by using immunofluorescence and cell fractionation analysis. A11 was found to associate with membranes and colocalize with virion membrane proteins in viral replication factories during normal VACV replication. A11 partitioned almost equally between the detergent and aqueous phases upon Triton X-114 phase separation, demonstrating an intrinsic affinity with lipids. However, in the absence of infection or VACV late protein synthesis, A11 did not associate with cellular membranes. Furthermore, when A6 expression was repressed, A11 did not colocalize with any viral membrane proteins or associate with membranes. In contrast, when virion envelope formation was blocked at a later step by repression of A14 expression or by rifampin treatment, A11 colocalized with virion membrane proteins in the factories. Altogether, our data showed that A11 associates with viral membranes during VACV replication, and this association requires A6 expression. This study provides a physical connection between A11 and viral membranes and suggests that A6 regulates A11 membrane association.
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24
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Prichard MN, Kern ER. Orthopoxvirus targets for the development of new antiviral agents. Antiviral Res 2012; 94:111-25. [PMID: 22406470 PMCID: PMC3773844 DOI: 10.1016/j.antiviral.2012.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/10/2012] [Accepted: 02/21/2012] [Indexed: 12/29/2022]
Abstract
Investments in the development of new drugs for orthopoxvirus infections have fostered new avenues of research, provided an improved understanding of orthopoxvirus biology and yielded new therapies that are currently progressing through clinical trials. These broad-based efforts have also resulted in the identification of new inhibitors of orthopoxvirus replication that target many different stages of viral replication cycle. This review will discuss progress in the development of new anti-poxvirus drugs and the identification of new molecular targets that can be exploited for the development of new inhibitors. The prototype of the orthopoxvirus group is vaccinia virus and its replication cycle will be discussed in detail noting specific viral functions and their associated gene products that have the potential to serve as new targets for drug development. Progress that has been achieved in recent years should yield new drugs for the treatment of these infections and might also reveal new approaches for antiviral drug development with other viruses.
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Affiliation(s)
- Mark N Prichard
- Department of Pediatrics, The University of Alabama at Birmingham, Birmingham, AL 35233-1711, United States.
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25
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Development of ST-246® for Treatment of Poxvirus Infections. Viruses 2010; 2:2409-2435. [PMID: 21994624 PMCID: PMC3185582 DOI: 10.3390/v2112409] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 10/26/2010] [Accepted: 10/26/2010] [Indexed: 12/26/2022] Open
Abstract
ST-246 (Tecovirimat) is a small synthetic antiviral compound being developed to treat pathogenic orthopoxvirus infections of humans. The compound was discovered as part of a high throughput screen designed to identify inhibitors of vaccinia virus-induced cytopathic effects. The antiviral activity is specific for orthopoxviruses and the compound does not inhibit the replication of other RNA- and DNA-containing viruses or inhibit cell proliferation at concentrations of compound that are antiviral. ST-246 targets vaccinia virus p37, a viral protein required for envelopment and secretion of extracellular forms of virus. The compound is orally bioavailable and protects multiple animal species from lethal orthopoxvirus challenge. Preclinical safety pharmacology studies in mice and non-human primates indicate that ST-246 is readily absorbed by the oral route and well tolerated with the no observable adverse effect level (NOAEL) in mice measured at 2000 mg/kg and the no observable effect level (NOEL) in non-human primates measured at 300 mg/kg. Drug substance and drug product processes have been developed and commercial scale batches have been produced using Good Manufacturing Processes (GMP). Human phase I clinical trials have shown that ST-246 is safe and well tolerated in healthy human volunteers. Based on the results of the clinical evaluation, once a day dosing should provide plasma drug exposure in the range predicted to be antiviral based on data from efficacy studies in animal models of orthopoxvirus disease. These data support the use of ST-246 as a therapeutic to treat pathogenic orthopoxvirus infections of humans.
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26
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De Clercq E. Historical perspectives in the development of antiviral agents against poxviruses. Viruses 2010; 2:1322-1339. [PMID: 21994682 PMCID: PMC3185982 DOI: 10.3390/v2061322] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 05/28/2010] [Accepted: 05/28/2010] [Indexed: 12/02/2022] Open
Abstract
The poxvirus vaccinia virus (VV) served as the model virus for which the first antivirals, the thiosemicarbazones, were identified. This dates back to 1950; and, although there is at present no single antiviral drug specifically licensed for the chemotherapy or -prophylaxis of poxvirus infections, numerous candidate compounds have been described over the past 50 years. These compounds include interferon and inducers thereof (i.e., polyacrylic acid), 5-substituted 2’-deoxyuridines (i.e., idoxuridine), IMP dehydrogenase inhibitors, S-adenosylhomocysteine hydrolase inhibitors, acyclic nucleoside phosphonates (such as cidofovir) and alkoxyalkyl prodrugs thereof (such as CMX001), viral egress inhibitors (such as tecovirimat), and cellular kinase inhibitors (such as imatinib).
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Affiliation(s)
- Erik De Clercq
- Rega Institute for Medical Research, Department of Microbiology and Immunology, Minderbroedersstraat 10, B-3000 Leuven, Belgium
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27
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Abstract
Studies of the functional proteins encoded by the poxvirus genome provide information about the composition of the virus as well as individual virus-virus protein and virus-host protein interactions, which provides insight into viral pathogenesis and drug discovery. Widely used proteomic techniques to identify and characterize specific protein-protein interactions include yeast two-hybrid studies and coimmunoprecipitations. Recently, various mass spectrometry techniques have been employed to identify viral protein components of larger complexes. These methods, combined with structural studies, can provide new information about the putative functions of viral proteins as well as insights into virus-host interaction dynamics. For viral proteins of unknown function, identification of either viral or host binding partners provides clues about their putative function. In this review, we discuss poxvirus proteomics, including the use of proteomic methodologies to identify viral components and virus-host protein interactions. High-throughput global protein expression studies using protein chip technology as well as new methods for validating putative protein-protein interactions are also discussed.
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The E6 protein from vaccinia virus is required for the formation of immature virions. Virology 2010; 399:201-11. [PMID: 20116821 DOI: 10.1016/j.virol.2010.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 01/04/2010] [Accepted: 01/07/2010] [Indexed: 11/22/2022]
Abstract
An IPTG-inducible mutant in the E6R gene of vaccinia virus was used to study the role of the E6 virion core protein in viral replication. In the absence of the inducer, the mutant exhibited a normal pattern DNA replication, concatemer resolution and late gene expression, but it showed an inhibition of virion structural protein processing it failed to produce infectious particles. Electron microscopic analysis showed that in the absence of IPTG viral morphogenesis was arrested before IV formation: crescents, aberrant or empty IV-like structures, and large aggregated virosomes were observed throughout the cytoplasm. The addition of IPTG to release a 12-h block showed that virus infectious particles could be formed in the absence of de novo DNA synthesis. Our observations show that in the absence of E6 the association of viroplasm with viral membrane crescents is impaired.
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Assembly and disassembly of the capsid-like external scaffold of immature virions during vaccinia virus morphogenesis. J Virol 2009; 83:9140-50. [PMID: 19570860 DOI: 10.1128/jvi.00875-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Infectious poxvirus particles are unusual in that they are brick shaped and lack symmetry. Nevertheless, an external honeycomb lattice comprised of a capsid-like protein dictates the spherical shape and size of immature poxvirus particles. In the case of vaccinia virus, trimers of 63-kDa D13 polypeptides form the building blocks of the lattice. In the present study, we addressed two questions: how D13, which has no transmembrane domain, associates with the immature virion (IV) membrane to form the lattice structure and how this scaffold is removed during the subsequent stage of morphogenesis. Interaction of D13 with the A17 membrane protein was demonstrated by immunoaffinity purification and Western blot analysis. In addition, the results of immunogold electron microscopy indicated a close association of A17 and D13 in crescents, as well as in vesicular structures when crescent formation was prevented. Further studies indicated that binding of A17 to D13 was abrogated by truncation of the N-terminal segment of A17. The N-terminal region of A17 was also required for the formation of crescent and IV structures. Disassembly of the D13 scaffold correlated with the processing of A17 by the I7 protease. When I7 expression was repressed, D13 was retained on aberrant virus particles. Furthermore, the morphogenesis of IVs to mature virions was blocked by mutation of the N-terminal but not the C-terminal cleavage site on A17. Taken together, these data indicate that A17 and D13 interactions regulate the assembly and disassembly of the IV scaffold.
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Ethacrynic and alpha-lipoic acids inhibit vaccinia virus late gene expression. Antiviral Res 2008; 81:156-65. [PMID: 19061917 PMCID: PMC7114351 DOI: 10.1016/j.antiviral.2008.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 11/04/2008] [Accepted: 11/10/2008] [Indexed: 01/19/2023]
Abstract
Smallpox was declared eradicated in 1980. However recently, the need of agents effective against poxvirus infection has emerged again. In this paper, we report an original finding that two redox-modulating agents, the ethacrynic and α-lipoic acids (EA, LA), inhibit growth of vaccinia virus (VACV) in vitro. The effect of EA and LA was compared with those of β-mercaptoethanol, DTT and ascorbic acid, but these agents increased VACV growth in HeLa G cells. The inhibitory effects of EA and LA on the growth of VACV were further confirmed in several cell lines of different embryonic origin, in epithelial cells, fibroblasts, macrophages and T-lymphocytes. Finally, we have analyzed the mechanism of action of the two agents. They both decreased expression of VACV late genes, as demonstrated by western blot analysis and activity of luciferase expressed under control of different VACV promoters. In contrast, they did not inhibit virus entry into the cell, expression of VACV early genes or VACV DNA synthesis. The results suggest new directions in development of drugs effective against poxvirus infection.
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Abstract
Genetic and biochemical studies have provided evidence for an entry/fusion complex (EFC) comprised of at least eight viral proteins (A16, A21, A28, G3, G9, H2, J5, and L5) that together with an associated protein (F9) participates in entry of vaccinia virus (VACV) into cells. The genes encoding these proteins are conserved in all poxviruses, are expressed late in infection, and are components of the mature virion membrane but are not required for viral morphogenesis. In addition, all but one component has intramolecular disulfides that are formed by the poxvirus cytoplasmic redox system. The L1 protein has each of the characteristics enumerated above except that it has been reported to be essential for virus assembly. To further investigate the role of L1, we constructed a recombinant VACV (vL1Ri) that inducibly expresses L1. In the absence of inducer, L1 synthesis was repressed and vL1Ri was unable to form plaques or produce infectious progeny. Unexpectedly, assembly and morphogenesis appeared normal and the noninfectious virus particles were indistinguishable from wild-type VACV as determined by transmission electron microscopy and analysis of the component polypeptides. Notably, the L1-deficient virions were able to attach to cells but the cores failed to penetrate into the cytoplasm. In addition, cells infected with vL1Ri in the absence of inducer did not form syncytia following brief low-pH treatment even though extracellular virus was produced. Coimmunoprecipitation experiments demonstrated that L1 interacted with the EFC and indirectly with F9, suggesting that L1 is an additional component of the viral entry apparatus.
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32
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Identification of novel antipoxviral agents: mitoxantrone inhibits vaccinia virus replication by blocking virion assembly. J Virol 2007; 81:13392-402. [PMID: 17928345 DOI: 10.1128/jvi.00770-07] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bioterror threat of a smallpox outbreak in an unvaccinated population has mobilized efforts to develop new antipoxviral agents. By screening a library of known drugs, we identified 13 compounds that inhibited vaccinia virus replication at noncytotoxic doses. The anticancer drug mitoxantrone is unique among the inhibitors identified in that it has no apparent impact on viral gene expression. Rather, it blocks processing of viral structural proteins and assembly of mature progeny virions. The isolation of mitoxantrone-resistant vaccinia strains underscores that a viral protein is the likely target of the drug. Whole-genome sequencing of mitoxantrone-resistant viruses pinpointed missense mutations in the N-terminal domain of vaccinia DNA ligase. Despite its favorable activity in cell culture, mitoxantrone administered intraperitoneally at the maximum tolerated dose failed to protect mice against a lethal intranasal infection with vaccinia virus.
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Katritch V, Byrd CM, Tseitin V, Dai D, Raush E, Totrov M, Abagyan R, Jordan R, Hruby DE. Discovery of small molecule inhibitors of ubiquitin-like poxvirus proteinase I7L using homology modeling and covalent docking approaches. J Comput Aided Mol Des 2007; 21:549-58. [PMID: 17960327 PMCID: PMC7087885 DOI: 10.1007/s10822-007-9138-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 09/30/2007] [Indexed: 11/20/2022]
Abstract
Essential for viral replication and highly conserved among poxviridae, the vaccinia virus I7L ubiquitin-like proteinase (ULP) is an attractive target for development of smallpox antiviral drugs. At the same time, the I7L proteinase exemplifies several interesting challenges from the rational drug design perspective. In the absence of a published I7L X-ray structure, we have built a detailed 3D model of the I7L ligand binding site (S2-S2' pocket) based on exceptionally high structural conservation of this site in proteases of the ULP family. The accuracy and limitations of this model were assessed through comparative analysis of available X-ray structures of ULPs, as well as energy based conformational modeling. The 3D model of the I7L ligand binding site was used to perform covalent docking and VLS of a comprehensive library of about 230,000 available ketone and aldehyde compounds. Out of 456 predicted ligands, 97 inhibitors of I7L proteinase activity were confirmed in biochemical assays ( approximately 20% overall hit rate). These experimental results both validate our I7L ligand binding model and provide initial leads for rational optimization of poxvirus I7L proteinase inhibitors. Thus, fragments predicted to bind in the prime portion of the active site can be combined with fragments on non-prime side to yield compounds with improved activity and specificity.
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34
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Rawlings ND, Morton FR. The MEROPS batch BLAST: a tool to detect peptidases and their non-peptidase homologues in a genome. Biochimie 2007; 90:243-59. [PMID: 17980477 DOI: 10.1016/j.biochi.2007.09.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 09/21/2007] [Indexed: 11/29/2022]
Abstract
Many of the 181 families of peptidases contain homologues that are known to have functions other than peptide bond hydrolysis. Distinguishing an active peptidase from a homologue that is not a peptidase requires specialist knowledge of the important active site residues, because replacement or lack of one of these catalytic residues is an important clue that the homologue in question is unlikely to hydrolyse peptide bonds. Now that the rate at which proteins are characterized is outstripped by the rate that genome sequences are determined, many genes are being incorrectly annotated because only sequence similarity is taken into consideration. We present a tool called the MEROPS batch BLAST which not only performs a comparison against the MEROPS sequence collection, but also does a pair-wise alignment with the closest homologue detected and calculates the position of the active site residues. A non-peptidase homologue can be distinguished by the absence or unacceptable replacement of any of these residues. An analysis of peptidase homologues in the genome of the bacterium Erythrobacter litoralis is presented as an example.
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Affiliation(s)
- Neil D Rawlings
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK.
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35
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Yang SJ. Characterization of vaccinia virus A12L protein proteolysis and its participation in virus assembly. Virol J 2007; 4:78. [PMID: 17678539 PMCID: PMC1959187 DOI: 10.1186/1743-422x-4-78] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Accepted: 08/01/2007] [Indexed: 02/02/2023] Open
Abstract
Vaccinia virus (VV) undergoes a proteolytic processing to evolve from immature virus particles into intracellular mature virus particles. Most of structural core protein precursors such as p4a, p4b, and p25K are assembled into previrions and then proteolytically processed to yield core proteins, 4a, 4b, and 25 K, which become components of a mature virus particle. These structural rearrangements take place at a conserved cleavage motif, Ala-Gly-X (where X is any amino acid) and catalyzed by a VV encoded proteinase, the I7L gene product. The VV A12L gene product, a 25 kDa protein synthesized at late times during infection is cleaved at an N-terminal AG/A site, resulting in a 17 kDa cleavage product. However, due to the distinct characteristics of A12L proteolysis such as the localization of both the A12L full-length protein and its cleavage product in mature virions and two putative cleavage sites (Ala-Gly-Lys) located at internal and C-terminal region of A12L ORF, it was of interest to examine the A12L proteolysis for better understanding of regulation and function of VV proteolysis. Here, we attempted to examine the in vivo A12L processing by: determining the kinetics of the A12L proteolysis, the responsible viral protease, and the function of the A12L protein and its cleavage events. Surprisingly, the A12L precursor was cleaved into multiple peptides not only at an N-terminal AG/A but also at both an N- and a C-terminus. Despite the involvement of I7L proteinase for A12L proteolysis, its incomplete processing with slow kinetics and additional cleavages not at the two AG/K sites demonstrate unique regulation of VV proteolysis. An immunoprecipitation experiment in concert with N-terminal sequencing analyses and mass spectrometry led to the identification of VV core and membrane proteins, which may be associated with the A12L protein and suggested possible involvement of A12L protein and its cleavage products in multiple stages in virus morphogenesis.
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Affiliation(s)
- Su Jung Yang
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331-3804, USA.
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36
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Honeychurch KM, Yang G, Jordan R, Hruby DE. The vaccinia virus F13L YPPL motif is required for efficient release of extracellular enveloped virus. J Virol 2007; 81:7310-5. [PMID: 17475658 PMCID: PMC1933313 DOI: 10.1128/jvi.00034-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Tyr-X-X-Leu (YxxL) motif of the vaccinia virus F13L protein was examined for late (L) domain activity. The ability of an F13L deletion virus to form plaques was restored by PCR products containing single alanine substitutions within the motif and a YAAL construct but not by constructs lacking both the Y and L residues. Recombinant viruses possessing alanine substitutions in place of the tyrosine or the leucine residue in the YxxL motif demonstrated small, asymmetrical plaques. RNA interference-dependent depletion of Alix and TSG101 (host proteins involved in L domain-dependent protein trafficking) diminished extracellular enveloped virion production to various degrees, suggesting that the YxxL motif is a genuine L domain.
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Affiliation(s)
- Kady M Honeychurch
- Department of Microbiology, Oregon State University, 220 Nash Hall, Corvallis, OR 97331, USA
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37
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Ojeda S, Senkevich TG, Moss B. Entry of vaccinia virus and cell-cell fusion require a highly conserved cysteine-rich membrane protein encoded by the A16L gene. J Virol 2007; 80:51-61. [PMID: 16352530 PMCID: PMC1317547 DOI: 10.1128/jvi.80.1.51-61.2006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vaccinia virus A16L open reading frame encodes a 378-amino-acid protein with a predicted C-terminal transmembrane domain and 20 invariant cysteine residues that is conserved in all sequenced members of the poxvirus family. The A16 protein was expressed late in infection and incorporated into intracellular virus particles with the N-terminal segment of the protein exposed on the surface. The cysteine residues were disulfide bonded via the poxvirus cytoplasmic redox system. Unsuccessful attempts to isolate a mutant virus with the A16L gene deleted suggested that the protein is essential for replication. To study the role of the A16 protein, we made a recombinant vaccinia virus that has the Escherichia coli lac operator system regulating transcription of the A16L gene. In the absence of inducer, A16 synthesis was repressed and plaque size and virus yield were greatly reduced. Nevertheless, virus morphogenesis occurred and normal-looking intracellular and extracellular virus particles formed. Purified virions made in the presence and absence of inducer were indistinguishable, though the latter had 60- to 100-fold-lower specific infectivity. A16-deficient virions bound to cells, but their cores did not penetrate into the cytoplasm. Furthermore, A16-deficient virions were unable to induce low-pH-triggered syncytium formation. The phenotype of the inducible A16L mutant was similar to those of mutants in which synthesis of the A21, A28, H2, or L5 membrane protein was repressed, indicating that at least five conserved viral proteins are required for entry of poxviruses into cells as well as for cell-cell fusion.
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Affiliation(s)
- Suany Ojeda
- Laboratory of Viral Diseases, National Institutes of Health, 4 Center Dr., MSC 0445, Bethesda, MD 20892-0445, USA
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38
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Resch W, Hixson KK, Moore RJ, Lipton MS, Moss B. Protein composition of the vaccinia virus mature virion. Virology 2006; 358:233-47. [PMID: 17005230 DOI: 10.1016/j.virol.2006.08.025] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 08/03/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
The protein content of vaccinia virus mature virions, purified by rate zonal and isopycnic centrifugations and solubilized by SDS or a solution of urea and thiourea, was determined by the accurate mass and time tag technology which uses both tandem mass spectrometry and Fourier transform-ion cyclotron resonance mass spectrometry to detect tryptic peptides separated by high-resolution liquid chromatography. Eighty vaccinia virus-encoded proteins representing 37% of the 218 genes annotated in the complete genome sequence were detected in at least three analyses. Ten proteins accounted for approximately 80% of the virion mass. Thirteen identified proteins were not previously reported as components of virions. On the other hand, 8 previously described virion proteins were not detected here, presumably due to technical reasons including small size and hydrophobicity. In addition to vaccinia virus-encoded proteins, 24 host proteins omitting isoforms were detected. The most abundant of these were cytoskeletal proteins, heat shock proteins and proteins involved in translation.
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Affiliation(s)
- Wolfgang Resch
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Center Drive, MSC 0445, Bethesda, MD 20892-0445, USA
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Moerdyk MJ, Byrd CM, Hruby DE. Analysis of vaccinia virus temperature-sensitive I7L mutants reveals two potential functional domains. Virol J 2006; 3:64. [PMID: 16945137 PMCID: PMC1570340 DOI: 10.1186/1743-422x-3-64] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Accepted: 08/31/2006] [Indexed: 11/23/2022] Open
Abstract
As an approach to initiating a structure-function analysis of the vaccinia virus I7L core protein proteinase, a collection of conditional-lethal mutants in which the mutation had been mapped to the I7L locus were subjected to genomic sequencing and phenotypic analyses. Mutations in six vaccinia virus I7L temperature sensitive mutants fall into two groups: changes at three positions at the N-terminal end between amino acids 29 and 37 and two different substitutions at amino acid 344, near the catalytic domain. Regardless of the position of the mutation, mutants at the non-permissive temperature failed to cleave core protein precursors and had their development arrested prior to core condensation. Thus it appears that the two clusters of mutations may affect two different functional domains required for proteinase activity.
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Affiliation(s)
- Megan J Moerdyk
- Department of Microbiology, Oregon State University, Corvallis, OR, 97331, USA
| | - Chelsea M Byrd
- SIGA Technologies, Inc., 4575 SW Research Way, Corvallis, OR, 97333, USA
| | - Dennis E Hruby
- Department of Microbiology, Oregon State University, Corvallis, OR, 97331, USA
- SIGA Technologies, Inc., 4575 SW Research Way, Corvallis, OR, 97333, USA
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Abstract
Poxviruses comprise a large family of viruses characterized by a large, linear dsDNA genome, a cytoplasmic site of replication and a complex virion morphology. The most notorious member of the poxvirus family is variola, the causative agent of smallpox. The laboratory prototype virus used for the study of poxviruses is vaccinia, the virus that was used as a live, naturally attenuated vaccine for the eradication of smallpox. Both the morphogenesis and structure of poxvirus virions are unique among viruses. Poxvirus virions apparently lack any of the symmetry features common to other viruses such as helical or icosahedral capsids or nucleocapsids. Instead poxvirus virions appear as "brick shaped" or "ovoid" membrane-bound particles with a complex internal structure featuring a walled, biconcave core flanked by "lateral bodies." The virion assembly pathway involves a remarkable fabrication of membrane-containing crescents and immature virions, which evolve into mature virions in a process that is unparalleled in virology. As a result of significant advances in poxvirus genetics and molecular biology during the past 15 years, we can now positively identify over 70 specific gene products contained in poxvirus virions, and we can describe the effects of mutations in over 50 specific genes on poxvirus assembly. This review summarizes these advances and attempts to assemble them into a comprehensible and thoughtful picture of poxvirus structure and assembly.
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Affiliation(s)
- Richard C Condit
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, 32610, USA
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Jordan R, Hruby D. Smallpox antiviral drug development: satisfying the animal efficacy rule. Expert Rev Anti Infect Ther 2006; 4:277-89. [PMID: 16597208 PMCID: PMC9709928 DOI: 10.1586/14787210.4.2.277] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Concerns over the potential use of variola virus as a biological weapon have prompted new interest in the development of small molecule therapeutics to prevent and treat smallpox infection. Since smallpox is no longer endemic, human clinical trials designed to link antiviral efficacy to clinical outcome have been supplanted by antiviral efficacy evaluations in animal models of orthopoxvirus disease. This poses a unique challenge for drug development; how can animal efficacy data with a surrogate virus be used to establish clinical correlates predictive of human disease outcome? This review will examine the properties of selected animal models that are being used to evaluate poxvirus antiviral drug candidates, and discuss how data from these models can be used to link drug efficacy to clinical correlates of human disease.
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42
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Byrd CM, Hruby DE. Vaccinia virus proteolysis--a review. Rev Med Virol 2006; 16:187-202. [PMID: 16710840 PMCID: PMC7169229 DOI: 10.1002/rmv.499] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 01/24/2006] [Accepted: 01/24/2006] [Indexed: 01/15/2023]
Abstract
It is well known that viruses, as obligate intracellular parasites, must use their hosts' metabolic machinery in order to replicate their genomes and form infectious progeny virions. What is less well known are the details of how viruses make sure that once all the necessary proteins are made, that they assume the correct configuration at the proper time in order to catalyse the efficient assembly of infectious virions. One of the methods employed by viruses to regulate this process is the proteolytic cleavage of viral proteins. Over the past several decades, studies in numerous laboratories have demonstrated that morphogenic proteolysis plays a major and essential role during the assembly and maturation of infectious poxvirus virions. In this review we describe the history of vaccinia virus proteolysis as a prototypic viral system.
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Affiliation(s)
| | - Dennis E. Hruby
- SIGA Technologies, Inc., Corvallis, Oregon 97333, USA
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA
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43
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Yoder JD, Chen TS, Gagnier CR, Vemulapalli S, Maier CS, Hruby DE. Pox proteomics: mass spectrometry analysis and identification of Vaccinia virion proteins. Virol J 2006; 3:10. [PMID: 16509968 PMCID: PMC1540416 DOI: 10.1186/1743-422x-3-10] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 03/01/2006] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Although many vaccinia virus proteins have been identified and studied in detail, only a few studies have attempted a comprehensive survey of the protein composition of the vaccinia virion. These projects have identified the major proteins of the vaccinia virion, but little has been accomplished to identify the unknown or less abundant proteins. Obtaining a detailed knowledge of the viral proteome of vaccinia virus will be important for advancing our understanding of orthopoxvirus biology, and should facilitate the development of effective antiviral drugs and formulation of vaccines. RESULTS In order to accomplish this task, purified vaccinia virions were fractionated into a soluble protein enriched fraction (membrane proteins and lateral bodies) and an insoluble protein enriched fraction (virion cores). Each of these fractions was subjected to further fractionation by either sodium dodecyl sulfate-polyacrylamide gel electophoresis, or by reverse phase high performance liquid chromatography. The soluble and insoluble fractions were also analyzed directly with no further separation. The samples were prepared for mass spectrometry analysis by digestion with trypsin. Tryptic digests were analyzed by using either a matrix assisted laser desorption ionization time of flight tandem mass spectrometer, a quadrupole ion trap mass spectrometer, or a quadrupole-time of flight mass spectrometer (the latter two instruments were equipped with electrospray ionization sources). Proteins were identified by searching uninterpreted tandem mass spectra against a vaccinia virus protein database created by our lab and a non-redundant protein database. CONCLUSION Sixty three vaccinia proteins were identified in the virion particle. The total number of peptides found for each protein ranged from 1 to 62, and the sequence coverage of the proteins ranged from 8.2% to 94.9%. Interestingly, two vaccinia open reading frames were confirmed as being expressed as novel proteins: E6R and L3L.
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Affiliation(s)
- Jennifer D Yoder
- Oregon State University, Department of Microbiology, 220 Nash Hall, Corvallis, OR 97331-3804, USA
| | - Tsefang S Chen
- Oregon State University, Department of Microbiology, 220 Nash Hall, Corvallis, OR 97331-3804, USA
| | - Cliff R Gagnier
- Oregon State University, Department of Microbiology, 220 Nash Hall, Corvallis, OR 97331-3804, USA
| | - Srilakshmi Vemulapalli
- Oregon State University, Applied Biotechnology Program, 2082 Cordley Hall, Corvallis, OR 97331-8530, USA
| | - Claudia S Maier
- Oregon State University, Department of Chemistry, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA
| | - Dennis E Hruby
- Oregon State University, Department of Microbiology, 220 Nash Hall, Corvallis, OR 97331-3804, USA
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44
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Chung CS, Chen CH, Ho MY, Huang CY, Liao CL, Chang W. Vaccinia virus proteome: identification of proteins in vaccinia virus intracellular mature virion particles. J Virol 2006; 80:2127-40. [PMID: 16474121 PMCID: PMC1395410 DOI: 10.1128/jvi.80.5.2127-2140.2006] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 12/05/2005] [Indexed: 12/17/2022] Open
Abstract
Vaccinia virus is a large enveloped poxvirus with more than 200 genes in its genome. Although many poxvirus genomes have been sequenced, knowledge of the host and viral protein components of the virions remains incomplete. In this study, we used gel-free liquid chromatography and tandem mass spectroscopy to identify the viral and host proteins in purified vaccinia intracellular mature virions (IMV). Analysis of the proteins in the IMV showed that it contains 75 viral proteins, including structural proteins, enzymes, transcription factors, and predicted viral proteins not known to be expressed or present in the IMV. We also determined the relative abundances of the individual protein components in the IMV. Finally, 23 IMV-associated host proteins were also identified. This study provides the first comprehensive structural analysis of the infectious vaccinia virus IMV.
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Affiliation(s)
- Che-Sheng Chung
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
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45
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Honeychurch KM, Byrd CM, Hruby DE. Mutational analysis of the potential catalytic residues of the VV G1L metalloproteinase. Virol J 2006; 3:7. [PMID: 16504157 PMCID: PMC1420270 DOI: 10.1186/1743-422x-3-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Accepted: 02/27/2006] [Indexed: 11/10/2022] Open
Abstract
The vaccinia virus G1L open-reading frame is predicted to be a metalloproteinase based upon the presence of a conserved zinc-binding motif. Western blot analysis demonstrates G1L undergoes proteolytic processing during the course of infection, although the significance of this event is unknown. In order to determine which amino acid residues are important for G1L activity, a plasmid-borne library of G1L constructs containing mutations in and about the active site was created. Transient expression analysis coupled with a trans complementation assay of a conditionally-lethal mutant virus suggest that, of the mutants, only glutamic acid 120 is non-essential for G1L processing to occur.
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Affiliation(s)
- Kady M Honeychurch
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA
| | | | - Dennis E Hruby
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA
- SIGA Technologies, Inc, Corvallis, Oregon 97333, USA
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Iyer LM, Balaji S, Koonin EV, Aravind L. Evolutionary genomics of nucleo-cytoplasmic large DNA viruses. Virus Res 2006; 117:156-84. [PMID: 16494962 DOI: 10.1016/j.virusres.2006.01.009] [Citation(s) in RCA: 433] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Revised: 01/06/2006] [Accepted: 01/09/2006] [Indexed: 11/19/2022]
Abstract
A previous comparative-genomic study of large nuclear and cytoplasmic DNA viruses (NCLDVs) of eukaryotes revealed the monophyletic origin of four viral families: poxviruses, asfarviruses, iridoviruses, and phycodnaviruses [Iyer, L.M., Aravind, L., Koonin, E.V., 2001. Common origin of four diverse families of large eukaryotic DNA viruses. J. Virol. 75 (23), 11720-11734]. Here we update this analysis by including the recently sequenced giant genome of the mimiviruses and several additional genomes of iridoviruses, phycodnaviruses, and poxviruses. The parsimonious reconstruction of the gene complement of the ancestral NCLDV shows that it was a complex virus with at least 41 genes that encoded the replication machinery, up to four RNA polymerase subunits, at least three transcription factors, capping and polyadenylation enzymes, the DNA packaging apparatus, and structural components of an icosahedral capsid and the viral membrane. The phylogeny of the NCLDVs is reconstructed by cladistic analysis of the viral gene complements, and it is shown that the two principal lineages of NCLDVs are comprised of poxviruses grouped with asfarviruses and iridoviruses grouped with phycodnaviruses-mimiviruses. The phycodna-mimivirus grouping was strongly supported by several derived shared characters, which seemed to rule out the previously suggested basal position of the mimivirus [Raoult, D., Audic, S., Robert, C., Abergel, C., Renesto, P., Ogata, H., La Scola, B., Suzan, M., Claverie, J.M. 2004. The 1.2-megabase genome sequence of Mimivirus. Science 306 (5700), 1344-1350]. These results indicate that the divergence of the major NCLDV families occurred at an early stage of evolution, prior to the divergence of the major eukaryotic lineages. It is shown that subsequent evolution of the NCLDV genomes involved lineage-specific expansion of paralogous gene families and acquisition of numerous genes via horizontal gene transfer from the eukaryotic hosts, other viruses, and bacteria (primarily, endosymbionts and parasites). Amongst the expansions, there are multiple families of predicted virus-specific signaling and regulatory domains. Most NCLDVs have also acquired large arrays of genes related to ubiquitin signaling, and the animal viruses in particular have independently evolved several defenses against apoptosis and immune response, including growth factors and potential inhibitors of cytokine signaling. The mimivirus displays an enormous array of genes of bacterial provenance, including a representative of a new class of predicted papain-like peptidases. It is further demonstrated that a significant number of genes found in NCLDVs also have homologs in bacteriophages, although a vertical relationship between the NCLDVs and a particular bacteriophage group could not be established. On the basis of these observations, two alternative scenarios for the origin of the NCLDVs and other groups of large DNA viruses of eukaryotes are considered. One of these scenarios posits an early assembly of an already large DNA virus precursor from which various large DNA viruses diverged through an ongoing process of displacement of the original genes by xenologous or non-orthologous genes from various sources. The second scenario posits convergent emergence, on multiple occasions, of large DNA viruses from small plasmid-like precursors through independent accretion of similar sets of genes due to strong selective pressures imposed by their life cycles and hosts.
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Affiliation(s)
- Lakshminarayan M Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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Abstract
During antiviral drug development, any essential stage of the viral life cycle can serve as a potential drug target. Since most viruses encode specific proteases whose cleavage activity is required for viral replication, and whose structure and activity are unique to the virus and not the host cell, these enzymes make excellent targets for drug development. Success using this approach has been demonstrated with the plethora of protease inhibitors approved for use against HIV. This discussion is designed to review the field of antiviral drug development, focusing on the search for protease inhibitors, while highlighting some of the challenges encountered along the way. Protease inhibitor drug discovery efforts highlighting progress made with HIV, HCV, HRV, and vaccinia virus as a model system are included. Drug Dev. Res. 67:501–510, 2006. © 2006 Wiley‐Liss, Inc.
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Affiliation(s)
| | - Dennis E. Hruby
- SIGA Technologies, Inc., Corvallis, Oregon
- Department of Microbiology, Oregon State University, Corvallis, Oregon
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Byrd CM, Hruby DE. Development of an in vitro cleavage assay system to examine vaccinia virus I7L cysteine proteinase activity. Virol J 2005; 2:63. [PMID: 16105175 PMCID: PMC1198262 DOI: 10.1186/1743-422x-2-63] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 08/16/2005] [Indexed: 02/05/2023] Open
Abstract
Through the use of transient expression assays and directed genetics, the vaccinia virus (VV) I7L gene product has been implicated as the major maturational proteinase required for viral core protein cleavage to occur during virion assembly. To confirm this hypothesis and to enable a biochemical examination of the I7L cysteine proteinase, an in vitro cleavage assay was developed. Using extracts of VV infected cells as the source of enzyme, reaction conditions were developed which allowed accurate and efficient cleavage of exogenously added core protein precursors (P4a, P4b and P25K). The cleavage reaction proceeded in a time-dependent manner and was optimal when incubated at 25°C. I7L-mediated cleavage was not affected by selected inhibitors of metalloproteinases, aspartic acid proteinases or serine proteinases (EDTA, pepstatin, and PMSF, respectively), but was sensitive to several general cysteine proteinase inhibitors (E-64, EST, Iodoacetic acid, and NEM) as well as the I7L active site inhibitor TTP-6171 [C. Byrd et al., J. Virol. 78:12147–12156 (2004)]. Finally, in antibody pull down experiments, it could be demonstrated that monospecific αI7L serum depleted the enzyme activity whereas control sera including αG1L, directed against the VV metalloproteinase, did not. Taken together, these data provide biochemical evidence that I7L is a cysteine proteinase which is directly involved in VV core protein cleavage. Furthermore, establishment of this I7L-mediated in vitro cleavage assay should enable future studies into the enzymology and co-factor requirements of the proteolysis reaction, and facilitate antiviral drug development against this essential target.
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Affiliation(s)
- Chelsea M Byrd
- Molecular and Cellular Biology Program, Oregon State University, 220 Nash Hall, Corvallis, Oregon, 97331, USA
| | - Dennis E Hruby
- Molecular and Cellular Biology Program, Oregon State University, 220 Nash Hall, Corvallis, Oregon, 97331, USA
- Siga Technologies, 4575 SW Research Way, Suite 230, Corvallis, Oregon, 97333, USA
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Punjabi A, Traktman P. Cell biological and functional characterization of the vaccinia virus F10 kinase: implications for the mechanism of virion morphogenesis. J Virol 2005; 79:2171-90. [PMID: 15681420 PMCID: PMC546551 DOI: 10.1128/jvi.79.4.2171-2190.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vaccinia virus F10 protein is one of two virally encoded protein kinases. A phenotypic analysis of infections involving a tetracycline-inducible recombinant (vDeltaiF10) indicated that F10 is involved in the early stages of virion morphogenesis, as previously reported for the mutants ts28 and ts15. The proteins encoded by ts28 and ts15 have primary defects in enzymatic activity and thermostability, respectively. Using a transient complementation assay, we demonstrated that the enzymatic activity of F10 is essential for its biological function and that both its enzymatic and biological functions depend upon N-terminal sequences that precede the catalytic domain. An execution point analysis indicated that in addition to its role at the onset of morphogenesis, F10 is also required at later stages, when membrane crescents surround virosomal contents and develop into immature virions. The F10 protein is phosphorylated in vivo, appears to be tightly associated with intracellular membranes, and can bind to specific phosphoinositides in vitro. When F10 is repressed or impaired, the phosphorylation of several cellular and viral proteins appears to increase in intensity, suggesting that F10 may normally intersect with cellular signaling cascades via the activation of a phosphatase or the inhibition of another kinase. These cascades may drive the F10-induced remodeling of membranes that accompanies virion biogenesis. Upon the release of ts28-infected cultures from a 40 degrees C-induced block, a synchronous resumption of morphogenesis that culminates in the production of infectious virus can be observed. The pharmacological agents H89 and cerulenin, which are inhibitors of endoplasmic reticulum exit site formation and de novo lipid synthesis, respectively, block this recovery.
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Affiliation(s)
- Almira Punjabi
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Rd., BSB-273, Milwaukee, WI 53226, USA
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Resch W, Weisberg AS, Moss B. Vaccinia virus nonstructural protein encoded by the A11R gene is required for formation of the virion membrane. J Virol 2005; 79:6598-609. [PMID: 15890898 PMCID: PMC1112135 DOI: 10.1128/jvi.79.11.6598-6609.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The vaccinia virus A11R gene has orthologs in all known poxvirus genomes, and the A11 protein has been previously reported to interact with the putative DNA packaging protein A32 in a yeast two-hybrid screen. Using antisera raised against A11 peptides, we show that the A11 protein was (i) expressed at late times with an apparent mass of 40 kDa, (ii) not incorporated into virus particles, (iii) phosphorylated independently of the viral F10 kinase, (iv) coimmunoprecipitated with A32, and (v) localized to the viral factory. To determine the role of the A11 protein and test whether it is indeed involved in DNA packaging, we constructed a recombinant vaccinia virus with an inducible A11R gene. This recombinant was dependent on inducer for single-cycle growth and plaque formation. In the absence of inducer, viral late proteins were produced at normal levels, but proteolytic processing and other posttranslational modifications of some proteins were inhibited, suggesting a block in virus particle assembly. Consistent with this observation, electron microscopy of cells infected in the absence of inducer showed virus factories with abnormal electron-dense viroplasms and intermediate density regions associated with membranes and containing the D13 protein. However, no viral membrane crescents, immature virions, or mature virions were produced. The requirement for nonvirion protein A11 in order to make normal viral membranes was an unexpected and exciting finding, since neither the origin of these membranes nor their mechanism of formation in the cytoplasm of infected cells is understood.
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Affiliation(s)
- Wolfgang Resch
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0445, USA
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