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Lee W, Kim YJ, Lee SJ, Ahn DG, Kim SJ. Current Status of Epidemiology, Diagnosis, Therapeutics, and Vaccines for the Re-Emerging Human Monkeypox Virus. J Microbiol Biotechnol 2023; 33:981-991. [PMID: 37519276 PMCID: PMC10468680 DOI: 10.4014/jmb.2306.06033] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 08/01/2023]
Abstract
Monkeypox (Mpox) virus, a member of the Poxviridae family, causes a severe illness similar to smallpox, which is characterized by symptoms such as high fever, rash, and pustules. Human-to-human transmission cases have been reported but remained low since the first recorded case of human infection occurred in the Congo in 1970. Recently, Mpox has re-emerged, leading to an alarming surge in infections worldwide since 2022, originating in the United Kingdom. Consequently, the World Health Organization (WHO) officially declared the '2022-23 Mpox outbreak'. Currently, no specific therapy or vaccine is available for Mpox. Therefore, patients infected with Mpox are treated using conventional therapies developed for smallpox. However, the vaccines developed for smallpox have demonstrated only partial efficacy against Mpox, allowing viral transmission among humans. In this review, we discuss the current epidemiology of the ongoing Mpox outbreak and provide an update on the progress made in diagnosis, treatment, and development of vaccines for Mpox.
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Affiliation(s)
- Wooseong Lee
- Department of Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Yu-Jin Kim
- Department of Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Su Jin Lee
- Department of Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Dae-Gyun Ahn
- Department of Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Seong-Jun Kim
- Department of Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
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The Vaccinia Virus B12 Pseudokinase Represses Viral Replication via Interaction with the Cellular Kinase VRK1 and Activation of the Antiviral Effector BAF. J Virol 2021; 95:JVI.02114-20. [PMID: 33177193 DOI: 10.1128/jvi.02114-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 10/31/2020] [Indexed: 11/20/2022] Open
Abstract
The poxviral B1 and B12 proteins are a homologous kinase-pseudokinase pair, which modulates a shared host pathway governing viral DNA replication and antiviral defense. While the molecular mechanisms involved are incompletely understood, B1 and B12 seem to intersect with signaling processes mediated by their cellular homologs termed the vaccinia-related kinases (VRKs). In this study, we expand upon our previous characterization of the B1-B12 signaling axis to gain insights into B12 function. We begin our studies by demonstrating that modulation of B12 repressive activity is a conserved function of B1 orthologs from divergent poxviruses. Next, we characterize the protein interactome of B12 using multiple cell lines and expression systems and discover that the cellular kinase VRK1 is a highly enriched B12 interactor. Using complementary VRK1 knockdown and overexpression assays, we first demonstrate that VRK1 is required for the rescue of a B1-deleted virus upon mutation of B12. Second, we find that VRK1 overexpression is sufficient to overcome repressive B12 activity during B1-deleted virus replication. Interestingly, we also evince that B12 interferes with the ability of VRK1 to phosphoinactivate the host defense protein BAF. Thus, B12 restricts vaccinia virus DNA accumulation in part by repressing the ability of VRK1 to inactivate BAF. Finally, these data establish that a B12-VRK1-BAF signaling axis forms during vaccinia virus infection and is modulated via kinases B1 and/or VRK2. These studies provide novel insights into the complex mechanisms that poxviruses use to hijack homologous cellular signaling pathways during infection.IMPORTANCE Viruses from diverse families encode both positive and negative regulators of viral replication. While their functions can sometimes be enigmatic, investigation of virus-encoded, negative regulators of viral replication has revealed fascinating aspects of virology. Studies of poxvirus-encoded genes have largely concentrated on positive regulators of their replication; however, examples of fitness gains attributed to poxvirus gene loss suggests that negative regulators of poxvirus replication also impact infection dynamics. This study focuses on the vaccinia B12 pseudokinase, a protein capable of inhibiting vaccinia DNA replication. Here, we elucidate the mechanisms by which B12 inhibits vaccinia DNA replication, demonstrating that B12 activates the antiviral protein BAF by inhibiting the activity of VRK1, a cellular modulator of BAF. Combined with previous data, these studies provide evidence that poxviruses govern their replication by employing both positive and negative regulators of viral replication.
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Sroor FM, Khatab TK, Basyouni WM, El-Bayouki KAM. Synthesis and molecular docking studies of some new thiosemicarbazone derivatives as HCV polymeraseinhibitors. SYNTHETIC COMMUN 2019. [DOI: 10.1080/00397911.2019.1605443] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Farid M. Sroor
- Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt
| | - Tamer K. Khatab
- Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt
| | - Wahid M. Basyouni
- Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt
| | - Khairy A. M. El-Bayouki
- Organometallic and Organometalloid Chemistry Department, National Research Centre, Cairo, Egypt
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Combined Proteomics/Genomics Approach Reveals Proteomic Changes of Mature Virions as a Novel Poxvirus Adaptation Mechanism. Viruses 2017; 9:v9110337. [PMID: 29125539 PMCID: PMC5707544 DOI: 10.3390/v9110337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 12/16/2022] Open
Abstract
DNA viruses, like poxviruses, possess a highly stable genome, suggesting that adaptation of virus particles to specific cell types is not restricted to genomic changes. Cowpox viruses are zoonotic poxviruses with an extraordinarily broad host range, demonstrating their adaptive potential in vivo. To elucidate adaptation mechanisms of poxviruses, we isolated cowpox virus particles from a rat and passaged them five times in a human and a rat cell line. Subsequently, we analyzed the proteome and genome of the non-passaged virions and each passage. While the overall viral genome sequence was stable during passaging, proteomics revealed multiple changes in the virion composition. Interestingly, an increased viral fitness in human cells was observed in the presence of increased immunomodulatory protein amounts. As the only minor variant with increasing frequency during passaging was located in a viral RNA polymerase subunit and, moreover, most minor variants were found in transcription-associated genes, protein amounts were presumably regulated at transcription level. This study is the first comparative proteome analysis of virus particles before and after cell culture propagation, revealing proteomic changes as a novel poxvirus adaptation mechanism.
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Emergence of a Viral RNA Polymerase Variant during Gene Copy Number Amplification Promotes Rapid Evolution of Vaccinia Virus. J Virol 2017; 91:JVI.01428-16. [PMID: 27928012 DOI: 10.1128/jvi.01428-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/29/2016] [Indexed: 01/21/2023] Open
Abstract
Viruses are under relentless selective pressure from host immune defenses. To study how poxviruses adapt to innate immune detection pathways, we performed serial vaccinia virus infections in primary human cells. Independent courses of experimental evolution with a recombinant strain lacking E3L revealed several high-frequency point mutations in conserved poxvirus genes, suggesting important roles for essential poxvirus proteins in innate immune subversion. Two distinct mutations were identified in the viral RNA polymerase gene A24R, which seem to act through different mechanisms to increase virus replication. Specifically, a Leu18Phe substitution encoded within A24R conferred fitness trade-offs, including increased activation of the antiviral factor protein kinase R (PKR). Intriguingly, this A24R variant underwent a drastic selective sweep during passaging, despite enhanced PKR activity. We showed that the sweep of this variant could be accelerated by the presence of copy number variation (CNV) at the K3L locus, which in multiple copies strongly reduced PKR activation. Therefore, adaptive cases of CNV can facilitate the accumulation of point mutations separate from the expanded locus. This study reveals how rapid bouts of gene copy number amplification during accrual of distant point mutations can potently facilitate poxvirus adaptation to host defenses. IMPORTANCE Viruses can evolve quickly to defeat host immune functions. For poxviruses, little is known about how multiple adaptive mutations emerge in populations at the same time. In this study, we uncovered a means of vaccinia virus adaptation involving the accumulation of distinct genetic variants within a single population. We identified adaptive point mutations in the viral RNA polymerase gene A24R and, surprisingly, found that one of these mutations activates the nucleic acid sensing factor PKR. We also found that gene copy number variation (CNV) can provide dual benefits to evolving virus populations, including evidence that CNV facilitates the accumulation of a point mutation distant from the expanded locus. Our data suggest that transient CNV can accelerate the fixation of mutations conferring modest benefits, or even fitness trade-offs, and highlight how structural variation might aid poxvirus adaptation through both direct and indirect actions.
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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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Saravanan RR, Seshadri S, Gunasekaran S, Mendoza-Meroño R, Garcia-Granda S. Conformational analysis, X-ray crystallographic, FT-IR, FT-Raman, DFT, MEP and molecular docking studies on 1-(1-(3-methoxyphenyl) ethylidene) thiosemicarbazide. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 139:321-328. [PMID: 25574651 DOI: 10.1016/j.saa.2014.12.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 11/22/2014] [Accepted: 12/10/2014] [Indexed: 06/04/2023]
Abstract
Conformational analysis, X-ray crystallographic, FT-IR, FT-Raman, DFT, MEP and molecular docking studies on 1-(1-(3-methoxyphenyl) ethylidene) thiosemicarbazide (MPET) are investigated. From conformational analysis the examination of the positions of a molecule taken and the energy changes is observed. The docking studies of the ligand MPET with target protein showed that this is a good molecule which docks well with target related to HMG-CoA. Hence MPET can be considered for developing into a potent anti-cholesterol drug. MEP assists in optimization of electrostatic interactions between the protein and the ligand. The MEP surface displays the molecular shape, size and electrostatic potential values. The optimized geometry of the compound was calculated from the DFT-B3LYP gradient calculations employing 6-31G (d, p) basis set and calculated vibrational frequencies are evaluated via comparison with experimental values.
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Affiliation(s)
- R R Saravanan
- Department of Physics, Misrimal Navajee Munoth Jain Engineering College, Thoraipakkam, Chennai 600 097, India.
| | - S Seshadri
- Department of Physics, L.N. Govt. Arts College, Ponneri, Thiruvallur 601 001, India
| | - S Gunasekaran
- Research & Development, St. Peter's University, Avadi, Chennai 600 054, India
| | - R Mendoza-Meroño
- Faculty of Chemistry, Department of Physical and Analytical Chemistry, University Oviedo, C/ Julian Claveria, 8, 33006 Oviedo, Asturias, Spain
| | - S Garcia-Granda
- Faculty of Chemistry, Department of Physical and Analytical Chemistry, University Oviedo, C/ Julian Claveria, 8, 33006 Oviedo, Asturias, Spain
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Ibrahim N, Wicklund A, Jamin A, Wiebe MS. Barrier to autointegration factor (BAF) inhibits vaccinia virus intermediate transcription in the absence of the viral B1 kinase. Virology 2013; 444:363-73. [PMID: 23891157 DOI: 10.1016/j.virol.2013.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/01/2013] [Accepted: 07/02/2013] [Indexed: 11/16/2022]
Abstract
Barrier to autointegration factor (BAF/BANF1) is a cellular DNA-binding protein found in the nucleus and cytoplasm. Cytoplasmic BAF binds to foreign DNA and can act as a defense against vaccinia DNA replication. To evade BAF, vaccinia expresses the B1 kinase, which phosphorylates BAF and blocks its ability to bind DNA. Interestingly, B1 is also needed for viral intermediate gene expression via an unknown mechanism. Therefore, we evaluated the impact of B1-BAF signaling on vaccinia transcription. Strikingly, the decrease in vaccinia transcription caused by loss of B1 can be rescued by depletion of BAF. The repressive action of BAF is greatest on a viral promoter, and is more modest when non-vaccinia promoters are employed, which suggests BAF acts in a gene specific manner. These studies expand our understanding of the role of the B1 kinase during infection and provide the first evidence that BAF is a defense against viral gene expression.
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Affiliation(s)
- Nouhou Ibrahim
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900, USA
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Ettari R, Tamborini L, Angelo IC, Micale N, Pinto A, De Micheli C, Conti P. Inhibition of Rhodesain as a Novel Therapeutic Modality for Human African Trypanosomiasis. J Med Chem 2013; 56:5637-58. [DOI: 10.1021/jm301424d] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Roberta Ettari
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli
25, 20133 Milano, Italy
| | - Lucia Tamborini
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli
25, 20133 Milano, Italy
| | - Ilenia C. Angelo
- Dipartimento di Scienze del
Farmaco e Prodotti per la Salute, Università degli Studi di Messina, Viale Annunziata, 98168 Messina, Italy
| | - Nicola Micale
- Dipartimento di Scienze del
Farmaco e Prodotti per la Salute, Università degli Studi di Messina, Viale Annunziata, 98168 Messina, Italy
| | - Andrea Pinto
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli
25, 20133 Milano, Italy
| | - Carlo De Micheli
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli
25, 20133 Milano, Italy
| | - Paola Conti
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli
25, 20133 Milano, Italy
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Rhenium(I) tricarbonyl complexes of salicylaldehyde semicarbazones: Synthesis, crystal structures and cytotoxicity. J Inorg Biochem 2013; 119:10-20. [DOI: 10.1016/j.jinorgbio.2012.10.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/10/2012] [Accepted: 10/23/2012] [Indexed: 11/23/2022]
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12
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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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Caputto ME, Fabian LE, Benítez D, Merlino A, Ríos N, Cerecetto H, Moltrasio GY, Moglioni AG, González M, Finkielsztein LM. Thiosemicarbazones derived from 1-indanones as new anti-Trypanosoma cruzi agents. Bioorg Med Chem 2011; 19:6818-26. [DOI: 10.1016/j.bmc.2011.09.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 09/14/2011] [Accepted: 09/20/2011] [Indexed: 11/25/2022]
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Parrilha GL, da Silva JG, Gouveia LF, Gasparoto AK, Dias RP, Rocha WR, Santos DA, Speziali NL, Beraldo H. Pyridine-derived thiosemicarbazones and their tin(IV) complexes with antifungal activity against Candida spp. Eur J Med Chem 2011; 46:1473-82. [PMID: 21353348 DOI: 10.1016/j.ejmech.2011.01.041] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 01/18/2011] [Accepted: 01/25/2011] [Indexed: 11/28/2022]
Abstract
[(n-Bu)Sn(2Ac4oClPh)Cl2] (1), [(n-Bu)Sn(2Ac4oFPh)Cl2] (2), [(n-Bu)Sn(2Ac4oNO2Ph)Cl2] (3), [(n-Bu)Sn(2Bz4oClPh)Cl2] (4), [(n-Bu)Sn(2Bz4oFPh)Cl2] (5) and [(n-Bu)Sn(2Bz4oNO2Ph)Cl2] (6) were obtained by reacting [(n-Bu)SnCl3] with 2-acetylpyridine-N4-orthochlorophenyl thiosemicarbazone (H2Ac4oClPh), 2-acetylpyridine-N4-orthofluorphenyl thiosemicarbazone (H2Ac4oFPh), 2-acetylpyridine-N4-orthonitrophenyl thiosemicarbazone (H2Ac4oNO2Ph), and with the corresponding 2-benzoylpyridine-derived thiosemicarbazones (H2Bz4oClPh, H2ABz4oFPh and H2Bz4oNO2Ph). The antifungal activity of the studied compounds was evaluated against several Candida species. Upon coordination of H2Bz4oNO2Ph to tin in complex (6) the antifungal activity increased three times against Candida albicans and Candida krusei and six times against Candida glabrata and Candida parapsilosis. The minimum inhibitory concentration (MIC) values of H2Ac4oNO2Ph and its complex (3) against C. albicans, C. parapsilosis and C. glabrata are similar to that of fluconazole. All studied compounds were more active than fluconazole against C. krusei.
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Affiliation(s)
- Gabrieli L Parrilha
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil
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Manganese(II) complexes with N4-methyl-4-nitrobenzaldehyde, N4-methyl-4-nitroacetofenone, and N4-methyl-4-nitrobenzophenone thiosemicarbazone: Investigation of in vitro activity against Trypanosoma cruzi. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.04.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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In vitro susceptibility of sea lion poxvirus to cidofovir. Antiviral Res 2008; 80:77-80. [DOI: 10.1016/j.antiviral.2008.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 03/14/2008] [Accepted: 03/19/2008] [Indexed: 11/21/2022]
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17
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Heterocyclic substituted thiosemicarbazones and their Cu(II) complexes: Synthesis, characterization and studies of substituent effects on coordination and DNA binding. Polyhedron 2008. [DOI: 10.1016/j.poly.2007.12.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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18
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D'Costa SM, Bainbridge TW, Condit RC. Purification and properties of the vaccinia virus mRNA processing factor. J Biol Chem 2007; 283:5267-75. [PMID: 18089571 DOI: 10.1074/jbc.m709258200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mRNAs encoding the vaccinia virus F17 protein and the cowpox A-type inclusion protein are known to possess sequence-homogeneous 3' ends, generated by a post-transcriptional cleavage event. By using partially purified extracts, we have previously shown that the same factor probably cleaves both the F17 and A-type inclusion protein transcripts and that the cleavage factor is either virus-coded or virus-induced during the post-replicative phase of virus replication. In this study, we have purified the cleavage factor from vaccinia-infected HeLa cells using column chromatography and gel filtration. The factor eluted from the gel filtration column with an apparent molecular mass of approximately 440 kDa. Mass spectrometric analyses of the proteins present in the peak active fractions revealed the presence of at least one vaccinia protein with a high degree of certainty, the H5R gene product. To extend this finding, extracts were prepared from HeLa cells infected with vaccinia virus overexpressing His-tagged H5, chromatographed on a nickel affinity column, and eluted using an imidazole gradient. Cleavage activity eluted with the peak of His-tagged H5. Gel filtration of the affinity-purified material further demonstrated that cleavage activity and His-tagged H5 co-chromatographed with an apparent molecular mass of 463 kDa. We therefore conclude that H5 is specifically associated with post-transcriptional cleavage of F17R transcripts. In addition, we show that dephosphorylation of a cleavage competent extract with a nonspecific phosphatase abolishes cleavage activity implying a role for phosphorylation in cleavage activity.
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Affiliation(s)
- Susan M D'Costa
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida 32610-0266, USA.
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Synthesis, characterization, crystal structure and antiproliferative in vitro activity of long-chain aliphatic thiosemicarbazones and their Ni(II) complexes. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.07.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Cresawn SG, Condit RC. A targeted approach to identification of vaccinia virus postreplicative transcription elongation factors: genetic evidence for a role of the H5R gene in vaccinia transcription. Virology 2007; 363:333-41. [PMID: 17376501 PMCID: PMC1950266 DOI: 10.1016/j.virol.2007.02.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 11/18/2006] [Accepted: 02/05/2007] [Indexed: 11/17/2022]
Abstract
Treatment of wild-type vaccinia virus infected cells with the anti-poxviral drug isatin-beta-thiosemicarbazone (IBT) induces the viral postreplicative transcription apparatus to synthesize longer-than-normal mRNAs through an unknown mechanism. Prior studies have shown that virus mutants resistant to or dependent on IBT affect proteins involved in control of viral postreplicative transcription elongation, including G2, J3, and the viral RNA polymerase. Prior studies also suggest that there exist additional unidentified vaccinia genes that influence transcription elongation. The present study was undertaken to target candidate transcription elongation factor genes in an error-prone mutagenesis protocol to determine whether IBT-resistant or -dependent alleles could be isolated in those candidate genes. Mutagenesis of genes in which IBT resistance alleles have previously been isolated, namely A24R (encoding the second largest RNA polymerase subunit, rpo132) and G2R (encoding a positive transcription elongation factor), resulted in isolation of novel IBT resistance and dependence alleles therefore providing proof of principle of the targeted mutagenesis technique. The vaccinia H5 protein has been implicated previously in transcription elongation by virtue of its association with the positive elongation factor G2. Mutagenesis of the vaccinia H5R gene resulted in a novel H5R IBT resistance allele, strongly suggesting that H5 is a positive transcription elongation factor.
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Affiliation(s)
| | - Richard C. Condit
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610
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Cresawn SG, Prins C, Latner DR, Condit RC. Mapping and phenotypic analysis of spontaneous isatin-beta-thiosemicarbazone resistant mutants of vaccinia virus. Virology 2007; 363:319-32. [PMID: 17336362 PMCID: PMC1950264 DOI: 10.1016/j.virol.2007.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 02/05/2007] [Accepted: 02/05/2007] [Indexed: 11/22/2022]
Abstract
Treatment of wild type vaccinia virus infected cells with the anti-poxviral drug isatin-beta-thiosemicarbazone (IBT) induces the viral postreplicative transcription apparatus to synthesize longer-than-normal mRNAs through an unknown mechanism. Previous studies have shown that virus mutants resistant to or dependent on IBT affect genes involved in control of viral postreplicative transcription elongation. This study was initiated in order to identify additional viral genes involved in control of vaccinia postreplicative transcription elongation. Eight independent, spontaneous IBT resistant mutants of vaccinia virus were isolated. Marker rescue experiments mapped two mutants to gene G2R, which encodes a previously characterized postreplicative gene positive transcription elongation factor. Three mutants mapped to the largest subunit of the viral RNA polymerase, rpo147, the product of gene J6R. One mutant contained missense mutations in both G2R and A24R (rpo132, the second largest subunit of the RNA polymerase). Two mutants could not be mapped, however sequence analysis demonstrated that neither of these mutants contained mutations in previously identified IBT resistance or dependence genes. Phenotypic and biochemical analysis of the mutants suggests that they possess defects in transcription elongation that compensate for the elongation enhancing effects of IBT. The results implicate the largest subunit of the RNA polymerase (rpo147) in the control of elongation, and suggest that there exist additional gene products which mediate intermediate and late transcription elongation in vaccinia virus.
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Affiliation(s)
| | | | | | - Richard C. Condit
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610
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22
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Andrei G, Gammon DB, Fiten P, De Clercq E, Opdenakker G, Snoeck R, Evans DH. Cidofovir resistance in vaccinia virus is linked to diminished virulence in mice. J Virol 2006; 80:9391-401. [PMID: 16973545 PMCID: PMC1617232 DOI: 10.1128/jvi.00605-06] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC)] is recognized as a promising drug for the treatment of poxvirus infections, but drug resistance can arise by a mechanism that is poorly understood. We show here that in vitro selection for high levels of resistance to HPMPC produces viruses encoding two substitution mutations in the virus DNA polymerase (E9L) gene. These mutations are located within the regions of the gene encoding the 3'-5' exonuclease (A314T) and polymerase (A684V) catalytic domains. These mutant viruses exhibited cross-resistance to other nucleoside phosphonate drugs, while they remained sensitive to other unrelated DNA polymerase inhibitors. Marker rescue experiments were used to transfer A314T and/or A684V alleles into a vaccinia virus Western Reserve strain. Either mutation alone could confer a drug resistance phenotype, although the degree of resistance was significantly lower than when virus encoded both mutations. The A684V substitution, but not the A314T change, also conferred a spontaneous mutator phenotype. All of the HPMPC-resistant recombinant viruses exhibited reduced virulence in mice, demonstrating that these E9L mutations are inextricably linked to reduced fitness in vivo. HPMPC, at a dose of 50 mg/kg of body weight/day for 5 days, still protected mice against intranasal challenge with the drug-resistant virus with A314T and A684V mutations. Our studies show that proposed drug therapies offer a reasonable likelihood of controlling orthopoxvirus infections, even if the viruses encode drug resistance markers.
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Affiliation(s)
- Graciela Andrei
- Laboratory of Virology, Katholieke Universiteit Leuven, Leuven B-3000, Belgium
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23
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Mackey ZB, Baca AM, Mallari JP, Apsel B, Shelat A, Hansell EJ, Chiang PK, Wolff B, Guy KR, Williams J, McKerrow JH. Discovery of trypanocidal compounds by whole cell HTS of Trypanosoma brucei. Chem Biol Drug Des 2006; 67:355-63. [PMID: 16784460 DOI: 10.1111/j.1747-0285.2006.00389.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Chemotherapy against human African trypanosomiasis relies on four drugs that cause frequent and occasionally severe side-effects. Because human African trypanosomiasis is a disease of poor people in Africa, the traditional market-driven pathways to drug development are not available. One potentially rapid and cost-effective approach to identifying and developing new trypanocidal drugs would be high throughput-screening of existing drugs already approved for other uses, as well as clinical candidates in late development. We have developed an ATP-bioluminescence assay that could be used to rapidly and efficiently screen compound libraries against trypanosomes in a high throughput-screening format to validate this notion. We screened a collection of 2160 FDA-approved drugs, bioactive compounds and natural products to identify hits that were cytotoxic to cultured Trypanosoma brucei at a concentration of 1 mum or less. This meant that any hit identified would be effective at a concentration readily achievable by standard drug dosing in humans. From the screen, 35 hits from seven different drug categories were identified. These included the two approved trypanocidal drugs, suramin and pentamidine, several other drugs suspected but never validated as trypanocidal, and 17 novel trypanocidal drugs.
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Affiliation(s)
- Zachary B Mackey
- Department of Pathology and the Sandler Center for Basic Research in Parasitic Diseases, University of California, QB3 1700 4th St, San Francisco, CA 94158, USA
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24
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Maurya MR, Kumar A, Abid M, Azam A. Dioxovanadium(V) and μ-oxo bis[oxovanadium(V)] complexes containing thiosemicarbazone based ONS donor set and their antiamoebic activity. Inorganica Chim Acta 2006. [DOI: 10.1016/j.ica.2006.02.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Pirrung MC, Pansare SV, Sarma KD, Keith KA, Kern ER. Combinatorial Optimization of Isatin-β-Thiosemicarbazones as Anti-poxvirus Agents. J Med Chem 2005; 48:3045-50. [PMID: 15828843 DOI: 10.1021/jm049147h] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel strategies are required to combat pox virus infections, whether caused by escape of viruses such as monkeypox from indigenous areas or intentional release of smallpox. Anti-smallpox drugs with a unique mode of antiviral action, inhibition of transcription termination, were known but not therapeutically useful. Using a combinatorial method, variants of the basic isatin-beta-thiosemicarbazone structure were prepared and examined for cytotoxicity and antiviral activity in vaccinia virus- and cowpox virus-infected human cells. Potent and much more selective N-aminomethyl-isatin-beta-thiosemicarbazones were discovered.
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Affiliation(s)
- Michael C Pirrung
- Department of Chemistry, Levine Science Research Center, Box 90317, Duke University, Durham, North Carolina 27708-0317, USA.
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26
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Prins C, Cresawn SG, Condit RC. An isatin-beta-thiosemicarbazone-resistant vaccinia virus containing a mutation in the second largest subunit of the viral RNA polymerase is defective in transcription elongation. J Biol Chem 2004; 279:44858-71. [PMID: 15294890 DOI: 10.1074/jbc.m408167200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The vaccinia virus RNA polymerase is a multi-subunit enzyme that contains eight subunits in the postreplicative form. A prior study of a virus called IBT(r90), which contains a mutation in the A24 gene encoding the RPO132 subunit of the RNA polymerase, demonstrated that the mutation results in resistance to the anti-poxvirus drug isatin-beta-thiosemicarbazone (IBT). In this study, we utilized an in vitro transcription elongation assay to determine the effect of this mutation on transcription elongation. Both wild type and IBT(r90) polymerase complexes were studied with regard to their ability to pause during elongation, their stability in a paused state, their ability to release transcripts, and their elongation rate. We have determined that the IBT(r90) complex is specifically defective in elongation compared with the WT complex, pausing longer and more frequently than the WT complex. We have built a homology model of the RPO132 subunit with the yeast pol II rpb2 subunit to propose a structural mechanism for this elongation defect.
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Affiliation(s)
- Cindy Prins
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida 32610-0266, USA
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27
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Greenbaum DC, Mackey Z, Hansell E, Doyle P, Gut J, Caffrey CR, Lehrman J, Rosenthal PJ, McKerrow JH, Chibale K. Synthesis and Structure−Activity Relationships of Parasiticidal Thiosemicarbazone Cysteine Protease Inhibitors againstPlasmodium falciparum,Trypanosoma brucei, andTrypanosoma cruzi. J Med Chem 2004; 47:3212-9. [PMID: 15163200 DOI: 10.1021/jm030549j] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have synthesized a library of thiosemicarbazones and screened them against three parasitic cysteine proteases, cruzain, falcipain-2, and rhodesain, and against the respective parasite sources of these three proteases, Trypanosoma cruzi, Plasmodium falciparum, and Trypanosoma brucei. The screens identified compounds that were effective against the enzymes and the parasites but also some compounds that were parasiticidal despite a lack of activity against the proteases. Several compounds were effective in killing all tested parasites. These promising lead compounds were tested for general toxicity in mice, and only one produced observable toxicity after 62 h. Our results suggest that thiosemicarbazones represent validated drug leads that kill several species of protozoan parasites through the inhibition of cysteine proteases as well as other novel targets.
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Affiliation(s)
- Doron C Greenbaum
- Sandler Center for Basic Research in Parasitic Diseases, Department of Pathology, University of California-San Francisco, San Francisco, CA 94143, USA.
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28
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Latner DR, Thompson JM, Gershon PD, Storrs C, Condit RC. The positive transcription elongation factor activity of the vaccinia virus J3 protein is independent from its (nucleoside-2'-O-) methyltransferase and poly(A) polymerase stimulatory functions. Virology 2002; 301:64-80. [PMID: 12359447 DOI: 10.1006/viro.2002.1538] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous genetic and biochemical experiments have shown that the vaccinia virus J3 protein has three different roles in mRNA synthesis and modification. First, J3 is a (nucleoside-2'-O-)methyltransferase which methylates the 2' position of the first transcribed nucleotide, thus converting a cap-0 to a cap-1 structure at the 5' ends of mRNAs. Second, J3 is a processivity factor for the virus coded poly(A) polymerase. Third, J3 has recently been shown to have intermediate and late gene positive transcription elongation factor activity in vivo. Previous experiments have shown that the poly(A) polymerase stimulatory activity and the (nucleoside-2'-O-)methyltransferase activity are two independent functions of the protein that can be genetically separated through site-directed mutagenesis. In this article, the relationship between the J3-mediated transcription elongation activity and the two other functions of the protein was investigated by constructing several site-directed mutant viruses that contain specific defects in either methyltransferase or poly(A) polymerase processivity functions. The results demonstrate that the J3 positive transcription elongation factor activity is a third independent function of the protein that is genetically separable from its two other functions in mRNA modification. The results also show that neither the poly(A) polymerase stimulatory nor the methyltransferase activities of the J3 protein is essential for virus growth in cell culture.
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Affiliation(s)
- Donald R Latner
- Department of molecular Genetics and microbiology and Center for Mammalian Genetics, University of Florida, Gainesville, Florida 32610, USA
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29
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Condit RC, Niles EG. Regulation of viral transcription elongation and termination during vaccinia virus infection. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1577:325-36. [PMID: 12213661 DOI: 10.1016/s0167-4781(02)00461-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Vaccinia virus provides a useful genetic and biochemical tool for studies of the basic mechanisms of eukaryotic transcription. Vaccinia genes are transcribed in three successive gene classes during infection, early, intermediate, and late. Vaccinia transcription is regulated primarily by virus gene products not only during initiation, but also during elongation and termination. The factors and mechanisms regulating early elongation and termination differ from those regulating intermediate and late gene expression. Control of transcription elongation and termination in vaccinia virus bears some similarity to the same process in other prokaryotic and eukaryotic systems, yet features some novel mechanisms as well.
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Affiliation(s)
- Richard C Condit
- Department of Molecular Genetics and Microbiology, P.O. Box 100266, University of Florida, Gainesville, FL 32610, USA.
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30
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Xiang Y, Simpson DA, Spiegel J, Zhou A, Silverman RH, Condit RC. The vaccinia virus A18R DNA helicase is a postreplicative negative transcription elongation factor. J Virol 1998; 72:7012-23. [PMID: 9696793 PMCID: PMC109921 DOI: 10.1128/jvi.72.9.7012-7023.1998] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Loss of vaccinia virus A18R gene function results in an aberrant transcription profile termed promiscuous transcription, defined as transcription within regions of the genome which are normally transcriptionally silent late during infection. Promiscuous transcription results in an increase in the intracellular concentration of double-stranded RNA, which in turn results in activation of the cellular 2-5A pathway and subsequent RNase L-catalyzed degradation of viral and cellular RNAs. One of three hypotheses could account for promiscuous transcription: (i) reactivation of early promoters late during infection, (ii) random transcription initiation, (iii) readthrough transcription from upstream promoters. Transcriptional analysis of several viral genes, presented here, argues strongly against the first two hypotheses. We have tested the readthrough hypothesis by conducting a detailed transcriptional analysis of a region of the vaccinia virus genome which contains three early genes (M1L, M2L, and K1L) positioned directly downstream of the intermediate gene, K2L. The results show that mutation of the A18R gene results in increased readthrough transcription of the M1L gene originating from the K2L intermediate promoter. A18R mutant infection of RNase L knockout mouse fibroblast (KO3) cells does not result in 2-5A pathway activation, yet the virus mutant is defective in late viral gene expression and remains temperature sensitive. These results demonstrate that the A18R gene product is a negative transcription elongation factor for postreplicative viral genes.
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Affiliation(s)
- Y Xiang
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida 32610-0266, USA
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31
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Black EP, Moussatche N, Condit RC. Characterization of the interactions among vaccinia virus transcription factors G2R, A18R, and H5R. Virology 1998; 245:313-22. [PMID: 9636370 DOI: 10.1006/viro.1998.9166] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prior genetic analysis suggests that there may exist an interaction between the products of the vaccinia virus genes A18R, a putative negative transcription elongation factor, and G2R, a putative positive transcription elongation factor. In addition, affinity purification of polyhistidine-tagged G2R protein overexpressed in vaccinia virus-infected cells, reported here, results in copurification of the vaccinia H5R protein, previously characterized as a late viral transcription factor. We have therefore used several methods to screen further for interactions among the G2R, A18R, and H5R proteins. Methods include copurification or co-immunoprecipitation of proteins overexpressed during vaccinia virus infection, activation of the gal 4 promoter by gal 4 fusions in the yeast two-hybrid system, and co-immunoprecipitation of proteins synthesized in vitro in a rabbit reticulocyte lysate. The results reveal interactions which include all possible pairwise combinations of the three proteins G2R, A18R, and H5R; however, not all possible permutations of the interactions are observed and the interactions are not observed in all environments tested. The results suggest that the vaccinia virus proteins G2R, A18R, and H5R interact as part of a higher order transcription complex.
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Affiliation(s)
- E P Black
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville 32610, USA
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32
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Sekiguchi J, Shuman S. Novobiocin inhibits vaccinia virus replication by blocking virus assembly. Virology 1997; 235:129-37. [PMID: 9300044 DOI: 10.1006/viro.1997.8684] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Novobiocin inhibits the replication of vaccinia virus in cultured BSC40 cells. All classes of viral proteins were synthesized during synchronous infection in the presence of drug. The onset of DNA replication was delayed slightly, yet the extent of DNA replication in the presence of novobiocin was comparable to that of a control infection. A delay in the temporal transition to late viral protein synthesis was in keeping with the effects on DNA replication. Although the precursor forms of the major viral structural proteins were synthesized normally at late times, the proteolytic processing of these polypeptides was inhibited, which suggested an impediment to virus assembly. Electron microscopy revealed that novobiocin blocked virus morphogenesis at an early stage. Conversion of the concatemeric DNA replication intermediates into hairpin telomeres occurred in the presence of novobiocin, confirming that telomere resolution was not coupled to virus assembly. Novobiocin is the latest addition to a class of antipoxviral agents, which includes rifampin and IMCBH, that arrest morphogenesis.
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Affiliation(s)
- J Sekiguchi
- Program in Molecular Biology, Sloan-Kettering Institute, New York, New York 10021, USA
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33
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Black EP, Condit RC. Phenotypic characterization of mutants in vaccinia virus gene G2R, a putative transcription elongation factor. J Virol 1996; 70:47-54. [PMID: 8523560 PMCID: PMC189786 DOI: 10.1128/jvi.70.1.47-54.1996] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The phenotypic defects of two mutants of vaccinia virus, the lesions of which map to gene G2R, were characterized in vivo, and the results suggest a role for the G2R protein in viral transcription elongation. Both a temperature-sensitive mutant, Cts56, and an isatin-beta-thiosemicarbazone-dependent deletion mutant, G2A, in gene G2R have a characteristic and unique defect in late viral gene expression. The G2R mutants synthesize early viral RNA, early viral proteins, and viral DNA normally under nonpermissive conditions. In G2R mutants, late viral protein synthesis begins at the normal time, low-molecular-weight viral proteins are synthesized in normal quantities, but synthesis of high-molecular-weight viral proteins is reduced in amount. Intermediate and late promoter utilization is normal in G2R mutants, but intermediate and late RNAs are reduced in size. The reduction in length of the intermediate and late mRNAs represents a truncation of mRNA 3' ends. Thus, intermediate and late RNAs are too short to encode large proteins but long enough to encode small proteins, therefore accounting for the protein synthesis phenotype. These results suggest that the G2R protein acts to regulate the elongation potential of the viral RNA polymerase late during a vaccinia virus infection.
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Affiliation(s)
- E P Black
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville 32610-0266, USA
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34
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Kane EM, Shuman S. Adenosine N1-oxide inhibits vaccinia virus replication by blocking translation of viral early mRNAs. J Virol 1995; 69:6352-8. [PMID: 7666536 PMCID: PMC189534 DOI: 10.1128/jvi.69.10.6352-6358.1995] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Adenosine N1-oxide (ANO) is a potent and highly selective inhibitor of vaccinia virus replication. We examined the impact of ANO on vaccinia virus macromolecular synthesis during synchronous infection of BSC40 cells. Viral DNA replication and viral late protein synthesis were blocked completely by ANO, effects that were attributable to a defect in the expression of viral early genes. Vaccinia virus early proteins were not synthesized in the presence of ANO, even though vaccinia virus early mRNAs were produced. Cellular protein synthesis was unaffected by ANO, and virus infection in the presence of the drug did not elicit the normal shutoff of host protein synthesis. Adenosine N1-oxide triphosphate (ANO-TP), the predominant metabolite of the drug in vivo, could substitute for ATP in RNA synthesis by purified vaccinia virus RNA polymerase. ANO-TP could support early transcription by purified virions if dATP was provided as an energy source. ANO-TP did not inhibit early transcription in the presence of ATP. These findings suggest a novel antiviral mechanism whereby incorporation of a modified nucleotide into viral mRNAs might selectively block viral gene expression at the level of translation. We believe that ANO merits consideration as an antipoxvirus drug for topical treatment of molluscum contagiosum in humans.
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Affiliation(s)
- E M Kane
- Program in Molecular Biology, Sloan-Kettering Institute, New York, New York 10021, USA
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35
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DeLange AM, Carpenter MS, Choy J, Newsway VE. An etoposide-induced block in vaccinia virus telomere resolution is dependent on the virus-encoded DNA ligase. J Virol 1995; 69:2082-91. [PMID: 7884854 PMCID: PMC188874 DOI: 10.1128/jvi.69.4.2082-2091.1995] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Etoposide, an inhibitor of the breakage-reunion reaction associated with cellular type II DNA topoisomerases, was shown to inhibit plaque formation of vaccinia virus. This drug had a major effect on the segregation of newly replicated DNA concatemers. Gene expression and the initiation and elongation phases of viral DNA replication were essentially unaffected. Pulsed-field gel electrophoresis of viral DNA replicated in the presence of etoposide revealed two major classes of DNA: the mature monomeric linear genome and DNA that failed to enter the gel (the relative proportions depending on the concentrations of drug). Restriction enzyme analysis showed a severe defect in telomere resolution. In addition, slowly migrating restriction fragments were suggestive of a general recombination defect. We have isolated several etoposide-resistant mutants and used marker rescue and DNA sequencing to localize the resistance-causing mutation to the amino terminus of the viral DNA ligase gene. Inactivation of the DNA ligase also resulted in an etoposide-resistant phenotype, but to a lesser extent. The telomere resolution and segregation defects were corrected both in the drug-resistant mutants and in the DNA ligase knockout mutants. Reinsertion of wild-type or mutant DNA ligase in the viral thymidine kinase locus confirmed the role of the viral DNA ligase in conferring sensitivity not only to etoposide but also to another topoisomerase II inhibitor, 4'-(9-acridinylamino) methanesulphon-m-anisidide (mAMSA). The data suggest that the nonessential DNA ligase is involved in telomere resolution, possibly as part of a general recombinase.
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Affiliation(s)
- A M DeLange
- Department of Human Genetics, University of Manitoba, Winnipeg, Canada
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36
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Abstract
The predicted amino acid sequence of the vaccinia virus gene A18R shows significant homology to the human ERCC3 gene product, which is a member of the DEXH subfamily of the DNA and RNA helicase superfamily II and which plays a role in both RNA polymerase II transcription and nucleotide excision repair of DNA. The vaccinia virus A18R gene product is expressed throughout infection and is encapsidated in virions. Vaccinia virions containing mutant A18R gene product are defective in early viral transcription in vitro, and infection with A18R mutant virus results in aberrant viral transcription late during infection. Thus we hypothesize that the vaccinia virus A18R gene product is a helicase that plays a role in viral transcription and possibly DNA repair. As a first test of this hypothesis, we have affinity purified an amino-terminal polyhistidine-tagged A18R protein and shown that it has DNA-dependent ATPase activity. The A18R ATPase activity is stimulated by both single-stranded and double-stranded DNA and by RNA.DNA hybrids, but not by either single-stranded or double-stranded RNA.
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Affiliation(s)
- C D Bayliss
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville 32610
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37
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Taddie JA, Traktman P. Genetic characterization of the vaccinia virus DNA polymerase: cytosine arabinoside resistance requires a variable lesion conferring phosphonoacetate resistance in conjunction with an invariant mutation localized to the 3'-5' exonuclease domain. J Virol 1993; 67:4323-36. [PMID: 8389930 PMCID: PMC237803 DOI: 10.1128/jvi.67.7.4323-4336.1993] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In this report, we describe the isolation, molecular genetic mapping, and phenotypic characterization of vaccinia virus mutants resistant to cytosine arabinoside (araC) and phosphonoacetic acid (PAA). At 37 degrees C, 8 microM araC was found to prevent macroscopic plaque formation by wild-type virus and to cause a 10(4)-fold reduction in viral yield. Mutants resistant to 8 microM araC were selected by serial passage of a chemically mutagenized viral stock in the presence of drug. Because recovery of mutants required that initial passages be performed under less stringent selective conditions, and because plaque-purified isolates were found to be cross-resistant to 200 micrograms of PAA per ml, it seemed likely that resistance to araC required more than one genetic lesion. This hypothesis was confirmed by genetic and physical mapping of the responsible mutations. PAAr was accorded by the acquisition of one of three G-A transitions in the DNA polymerase gene which individually alter cysteine 356 to tyrosine, glycine 372 to aspartic acid, or glycine 380 to serine. AraCr was found to require one of these substitutions plus an additional T-C transition within codon 171 of the DNA polymerase gene, a change which replaces the wild-type phenylalanine with serine. Congenic viral stocks carrying one of the three PAAr lesions, either alone or in conjunction with the upstream araCr lesion, in an otherwise wild-type background were generated. The PAAr mutations conferred nearly complete resistance to PAA, a slight degree of resistance to araC, hypersensitivity to aphidicolin, and decreased spontaneous mutation frequency. Addition of the mutation at codon 171 significantly augmented araC resistance and aphidicolin hypersensitivity but caused no further change in mutation frequency. Several lines of evidence suggest that the PAAr mutations primarily affect the deoxynucleoside triphosphate-binding site, whereas the codon 171 mutation, lying within a conserved motif associated with 3'-5' exonuclease function, is postulated to affect the proofreading exonuclease of the DNA polymerase.
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Affiliation(s)
- J A Taddie
- Department of Cell Biology, Cornell University Medical College, New York, New York 10021
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