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Millet R, Jolinon N, Nguyen XN, Berger G, Cimarelli A, Greco A, Bertrand P, Odenthal M, Büning H, Salvetti A. Impact of the MRN Complex on Adeno-Associated Virus Integration and Replication during Coinfection with Herpes Simplex Virus 1. J Virol 2015; 89:6824-34. [PMID: 25903339 PMCID: PMC4468484 DOI: 10.1128/jvi.00171-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Adeno-associated virus (AAV) is a helper-dependent parvovirus that requires coinfection with adenovirus (AdV) or herpes simplex virus 1 (HSV-1) to replicate. In the absence of the helper virus, AAV can persist in an episomal or integrated form. Previous studies have analyzed the DNA damage response (DDR) induced upon AAV replication to understand how it controls AAV replication. In particular, it was shown that the Mre11-Rad50-Nbs1 (MRN) complex, a major player of the DDR induced by double-stranded DNA breaks and stalled replication forks, could negatively regulate AdV and AAV replication during coinfection. In contrast, MRN favors HSV-1 replication and is recruited to AAV replication compartments that are induced in the presence of HSV-1. In this study, we examined the role of MRN during AAV replication induced by HSV-1. Our results indicated that knockdown of MRN significantly reduced AAV DNA replication after coinfection with wild-type (wt) HSV-1 or HSV-1 with the polymerase deleted. This effect was specific to wt AAV, since it did not occur with recombinant AAV vectors. Positive regulation of AAV replication by MRN was dependent on its DNA tethering activity but did not require its nuclease activities. Importantly, knockdown of MRN also negatively regulated AAV integration within the human AAVS1 site, both in the presence and in the absence of HSV-1. Altogether, this work identifies a new function of MRN during integration of the AAV genome and demonstrates that this DNA repair complex positively regulates AAV replication in the presence of HSV-1. IMPORTANCE Viral DNA genomes trigger a DNA damage response (DDR), which can be either detrimental or beneficial for virus replication. Adeno-associated virus (AAV) is a defective parvovirus that requires the help of an unrelated virus such as adenovirus (AdV) or herpes simplex virus 1 (HSV-1) for productive replication. Previous studies have demonstrated that the cellular Mre11-Rad50-Nbs1 (MRN) complex, a sensor and regulator of the DDR, negatively regulates AAV replication during coinfection with AdV, which counteracts this effect by inactivating the complex. Here, we demonstrate that MRN positively regulates AAV replication during coinfection with HSV-1. Importantly, our study also indicates that MRN also favors integration of AAV genomes within the human AAVS1 site. Altogether, this work indicates that MRN differentially regulates AAV replication depending on the helper virus which is present and identifies a new function of this DNA repair complex during AAV integration.
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Affiliation(s)
- Rachel Millet
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France LabEx Ecofect, Université de Lyon, Lyon, France
| | - Nelly Jolinon
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France
| | - Xuan-Nhi Nguyen
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France LabEx Ecofect, Université de Lyon, Lyon, France
| | - Gregory Berger
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France
| | - Andrea Cimarelli
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France LabEx Ecofect, Université de Lyon, Lyon, France
| | - Anna Greco
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France LabEx Ecofect, Université de Lyon, Lyon, France
| | - Pascale Bertrand
- INSERM U967, CEA, Université Paris Diderot, Université Paris Sud, CEA DSV, Institut de Radiobiologie Moléculaire et Cellulaire, Fontenay-aux-Roses, France
| | - Margarete Odenthal
- Institute for Pathology, University Hospital of Cologne, Cologne, Germany Center for Molecular Medicine of Cologne, University of Cologne, Cologne, Germany
| | - Hildegard Büning
- Center for Molecular Medicine of Cologne, University of Cologne, Cologne, Germany Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany German Center for Infection Research, Bonn-Cologne Partner Site, Bonn-Cologne, Germany
| | - Anna Salvetti
- International Center for Research in Infectiology, INSERM U1111, CNRS UMR5308, Lyon, France Ecole Normale Supérieure de Lyon, Lyon, France Université de Lyon, UCB-Lyon 1, Lyon, France LabEx Ecofect, Université de Lyon, Lyon, France
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Dembowski JA, DeLuca NA. Selective recruitment of nuclear factors to productively replicating herpes simplex virus genomes. PLoS Pathog 2015; 11:e1004939. [PMID: 26018390 PMCID: PMC4446364 DOI: 10.1371/journal.ppat.1004939] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/07/2015] [Indexed: 01/01/2023] Open
Abstract
Much of the HSV-1 life cycle is carried out in the cell nucleus, including the expression, replication, repair, and packaging of viral genomes. Viral proteins, as well as cellular factors, play essential roles in these processes. Isolation of proteins on nascent DNA (iPOND) was developed to label and purify cellular replication forks. We adapted aspects of this method to label viral genomes to both image, and purify replicating HSV-1 genomes for the identification of associated proteins. Many viral and cellular factors were enriched on viral genomes, including factors that mediate DNA replication, repair, chromatin remodeling, transcription, and RNA processing. As infection proceeded, packaging and structural components were enriched to a greater extent. Among the more abundant proteins that copurified with genomes were the viral transcription factor ICP4 and the replication protein ICP8. Furthermore, all seven viral replication proteins were enriched on viral genomes, along with cellular PCNA and topoisomerases, while other cellular replication proteins were not detected. The chromatin-remodeling complexes present on viral genomes included the INO80, SWI/SNF, NURD, and FACT complexes, which may prevent chromatinization of the genome. Consistent with this conclusion, histones were not readily recovered with purified viral genomes, and imaging studies revealed an underrepresentation of histones on viral genomes. RNA polymerase II, the mediator complex, TFIID, TFIIH, and several other transcriptional activators and repressors were also affinity purified with viral DNA. The presence of INO80, NURD, SWI/SNF, mediator, TFIID, and TFIIH components is consistent with previous studies in which these complexes copurified with ICP4. Therefore, ICP4 is likely involved in the recruitment of these key cellular chromatin remodeling and transcription factors to viral genomes. Taken together, iPOND is a valuable method for the study of viral genome dynamics during infection and provides a comprehensive view of how HSV-1 selectively utilizes cellular resources.
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Affiliation(s)
- Jill A. Dembowski
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Neal A. DeLuca
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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53
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Berard AR, Coombs KM, Severini A. Quantification of the host response proteome after herpes simplex virus type 1 infection. J Proteome Res 2015; 14:2121-42. [PMID: 25815715 DOI: 10.1021/pr5012284] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Viruses employ numerous host cell metabolic functions to propagate and manage to evade the host immune system. For herpes simplex virus type 1 (HSV1), a virus that has evolved to efficiently infect humans without seriously harming the host in most cases, the virus-host interaction is specifically interesting. This interaction can be best characterized by studying the proteomic changes that occur in the host during infection. Previous studies have been successful at identifying numerous host proteins that play important roles in HSV infection; however, there is still much that we do not know. This study identifies host metabolic functions and proteins that play roles in HSV infection, using global quantitative stable isotope labeling by amino acids in cell culture (SILAC) proteomic profiling of the host cell combined with LC-MS/MS. We showed differential proteins during early, mid and late infection, using both cytosolic and nuclear fractions. We identified hundreds of differentially regulated proteins involved in fundamental cellular functions, including gene expression, DNA replication, inflammatory response, cell movement, cell death, and RNA post-transcriptional modification. Novel differentially regulated proteins in HSV infections include some previously identified in other virus systems, as well as fusion protein, involved in malignant liposarcoma (FUS) and hypoxia up-regulated 1 protein precursor (HYOU1), which have not been identified previously in any virus infection.
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Affiliation(s)
- Alicia R Berard
- †Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0J9.,‡Manitoba Center for Proteomics and Systems Biology, University of Manitoba, Room 799 John Buhler Research Centre, Winnipeg, Manitoba, Canada R3E 3P4
| | - Kevin M Coombs
- †Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0J9.,‡Manitoba Center for Proteomics and Systems Biology, University of Manitoba, Room 799 John Buhler Research Centre, Winnipeg, Manitoba, Canada R3E 3P4.,§Manitoba Institute of Child Health, University of Manitoba, Room 641 John Buhler Research Centre, Winnipeg, Manitoba, Canada R3E 3P4
| | - Alberto Severini
- †Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3E 0J9.,∥National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba, Canada R3E 3P6
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Abstract
Peter Wildy first observed genetic recombination between strains of HSV in 1955. At the time, knowledge of DNA repair mechanisms was limited, and it has only been in the last decade that particular DNA damage response (DDR) pathways have been examined in the context of viral infections. One of the first reports addressing the interaction between a cellular DDR protein and HSV-1 was the observation by Lees-Miller et al. that DNA-dependent protein kinase catalytic subunit levels were depleted in an ICP0-dependent manner during Herpes simplex virus 1 infection. Since then, there have been numerous reports describing the interactions between HSV infection and cellular DDR pathways. Due to space limitations, this review will focus predominantly on the most recent observations regarding how HSV navigates a potentially hostile environment to replicate its genome.
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Affiliation(s)
- Samantha Smith
- Department of Molecular Biology & Biophysics, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Sandra K Weller
- Department of Molecular Biology & Biophysics, University of Connecticut Health Center, Farmington, CT 06030, USA
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55
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Pérez-Losada M, Arenas M, Galán JC, Palero F, González-Candelas F. Recombination in viruses: mechanisms, methods of study, and evolutionary consequences. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2015; 30:296-307. [PMID: 25541518 PMCID: PMC7106159 DOI: 10.1016/j.meegid.2014.12.022] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 12/15/2014] [Accepted: 12/17/2014] [Indexed: 02/08/2023]
Abstract
Recombination is a pervasive process generating diversity in most viruses. It joins variants that arise independently within the same molecule, creating new opportunities for viruses to overcome selective pressures and to adapt to new environments and hosts. Consequently, the analysis of viral recombination attracts the interest of clinicians, epidemiologists, molecular biologists and evolutionary biologists. In this review we present an overview of three major areas related to viral recombination: (i) the molecular mechanisms that underlie recombination in model viruses, including DNA-viruses (Herpesvirus) and RNA-viruses (Human Influenza Virus and Human Immunodeficiency Virus), (ii) the analytical procedures to detect recombination in viral sequences and to determine the recombination breakpoints, along with the conceptual and methodological tools currently used and a brief overview of the impact of new sequencing technologies on the detection of recombination, and (iii) the major areas in the evolutionary analysis of viral populations on which recombination has an impact. These include the evaluation of selective pressures acting on viral populations, the application of evolutionary reconstructions in the characterization of centralized genes for vaccine design, and the evaluation of linkage disequilibrium and population structure.
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Affiliation(s)
- Marcos Pérez-Losada
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Portugal; Computational Biology Institute, George Washington University, Ashburn, VA 20147, USA
| | - Miguel Arenas
- Centre for Molecular Biology "Severo Ochoa", Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Juan Carlos Galán
- Servicio de Microbiología, Hospital Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain; CIBER en Epidemiología y Salud Pública, Spain
| | - Ferran Palero
- CIBER en Epidemiología y Salud Pública, Spain; Unidad Mixta Infección y Salud Pública, FISABIO-Universitat de València, Valencia, Spain
| | - Fernando González-Candelas
- CIBER en Epidemiología y Salud Pública, Spain; Unidad Mixta Infección y Salud Pública, FISABIO-Universitat de València, Valencia, Spain.
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Royer DJ, Cohen A, Carr D. The Current State of Vaccine Development for Ocular HSV-1 Infection. EXPERT REVIEW OF OPHTHALMOLOGY 2015; 10:113-126. [PMID: 25983856 DOI: 10.1586/17469899.2015.1004315] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
HSV-1 continues to be the leading cause of infectious corneal blindness. Clinical trials for vaccines against genital HSV infection have been ongoing for more than three decades. Despite this, no approved vaccine exists, and no formal clinical trials have evaluated the impact of HSV vaccines on eye health. We review here the current state of development for an efficacious HSV-1 vaccine and call for involvement of ophthalmologists and vision researchers.
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Affiliation(s)
- D J Royer
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center
| | - A Cohen
- Ophthalmology, University of Oklahoma Health Sciences Center
| | - Djj Carr
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center ; Ophthalmology, University of Oklahoma Health Sciences Center
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57
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Stutika C, Hüser D, Weger S, Rutz N, Heßler M, Heilbronn R. Definition of herpes simplex virus helper functions for the replication of adeno-associated virus type 5. J Gen Virol 2014; 96:840-850. [PMID: 25535322 DOI: 10.1099/vir.0.000034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adeno-associated virus (AAV) type 5 represents the genetically most distant AAV serotype and the only one isolated directly from human tissue. Seroepidemiological evidence suggests herpes simplex virus (HSV) as a helper virus for human AAV5 infections, underlining the in vivo relevance of the AAV-herpesvirus relationship. In this study we analysed, for the first time, HSV helper functions for productive AAV5 replication, and compared these to AAV2. Using a combination of HSV strains and plasmids for individual genes, the previously defined HSV helper functions for AAV2 replication were shown to induce AAV5 gene expression, DNA replication and production of infectious progeny. The helper functions comprise the replication genes for ICP8 (UL29), helicase-primase (UL5/8/52), and DNA polymerase (UL30/42). HSV immediate-early genes for ICP0 and ICP4 further enhanced AAV5 replication, mainly by induction of rep gene expression. In the presence of HSV helper functions, AAV5 Rep co-localized with ICP8 in nuclear replication compartments, and HSV alkaline exonuclease (UL12) enhanced AAV5 replication, similarly to AAV2. UL12, in combination with ICP8, was shown to induce DNA strand exchange on partially double-stranded templates to resolve and repair concatemeric HSV replication intermediates. Similarly, concatemeric AAV replication intermediates appeared to be processed to yield AAV unit-length molecules, ready for AAV packaging. Taken together, our findings show that productive AAV5 replication is promoted by the same combination of HSV helper functions as AAV2.
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Affiliation(s)
- Catrin Stutika
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
| | - Daniela Hüser
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
| | - Stefan Weger
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
| | - Natalja Rutz
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
| | - Melanie Heßler
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
| | - Regine Heilbronn
- Institute of Virology, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Germany
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Deng Z, Kim ET, Vladimirova O, Dheekollu J, Wang Z, Newhart A, Liu D, Myers JL, Hensley SE, Moffat J, Janicki SM, Fraser NW, Knipe DM, Weitzman MD, Lieberman PM. HSV-1 remodels host telomeres to facilitate viral replication. Cell Rep 2014; 9:2263-78. [PMID: 25497088 DOI: 10.1016/j.celrep.2014.11.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 10/12/2014] [Accepted: 11/11/2014] [Indexed: 12/23/2022] Open
Abstract
Telomeres protect the ends of cellular chromosomes. We show here that infection with herpes simplex virus 1 (HSV-1) results in chromosomal structural aberrations at telomeres and the accumulation of telomere dysfunction-induced DNA damage foci (TIFs). At the molecular level, HSV-1 induces transcription of telomere repeat-containing RNA (TERRA), followed by the proteolytic degradation of the telomere protein TPP1 and loss of the telomere repeat DNA signal. The HSV-1-encoded E3 ubiquitin ligase ICP0 is required for TERRA transcription and facilitates TPP1 degradation. Small hairpin RNA (shRNA) depletion of TPP1 increases viral replication, indicating that TPP1 inhibits viral replication. Viral replication protein ICP8 forms foci that coincide with telomeric proteins, and ICP8-null virus failed to degrade telomere DNA signal. These findings suggest that HSV-1 reorganizes telomeres to form ICP8-associated prereplication foci and to promote viral genomic replication.
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Affiliation(s)
- Zhong Deng
- The Wistar Institute, Philadelphia, PA 19104, USA
| | - Eui Tae Kim
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | | | - Zhuo Wang
- The Wistar Institute, Philadelphia, PA 19104, USA
| | | | - Dongmei Liu
- Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | | | | | - Jennifer Moffat
- Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | | | - Nigel W Fraser
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David M Knipe
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Matthew D Weitzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
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Tang KW, Norberg P, Holmudden M, Elias P, Liljeqvist JÅ. Rad51 and Rad52 are involved in homologous recombination of replicating herpes simplex virus DNA. PLoS One 2014; 9:e111584. [PMID: 25365323 PMCID: PMC4218770 DOI: 10.1371/journal.pone.0111584] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 10/04/2014] [Indexed: 12/27/2022] Open
Abstract
Replication of herpes simplex virus 1 is coupled to recombination, but the molecular mechanisms underlying this process are poorly characterized. The role of Rad51 and Rad52 recombinases in viral recombination was examined in human fibroblast cells 1BR.3.N (wild type) and in GM16097 with replication defects caused by mutations in DNA ligase I. Intermolecular recombination between viruses, tsS and tsK, harboring genetic markers gave rise to ∼17% recombinants in both cell lines. Knock-down of Rad51 and Rad52 by siRNA reduced production of recombinants to 11% and 5%, respectively, in wild type cells and to 3% and 5%, respectively, in GM16097 cells. The results indicate a specific role for Rad51 and Rad52 in recombination of replicating herpes simplex virus 1 DNA. Mixed infections using clinical isolates with restriction enzyme polymorphisms in the US4 and US7 genes revealed recombination frequencies of 0.7%/kbp in wild type cells and 4%/kbp in GM16097 cells. Finally, tandem repeats in the US7 gene remained stable upon serial passage, indicating a high fidelity of recombination in infected cells.
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Affiliation(s)
- Ka-Wei Tang
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Norberg
- Department of Infectious Diseases, Section of Virology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Martin Holmudden
- Department of Infectious Diseases, Section of Virology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Per Elias
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Jan-Åke Liljeqvist
- Department of Infectious Diseases, Section of Virology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Inhibitors of nucleotidyltransferase superfamily enzymes suppress herpes simplex virus replication. Antimicrob Agents Chemother 2014; 58:7451-61. [PMID: 25267681 DOI: 10.1128/aac.03875-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Herpesviruses are large double-stranded DNA viruses that cause serious human diseases. Herpesvirus DNA replication depends on multiple processes typically catalyzed by nucleotidyltransferase superfamily (NTS) enzymes. Therefore, we investigated whether inhibitors of NTS enzymes would suppress replication of herpes simplex virus 1 (HSV-1) and HSV-2. Eight of 42 NTS inhibitors suppressed HSV-1 and/or HSV-2 replication by >10-fold at 5 μM, with suppression at 50 μM reaching ∼1 million-fold. Five compounds in two chemical families inhibited HSV replication in Vero and human foreskin fibroblast cells as well as the approved drug acyclovir did. The compounds had 50% effective concentration values as low as 0.22 μM with negligible cytotoxicity in the assays employed. The inhibitors suppressed accumulation of viral genomes and infectious particles and blocked events in the viral replication cycle before and during viral DNA replication. Acyclovir-resistant mutants of HSV-1 and HSV-2 remained highly sensitive to the NTS inhibitors. Five of six NTS inhibitors of the HSVs also blocked replication of another herpesvirus pathogen, human cytomegalovirus. Therefore, NTS enzyme inhibitors are promising candidates for new herpesvirus treatments that may have broad efficacy against members of the herpesvirus family.
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The UL12 protein of herpes simplex virus 1 is regulated by tyrosine phosphorylation. J Virol 2014; 88:10624-34. [PMID: 24991005 DOI: 10.1128/jvi.01634-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED The herpes simplex virus 1 (HSV-1) UL12 protein (pUL12) is a nuclease that is critical for viral replication in vitro and neurovirulence in vivo. In this study, mass spectrometric analysis of pUL12 and phosphate-affinity SDS-polyacrylamide gel electrophoresis analysis identified tyrosine at pUL12 residue 371 (Tyr-371) as a pUL12 phosphorylation site: Tyr-371 is conserved in pUL12 homologs in herpesviruses in all Herpesviridae subfamilies. Replacement of Tyr-371 with phenylalanine (Y371F) in pUL12 (i) abolished its exonuclease activity in HSV-1-infected Vero, HEL, and A549 cells, (ii) reduced viral replication, cell-cell spread, and pUL12 expression in infected cells in a cell type-dependent manner, (iii) led to aberrant subcellular localization of pUL12 in infected cells in a cell type-dependent manner, and (iv) reduced HSV-1 neurovirulence in mice. The effects of the pUL12 Y371F mutation in cell cultures and mice were similar to those of a nuclease-dead double mutation in pUL12, although the Y371F mutation reduced viral replication severalfold more than the nuclease-dead double mutation in a cell type- and multiplicity-of-infection-dependent manner. Replacement of Tyr-371 with glutamic acid, which mimics constitutive phosphorylation, restored the wild-type phenotype in cell cultures and mice. These results suggested that phosphorylation of pUL12 Tyr-371 was essential for pUL12 to express its nuclease activity in HSV-1-infected cells and that this phosphorylation promoted viral replication and cell-cell spread in cell cultures and neurovirulence in mice mainly by upregulating pUL12 nuclease activity and, in part, by regulating the subcellular localization and expression of pUL12 in HSV-1-infected cells. IMPORTANCE Herpesviruses encode a considerable number of enzymes for their replication. Like cellular enzymes, the viral enzymes need to be properly regulated in infected cells. Although the functional aspects of herpesvirus enzymes have gradually been clarified, information on how most of these enzymes are regulated in infected cells is lacking. In the present study, we report that the enzymatic activity of the herpes simplex virus 1 alkaline nuclease pUL12 was regulated by phosphorylation of pUL12 Tyr-371 in infected cells and that this phosphorylation promoted viral replication and cell-cell spread in cell cultures and neurovirulence in mice, mainly by upregulating pUL12 nuclease activity. Interestingly, pUL12 and tyrosine at pUL12 residue 371 appeared to be conserved in all herpesviruses in the family Herpesviridae, raising the possibility that the herpesvirus pUL12 homologs may also be regulated by phosphorylation of the conserved tyrosine residue.
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Structure of the herpes simplex virus 1 genome: manipulation of nicks and gaps can abrogate infectivity and alter the cellular DNA damage response. J Virol 2014; 88:10146-56. [PMID: 24965466 DOI: 10.1128/jvi.01723-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED The herpes simplex virus 1 (HSV-1) virion DNA contains nicks and gaps, and in this study a novel assay for estimating the size and number of gaps in virion DNA was developed. Consistent with previous reports, we estimate that there are approximately 15 gaps per genome, and we calculate the average gap length to be approximately 30 bases. Virion DNA was isolated and treated with DNA-modifying enzymes in order to fill in the gaps and modify the ends. Interestingly, filling in gaps, blunting the ends, or adding random sequences to the 3' ends of DNA, producing 3' flaps, did not impair the infectivity of treated DNA following transfection of Vero cells. On the other hand, the formation of 5' flaps in the DNA following treatment resulted in a dramatic reduction (95 to 100%) in infectivity. Virion DNA stimulated DNA-PKcs activity in transfected cells, and DNA with 5' flaps stimulated a higher level of DNA-PKcs activity than that observed in cells transfected with untreated virion DNA. The infectivity of 5'-flapped DNA was restored in cells that do not express DNA-PKcs and in cells cotransfected with the immediate early protein ICP0, which degrades DNA-PKcs. These results are consistent with previous reports that DNA-dependent protein kinase (DNA-PK) and the nonhomologous end joining (NHEJ) repair pathway are intrinsically antiviral and that ICP0 can counteract this effect. We suggest that HSV-1 DNA with 5' flaps may induce an antiviral state due to the induction of a DNA damage response, primarily mediated by NHEJ, that renders the HSV-1 genome less efficient for lytic infection. IMPORTANCE For productive lytic infection to occur, HSV-1 must counteract a variety of cellular intrinsic antiviral mechanisms, including the DNA damage response (DDR). DDR pathways have been associated with silencing of gene expression, cell cycle arrest, and induction of apoptosis. In addition, the fate of viral genomes is likely to play a role in whether viral genomes adopt a configuration suitable for lytic DNA replication. This study demonstrates that virion DNA activates the cellular DDR kinase, DNA-PK, and that this response is inhibitory to viral infection. Furthermore, we show that HSV-1 ubiquitin ligase, ICP0, plays an important role in counteracting the negative effects of DNA-PK activation. These findings support the notion that DNA-PK is antiviral and suggest that the fate of incoming viral DNA has important consequences for the progression of lytic infection. This study underscores the complex evolutionary relationships between HSV and its host.
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Karttunen H, Savas JN, McKinney C, Chen YH, Yates JR, Hukkanen V, Huang TT, Mohr I. Co-opting the Fanconi anemia genomic stability pathway enables herpesvirus DNA synthesis and productive growth. Mol Cell 2014; 55:111-22. [PMID: 24954902 DOI: 10.1016/j.molcel.2014.05.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 02/07/2014] [Accepted: 05/01/2014] [Indexed: 02/06/2023]
Abstract
DNA damage associated with viral DNA synthesis can result in double-strand breaks that threaten genome integrity and must be repaired. Here, we establish that the cellular Fanconi anemia (FA) genomic stability pathway is exploited by herpes simplex virus 1 (HSV-1) to promote viral DNA synthesis and enable its productive growth. Potent FA pathway activation in HSV-1-infected cells resulted in monoubiquitination of FA effector proteins FANCI and FANCD2 (FANCI-D2) and required the viral DNA polymerase. FANCD2 relocalized to viral replication compartments, and FANCI-D2 interacted with a multisubunit complex containing the virus-encoded single-stranded DNA-binding protein ICP8. Significantly, whereas HSV-1 productive growth was impaired in monoubiquitination-defective FA cells, this restriction was partially surmounted by antagonizing the DNA-dependent protein kinase (DNA-PK), a critical enzyme required for nonhomologous end-joining (NHEJ). This identifies the FA-pathway as a cellular factor required for herpesvirus productive growth and suggests that FA-mediated suppression of NHEJ is a fundamental step in the viral life cycle.
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Affiliation(s)
- Heidi Karttunen
- Department of Microbiology, NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA
| | - Jeffrey N Savas
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Caleb McKinney
- Department of Microbiology, NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA
| | - Yu-Hung Chen
- Department of Biochemistry and Molecular Pharmacology, NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Veijo Hukkanen
- Department of Virology, University of Turku, Turku 20520, Finland
| | - Tony T Huang
- Department of Biochemistry and Molecular Pharmacology, NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA.
| | - Ian Mohr
- Department of Microbiology, NYU Cancer Institute, NYU School of Medicine, New York, NY 10016, USA.
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Abstract
The purpose of this review is to explore recombination strategies in DNA viruses. Homologous recombination is a universal genetic process that plays multiple roles in the biology of all organisms, including viruses. Recombination and DNA replication are interconnected, with recombination being essential for repairing DNA damage and supporting replication of the viral genome. Recombination also creates genetic diversity, and viral recombination mechanisms have important implications for understanding viral origins as well as the dynamic nature of viral-host interactions. Both bacteriophage λ and herpes simplex virus (HSV) display high rates of recombination, both utilizing their own proteins and commandeering cellular proteins to promote recombination reactions. We focus primarily on λ and HSV, as they have proven amenable to both genetic and biochemical analysis and have recently been shown to exhibit some surprising similarities that will guide future studies.
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Affiliation(s)
- Sandra K. Weller
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - James A. Sawitzke
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702
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65
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Productive replication of human papillomavirus 31 requires DNA repair factor Nbs1. J Virol 2014; 88:8528-44. [PMID: 24850735 DOI: 10.1128/jvi.00517-14] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Activation of the ATM (ataxia telangiectasia-mutated kinase)-dependent DNA damage response (DDR) is necessary for productive replication of human papillomavirus 31 (HPV31). We previously found that DNA repair and homologous recombination (HR) factors localize to sites of HPV replication, suggesting that ATM activity is required to recruit factors to viral genomes that can productively replicate viral DNA in a recombination-dependent manner. The Mre11-Rad50-Nbs1 (MRN) complex is an essential component of the DDR that is necessary for ATM-mediated HR repair and localizes to HPV DNA foci. In this study, we demonstrate that the HPV E7 protein is sufficient to increase levels of the MRN complex and also interacts with MRN components. We have found that Nbs1 depletion blocks productive viral replication and results in decreased localization of Mre11, Rad50, and the principal HR factor Rad51 to HPV DNA foci upon differentiation. Nbs1 contributes to the DDR by acting as an upstream activator of ATM in response to double-strand DNA breaks (DSBs) and as a downstream effector of ATM activity in the intra-S-phase checkpoint. We have found that phosphorylation of ATM and its downstream target Chk2, as well as SMC1 (structural maintenance of chromosome 1), is maintained upon Nbs1 knockdown in differentiating cells. Given that ATM and Chk2 are required for productive replication, our results suggest that Nbs1 contributes to viral replication outside its role as an ATM activator, potentially through ensuring localization of DNA repair factors to viral genomes that are necessary for efficient productive replication. IMPORTANCE The mechanisms that regulate human papillomavirus (HPV) replication during the viral life cycle are not well understood. Our finding that Nbs1 is necessary for productive replication even in the presence of ATM (ataxia telangiectasia-mutated kinase) and Chk2 phosphorylation offers evidence that Nbs1 contributes to viral replication downstream of facilitating ATM activation. Nbs1 is required for the recruitment of Mre11 and Rad50 to viral genomes, suggesting that the MRN complex plays a direct role in facilitating productive viral replication, potentially through the processing of substrates that are recognized by the key homologous recombination (HR) factor Rad51. The discovery that E7 increases levels of MRN components, and MRN complex formation, identifies a novel role for E7 in facilitating productive replication. Our study not only identifies DNA repair factors necessary for HPV replication but also provides a deeper understanding of how HPV utilizes the DNA damage response to regulate viral replication.
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66
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Kulkarni AS, Fortunato EA. Modulation of homology-directed repair in T98G glioblastoma cells due to interactions between wildtype p53, Rad51 and HCMV IE1-72. Viruses 2014; 6:968-85. [PMID: 24576846 PMCID: PMC3970133 DOI: 10.3390/v6030968] [Citation(s) in RCA: 5] [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: 01/24/2014] [Revised: 02/15/2014] [Accepted: 02/17/2014] [Indexed: 12/29/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a ubiquitous pathogen capable of causing life threatening consequences in neonates and immune-compromised individuals. HCMV inflicts site-specific double strand breaks (DSBs) in the cellular genome. DNA damage infliction raises the corollary question of virus modulation of DNA repair. We recently reported HDR was stimulated in wt human foreskin fibroblasts (HFFs) during fully permissive infection or expression of the HCMV protein IE1-72 (IE72). These studies have been extended into semi-permissive T98G glioblastoma cells. T98Gs encode a mutant p53, which may contribute to their high baseline rate of HDR. We fully expected HCMV infection to increase HDR in T98Gs, similar to its effects in HFFs. Surprisingly in T98Gs HCMV infection, or sole expression of IE72, decreased HDR by two-fold. Transient expression of wt p53 in T98Gs also reduced HDR by two-fold. Dual transient expression of wt p53 and IE72 restored high baseline HDR levels. GST pulldown experiments revealed that both IE72 and wt p53 bound the important HDR protein, Rad51. We conclude that the expression of certain HCMV proteins can modulate HDR in an infected cell, dependent upon p53 status. We propose a model of the protein interactions explaining this behavior.
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Affiliation(s)
- Amit S Kulkarni
- Tumorvirologie (F010), Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69120, Heidelberg, Germany.
| | - Elizabeth A Fortunato
- Department of Biological Sciences and the Center for Reproductive Biology, University of Idaho, 875 Perimeter Drive, Mailstop 3051, Moscow, ID 83844, USA.
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67
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Role of the nuclease activities encoded by herpes simplex virus 1 UL12 in viral replication and neurovirulence. J Virol 2013; 88:2359-64. [PMID: 24335305 DOI: 10.1128/jvi.03621-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Enzyme-dead mutations in the herpes simplex virus 1 UL12 gene that abolished its endo- and exonuclease activities only slightly reduced viral replication in cell cultures. However, the UL12 null mutation significantly reduced viral replication, suggesting that a UL12 function(s) unrelated to its nuclease activities played a major role in viral replication. In contrast, the enzyme-dead mutations significantly reduced viral neurovirulence in mice, suggesting that UL12 nuclease activities were critical for viral pathogenesis in vivo.
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Mohni KN, Smith S, Dee AR, Schumacher AJ, Weller SK. Herpes simplex virus type 1 single strand DNA binding protein and helicase/primase complex disable cellular ATR signaling. PLoS Pathog 2013; 9:e1003652. [PMID: 24098119 PMCID: PMC3789782 DOI: 10.1371/journal.ppat.1003652] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 08/07/2013] [Indexed: 11/19/2022] Open
Abstract
Herpes Simplex Virus type 1 (HSV-1) has evolved to disable the cellular DNA damage response kinase, ATR. We have previously shown that HSV-1-infected cells are unable to phosphorylate the ATR substrate Chk1, even under conditions in which replication forks are stalled. Here we report that the HSV-1 single stranded DNA binding protein (ICP8), and the helicase/primase complex (UL8/UL5/UL52) form a nuclear complex in transfected cells that is necessary and sufficient to disable ATR signaling. This complex localizes to sites of DNA damage and colocalizes with ATR/ATRIP and RPA, but under these conditions, the Rad9-Rad1-Hus1 checkpoint clamp (9-1-1) do not. ATR is generally activated by substrates that contain ssDNA adjacent to dsDNA, and previous work from our laboratory has shown that ICP8 and helicase/primase also recognize this substrate. We suggest that these four viral proteins prevent ATR activation by binding to the DNA substrate and obstructing loading of the 9-1-1 checkpoint clamp. Exclusion of 9-1-1 prevents recruitment of TopBP1, the ATR kinase activator, and thus effectively disables ATR signaling. These data provide the first example of viral DNA replication proteins obscuring access to a DNA substrate that would normally trigger a DNA damage response and checkpoint signaling. This unusual mechanism used by HSV suggests that it may be possible to inhibit ATR signaling by preventing recruitment of the 9-1-1 clamp and TopBP1. DNA viruses that replicate in the nucleus have been shown to both activate and inactivate various components of the cellular DNA damage response (DDR). Previous reports from our laboratory and others have demonstrated that Herpes Simplex Virus (HSV) utilizes some aspects of the DDR while inactivating others. Paradoxically, HSV utilizes the DDR kinase ATR to complete its life cycle while at the same time disabling the kinase from activating DDR signaling. In this report we provide detail describing the mechanism of ATR inactivation. ATR is normally activated in response to single strand DNA (ssDNA), which serves as a scaffold to recruit several proteins required for complete ATR activation. In this paper we provide evidence that the HSV encoded ssDNA binding protein and helicase/primase complex function to mask the DNA substrate that recruits the ATR kinase activator. This represents the first example of viral DNA replication proteins masking a DNA substrate that could be sensed by the cell as damaged DNA and activate checkpoint signaling. It also explains how ATR can be recruited to sites of viral DNA replication in the absence of checkpoint signaling.
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Affiliation(s)
- Kareem N. Mohni
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Samantha Smith
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Alexander R. Dee
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - April J. Schumacher
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Sandra K. Weller
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail:
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69
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Weller SK, Kuchta RD. The DNA helicase-primase complex as a target for herpes viral infection. Expert Opin Ther Targets 2013; 17:1119-32. [PMID: 23930666 DOI: 10.1517/14728222.2013.827663] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
INTRODUCTION The Herpesviridae are responsible for debilitating acute and chronic infections, and some members of this family are associated with human cancers. Conventional anti-herpesviral therapy targets the viral DNA polymerase and has been extremely successful; however, the emergence of drug-resistant virus strains, especially in neonates and immunocompromised patients, underscores the need for continued development of anti-herpes drugs. In this article, we explore an alternative target for antiviral therapy, the HSV helicase/primase complex. AREAS COVERED This review addresses the current state of knowledge of HSV DNA replication and the important roles played by the herpesvirus helicase- primase complex. In the last 10 years several helicase/primase inhibitors (HPIs) have been described, and in this article, we discuss and contrast these new agents with established inhibitors. EXPERT OPINION The outstanding safety profile of existing nucleoside analogues for α-herpesvirus infection make the development of new therapeutic agents a challenge. Currently used nucleoside analogues exhibit few side effects and have low occurrence of clinically relevant resistance. For HCMV, however, existing drugs have significant toxicity issues and the frequency of drug resistance is high, and no antiviral therapies are available for EBV and KSHV. The development of new anti-herpesvirus drugs is thus well worth pursuing especially for immunocompromised patients and those who develop drug-resistant infections. Although the HPIs are promising, limitations to their development into a successful drug strategy remain.
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Affiliation(s)
- Sandra K Weller
- University of Connecticut Health Center, Department of Molecular Microbial and Structural Biology , Farmington CT 06030 , USA +1 860 679 2310 ;
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Mohni KN, Dee AR, Smith S, Schumacher AJ, Weller SK. Efficient herpes simplex virus 1 replication requires cellular ATR pathway proteins. J Virol 2013; 87:531-42. [PMID: 23097436 PMCID: PMC3536419 DOI: 10.1128/jvi.02504-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/15/2012] [Indexed: 02/02/2023] Open
Abstract
Herpes simplex virus 1 (HSV-1) is a double-stranded DNA virus that replicates in the nucleus of the host cell and is known to interact with several components of the cellular DNA-damage-signaling machinery. We have previously reported that the DNA damage response kinase, ATR, is specifically inactivated in HSV-1-infected cells. On the other hand, we have also shown that ATR and its scaffolding protein, ATRIP, are recruited to viral replication compartments, where they play beneficial roles during HSV-1 replication. In order to better understand this apparent discrepancy, we tested the hypothesis that some of the components of the ATR pathway may exert an antiviral effect on infection. In fact, we learned that all 10 of the canonical ATR pathway proteins are stable in HSV-infected cells and are recruited to viral replication compartments; furthermore, short hairpin RNA (shRNA) knockdown shows that several, including ATRIP, RPA70, TopBP1, Claspin, and CINP, are required for efficient HSV-1 replication. We also determined that activation of the ATR kinase prior to infection did not affect virus yield but did result in reduced levels of recombination between coinfecting viruses. Together, these data suggest that ATR pathway proteins are not antiviral per se but that activation of ATR signaling may have negative consequences during viral replication, such as inhibiting recombination.
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Affiliation(s)
- Kareem N Mohni
- Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, USA
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71
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Abstract
Herpes simplex virus (HSV) encodes seven proteins necessary for viral DNA synthesis-UL9 (origin-binding protein), ICP8 (single-strand DNA [ssDNA]-binding protein), UL30/UL42 (polymerase), and UL5/UL8/UL52 (helicase/primase). It is our intention to provide an up-to-date analysis of our understanding of the structures of these replication proteins and how they function during HSV replication. The potential roles of host repair and recombination proteins will also be discussed.
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Affiliation(s)
- Sandra K Weller
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3205, USA.
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