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Collin V, Biquand É, Tremblay V, Lavoie ÉG, Blondeau A, Gravel A, Galloy M, Lashgari A, Dessapt J, Côté J, Flamand L, Fradet-Turcotte A. The immediate-early protein 1 of human herpesvirus 6B interacts with NBS1 and inhibits ATM signaling. EMBO Rep 2024; 25:725-744. [PMID: 38177923 PMCID: PMC10897193 DOI: 10.1038/s44319-023-00035-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 01/06/2024] Open
Abstract
Viral infection often trigger an ATM serine/threonine kinase (ATM)-dependent DNA damage response in host cells that suppresses viral replication. Viruses evolved different strategies to counteract this antiviral surveillance system. Here, we report that human herpesvirus 6B (HHV-6B) infection causes genomic instability by suppressing ATM signaling in host cells. Expression of immediate-early protein 1 (IE1) phenocopies this phenotype and blocks homology-directed double-strand break repair. Mechanistically, IE1 interacts with NBS1, and inhibits ATM signaling through two distinct domains. HHV-6B seems to efficiently inhibit ATM signaling as further depletion of either NBS1 or ATM do not significantly boost viral replication in infected cells. Interestingly, viral integration of HHV-6B into the host's telomeres is not strictly dependent on NBS1, challenging current models where integration occurs through homology-directed repair. Given that spontaneous IE1 expression has been detected in cells of subjects with inherited chromosomally-integrated form of HHV-6B (iciHHV-6B), a condition associated with several health conditions, our results raise the possibility of a link between genomic instability and the development of iciHHV-6-associated diseases.
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Affiliation(s)
- Vanessa Collin
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Élise Biquand
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
- INSERM, Centre d'Étude des Pathologies Respiratoires (CEPR), UMR 1100, Université de Tours, Tours, France
| | - Vincent Tremblay
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Élise G Lavoie
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Andréanne Blondeau
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Annie Gravel
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada
| | - Maxime Galloy
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Anahita Lashgari
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Julien Dessapt
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Jacques Côté
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada
| | - Louis Flamand
- Division of Infectious Disease and Immunity, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1V 4G2, Canada.
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, G1V 0A6, Canada.
| | - Amélie Fradet-Turcotte
- Oncology Division, Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, QC, G1R 2J6, Canada.
- Department of Molecular biology, Medical Biochemistry and Pathology, Faculty of Medicine, Université Laval, Québec City, QC, G1V 0A6, Canada.
- Université Laval Cancer Research Center, Université Laval, Quebec City, QC, G1R 3S3, Canada.
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Aimola G, Wight DJ, Flamand L, Kaufer BB. Excision of Integrated Human Herpesvirus 6A Genomes Using CRISPR/Cas9 Technology. Microbiol Spectr 2023; 11:e0076423. [PMID: 36926973 PMCID: PMC10100985 DOI: 10.1128/spectrum.00764-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/18/2023] Open
Abstract
Human herpesviruses 6A and 6B are betaherpesviruses that can integrate their genomes into the telomeres of latently infected cells. Integration can also occur in germ cells, resulting in individuals who harbor the integrated virus in every cell of their body and can pass it on to their offspring. This condition is termed inherited chromosomally integrated HHV-6 (iciHHV-6) and affects about 1% of the human population. The integrated HHV-6A/B genome can reactivate in iciHHV-6 patients and in rare cases can also cause severe diseases including encephalitis and graft-versus-host disease. Until now, it has remained impossible to prevent virus reactivation or remove the integrated virus genome. Therefore, we developed a system that allows the removal of HHV-6A from the host telomeres using the CRISPR/Cas9 system. We used specific guide RNAs (gRNAs) targeting the direct repeat region at the ends of the viral genome to remove the virus from latently infected cells generated in vitro and iciHHV-6A patient cells. Fluorescence-activated cell sorting (FACS), quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH) analyses revealed that the virus genome was efficiently excised and lost in most cells. Efficient excision was achieved with both constitutive and transient expression of Cas9. In addition, reverse transcription-qPCR (RT-qPCR) revealed that the virus genome did not reactivate upon excision. Taken together, our data show that our CRISPR/Cas9 approach allows efficient removal of the integrated virus genome from host telomeres. IMPORTANCE Human herpesvirus 6 (HHV-6) infects almost all humans and integrates into the telomeres of latently infected cells to persist in the host for life. In addition, HHV-6 can also integrate into the telomeres of germ cells, which results in about 80 million individuals worldwide who carry the virus in every cell of their body and can pass it on to their offspring. In this study, we develop the first system that allows excision of the integrated HHV-6 genome from host telomeres using CRISPR/Cas9 technology. Our data revealed that the integrated HHV-6 genome can be efficiently removed from the telomeres of latently infected cells and cells of patients harboring the virus in their germ line. Virus removal could be achieved with both stable and transient Cas9 expression, without inducing viral reactivation.
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Affiliation(s)
- Giulia Aimola
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | - Darren J. Wight
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | - Louis Flamand
- Division of Infectious and Immune Diseases, CHU de Quebec Research Center-Laval University, Québec, Canada
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Laval University, Québec, Canada
| | - Benedikt B. Kaufer
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, Berlin, Germany
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Inoue Y, Takeda H. Teratorn and Its Related Elements – a Novel Group of Herpesviruses Widespread in Teleost Genomes. Zoolog Sci 2023; 40:83-90. [PMID: 37042688 DOI: 10.2108/zs220069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 12/12/2022] [Indexed: 03/08/2023]
Abstract
Herpesviruses are a large family of DNA viruses infecting vertebrates and invertebrates, and are important pathogens in the field of aquaculture. In general, herpesviruses do not have the ability to integrate into the host genomes since they do not have a chromosomal integration step in their life cycles. Recently, we identified a novel group of herpesviruses, "Teratorn" and its related elements, in the genomes of various teleost fish species. At least some of the Teratorn-like herpesviruses are fused with a piggyBac-like DNA transposon, suggesting that they have acquired the transposon-like intragenomic lifestyle by hijacking the transposon system. In this review, we describe the sequence characteristics of Teratorn-like herpesviruses and phylogenetic relationships with other herpesviruses. Then we discuss the process of transposon-herpesvirus fusion, their life cycle, and the generality of transposon-virus fusion. Teratorn-like herpesviruses provide a piece of concrete evidence that even non-retroviral elements can become intragenomic parasites retaining replication capacity, by acquiring transposition machinery from other sources.
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Affiliation(s)
- Yusuke Inoue
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroyuki Takeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Wang JQ, Yang HY, Shao X, Jiang XY, Li JM. Latent, Early or Late Human Herpes Virus-6B Expression in Adult Mesial Temporal Lobe Epilepsy: Association of Virus Life Cycle with Inflammatory Cytokines in Brain Tissue and Cerebral Spinal Fluid. Neuroscience 2022; 504:21-32. [PMID: 36067950 DOI: 10.1016/j.neuroscience.2022.08.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 08/08/2022] [Accepted: 08/25/2022] [Indexed: 10/31/2022]
Abstract
BACKGROUND Human herpes virus-6B (HHV-6B) was suggested as an important etiologic factor of mesial temporal lobe epilepsy, while the mechanism is still unknown. Here, we aimed to analyze antigens representing latent, early and late HHV-6B infection and the association with inflammatory cytokines in brain tissue and cerebral spinal fluid (CSF) from MTLE patients with HHV-6B-positivity. METHODS Nested polymerase chain reaction (nPCR), real-time PCR, immunohistochemistry (ICH) and suspension bead array for cytokines were performed. RESULTS Nested polymerase chain reaction (nPCR) in brain tissue revealed HHV-6B DNA in 19 of 49 MTLE patients (39%) and 1 of 19 controls (5%) (P < 0.001), but not in CSF. ICH showed HHV-6B early antigen (P41) positivity in 3 patients (6%), late antigen (gp116/54/64) positivity in 5 patients (10%), latent antigen (U94) positivity in 8 patients (16%), and multiple antigen (early and late or/and latent) positivity in 9 patients (18%). None of these HHV-6B related proteins were found positive in control brain tissue. PCR revealed significant up-regulation of IL-1a, IL-2 and IL-7 mRNA levels in the brain tissue from MTLE patients expressing early antigens compared to those expressing late, latent, multiple antigens, negative antigens and the controls. Suspension bead array of the CSF confirmed significant up-regulation of IL-1a and IL-7 protein expression from MTLE patients expressing early antigens compared to the other groups. CONCLUSIONS Our finding suggests HHV-6B is a common etiologic agent of MTLE. Different virus life cycle may play an important modifying role in inflammatory biology that warrants further investigation. Though virus DNA is difficult detected in CSF, up-regulation of IL-1a and IL-7 in CSF indicates the two cytokines may be taken as indirect biomarker of HHV-6B infection.
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Affiliation(s)
- Jia-Qi Wang
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China
| | - Hong-Yu Yang
- University of Electronic Science and Technology of China Hospital, China
| | | | - Xin-Yue Jiang
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China; Chengdu Second People's Hospital, Chengdu, Sichuan Province, China
| | - Jin-Mei Li
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China.
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Impact of Host Telomere Length on HHV-6 Integration. Viruses 2022; 14:v14091864. [PMID: 36146670 PMCID: PMC9505050 DOI: 10.3390/v14091864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 12/04/2022] Open
Abstract
Human herpesvirus 6A and 6B are two closely related viruses that infect almost all humans. In contrast to most herpesviruses, HHV-6A/B can integrate their genomes into the telomeres during the infection process. Both viruses can also integrate in germ cells and subsequently be inherited in children. How HHV-6A/B integrate into host telomeres and the consequences of this remain a subject of active research. Here, we developed a method to measure telomere length by quantitative fluorescence in situ hybridization, confocal microscopy, and computational processing. This method was validated using a panel of HeLa cells having short or long telomeres. These cell lines were infected with HHV-6A, revealing that the virus could efficiently integrate into telomeres independent of their length. Furthermore, we assessed the telomere lengths after HHV-6A integration and found that the virus-containing telomeres display a variety of lengths, suggesting that either telomere length is restored after integration or telomeres are not shortened by integration. Our results highlight new aspects of HHV-6A/B biology and the role of telomere length on virus integration.
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Collin V, Flamand L. [The importance of telomeres in human herpesvirus-6A/B infections]. Med Sci (Paris) 2022; 38:168-176. [PMID: 35179471 DOI: 10.1051/medsci/2022008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Herpesviruses are undisputed masters of disguise. The ability to become invisible to the immune system effectors is a complex process resting on a variety of stealth approaches. Among these, human herpesviruses-6A and -6B (HHV-6A/B) have developed the unique ability to integrate their genome within the ends of chromosomes allowing viral persistence in the absence of viral protein expression. This aptitude, unique to HHV-6A/B among human herpesviruses, requires close interactions between the telomeric regions of chromosomes and the viral genome. In this review article, the biology of telomeres and the mechanisms responsible for viral integration are discussed. In closing, the possible biological consequences of HHV-6A/B integration into chromosomal DNA are discussed.
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Affiliation(s)
- Vanessa Collin
- Axe des maladies infectieuses et immunitaires, Centre de recherche du CHU de Québec - Université Laval, Québec, 2705 boulevard Laurier, Québec, Canada
| | - Louis Flamand
- Axe des maladies infectieuses et immunitaires, Centre de recherche du CHU de Québec - Université Laval, Québec, 2705 boulevard Laurier, Québec, Canada - Département de microbiologie, maladies infectieuses et immunologie, Faculté de médecine, Université Laval, Québec, 2705 boulevard Laurier, Québec, Canada
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7
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You Y, Vychodil T, Aimola G, Previdelli RL, Göbel TW, Bertzbach LD, Kaufer BB. A Cell Culture System to Investigate Marek's Disease Virus Integration into Host Chromosomes. Microorganisms 2021; 9:microorganisms9122489. [PMID: 34946091 PMCID: PMC8706938 DOI: 10.3390/microorganisms9122489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 01/02/2023] Open
Abstract
Marek’s disease virus (MDV) is a highly oncogenic alphaherpesvirus that causes a devastating neoplastic disease in chickens. MDV has been shown to integrate its genome into the telomeres of latently infected and tumor cells, which is crucial for efficient tumor formation. Telomeric repeat arrays present at the ends of the MDV genome facilitate this integration into host telomeres; however, the integration mechanism remains poorly understood. Until now, MDV integration could only be investigated qualitatively upon infection of chickens. To shed further light on the integration mechanism, we established a quantitative integration assay using chicken T cell lines, the target cells for MDV latency and transformation. We optimized the infection conditions and assessed the establishment of latency in these T cells. The MDV genome was efficiently maintained over time, and integration was confirmed in these cells by fluorescence in situ hybridization (FISH). To assess the role of the two distinct viral telomeric repeat arrays in the integration process, we tested various knockout mutants in our in vitro integration assay. Efficient genome maintenance and integration was thereby dependent on the presence of the telomeric repeat arrays in the virus genome. Taken together, we developed and validated a novel in vitro integration assay that will shed light on the integration mechanism of this highly oncogenic virus into host telomeres.
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Affiliation(s)
- Yu You
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
| | - Tereza Vychodil
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
| | - Giulia Aimola
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
| | - Renato L. Previdelli
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London NW1 0TU, UK
| | - Thomas W. Göbel
- Institute for Animal Physiology, Department of Veterinary Sciences, Ludwig Maximilian University Munich, 80539 Munich, Germany;
| | - Luca D. Bertzbach
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
- Department of Viral Transformation, Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
- Correspondence: (L.D.B.); (B.B.K.)
| | - Benedikt B. Kaufer
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (T.V.); (G.A.); (R.L.P.)
- Correspondence: (L.D.B.); (B.B.K.)
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8
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Evasion of the Host Immune Response by Betaherpesviruses. Int J Mol Sci 2021; 22:ijms22147503. [PMID: 34299120 PMCID: PMC8306455 DOI: 10.3390/ijms22147503] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023] Open
Abstract
The human immune system boasts a diverse array of strategies for recognizing and eradicating invading pathogens. Human betaherpesviruses, a highly prevalent subfamily of viruses, include human cytomegalovirus (HCMV), human herpesvirus (HHV) 6A, HHV-6B, and HHV-7. These viruses have evolved numerous mechanisms for evading the host response. In this review, we will highlight the complex interplay between betaherpesviruses and the human immune response, focusing on protein function. We will explore methods by which the immune system first responds to betaherpesvirus infection as well as mechanisms by which viruses subvert normal cellular functions to evade the immune system and facilitate viral latency, persistence, and reactivation. Lastly, we will briefly discuss recent advances in vaccine technology targeting betaherpesviruses. This review aims to further elucidate the dynamic interactions between betaherpesviruses and the human immune system.
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Wood ML, Veal CD, Neumann R, Suárez NM, Nichols J, Parker AJ, Martin D, Romaine SPR, Codd V, Samani NJ, Voors AA, Tomaszewski M, Flamand L, Davison AJ, Royle NJ. Variation in human herpesvirus 6B telomeric integration, excision, and transmission between tissues and individuals. eLife 2021; 10:70452. [PMID: 34545807 PMCID: PMC8492063 DOI: 10.7554/elife.70452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/20/2021] [Indexed: 12/12/2022] Open
Abstract
Human herpesviruses 6A and 6B (HHV-6A/6B) are ubiquitous pathogens that persist lifelong in latent form and can cause severe conditions upon reactivation. They are spread by community-acquired infection of free virus (acqHHV6A/6B) and by germline transmission of inherited chromosomally integrated HHV-6A/6B (iciHHV-6A/6B) in telomeres. We exploited a hypervariable region of the HHV-6B genome to investigate the relationship between acquired and inherited virus and revealed predominantly maternal transmission of acqHHV-6B in families. Remarkably, we demonstrate that some copies of acqHHV-6B in saliva from healthy adults gained a telomere, indicative of integration and latency, and that the frequency of viral genome excision from telomeres in iciHHV-6B carriers is surprisingly high and varies between tissues. In addition, newly formed short telomeres generated by partial viral genome release are frequently lengthened, particularly in telomerase-expressing pluripotent cells. Consequently, iciHHV-6B carriers are mosaic for different iciHHV-6B structures, including circular extra-chromosomal forms that have the potential to reactivate. Finally, we show transmission of an HHV-6B strain from an iciHHV-6B mother to her non-iciHHV-6B son. Altogether, we demonstrate that iciHHV-6B can readily transition between telomere-integrated and free virus forms.
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Affiliation(s)
- Michael L Wood
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Colin D Veal
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Rita Neumann
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Nicolás M Suárez
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Jenna Nichols
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Andrei J Parker
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Diana Martin
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Simon PR Romaine
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom,NIHR Leicester Biomedical Research Centre, Glenfield HospitalLeicesterUnited Kingdom
| | - Veryan Codd
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom
| | - Nilesh J Samani
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom
| | - Adriaan A Voors
- University of Groningen, Department of Cardiology, University Medical Center GroningenGroningenNetherlands
| | - Maciej Tomaszewski
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of ManchesterManchesterUnited Kingdom
| | - Louis Flamand
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université Laval, Quebec CityQuébecCanada
| | - Andrew J Davison
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Nicola J Royle
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
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10
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The U94 Gene of Human Herpesvirus 6: A Narrative Review of Its Role and Potential Functions. Cells 2020; 9:cells9122608. [PMID: 33291793 PMCID: PMC7762089 DOI: 10.3390/cells9122608] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/02/2020] [Accepted: 12/02/2020] [Indexed: 12/11/2022] Open
Abstract
Human herpesvirus 6 (HHV-6) is a β-herpesvirus that is highly prevalent in the human population. HHV-6 comprises two recognized species (HHV-6A and HHV-6B). Despite different cell tropism and disease association, HHV-6A/B show high genome homology and harbor the conserved U94 gene, which is limited to HHV-6 and absent in all the other human herpesviruses. U94 has key functions in the virus life cycle and associated diseases, having demonstrated or putative roles in virus replication, integration, and reactivation. During natural infection, U94 elicits an immune response, and the prevalence and extent of the anti-U94 response are associated with specific diseases. Notably, U94 can entirely reproduce some virus effects at the cell level, including inhibition of cell migration, induction of cytokines and HLA-G expression, and angiogenesis inhibition, supporting a direct U94 role in the development of HHV-6-associated diseases. Moreover, specific U94 properties, such as the ability to modulate angiogenesis pathways, have been exploited to counteract cancer development. Here, we review the information available on this key HHV-6 gene, highlighting its potential uses.
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11
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Abstract
Next-generation sequencing technologies allowed sequencing of thousands of genomes. However, there are genomic regions that remain difficult to characterize, including telomeres, centromeres, and other low-complexity regions, as well as transposable elements and endogenous viruses. Human herpesvirus 6A and 6B (HHV-6A and HHV-6B) are closely related viruses that infect most humans and can integrate their genomes into the telomeres of infected cells. Integration also occurs in germ cells, meaning that the virus can be inherited and result in individuals harboring the virus in every cell of their body. The integrated virus can reactivate and cause disease in humans. While it is well established that the virus resides in the telomere region, the integration locus is poorly defined due to the low sequence complexity (TTAGGG)n of telomeres that cannot be easily resolved through sequencing. We therefore employed genome imaging of the integrated HHV-6A and HHV-6B genomes using whole-genome optical site mapping technology. Using this technology, we identified which chromosome arm harbors the virus genome and obtained a high-resolution map of the integration loci of multiple patients. Surprisingly, this revealed long telomere sequences at the virus-subtelomere junction that were previously missed using PCR-based approaches. Contrary to what was previously thought, our technique revealed that the telomere lengths of chromosomes harboring the integrated virus genome were comparable to the other chromosomes. Taken together, our data shed light on the genetic structure of the HHV-6A and HHV-6B integration locus, demonstrating the utility of optical mapping for the analysis of genomic regions that are difficult to sequence.
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12
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Collin V, Gravel A, Kaufer BB, Flamand L. The Promyelocytic Leukemia Protein facilitates human herpesvirus 6B chromosomal integration, immediate-early 1 protein multiSUMOylation and its localization at telomeres. PLoS Pathog 2020; 16:e1008683. [PMID: 32658923 PMCID: PMC7394443 DOI: 10.1371/journal.ppat.1008683] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/31/2020] [Accepted: 06/04/2020] [Indexed: 02/05/2023] Open
Abstract
Human herpesvirus 6B (HHV-6B) is a betaherpesvirus capable of integrating its genome into the telomeres of host chromosomes. Until now, the cellular and/or viral proteins facilitating HHV-6B integration have remained elusive. Here we show that a cellular protein, the promyelocytic leukemia protein (PML) that forms nuclear bodies (PML-NBs), associates with the HHV-6B immediate early 1 (IE1) protein at telomeres. We report enhanced levels of SUMOylated IE1 in the presence of PML and have identified a putative SUMO Interacting Motif (SIM) within IE1, essential for its nuclear distribution, overall SUMOylation and association with PML to nuclear bodies. Furthermore, using PML knockout cell lines we made the original observation that PML is required for efficient HHV-6B integration into host chromosomes. Taken together, we could demonstrate that PML-NBs are important for IE1 multiSUMOylation and that PML plays an important role in HHV-6B integration into chromosomes, a strategy developed by this virus to maintain its genome in its host over long periods of time. Human herpesvirus 6B (HHV-6B) is a ubiquitous virus that can be life threatening in immunocompromised patients. HHV-6B is among a few other herpesviruses that integrate their genome in host chromosomes as a mean to establish dormancy. Integration of HHV-6B occurs in host telomeres, a region that protects our genome from deterioration and controls the cellular lifespan. To date, the mechanisms leading to HHV-6B integration remain elusive. Our laboratory has identified that the IE1 protein of HHV-6B associates with PML, a cellular protein that is responsible for the regulation of important cellular mechanisms including DNA recombination and repair. With the objective of understanding how IE1 is brought to PML, we discovered that PML aids the SUMOylation of IE1. This finding led us to identify a putative SUMO interaction motif on IE1 that is essentials for both its SUMOylation and IE1 oligomerization with PML-NBs. We next studied the role of PML on HHV-6B integration and identified that cells that are deficient for PML were less susceptible to HHV-6B integration. These results correlate with the fact that PML influences IE1 localization at telomeres, the site of HHV-6B integration. Our study further contributes to our understanding of the mechanisms leading to HHV-6B chromosomal integration.
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Affiliation(s)
- Vanessa Collin
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
| | - Annie Gravel
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
| | | | - Louis Flamand
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
- Department of microbiology, infectious disease and immunology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada
- * E-mail:
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13
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Current understanding of human herpesvirus 6 (HHV-6) chromosomal integration. Antiviral Res 2020; 176:104720. [PMID: 32044155 DOI: 10.1016/j.antiviral.2020.104720] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 12/12/2022]
Abstract
Human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) are members of the genus Roseolovirus in the Betaherpesvirinae subfamily. HHV-6B infects humans in the first years of life, has a seroprevalence of more than 90% and causes Roseola Infantum, but less is known about HHV-6A. While most other herpesviruses maintain their latent genome as a circular episome, HHV-6A and HHV-6B (HHV-6A/B) have been shown to integrate their genome into the telomeres of infected cells. HHV-6A/B can also integrate into the chromosomes of germ cells, resulting in individuals carrying a copy of the virus genome in every nucleated cell of their bodies. This review highlights our current understanding of HHV-6A/B integration and reactivation as well as aspects that should be addressed in the future of this relatively young research area. It forms part of an online symposium on the prevention and therapy of DNA virus infections, dedicated to the memory of Mark Prichard.
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Denner J, Bigley TM, Phan TL, Zimmermann C, Zhou X, Kaufer BB. Comparative Analysis of Roseoloviruses in Humans, Pigs, Mice, and Other Species. Viruses 2019; 11:E1108. [PMID: 31801268 PMCID: PMC6949924 DOI: 10.3390/v11121108] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/13/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Viruses of the genus Roseolovirus belong to the subfamily Betaherpesvirinae, family Herpesviridae. Roseoloviruses have been studied in humans, mice and pigs, but they are likely also present in other species. This is the first comparative analysis of roseoloviruses in humans and animals. The human roseoloviruses human herpesvirus 6A (HHV-6A), 6B (HHV-6B), and 7 (HHV-7) are relatively well characterized. In contrast, little is known about the murine roseolovirus (MRV), also known as murine thymic virus (MTV) or murine thymic lymphotrophic virus (MTLV), and the porcine roseolovirus (PRV), initially incorrectly named porcine cytomegalovirus (PCMV). Human roseoloviruses have gained attention because they can cause severe diseases including encephalitis in immunocompromised transplant and AIDS patients and febrile seizures in infants. They have been linked to a number of neurological diseases in the immunocompetent including multiple sclerosis (MS) and Alzheimer's. However, to prove the causality in the latter disease associations is challenging due to the high prevalence of these viruses in the human population. PCMV/PRV has attracted attention because it may be transmitted and pose a risk in xenotransplantation, e.g., the transplantation of pig organs into humans. Most importantly, all roseoloviruses are immunosuppressive, the humoral and cellular immune responses against these viruses are not well studied and vaccines as well as effective antivirals are not available.
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Affiliation(s)
- Joachim Denner
- Robert Koch Institute, Robert Koch Fellow, 13352 Berlin, Germany
| | - Tarin M. Bigley
- Division of Rheumatology, Department. of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Tuan L. Phan
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70118, USA;
- HHV-6 Foundation, Santa Barbara, CA 93108, USA
| | - Cosima Zimmermann
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany;
| | - Xiaofeng Zhou
- Division of Pulmonary and Critical Care Medicine, Department. of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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15
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The Role of Marek's Disease Virus UL12 and UL29 in DNA Recombination and the Virus Lifecycle. Viruses 2019; 11:v11020111. [PMID: 30696089 PMCID: PMC6409567 DOI: 10.3390/v11020111] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 01/22/2019] [Accepted: 01/25/2019] [Indexed: 02/07/2023] Open
Abstract
Marek’s disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and integrates its genome into the telomeres of latently infected cells. MDV encodes two proteins, UL12 and UL29 (ICP8), that are conserved among herpesviruses and could facilitate virus integration. The orthologues of UL12 and UL29 in herpes simplex virus 1 (HSV-1) possess exonuclease and single strand DNA-binding activity, respectively, and facilitate DNA recombination; however, the role of both proteins in the MDV lifecycle remains elusive. To determine if UL12 and/or UL29 are involved in virus replication, we abrogated their expression in the very virulent RB-1B strain. Abrogation of either UL12 or UL29 resulted in a severe impairment of virus replication. We also demonstrated that MDV UL12 can aid in single strand annealing DNA repair, using a well-established reporter cell line. Finally, we assessed the role of UL12 and UL29 in MDV integration and maintenance of the latent virus genome. We could demonstrate that knockdown of UL12 and UL29 does not interfere with the establishment or maintenance of latency. Our data therefore shed light on the role of MDV UL12 and UL29 in MDV replication, DNA repair, and maintenance of the latent virus genome.
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16
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Viral Proteins U41 and U70 of Human Herpesvirus 6A Are Dispensable for Telomere Integration. Viruses 2018; 10:v10110656. [PMID: 30469324 PMCID: PMC6267051 DOI: 10.3390/v10110656] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 11/16/2018] [Accepted: 11/17/2018] [Indexed: 12/24/2022] Open
Abstract
Human herpesvirus-6A and -6B (HHV-6A and -6B) are two closely related betaherpesviruses that infect humans. Upon primary infection they establish a life-long infection termed latency, where the virus genome is integrated into the telomeres of latently infected cells. Intriguingly, HHV-6A/B can integrate into germ cells, leading to individuals with inherited chromosomally-integrated HHV-6 (iciHHV-6), who have the HHV-6 genome in every cell. It is known that telomeric repeats flanking the virus genome are essential for integration; however, the protein factors mediating integration remain enigmatic. We have previously shown that the putative viral integrase U94 is not essential for telomere integration; thus, we set out to assess the contribution of potential viral recombination proteins U41 and U70 towards integration. We could show that U70 enhances dsDNA break repair via a homology-directed mechanism using a reporter cell line. We then engineered cells to produce shRNAs targeting both U41 and U70 to inhibit their expression during infection. Using these cells in our HHV-6A in vitro integration assay, we could show that U41/U70 were dispensable for telomere integration. Furthermore, additional inhibition of the cellular recombinase Rad51 suggested that it was also not essential, indicating that other cellular and/or viral factors must mediate telomere integration.
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Flamand L. Chromosomal Integration by Human Herpesviruses 6A and 6B. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1045:209-226. [PMID: 29896669 DOI: 10.1007/978-981-10-7230-7_10] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Upon infection and depending on the infected cell type, human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) can replicate or enter a state of latency. HHV-6A and HHV-6B can integrate their genomes into host chromosomes as one way to establish latency. Viral integration takes place near the subtelomeric/telomeric junction of chromosomes. When HHV-6 infection and integration occur in gametes, the virus can be genetically transmitted. Inherited chromosomally integrated HHV-6 (iciHHV-6)-positive individuals carry one integrated HHV-6 copy per somatic cell. The prevalence of iciHHV-6+ individuals varies between 0.6% and 2%, depending on the geographical region sampled. In this chapter, the mechanisms leading to viral integration and reactivation from latency, as well as some of the biological and medical consequences associated with iciHHV-6, were discussed.
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Affiliation(s)
- Louis Flamand
- Division of Infectious and Immune Diseases, CHU de Québec Research Center, QC, Quebec, Canada. .,Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Université Laval, QC, Quebec, Canada.
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HHV-6 encoded small non-coding RNAs define an intermediate and early stage in viral reactivation. NPJ Genom Med 2018; 3:25. [PMID: 30210807 PMCID: PMC6125432 DOI: 10.1038/s41525-018-0064-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/06/2018] [Accepted: 08/09/2018] [Indexed: 12/19/2022] Open
Abstract
Human herpesvirus 6A and 6B frequently acquires latency. HHV-6 activation has been associated with various human diseases. Germ line inheritance of chromosomally integrated HHV-6 makes viral DNA-based analysis difficult for determination of early stages of viral activation. We characterized early stages of HHV-6 activation using high throughput transcriptomics studies and applied the results to understand virus activation under clinical conditions. Using a latent HHV-6A cell culture model in U2OS cells, we identified an early stage of viral reactivation, which we define as transactivation that is marked by transcription of several viral small non-coding RNAs (sncRNAs) in the absence of detectable increase in viral replication and proteome. Using deep sequencing approaches, we detected previously known as well as a new viral sncRNAs that characterized viral transactivation and differentiated it from latency. Here we show changes in human transcriptome upon viral transactivation that reflect multiple alterations in mitochondria-associated pathways, which was supported by observation of increased mitochondrial fragmentation in virus reactivated cells. Furthermore, we present here a unique clinical case of DIHS/DRESS associated death where HHV-6 sncRNA-U14 was abundantly detected throughout the body of the patient in the presence of low viral DNA. In this study, we have identified a unique and early stage of viral activation that is characterized by abundant transcription of viral sncRNAs, which can serve as an ideal biomarker under clinical conditions.
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19
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Greninger AL, Roychoudhury P, Makhsous N, Hanson D, Chase J, Krueger G, Xie H, Huang ML, Saunders L, Ablashi D, Koelle DM, Cook L, Jerome KR. Copy Number Heterogeneity, Large Origin Tandem Repeats, and Interspecies Recombination in Human Herpesvirus 6A (HHV-6A) and HHV-6B Reference Strains. J Virol 2018; 92:e00135-18. [PMID: 29491155 PMCID: PMC5923074 DOI: 10.1128/jvi.00135-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 02/21/2018] [Indexed: 12/17/2022] Open
Abstract
Quantitative PCR is a diagnostic pillar for clinical virology testing, and reference materials are necessary for accurate, comparable quantitation between clinical laboratories. Accurate quantitation of human herpesvirus 6A/B (HHV-6A/B) is important for detection of viral reactivation and inherited chromosomally integrated HHV-6A/B in immunocompromised patients. Reference materials in clinical virology commonly consist of laboratory-adapted viral strains that may be affected by the culture process. We performed next-generation sequencing to make relative copy number measurements at single nucleotide resolution of eight candidate HHV-6A and seven HHV-6B reference strains and DNA materials from the HHV-6 Foundation and Advanced Biotechnologies Inc. Eleven of 17 (65%) HHV-6A/B candidate reference materials showed multiple copies of the origin of replication upstream of the U41 gene by next-generation sequencing. These large tandem repeats arose independently in culture-adapted HHV-6A and HHV-6B strains, measuring 1,254 bp and 983 bp, respectively. The average copy number measured was between 5 and 10 times the number of copies of the rest of the genome. We also report the first interspecies recombinant HHV-6A/B strain with a HHV-6A backbone and a >5.5-kb region from HHV-6B, from U41 to U43, that covered the origin tandem repeat. Specific HHV-6A reference strains demonstrated duplication of regions at U1/U2, U87, and U89, as well as deletion in the U12-to-U24 region and the U94/U95 genes. HHV-6A/B strains derived from cord blood mononuclear cells from different laboratories on different continents with fewer passages revealed no copy number differences throughout the viral genome. These data indicate that large origin tandem duplications are an adaptation of both HHV-6A and HHV-6B in culture and show interspecies recombination is possible within the Betaherpesvirinae.IMPORTANCE Anything in science that needs to be quantitated requires a standard unit of measurement. This includes viruses, for which quantitation increasingly determines definitions of pathology and guidelines for treatment. However, the act of making standard or reference material in virology can alter its very accuracy through genomic duplications, insertions, and rearrangements. We used deep sequencing to examine candidate reference strains for HHV-6, a ubiquitous human virus that can reactivate in the immunocompromised population and is integrated into the human genome in every cell of the body for 1% of people worldwide. We found large tandem repeats in the origin of replication for both HHV-6A and HHV-6B that are selected for in culture. We also found the first interspecies recombinant between HHV-6A and HHV-6B, a phenomenon that is well known in alphaherpesviruses but to date has not been seen in betaherpesviruses. These data critically inform HHV-6A/B biology and the standard selection process.
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Affiliation(s)
- Alexander L Greninger
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
- Fred Hutchinson Cancer Research Institute, Seattle, Washington, USA
| | - Pavitra Roychoudhury
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
- Fred Hutchinson Cancer Research Institute, Seattle, Washington, USA
| | - Negar Makhsous
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Derek Hanson
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Jill Chase
- HHV-6 Foundation, Santa Barbara, California, USA
| | - Gerhard Krueger
- Department of Pathology and Laboratory Medicine, University of Houston, Houston, Texas, USA
| | - Hong Xie
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Meei-Li Huang
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Lindsay Saunders
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | | | - David M Koelle
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
- Fred Hutchinson Cancer Research Institute, Seattle, Washington, USA
- Department of Medicine, University of Washington, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Linda Cook
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Keith R Jerome
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
- Fred Hutchinson Cancer Research Institute, Seattle, Washington, USA
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20
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Greninger AL, Knudsen GM, Roychoudhury P, Hanson DJ, Sedlak RH, Xie H, Guan J, Nguyen T, Peddu V, Boeckh M, Huang ML, Cook L, Depledge DP, Zerr DM, Koelle DM, Gantt S, Yoshikawa T, Caserta M, Hill JA, Jerome KR. Comparative genomic, transcriptomic, and proteomic reannotation of human herpesvirus 6. BMC Genomics 2018; 19:204. [PMID: 29554870 PMCID: PMC5859498 DOI: 10.1186/s12864-018-4604-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/13/2018] [Indexed: 12/19/2022] Open
Abstract
Background Human herpesvirus-6A and -6B (HHV-6) are betaherpesviruses that reach > 90% seroprevalence in the adult population. Unique among human herpesviruses, HHV-6 can integrate into the subtelomeric regions of human chromosomes; when this occurs in germ line cells it causes a condition called inherited chromosomally integrated HHV-6 (iciHHV-6). Only two complete genomes are available for replicating HHV-6B, leading to numerous conflicting annotations and little known about the global genomic diversity of this ubiquitous virus. Results Using a custom capture panel for HHV-6B, we report complete genomes from 61 isolates of HHV-6B from active infections (20 from Japan, 35 from New York state, and 6 from Uganda), and 64 strains of iciHHV-6B (mostly from North America). HHV-6B sequence clustered by geography and illustrated extensive recombination. Multiple iciHHV-6B sequences from unrelated individuals across the United States were found to be completely identical, consistent with a founder effect. Several iciHHV-6B strains clustered with strains from recent active pediatric infection. Combining our genomic analysis with the first RNA-Seq and shotgun proteomics studies of HHV-6B, we completely reannotated the HHV-6B genome, altering annotations for more than 10% of existing genes, with multiple instances of novel splicing and genes that hitherto had gone unannotated. Conclusion Our results are consistent with a model of intermittent de novo integration of HHV-6B into host germline cells during active infection with a large contribution of founder effect in iciHHV-6B. Our data provide a significant advance in the genomic annotation of HHV-6B, which will contribute to the detection, diversity, and control of this virus. Electronic supplementary material The online version of this article (10.1186/s12864-018-4604-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexander L Greninger
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA. .,, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
| | - Giselle M Knudsen
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Pavitra Roychoudhury
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.,, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Derek J Hanson
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Ruth Hall Sedlak
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Hong Xie
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Jon Guan
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Thuy Nguyen
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Vikas Peddu
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Michael Boeckh
- , Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Meei-Li Huang
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Linda Cook
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Daniel P Depledge
- Division of Infection and Immunity, University College London, London, UK
| | - Danielle M Zerr
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - David M Koelle
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - Soren Gantt
- University of British Columbia, BC Children's Hospital Research Institute, Vancouver, Canada
| | - Tetsushi Yoshikawa
- Department of Pediatrics, Fujita Health University, Fujita, Toyoake, Japan
| | - Mary Caserta
- University of Rochester Medical Center School of Medicine, Rochester, New York, USA
| | - Joshua A Hill
- , Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Keith R Jerome
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.,, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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Hogestyn JM, Mock DJ, Mayer-Proschel M. Contributions of neurotropic human herpesviruses herpes simplex virus 1 and human herpesvirus 6 to neurodegenerative disease pathology. Neural Regen Res 2018; 13:211-221. [PMID: 29557362 PMCID: PMC5879884 DOI: 10.4103/1673-5374.226380] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Human herpesviruses (HVs) have developed ingenious mechanisms that enable them to traverse the defenses of the central nervous system (CNS). The ability of HVs to enter a state of latency, a defining characteristic of this viral family, allows them to persist in the human host indefinitely. As such, HVs represent the most frequently detected pathogens in the brain. Under constant immune pressure, these infections are largely asymptomatic in healthy hosts. However, many neurotropic HVs have been directly connected with CNS pathology in the context of other stressors and genetic risk factors. In this review, we discuss the potential mechanisms by which neurotropic HVs contribute to neurodegenerative disease (NDD) pathology by highlighting two prominent members of the HV family, herpes simplex virus 1 (HSV-1) and human herpesvirus 6 (HHV-6). We (i) introduce the infectious pathways and replicative cycles of HSV-1 and HHV-6 and then (ii) review the clinical evidence supporting associations between these viruses and the NDDs Alzheimer's disease (AD) and multiple sclerosis (MS), respectively. We then (iii) highlight and discuss potential mechanisms by which these viruses exert negative effects on neurons and glia. Finally, we (iv) discuss how these viruses could interact with other disease-modifying factors to contribute to the initiation and/or progression of NDDs.
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Affiliation(s)
| | - David J Mock
- Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
| | - Margot Mayer-Proschel
- Department of Neuroscience, University of Rochester; Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
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Tweedy JG, Escriva E, Topf M, Gompels UA. Analyses of Tissue Culture Adaptation of Human Herpesvirus-6A by Whole Genome Deep Sequencing Redefines the Reference Sequence and Identifies Virus Entry Complex Changes. Viruses 2017; 10:v10010016. [PMID: 29301233 PMCID: PMC5795429 DOI: 10.3390/v10010016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/23/2017] [Accepted: 12/26/2017] [Indexed: 11/18/2022] Open
Abstract
Tissue-culture adaptation of viruses can modulate infection. Laboratory passage and bacterial artificial chromosome (BAC)mid cloning of human cytomegalovirus, HCMV, resulted in genomic deletions and rearrangements altering genes encoding the virus entry complex, which affected cellular tropism, virulence, and vaccine development. Here, we analyse these effects on the reference genome for related betaherpesviruses, Roseolovirus, human herpesvirus 6A (HHV-6A) strain U1102. This virus is also naturally “cloned” by germline subtelomeric chromosomal-integration in approximately 1% of human populations, and accurate references are key to understanding pathological relationships between exogenous and endogenous virus. Using whole genome next-generation deep-sequencing Illumina-based methods, we compared the original isolate to tissue-culture passaged and the BACmid-cloned virus. This re-defined the reference genome showing 32 corrections and 5 polymorphisms. Furthermore, minor variant analyses of passaged and BACmid virus identified emerging populations of a further 32 single nucleotide polymorphisms (SNPs) in 10 loci, half non-synonymous indicating cell-culture selection. Analyses of the BAC-virus genome showed deletion of the BAC cassette via loxP recombination removing green fluorescent protein (GFP)-based selection. As shown for HCMV culture effects, select HHV-6A SNPs mapped to genes encoding mediators of virus cellular entry, including virus envelope glycoprotein genes gB and the gH/gL complex. Comparative models suggest stabilisation of the post-fusion conformation. These SNPs are essential to consider in vaccine-design, antimicrobial-resistance, and pathogenesis.
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Affiliation(s)
- Joshua G Tweedy
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, University of London, London WC1E 7HT, UK.
| | - Eric Escriva
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, University of London, London WC1E 7HT, UK.
- Institute for Structural and Molecular Biology, Department Biology, Birkbeck College University of London, London WC1E 7HX, UK.
| | - Maya Topf
- Institute for Structural and Molecular Biology, Department Biology, Birkbeck College University of London, London WC1E 7HX, UK.
| | - Ursula A Gompels
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, University of London, London WC1E 7HT, UK.
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Pantry SN, Medveczky PG. Latency, Integration, and Reactivation of Human Herpesvirus-6. Viruses 2017; 9:v9070194. [PMID: 28737715 PMCID: PMC5537686 DOI: 10.3390/v9070194] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 12/14/2022] Open
Abstract
Human herpesvirus-6A (HHV-6A) and human herpesvirus-6B (HHV-6B) are two closely related viruses that infect T-cells. Both HHV-6A and HHV-6B possess telomere-like repeats at the terminal regions of their genomes that facilitate latency by integration into the host telomeres, rather than by episome formation. In about 1% of the human population, human herpes virus-6 (HHV-6) integration into germline cells allows the viral genome to be passed down from one generation to the other; this condition is called inherited chromosomally integrated HHV-6 (iciHHV-6). This review will cover the history of HHV-6 and recent works that define the biological differences between HHV-6A and HHV-6B. Additionally, HHV-6 integration and inheritance, the capacity for reactivation and superinfection of iciHHV-6 individuals with a second strain of HHV-6, and the role of hypomethylation of human chromosomes during integration are discussed. Overall, the data suggest that integration of HHV-6 in telomeres represent a unique mechanism of viral latency and offers a novel tool to study not only HHV-6 pathogenesis, but also telomere biology. Paradoxically, the integrated viral genome is often defective especially as seen in iciHHV-6 harboring individuals. Finally, gaps in the field of HHV-6 research are presented and future studies are proposed.
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Affiliation(s)
- Shara N Pantry
- College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC Box 7, Tampa, FL 33612, USA.
- Miller School of Medicine, University of Miami, Life Sciences and Technology Park, 1951 NW 7th Avenue Ste. 270, Miami, FL 33136, USA.
| | - Peter G Medveczky
- College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC Box 7, Tampa, FL 33612, USA.
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Wood ML, Royle NJ. Chromosomally Integrated Human Herpesvirus 6: Models of Viral Genome Release from the Telomere and Impacts on Human Health. Viruses 2017; 9:E184. [PMID: 28704957 PMCID: PMC5537676 DOI: 10.3390/v9070184] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/30/2017] [Accepted: 07/05/2017] [Indexed: 12/11/2022] Open
Abstract
Human herpesvirus 6A and 6B, alongside some other herpesviruses, have the striking capacity to integrate into telomeres, the terminal repeated regions of chromosomes. The chromosomally integrated forms, ciHHV-6A and ciHHV-6B, are proposed to be a state of latency and it has been shown that they can both be inherited if integration occurs in the germ line. The first step in full viral reactivation must be the release of the integrated viral genome from the telomere and here we propose various models of this release involving transcription of the viral genome, replication fork collapse, and t-circle mediated release. In this review, we also discuss the relationship between ciHHV-6 and the telomere carrying the insertion, particularly how the presence and subsequent partial or complete release of the ciHHV-6 genome may affect telomere dynamics and the risk of disease.
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Affiliation(s)
- Michael L Wood
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK.
| | - Nicola J Royle
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK.
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Telomeres and Telomerase: Role in Marek's Disease Virus Pathogenesis, Integration and Tumorigenesis. Viruses 2017; 9:v9070173. [PMID: 28677643 PMCID: PMC5537665 DOI: 10.3390/v9070173] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/15/2017] [Accepted: 06/26/2017] [Indexed: 12/21/2022] Open
Abstract
Telomeres protect the ends of vertebrate chromosomes from deterioration and consist of tandem nucleotide repeats (TTAGGG)n that are associated with a number of proteins. Shortening of the telomeres occurs during genome replication, thereby limiting the replication potential of somatic cells. To counteract this shortening, vertebrates encode the telomerase complex that maintains telomere length in certain cell types via de novo addition of telomeric repeats. Several herpesviruses, including the highly oncogenic alphaherpesvirus Marek's disease virus (MDV), harbor telomeric repeats (TMR) identical to the host telomere sequences at the ends of their linear genomes. These TMR facilitate the integration of the MDV genome into host telomeres during latency, allowing the virus to persist in the host for life. Integration into host telomeres is critical for disease and tumor induction by MDV, but also enables efficient reactivation of the integrated virus genome. In addition to the TMR, MDV also encodes a telomerase RNA subunit (vTR) that shares 88% sequence identity with the telomerase RNA in chicken (chTR). vTR is highly expressed during all stages of the virus lifecycle, enhances telomerase activity and plays an important role in MDV-induced tumor formation. This review will focus on the recent advances in understanding the role of viral TMR and vTR in MDV pathogenesis, integration and tumorigenesis.
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Stabilization of Telomere G-Quadruplexes Interferes with Human Herpesvirus 6A Chromosomal Integration. J Virol 2017; 91:JVI.00402-17. [PMID: 28468887 DOI: 10.1128/jvi.00402-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/29/2017] [Indexed: 11/20/2022] Open
Abstract
Human herpesviruses 6A and 6B (HHV-6A/B) can integrate their genomes into the telomeres of human chromosomes using a mechanism that remains poorly understood. To achieve a better understanding of the HHV-6A/B integration mechanism, we made use of BRACO-19, a compound that stabilizes G-quadruplex secondary structures and prevents telomere elongation by the telomerase complex. First, we analyzed the folding of telomeric sequences into G-quadruplex structures and their binding to BRACO-19 using G-quadruplex-specific antibodies and surface plasmon resonance. Circular dichroism studies indicate that BRACO-19 modifies the conformation and greatly stabilizes the G-quadruplexes formed in G-rich telomeric DNA. Subsequently we assessed the effects of BRACO-19 on the HHV-6A initial phase of infection. Our results indicate that BRACO-19 does not affect entry of HHV-6A DNA into cells. We next investigated if stabilization of G-quadruplexes by BRACO-19 affected HHV-6A's ability to integrate its genome into host chromosomes. Incubation of telomerase-expressing cells with BRACO-19, such as HeLa and MCF-7, caused a significant reduction in the HHV-6A integration frequency (P < 0.002); in contrast, BRACO-19 had no effect on HHV-6 integration frequency in U2OS cells that lack telomerase activity and elongate their telomeres through alternative lengthening mechanisms. Our data suggest that the fluidity of telomeres is important for efficient chromosomal integration of HHV-6A and that interference with telomerase activity negatively affects the generation of cellular clones containing integrated HHV-6A.IMPORTANCE HHV-6A/B can integrate their genomes into the telomeres of infected cells. Telomeres consist of repeated hexanucleotides (TTAGGG) of various lengths (up to several kilobases) and end with a single-stranded 3' extension. To avoid recognition and induce a DNA damage response, the single-stranded overhang folds back on itself and forms a telomeric loop (T-loop) or adopts a tertiary structure, referred to as a G-quadruplex. In the current study, we have examined the effects of a G-quadruplex binding and stabilizing agent, BRACO-19, on HHV-6A chromosomal integration. By stabilizing G-quadruplex structures, BRACO-19 affects the ability of the telomerase complex to elongate telomeres. Our results indicate that BRACO-19 reduces the number of clones harboring integrated HHV-6A. This study is the first of its kind and suggests that telomerase activity is essential to restore a functional telomere of adequate length following HHV-6A integration.
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Collin V, Flamand L. HHV-6A/B Integration and the Pathogenesis Associated with the Reactivation of Chromosomally Integrated HHV-6A/B. Viruses 2017; 9:E160. [PMID: 28672870 PMCID: PMC5537652 DOI: 10.3390/v9070160] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 01/03/2023] Open
Abstract
Unlike other human herpesviruses, human herpesvirus 6A and 6B (HHV-6A/B) infection can lead to integration of the viral genome in human chromosomes. When integration occurs in germinal cells, the integrated HHV-6A/B genome can be transmitted to 50% of descendants. Such individuals, carrying one copy of the HHV-6A/B genome in every cell, are referred to as having inherited chromosomally-integrated HHV-6A/B (iciHHV-6) and represent approximately 1% of the world's population. Interestingly, HHV-6A/B integrate their genomes in a specific region of the chromosomes known as telomeres. Telomeres are located at chromosomes' ends and play essential roles in chromosomal stability and the long-term proliferative potential of cells. Considering that the integrated HHV-6A/B genome is mostly intact without any gross rearrangements or deletions, integration is likely used for viral maintenance into host cells. Knowing the roles played by telomeres in cellular homeostasis, viral integration in such structure is not likely to be without consequences. At present, the mechanisms and factors involved in HHV-6A/B integration remain poorly defined. In this review, we detail the potential biological and medical impacts of HHV-6A/B integration as well as the possible chromosomal integration and viral excision processes.
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Affiliation(s)
- Vanessa Collin
- Division of Infectious and Immune Diseases, CHU de Quebec Research Center-Laval University, Québec, QC G1V 4G2, Canada.
| | - Louis Flamand
- Division of Infectious and Immune Diseases, CHU de Quebec Research Center-Laval University, Québec, QC G1V 4G2, Canada.
- Department of Microbiology, Infectious Disease and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 0A6, Canada.
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Cell Culture Systems To Study Human Herpesvirus 6A/B Chromosomal Integration. J Virol 2017; 91:JVI.00437-17. [PMID: 28468878 DOI: 10.1128/jvi.00437-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 04/22/2017] [Indexed: 01/01/2023] Open
Abstract
Human herpesviruses 6A/B (HHV-6A/B) can integrate their viral genomes in the telomeres of human chromosomes. The viral and cellular factors contributing to HHV-6A/B integration remain largely unknown, mostly due to the lack of efficient and reproducible cell culture models to study HHV-6A/B integration. In this study, we characterized the HHV-6A/B integration efficiencies in several human cell lines using two different approaches. First, after a short-term infection (5 h), cells were processed for single-cell cloning and analyzed for chromosomally integrated HHV-6A/B (ciHHV-6A/B). Second, cells were infected with HHV-6A/B and allowed to grow in bulk for 4 weeks or longer and then analyzed for the presence of ciHHV-6. Using quantitative PCR (qPCR), droplet digital PCR, and fluorescent in situ hybridization, we could demonstrate that HHV-6A/B integrated in most human cell lines tested, including telomerase-positive (HeLa, MCF-7, HCT-116, and HEK293T) and telomerase-negative cell lines (U2OS and GM847). Our results also indicate that inhibition of DNA replication, using phosphonoacetic acid, did not affect HHV-6A/B integration. Certain clones harboring ciHHV-6A/B spontaneously express viral genes and proteins. Treatment of cells with phorbol ester or histone deacetylase inhibitors triggered the expression of many viral genes, including U39, U90, and U100, without the production of infectious virus, suggesting that the tested stimuli were not sufficient to trigger full reactivation. In summary, both integration models yielded comparable results and should enable the identification of viral and cellular factors contributing to HHV-6A/B integration and the screening of drugs influencing viral gene expression, as well as the release of infectious HHV-6A/B from the integrated state.IMPORTANCE The analysis and understanding of HHV-6A/B genome integration into host DNA is currently limited due to the lack of reproducible and efficient viral integration systems. In the present study, we describe two quantitative cell culture viral integration systems. These systems can be used to define cellular and viral factors that play a role in HHV-6A/B integration. Furthermore, these systems will allow us to decipher the conditions resulting in virus gene expression and excision of the integrated viral genome resulting in reactivation.
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Human Herpesvirus 6B Induces Hypomethylation on Chromosome 17p13.3, Correlating with Increased Gene Expression and Virus Integration. J Virol 2017; 91:JVI.02105-16. [PMID: 28298607 DOI: 10.1128/jvi.02105-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/03/2017] [Indexed: 12/21/2022] Open
Abstract
Human herpesvirus 6B (HHV-6B) is a neurotropic betaherpesvirus that achieves latency by integrating its genome into host cell chromosomes. Several viruses can induce epigenetic modifications in their host cells, but no study has investigated the epigenetic modifications induced by HHV-6B. This study analyzed methylation with an Illumina 450K array, comparing HHV-6B-infected and uninfected Molt-3 T cells 3 days postinfection. Bisulfite pyrosequencing was used to validate the Illumina results and to investigate methylation over time in vitro Expression of genes was investigated using quantitative PCR (qPCR), and virus integration was investigated with PCR. A total of 406 CpG sites showed a significant HHV-6B-induced change in methylation in vitro Remarkably, 86% (351/406) of these CpGs were located <1 Mb from chromosomal ends and were all hypomethylated in virus-infected cells. This was most evident at chromosome 17p13.3, where HHV-6B had induced CpG hypomethylation after 2 days of infection, possibly through TET2, which was found to be upregulated by the virus. In addition, virus-induced cytosine hydroxymethylation was observed. Genes located in the hypomethylated region at 17p13.3 showed significantly upregulated expression in HHV-6B-infected cells. A temporal experiment revealed HHV-6B integration in Molt-3 cell DNA 3 days after infection. The telomere at 17p has repeatedly been described as an integration site for HHV-6B, and we show for the first time that HHV-6B induces hypomethylation in this region during acute infection, which may play a role in the integration process, possibly by making the DNA more accessible.IMPORTANCE The ability to establish latency in the host is a hallmark of herpesviruses, but the mechanisms differ. Human herpesvirus 6B (HHV-6B) is known to establish latency through integration of its genome into the telomeric regions of host cells, with the ability to reactivate. Our study is the first to show that HHV-6B specifically induces hypomethylated regions close to the telomeres and that integrating viruses may use the host methylation machinery to facilitate their integration process. The results from this study contribute to knowledge of HHV-6B biology and virus-host interaction. This in turn will lead to further progress in our understanding of the underlying mechanisms by which HHV-6B contributes to pathological processes and may have important implications in both disease prevention and treatment.
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Chromosomal integration of HHV-6A during non-productive viral infection. Sci Rep 2017; 7:512. [PMID: 28360414 PMCID: PMC5428774 DOI: 10.1038/s41598-017-00658-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/07/2017] [Indexed: 11/28/2022] Open
Abstract
Human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) are two different species of betaherpesviruses that integrate into sub-telomeric ends of human chromosomes, for which different prevalence rates of integration have been reported. It has been demonstrated that integrated viral genome is stable and is fully retained. However, study of chromosomally integrated viral genome in individuals carrying inherited HHV-6 (iciHHV-6) showed unexpected number of viral DR copies. Hence, we created an in vitro infection model and studied retention of full or partial viral genome over a period of time. We observed an exceptional event where cells retained viral direct repeats (DRs) alone in the absence of the full viral genome. Finally, we found evidence for non-telomeric integration of HHV-6A DR in both cultured cells and in an iciHHV-6 individual. Our results shed light on several novel features of HHV-6A chromosomal integration and provide valuable information for future screening techniques.
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