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Bahramian E, Furr M, Wu JT, Ceballos RM. Differential Impacts of HHV-6A versus HHV-6B Infection in Differentiated Human Neural Stem Cells. Front Immunol 2022; 13:847106. [PMID: 35911725 PMCID: PMC9326508 DOI: 10.3389/fimmu.2022.847106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 06/16/2022] [Indexed: 12/02/2022] Open
Abstract
Within the family Herpesviridae, sub-family β-herpesvirinae, and genus Roseolovirus, there are only three human herpesviruses that have been described: HHV-6A, HHV-6B, and HHV-7. Initially, HHV-6A and HHV-6B were considered as two variants of the same virus (i.e., HHV6). Despite high overall genetic sequence identity (~90%), HHV-6A and HHV-6B are now recognized as two distinct viruses. Sequence divergence (e.g., >30%) in key coding regions and significant differences in physiological and biochemical profiles (e.g., use of different receptors for viral entry) underscore the conclusion that HHV-6A and HHV-6B are distinct viruses of the β-herpesvirinae. Despite these viruses being implicated as causative agents in several nervous system disorders (e.g., multiple sclerosis, epilepsy, and chronic fatigue syndrome), the mechanisms of action and relative contributions of each virus to neurological dysfunction are unclear. Unresolved questions regarding differences in cell tropism, receptor use and binding affinity (i.e., CD46 versus CD134), host neuro-immunological responses, and relative virulence between HHV-6A versus HHV-6B prevent a complete characterization. Although it has been shown that both HHV-6A and HHV-6B can infect glia (and, recently, cerebellar Purkinje cells), cell tropism of HHV-6A versus HHV-6B for different nerve cell types remains vague. In this study, we show that both viruses can infect different nerve cell types (i.e., glia versus neurons) and different neurotransmitter phenotypes derived from differentiated human neural stem cells. As demonstrated by immunofluorescence, HHV-6A and HHV-6B productively infect VGluT1-containing cells (i.e., glutamatergic neurons) and dopamine-containing cells (i.e., dopaminergic neurons). However, neither virus appears to infect GAD67-containing cells (i.e., GABAergic neurons). As determined by qPCR, expression of immunological factors (e.g., cytokines) in cells infected with HHV-6A versus HHV6-B also differs. These data along with morphometric and image analyses of infected differentiated neural stem cell cultures indicate that while HHV-6B may have greater opportunity for transmission, HHV-6A induces more severe cytopathic effects (e.g., syncytia) at the same post-infection end points. Cumulatively, results suggest that HHV-6A is more virulent than HHV-6B in susceptible cells, while neither virus productively infects GABAergic cells. Consistency between these in vitro data and in vivo experiments would provide new insights into potential mechanisms for HHV6-induced epileptogenesis.
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Affiliation(s)
- Elham Bahramian
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, United States
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
| | - Mercede Furr
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, United States
| | - Jerry T. Wu
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Ruben Michael Ceballos
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, United States
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
- Ecology, Evolution, and Organismal Biology Group, University of Arkansas, Fayetteville, AR, United States
- Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR, United States
- *Correspondence: Ruben Michael Ceballos,
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2
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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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3
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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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4
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Bonnafous P, Phan TL, Himes R, Eldin K, Gautheret-Dejean A, Prusty BK, Agut H, Munoz FM. Evaluation of liver failure in a pediatric transplant recipient of a liver allograft with inherited chromosomally integrated HHV-6B. J Med Virol 2019; 92:241-250. [PMID: 31579937 DOI: 10.1002/jmv.25600] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 09/25/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Active infections of human herpesvirus 6B (HHV-6B) are frequent in immunocompromised recipients after transplantation. Nevertheless, they need to be distinguished from latent inherited chromosomally integrated genomes (iciHHV-6) present in about 1% of the population to avoid unnecessary administration of toxic antivirals. METHODS A 5-year-old child presented with acute liver allograft rejection associated with HHV-6 DNA in plasma, which led to an unfavorable outcome. We investigated the possibility of HHV-6 infection derived from an iciHHV-6 present in the donor's liver using molecular and histopathology studies in various tissues, including quantification of HHV-6 DNA, genotyping, sequencing for antiviral resistance genes, relative quantification of viral transcripts, and detection of gB and gH viral proteins. RESULTS The presence of iciHHV-6B was evidenced in the donor with signs of reactivation in the gallbladder and transplanted liver (detection of HHV-6B mRNA and late proteins). This localized expression could have played a role in liver rejection. Low viral loads in the recipient's plasma, with identical partial U39 sequences, were in favor of viral DNA released from the transplanted liver rather than a systemic infection. CONCLUSIONS Determination of iciHHV-6 status before transplantation should be considered to guide clinical decisions, such as antiviral prophylaxis, viral load monitoring, and antiviral therapy.
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Affiliation(s)
- Pascale Bonnafous
- Sorbonne Department, INSERM, Institut Pierre Louis d'Épidémiologie et de Santé Publique (IPLESP), THERAVIR team, Paris, France
| | - Tuan L Phan
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, Louisiana
- HHV-6 Foundation, Santa Barbara, California
| | - Ryan Himes
- Departments of Pediatrics, Molecular Virology and Microbiology, Hepatology, and Pathology, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas
| | - Karen Eldin
- Departments of Pediatrics, Molecular Virology and Microbiology, Hepatology, and Pathology, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas
| | - Agnès Gautheret-Dejean
- AP-HP, Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Service de Virologie, Paris, France
- Department Paris Descartes, Institute de Pharmacie de Paris, UMR-S 1139 (3PHM), Paris, France
| | | | - Henri Agut
- AP-HP, Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Service de Virologie, Paris, France
| | - Flor M Munoz
- Departments of Pediatrics, Molecular Virology and Microbiology, Hepatology, and Pathology, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas
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5
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Bonnafous P, Marlet J, Bouvet D, Salamé E, Tellier AC, Guyetant S, Goudeau A, Agut H, Gautheret-Dejean A, Gaudy-Graffin C. Fatal outcome after reactivation of inherited chromosomally integrated HHV-6A (iciHHV-6A) transmitted through liver transplantation. Am J Transplant 2018; 18:1548-1551. [PMID: 29316259 DOI: 10.1111/ajt.14657] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 12/26/2017] [Accepted: 12/30/2017] [Indexed: 01/25/2023]
Abstract
HHV-6A and HHV-6B are found as inherited and chromosomally integrated forms (iciHHV-6A and -6B) into all germinal and somatic cells and vertically transmitted in a Mendelian manner in about 1% of the population. They were occasionally shown to be horizontally transmitted through hematopoietic stem cell transplantation. Here, we present a clinical case of horizontal transmission of iciHHV-6A from donor to recipient through liver transplantation. Molecular analysis performed on three viral genes (7.2 kb) in the recipient and donor samples supports transmission of iciHHV-6A from the graft. Transmission was followed by reactivation, with high viral loads in several compartments. The infection was uncontrollable, leading to severe disease and death, despite antiviral treatments and the absence of resistance mutations. This case highlights the fact that physicians should be aware of the possible horizontal transmission of iciHHV-6 and its consequences in case of reactivation in immunocompromised patients.
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Affiliation(s)
- P Bonnafous
- Sorbonne Université, Faculté de médecine, INSERM, CIMI-Paris U1135, Equipe PVI, F-75013 Paris, France
| | - J Marlet
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites Tours, Inserm U1259, Université de Tours, Tours, France.,Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Tours, Tours, France
| | - D Bouvet
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites Tours, Inserm U1259, Université de Tours, Tours, France
| | - E Salamé
- Unité de Chirurgie Hépato-Biliaire et pancréatique-Transplantation hépatique, CHU de Tours, Tours, France
| | - A-C Tellier
- Réanimation Chirurgicale Tours, CHU de Tours, Tours, France
| | - S Guyetant
- Service d'Anatomie et Cytologie Pathologiques, CHU de Tours, Tours, France
| | - A Goudeau
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites Tours, Inserm U1259, Université de Tours, Tours, France.,Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Tours, Tours, France
| | - H Agut
- Sorbonne Université, Faculté de médecine, INSERM, CIMI-Paris U1135, Equipe PVI, F-75013 Paris, France.,Service de Virologie HU La Pitié Salpêtrière-Charles Foix Paris, APHP, Paris, France
| | - A Gautheret-Dejean
- Sorbonne Université, Faculté de médecine, INSERM, CIMI-Paris U1135, Equipe PVI, F-75013 Paris, France.,Service de Virologie HU La Pitié Salpêtrière-Charles Foix Paris, APHP, Paris, France.,Laboratoire de Microbiologie Paris, équipe UPRES EA4065, Faculté de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - C Gaudy-Graffin
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites Tours, Inserm U1259, Université de Tours, Tours, France.,Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Tours, Tours, France
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6
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Tang H, Mori Y. Glycoproteins of HHV-6A and HHV-6B. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1045:145-165. [PMID: 29896667 DOI: 10.1007/978-981-10-7230-7_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recently, human herpesvirus 6A and 6B (HHV-6A and HHV-6B) were classified into distinct species. Although these two viruses share many similarities, cell tropism is one of their striking differences, which is partially because of the difference in their entry machinery. Many glycoproteins of HHV-6A/B have been identified and analyzed in detail, especially in their functions during entry process into host cells. Some of these glycoproteins were unique to HHV-6A/B. The cellular factors associated with these viral glycoproteins (or glycoprotein complex) were also identified in recent years. Detailed interaction analyses were also conducted, which could partially prove the difference of entry machinery in these two viruses. Although there are still issues that should be addressed, all the knowledges that have been earned in recent years could not only help us to understand these viruses' entry mechanism well but also would contribute to the development of the therapy and/or prophylaxis methods for HHV-6A/B-associated diseases.
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Affiliation(s)
- Huamin Tang
- Department of Immunology, Nanjing Medical University, Nanjing, China.
| | - Yasuko Mori
- Division of Clinical Virology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
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7
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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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8
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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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9
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Abstract
Human roseoloviruses include three different species, human herpesviruses 6A, 6B, and 7 (HHV-6A, HHV-6B, HHV-7), genetically related to human cytomegalovirus. They exhibit a wide cell tropism in vivo and, like other herpesviruses, induce a lifelong latent infection in humans. In about 1% of the general population, HHV-6 DNA is covalently integrated into the subtelomeric region of cell chromosomes (ciHHV-6). Many active infections, corresponding to primary infections, reactivations, or exogenous reinfections, are asymptomatic. They also may cause serious diseases, particularly in immunocompromised individuals, including hematopoietic stem-cell transplant (HSCT) and solid-organ transplant recipients, and acquired immunodeficiency syndrome (AIDS) patients. This opportunistic pathogenic role is formally established for HHV-6 infection and less clear for HHV-7. It mainly concerns the central-nervous system, bone marrow, lungs, gastrointestinal tract, skin, and liver. As the best example, HHV-6 causes both exanthema subitum, a benign disease associated with primary infection, and severe encephalitis associated with virus reactivations in HSCT recipients. Diagnosis using serologic and direct antigen-detection methods currently exhibits limitations. The most prominent technique is the quantification of viral DNA in blood, other body fluids, and organs by means of real-time polymerase-chain reaction (PCR). The antiviral compounds ganciclovir, foscarnet, and cidofovir are effective against active infections, but there is currently no consensus regarding the indications of treatment or specifics of drug administration. Numerous questions about HHV-6A, HHV-6B, HHV-7 are still pending, concerning in particular clinical impact and therapeutic options in immunocompromised patients.
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10
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Strojnik T, Duh D, Lah TT. Prevalence of Neurotropic Viruses in Malignant Glioma and Their Onco-Modulatory Potential. ACTA ACUST UNITED AC 2017; 31:221-229. [PMID: 28358704 DOI: 10.21873/invivo.11049] [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: 11/14/2016] [Revised: 12/28/2016] [Accepted: 01/06/2017] [Indexed: 12/21/2022]
Abstract
BACKGROUND the association between infectious agents and tumour aetiology is relevant in about 20% of cases. PATIENTS AND METHODS We tested high-grade glioma tissues from 45 patients for the presence of viral nucleic acids of six herpes viruses, human adenoviruses (A-G), and two neurotropic human viruses (enteroviruses, tick-borne encephalitis virus). Real-time polymerase chain reaction was used with immunolabelling. RESULTS Three species of herpes viruses were detected: HSV-2, Epstein-Barr virus (EBV), HHV-6, and one human enterovirus. Plasma of these patients was not infected with viruses. In sera of patients, low HSV-1 and HSV-2 immunoreactivity were found in five cases, although these were not detected in their tumour tissue. CONCLUSION Certain common viruses (HSV-1, HSV-2, EBV, human cytomegalovirus) are chronically present in the sera of patients with glioblastoma, but not necessarily in their tissues. Possibly both are associated with glioma progression, as we only found viruses in glioblastoma multiforme, but not in lower stages of glioma. Low titres of viruses in the blood indicate chronic viral virulence.
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Affiliation(s)
- Tadej Strojnik
- Department of Neurosurgery, University Clinical Centre Maribor, Maribor, Slovenia .,Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Darja Duh
- Department for Medical Microbiology Maribor, National Laboratory of Health, Environment and Food (NLZOH), Maribor, Slovenia
| | - Tamara T Lah
- Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Engineering, University of Ljubljana, Ljubljana, Slovenia
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11
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Agut H, Bonnafous P, Gautheret-Dejean A. Update on infections with human herpesviruses 6A, 6B, and 7. Med Mal Infect 2016; 47:83-91. [PMID: 27773488 DOI: 10.1016/j.medmal.2016.09.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 09/19/2016] [Indexed: 11/19/2022]
Abstract
Human herpesviruses 6A, 6B, and 7 (HHV-6A, HHV-6B, HHV-7) are genetically related to cytomegalovirus. They belong to the Roseolovirus genus and to the Betaherpesvirinae subfamily. They infect T cells, monocytes-macrophages, epithelial cells, and central nervous system cells. These viruses are ubiquitous and are responsible for lifelong chronic infections, most often asymptomatic, in the vast majority of the general adult population. HHV-6B is responsible for exanthema subitum, which is a benign disease of infants. HHV-6A and HHV-6B also cause opportunistic infections in immunocompromised patients: encephalitis, hepatitis, bone marrow suppression, colitis, and pneumonitis. Their etiological role in chronic diseases such as multiple sclerosis, cardiomyopathy, and thyroiditis is still controversial. The pathogenicity of HHV-7 is less clear and seems to be much more restricted. Chromosomal integration of HHV-6A and HHV-6B is transmissible from parents to offspring and observed in about 1% of the general population. This integration raises the question of potential associated diseases and can be a confounding factor for the diagnosis of active infections by both viruses. The diagnosis of HHV-6A, HHV-6B, and HHV-7 infections is rather based on gene amplification (PCR), which allows for the detection and quantification of the viral genome, than on serology, which is mainly indicated in case of primary infection. Ganciclovir, foscarnet, and cidofovir inhibit the replication of HHV-6A, HHV-6B, and HHV-7. Severe infections may thus be treated but these therapeutic indications are still poorly defined.
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Affiliation(s)
- H Agut
- Service de virologie, CERVI, hôpitaux universitaires La Pitié Salpêtrière-Charles-Foix, Assistance publique-Hôpitaux de Paris, 83, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Inserm, CIMI-Paris UMR 1135, Équipe 1 PVI, Sorbonne universités, UPMC université Paris 6, 75013 Paris, France.
| | - P Bonnafous
- Inserm, CIMI-Paris UMR 1135, Équipe 1 PVI, Sorbonne universités, UPMC université Paris 6, 75013 Paris, France.
| | - A Gautheret-Dejean
- Service de virologie, CERVI, hôpitaux universitaires La Pitié Salpêtrière-Charles-Foix, Assistance publique-Hôpitaux de Paris, 83, boulevard de l'Hôpital, 75651 Paris cedex 13, France; Inserm, CIMI-Paris UMR 1135, Équipe 1 PVI, Sorbonne universités, UPMC université Paris 6, 75013 Paris, France; Faculté de pharmacie, université Paris-Descartes, 75006 Paris, France.
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12
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Back H, Ullman K, Leijon M, Söderlund R, Penell J, Ståhl K, Pringle J, Valarcher JF. Genetic variation and dynamics of infections of equid herpesvirus 5 in individual horses. J Gen Virol 2015; 97:169-178. [PMID: 26518010 DOI: 10.1099/jgv.0.000332] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Equid herpesvirus 5 (EHV-5) is related to the human Epstein-Barr virus (human herpesvirus 4) and has frequently been observed in equine populations worldwide. EHV-5 was previously assumed to be low to non-pathogenic; however, studies have also related the virus to the severe lung disease equine multinodular pulmonary fibrosis (EMPF). Genetic information of EHV-5 is scanty: the whole genome was recently described and only limited nucleotide sequences are available. In this study, samples were taken twice 1 year apart from eight healthy horses at the same professional training yard and samples from a ninth horse that was diagnosed with EMPF with samples taken pre- and post-mortem to analyse partial glycoprotein B (gB) gene of EHV-5 by using next-generation sequencing. The analysis resulted in 27 partial gB gene sequences, 11 unique sequence types and five amino acid sequences. These sequences could be classified within four genotypes (I-IV) of the EHV-5 gB gene based on the degree of similarity of the nucleotide and amino acid sequences, and in this work horses were shown to be identified with up to three different genotypes simultaneously. The observations showed a range of interactions between EHV-5 and the host over time, where the same virus persists in some horses, whereas others have a more dynamic infection pattern including strains from different genotypes. This study provides insight into the genetic variation and dynamics of EHV-5, and highlights that further work is needed to understand the EHV-5 interaction with its host.
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Affiliation(s)
- Helena Back
- Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden
| | - Karin Ullman
- Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden
| | - Mikael Leijon
- Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden
| | - Robert Söderlund
- Department of Bacteriology, National Veterinary Institute, Uppsala, Sweden
| | - Johanna Penell
- Department of Veterinary Epidemiology and Public Health, University of Surrey, Guildford, UK
| | - Karl Ståhl
- Department of Disease Control and Epidemiology, National Veterinary Institute, Uppsala, Sweden
| | - John Pringle
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jean-François Valarcher
- Department of Virology, Immunobiology and Parasitology, National Veterinary Institute, Uppsala, Sweden.,Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
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13
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Quintela A, Escuret V, Roux S, Bonnafous P, Gilis L, Barraco F, Labussière-Wallet H, Duscastelle-Leprêtre S, Nicolini FE, Thomas X, Chidiac C, Ferry T, Frobert E, Morisset S, Poitevin-Later F, Monneret G, Michallet M, Ader F. HHV-6 infection after allogeneic hematopoietic stem cell transplantation: From chromosomal integration to viral co-infections and T-cell reconstitution patterns. J Infect 2015; 72:214-22. [PMID: 26518057 DOI: 10.1016/j.jinf.2015.09.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 08/29/2015] [Accepted: 09/29/2015] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Human herpes virus 6 (HHV-6) can reactivate after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and may be associated with significant clinical manifestations. METHODS Case control study of HHV-6 infections after allo-HSCT. Chromosomal integration (ciHHV-6) for viral loads ≥ 5.5-log10 copies/mL was investigated. Viral co-infections, T-cell recovery, risk factors and outcome were compared in HHV-6- and non-HHV-6-infected patients. Antiviral treatment strategies were reviewed. RESULTS Among 366 adult allo-HSCT recipients, 75 HHV-6 infections occurred. Three (4%) recipients were ciHHV-6. HHV-6 infections were associated with CMV (p = 0.05; sdHR 1.73, CI 0.99-3.02) and/or BKV infections (p < 0.0001; sdHR 4.63, CI 2.04-10.53) but not EBV reactivation (p = 0.34). A slower CD8+ T-cells recovery was observed until 6 months after allo-HSCT in the HHV-6-infected group (p < 0.001), independently of acute and/or chronic graft-versus-host disease. The overall probability of survival after allo-HSCT was diminished for active HHV-6-infected patients (p = 0.0326). Cord blood unit recipients had a higher risk of developing HHV-6 infection compared to bone marrow recipients (p = 0.0007; sdHR 3.82, CI 1.76-8.27). Anti-HHV-6 treatment achieved complete response in only 2/3 of the cases. CONCLUSIONS In this series of allo-HSCT recipients, 4% were ciHHV-6, active HHV-6 infection was likely associated with CMV and BKV co-reactivations, delayed CD8+ T-cell recovery and poorer outcome.
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Affiliation(s)
- Adrien Quintela
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Vanessa Escuret
- Virology Laboratory, Laboratoire de Virologie Est, Hospices Civils de Lyon, F-69677 Bron, France
| | - Sandrine Roux
- Infectious Diseases Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, F-69004 Lyon, France
| | - Pascale Bonnafous
- Sorbonne Universités, UPMC, CIMI-Paris UMRS CR7, Inserm U1135, PVI Team, Paris, France
| | - Lila Gilis
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Fiorenza Barraco
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Hélène Labussière-Wallet
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | | | - Franck-Emmanuel Nicolini
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Xavier Thomas
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Christian Chidiac
- Infectious Diseases Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, F-69004 Lyon, France
| | - Tristan Ferry
- Infectious Diseases Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, F-69004 Lyon, France; Inserm U1111 CIRI, Claude Bernard Lyon I University, Lyon, France
| | - Emilie Frobert
- Virology Laboratory, Laboratoire de Virologie Est, Hospices Civils de Lyon, F-69677 Bron, France
| | - Stéphane Morisset
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Françoise Poitevin-Later
- Cellular Immunology Laboratory, Hôpital E. Herriot, Hospices Civils de Lyon, F-69003 Lyon, France
| | - Guillaume Monneret
- Cellular Immunology Laboratory, Hôpital E. Herriot, Hospices Civils de Lyon, F-69003 Lyon, France
| | - Mauricette Michallet
- Hematology Department, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France
| | - Florence Ader
- Infectious Diseases Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, F-69004 Lyon, France; Inserm U1111 CIRI, Claude Bernard Lyon I University, Lyon, France.
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14
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Agut H, Bonnafous P, Gautheret-Dejean A. Laboratory and clinical aspects of human herpesvirus 6 infections. Clin Microbiol Rev 2015; 28:313-35. [PMID: 25762531 PMCID: PMC4402955 DOI: 10.1128/cmr.00122-14] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Human herpesvirus 6 (HHV-6) is a widespread betaherpesvirus which is genetically related to human cytomegalovirus (HCMV) and now encompasses two different species: HHV-6A and HHV-6B. HHV-6 exhibits a wide cell tropism in vivo and, like other herpesviruses, induces a lifelong latent infection in humans. As a noticeable difference with respect to other human herpesviruses, genomic HHV-6 DNA is covalently integrated into the subtelomeric region of cell chromosomes (ciHHV-6) in about 1% of the general population. Although it is infrequent, this may be a confounding factor for the diagnosis of active viral infection. The diagnosis of HHV-6 infection is performed by both serologic and direct methods. The most prominent technique is the quantification of viral DNA in blood, other body fluids, and organs by means of real-time PCR. Many active HHV-6 infections, corresponding to primary infections, reactivations, or exogenous reinfections, are asymptomatic. However, the virus may be the cause of serious diseases, particularly in immunocompromised individuals. As emblematic examples of HHV-6 pathogenicity, exanthema subitum, a benign disease of infancy, is associated with primary infection, whereas further virus reactivations can induce severe encephalitis cases, particularly in hematopoietic stem cell transplant recipients. Generally speaking, the formal demonstration of the causative role of HHV-6 in many acute and chronic human diseases is difficult due to the ubiquitous nature of the virus, chronicity of infection, existence of two distinct species, and limitations of current investigational tools. The antiviral compounds ganciclovir, foscarnet, and cidofovir are effective against active HHV-6 infections, but the indications for treatment, as well as the conditions of drug administration, are not formally approved to date. There are still numerous pending questions about HHV-6 which should stimulate future research works on the pathophysiology, diagnosis, and therapy of this remarkable human virus.
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Affiliation(s)
- Henri Agut
- Sorbonne Universités, UPMC, CIMI-Paris UMRS CR7, PVI Team, Paris, France INSERM, CIMI-Paris U1135, PVI Team, Paris, France AP-HP, Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Service de Virologie, Paris, France
| | - Pascale Bonnafous
- Sorbonne Universités, UPMC, CIMI-Paris UMRS CR7, PVI Team, Paris, France INSERM, CIMI-Paris U1135, PVI Team, Paris, France
| | - Agnès Gautheret-Dejean
- Sorbonne Universités, UPMC, CIMI-Paris UMRS CR7, PVI Team, Paris, France INSERM, CIMI-Paris U1135, PVI Team, Paris, France AP-HP, Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Service de Virologie, Paris, France Université René Descartes, Faculté de Pharmacie, Laboratoire de Microbiologie UPRES EA 4065, Paris, France
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15
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Prevalence of chromosomally integrated human herpesvirus 6 in patients with human herpesvirus 6-central nervous system dysfunction. Biol Blood Marrow Transplant 2014; 21:371-3. [PMID: 25255164 DOI: 10.1016/j.bbmt.2014.09.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 09/15/2014] [Indexed: 11/24/2022]
Abstract
We identified 37 hematopoietic cell transplantation recipients with human herpesvirus 6 (HHV-6) central nervous system dysfunction and tested donor-recipient pairs for chromosomally integrated HHV-6 (ciHHV-6). One patient had ciHHV-6A with possible HHV-6A reactivation and encephalitis. There was no ciHHV-6 enrichment in this group, but larger studies are needed to determine if patients with ciHHV-6 are at increased risk for HHV-6-associated diseases or other complications.
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16
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de Paula VS, Perse da Silva A, Michel D, Melgaço JG, Vieira YR, dos Santos DC, Carvalho Viana de Araújo C, Pacheco-Moreira LF, Pelajo-Machado M, do Nascimento CM, Schmidt-Chanasit J, Alves Pinto M. Acute liver failure in an immunocompetent patient. J Clin Virol 2014; 60:1-3. [DOI: 10.1016/j.jcv.2014.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 03/10/2014] [Accepted: 03/14/2014] [Indexed: 11/28/2022]
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17
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Ablashi D, Agut H, Alvarez-Lafuente R, Clark DA, Dewhurst S, DiLuca D, Flamand L, Frenkel N, Gallo R, Gompels UA, Höllsberg P, Jacobson S, Luppi M, Lusso P, Malnati M, Medveczky P, Mori Y, Pellett PE, Pritchett JC, Yamanishi K, Yoshikawa T. Classification of HHV-6A and HHV-6B as distinct viruses. Arch Virol 2014; 159:863-70. [PMID: 24193951 PMCID: PMC4750402 DOI: 10.1007/s00705-013-1902-5] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/18/2013] [Indexed: 12/18/2022]
Abstract
Shortly after the discovery of human herpesvirus 6 (HHV-6), two distinct variants, HHV-6A and HHV-6B, were identified. In 2012, the International Committee on Taxonomy of Viruses (ICTV) classified HHV-6A and HHV-6B as separate viruses. This review outlines several of the documented epidemiological, biological, and immunological distinctions between HHV-6A and HHV-6B, which support the ICTV classification. The utilization of virus-specific clinical and laboratory assays for distinguishing HHV-6A and HHV-6B is now required for further classification. For clarity in biological and clinical distinctions between HHV-6A and HHV-6B, scientists and physicians are herein urged, where possible, to differentiate carefully between HHV-6A and HHV-6B in all future publications.
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18
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Copy numbers of telomeric repeat sequences of human herpesvirus 6B in clinical isolates: possibility of mixed infections. J Clin Microbiol 2013; 52:419-24. [PMID: 24478470 DOI: 10.1128/jcm.02192-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to determine whether mixed infections of human herpesvirus 6B (HHV-6B) occur in immunocompetent and immunocompromised individuals, we examined the copy numbers of telomeric repeat sequences (TRS) of clinical isolates. In clinical isolates obtained from patients with exanthem subitum caused by primary HHV-6B infection, PCR products with HHV-6B TRS ranging between 400 and 800 bp were amplified. PCR products of various sizes were amplified in four clinical isolates from drug-induced hypersensitivity syndrome (DIHS) patients and 15 isolates from hematopoietic stem cell transplant (HSCT) recipients with HHV-6B reactivation. Based on the sequence analysis of the PCR products, the copy numbers of TRS in DIHS and HSCT patients were between 42 and 82 and 22 and >90, respectively. For two of the HSCT recipients, HHV-6B TRS PCR products of different sizes were detected in several isolates from each patient, which suggests mixed HHV-6B infections. In two of the posttransplant HHV-6B encephalitis patients, the sizes of the TRS nested PCR products amplified from the reactivated virus detected in the central nervous system differed from those of the virus detected in initial isolates from peripheral blood mononuclear cells. Taken together, these results suggest that PCR analysis of TRS copy number is a reliable tool for the discrimination of HHV-6B clinical isolates. Additionally, mixed HHV-6B infections occurred in HSCT recipients, and in some cases, compartmentalization of the HHV-6B strains to the central nervous system versus the blood compartment occurred in posttransplant HHV-6B encephalitis patients.
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19
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Gravel A, Hall CB, Flamand L. Sequence Analysis of Transplacentally Acquired Human Herpesvirus 6 DNA Is Consistent With Transmission of a Chromosomally Integrated Reactivated Virus. J Infect Dis 2013; 207:1585-9. [DOI: 10.1093/infdis/jit060] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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20
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Smith LM, McWhorter AR, Shellam GR, Redwood AJ. The genome of murine cytomegalovirus is shaped by purifying selection and extensive recombination. Virology 2012; 435:258-68. [PMID: 23107009 DOI: 10.1016/j.virol.2012.08.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 08/02/2012] [Accepted: 08/24/2012] [Indexed: 11/19/2022]
Abstract
The herpesvirus lifestyle results in a long-term interaction between host and invading pathogen, resulting in exquisite adaptation of virus to host. We have sequenced the genomes of nine strains of murine cytomegalovirus (a betaherpesvirus), isolated from free-living mice trapped at locations separated geographically and temporally. Despite this separation these genomes were found to have low levels of nucleotide variation. Of the more than 160 open reading frames, almost 90% had a dN/dS ratio of amino acid substitutions of less than 0.6, indicating the level of purifying selection on the coding potential of MCMV. Examination of selection acting on individual genes at the codon level however indicates some level of positive selection, with 0.03% of codons showing strong evidence for positive selection. Conversely, 1.3% of codons show strong evidence of purifying selection. Alignments of both genome sequences and coding regions suggested that high levels of recombination have shaped the MCMV genome.
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Affiliation(s)
- L M Smith
- School of Pathology and Laboratory Medicine, University of Western Australia, Australia
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21
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Wolz MM, Sciallis GF, Pittelkow MR. Human herpesviruses 6, 7, and 8 from a dermatologic perspective. Mayo Clin Proc 2012; 87:1004-14. [PMID: 22819486 PMCID: PMC3538396 DOI: 10.1016/j.mayocp.2012.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/30/2012] [Accepted: 04/05/2012] [Indexed: 12/13/2022]
Abstract
Human herpesviruses (HHVs) have frequently been suspected as etiologic agents or cofactors in cutaneous disease. However, clearly established associations are rare. Investigations into an etiologic association between HHVs and cutaneous disease are complicated by the ubiquity and nearly universal prevalence of some herpesviruses. This article summarizes the associations between cutaneous disease and HHV-6, HHV-7, and HHV-8. In addition to a personal library of references, the PubMed database of biomedical literature was searched using the following Medical Subject Heading terms: HHV-6, HHV-7, and HHV-8, each in conjunction with cutaneous manifestations, virology, epidemiology, dermatopathology, and therapeutics, between 1998 and March 2011. Free-text searches with known or suspected disease associations were added for broader coverage. The results have been summarized to provide a practical review for the physician likely to encounter cutaneous diseases.
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Affiliation(s)
| | - Gabriel F. Sciallis
- Correspondence: Address to Gabriel F. Sciallis, MD, Division of Clinical Dermatology, Mayo Clinic, 200 First St SW, Rochester, MN 55905
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22
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Agut H. Deciphering the clinical impact of acute human herpesvirus 6 (HHV-6) infections. J Clin Virol 2011; 52:164-71. [DOI: 10.1016/j.jcv.2011.06.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 06/09/2011] [Accepted: 06/24/2011] [Indexed: 02/07/2023]
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23
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Flamand L, Komaroff AL, Arbuckle JH, Medveczky PG, Ablashi DV. Review, part 1: Human herpesvirus-6-basic biology, diagnostic testing, and antiviral efficacy. J Med Virol 2010; 82:1560-8. [PMID: 20648610 DOI: 10.1002/jmv.21839] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Louis Flamand
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, Canada
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24
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Abstract
Herpesviruses are members of a diverse family of viruses that colonize all vertebrates from fish to mammals. Although more than one hundred herpesviruses exist, all are nearly identical architecturally, with a genome consisting of a linear double-stranded DNA molecule (100 to 225 kbp) protected by an icosahedral capsid made up of 162 hollow-centered capsomeres, a tegument surrounding the nucleocapsid, and a viral envelope derived from host membranes. Upon infection, the linear viral DNA is delivered to the nucleus, where it circularizes to form the viral episome. Depending on several factors, the viral cycle can proceed either to a productive infection or to a state of latency. In either case, the viral genetic information is maintained as extrachromosomal circular DNA. Interestingly, however, certain oncogenic herpesviruses such as Marek's disease virus and Epstein-Barr virus can be found integrated at low frequencies in the host's chromosomes. These findings have mostly been viewed as anecdotal and considered exceptions rather than properties of herpesviruses. In recent years, the consistent and rather frequent detection (in approximately 1% of the human population) of human herpesvirus 6 (HHV-6) viral DNA integrated into human chromosomes has spurred renewed interest in our understanding of how these viruses infect, replicate, and propagate themselves. In this review, we provide a historical perspective on chromosomal integration by herpesviruses and present the current state of knowledge on integration by HHV-6 with the possible clinical implications associated with viral integration.
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25
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Bates M, Monze M, Bima H, Kapambwe M, Clark D, Kasolo FC, Gompels UA. Predominant human herpesvirus 6 variant A infant infections in an HIV-1 endemic region of Sub-Saharan Africa. J Med Virol 2009; 81:779-89. [PMID: 19319952 DOI: 10.1002/jmv.21455] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Human herpesvirus 6, HHV-6, commonly infects children, causing febrile illness and can cause more severe pathology, especially in an immune compromised setting. There are virulence distinctions between variants HHV-6A and B, with evidence for increased severity and neurotropism for HHV-6A. While HHV-6B is the predominant infant infection in USA, Europe and Japan, HHV-6A appears rare. Here HHV-6 prevalence, loads and variant genotypes, in asymptomatic compared to symptomatic infants were investigated from an African region with endemic HIV-1/AIDS. DNA was extracted from blood or sera from asymptomatic infants at 6 and 18 months age in a population-based micronutrient study, and from symptomatic infants hospitalised for febrile disease. DNA was screened by qualitative and quantitative real-time PCR, then genotyped by sequencing at variable loci, U46 (gN) and U47 (gO). HIV-1 serostatus of infants and mothers were also determined. HHV-6 DNA prevalence rose from 15% to 22% (80/371) by 18 months. At 6 months, infants born to HIV-1 positive mothers had lower HHV-6 prevalence (11%, 6/53), but higher HCMV prevalence (25%, 17/67). HHV-6 positive febrile hospitalized infants had higher HIV-1, 57% (4/7), compared to asymptomatic infants, 3% (2/74). HHV-6A was detected exclusively in 86% (48/56) of asymptomatic HHV-6 positive samples genotyped. Co-infections with both strain variants were linked with higher viral loads and found in 13% (7/56) asymptomatic infants and 43% (3/7) HIV-1 positive febrile infants. Overall, the results show HHV-6A as the predominant variant significantly associated with viremic infant-infections in this African population, distinct from other global cohorts, suggesting emergent infections elsewhere.
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Affiliation(s)
- Matthew Bates
- Pathogen Molecular Biology Unit, Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, University of London, London, United Kingdom
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26
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Achour A, Malet I, Deback C, Bonnafous P, Boutolleau D, Gautheret-Dejean A, Agut H. Length variability of telomeric repeat sequences of human herpesvirus 6 DNA. J Virol Methods 2009; 159:127-30. [PMID: 19442857 DOI: 10.1016/j.jviromet.2009.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 02/25/2009] [Accepted: 03/02/2009] [Indexed: 11/19/2022]
Abstract
The telomeric repeat sequences (TRS) located near both ends of human herpesvirus 6 (HHV-6) genome are unique structures of unknown function among human herpesviruses. The goal of the present study was to investigate the variability of TRS copy number among different laboratory strains and HHV-6-infected clinical specimens regarding the two variants A and B of HHV-6. DNA obtained from infected cells was submitted to a PCR assay designed to amplify the part of genome containing TRS specifically either for HHV-6A or HHV-6B. Amplicons were analyzed by electrophoresis on agarose gel with ethidium bromide staining and nucleotide sequencing. The number of TRS copies was highly variable among the distinct laboratory strains and clinical specimens studied, ranging from 15 up to more than 180. However, this number was constant for a given strain after serial propagation in cell cultures as well as in different samples from the same subject. This permitted to detect a mixed infection with two distinct strains of HHV-6A within the same patient. The PCR-based analysis of HHV-6 TRS has a limited sensitivity but is highly specific, which provides the opportunity to include it in the set of molecular tools dedicated to the study of HHV-6 epidemiology.
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Affiliation(s)
- Abla Achour
- Laboratoire de Virologie, Université Pierre et Marie Curie-Paris 6 EA2387, AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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