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Kampouri E, Handley G, Hill JA. Human Herpes Virus-6 (HHV-6) Reactivation after Hematopoietic Cell Transplant and Chimeric Antigen Receptor (CAR)- T Cell Therapy: A Shifting Landscape. Viruses 2024; 16:498. [PMID: 38675841 PMCID: PMC11054085 DOI: 10.3390/v16040498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 03/04/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
HHV-6B reactivation affects approximately half of all allogeneic hematopoietic cell transplant (HCT) recipients. HHV-6B is the most frequent infectious cause of encephalitis following HCT and is associated with pleiotropic manifestations in this setting, including graft-versus-host disease, myelosuppression, pneumonitis, and CMV reactivation, although the causal link is not always clear. When the virus inserts its genome in chromosomes of germ cells, the chromosomally integrated form (ciHHV6) is inherited by offspring. The condition of ciHHV6 is characterized by the persistent detection of HHV-6 DNA, often confounding diagnosis of reactivation and disease-this has also been associated with adverse outcomes. Recent changes in clinical practice in the field of cellular therapies, including a wider use of post-HCT cyclophosphamide, the advent of letermovir for CMV prophylaxis, and the rapid expansion of novel cellular therapies require contemporary epidemiological studies to determine the pathogenic role and spectrum of disease of HHV-6B in the current era. Research into the epidemiology and clinical significance of HHV-6B in chimeric antigen receptor T cell (CAR-T cell) therapy recipients is in its infancy. No controlled trials have determined the optimal treatment for HHV-6B. Treatment is reserved for end-organ disease, and the choice of antiviral agent is influenced by expected toxicities. Virus-specific T cells may provide a novel, less toxic therapeutic modality but is more logistically challenging. Preventive strategies are hindered by the high toxicity of current antivirals. Ongoing study is needed to keep up with the evolving epidemiology and impact of HHV-6 in diverse and expanding immunocompromised patient populations.
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Affiliation(s)
- Eleftheria Kampouri
- Infectious Diseases Service, Lausanne University Hospital and University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Guy Handley
- Department of Medicine, Division of Infectious Disease and International Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA;
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA
| | - Joshua A. Hill
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA;
- Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
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Kampouri E, Zamora D, Kiem ES, Liu W, Ibrahimi S, Blazevic RL, Lovas EA, Kimball LE, Huang ML, Jerome KR, Ueda Oshima M, Mielcarek M, Zerr DM, Boeckh MJ, Krantz EM, Hill JA. Human herpesvirus-6 reactivation and disease after allogeneic haematopoietic cell transplantation in the era of letermovir for cytomegalovirus prophylaxis. Clin Microbiol Infect 2023; 29:1450.e1-1450.e7. [PMID: 37532126 PMCID: PMC10828110 DOI: 10.1016/j.cmi.2023.07.026] [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: 04/04/2023] [Revised: 07/12/2023] [Accepted: 07/27/2023] [Indexed: 08/04/2023]
Abstract
OBJECTIVES Letermovir for cytomegalovirus (CMV) prophylaxis in allogeneic haematopoietic cell transplant (HCT) recipients has decreased anti-CMV therapy use. Contrary to letermovir, anti-CMV antivirals are also active against human herpesvirus-6 (HHV-6). We assessed changes in HHV-6 epidemiology in the post-letermovir era. METHODS We conducted a retrospective cohort study of CMV-seropositive allogeneic HCT recipients comparing time periods before and after routine use of prophylactic letermovir. HHV-6 testing was at the discretion of clinicians. We computed the cumulative incidence of broad-spectrum antiviral initiation (foscarnet, (val)ganciclovir, and/or cidofovir), HHV-6 testing, and HHV-6 detection in blood and cerebrospinal fluid within 100 days after HCT. We used Cox proportional-hazards models with stabilized inverse probability of treatment weights to compare outcomes between cohorts balanced for baseline factors. RESULTS We analysed 738 patients, 376 in the pre-letermovir and 362 in the post-letermovir cohort. Broad-spectrum antiviral initiation incidence decreased from 65% (95% CI, 60-70%) pre-letermovir to 21% (95% CI, 17-25%) post-letermovir. The cumulative incidence of HHV-6 testing (17% [95% CI, 13-21%] pre-letermovir versus 13% [95% CI, 10-16%] post-letermovir), detection (3% [95% CI, 1-5%] in both cohorts), and HHV-6 encephalitis (0.5% [95% CI, 0.1-1.8%] pre-letermovir and 0.6% [95% CI, 0.1-1.9%] post-letermovir) were similar between cohorts. First HHV-6 detection occurred at a median of 37 days (interquartile range, 18-58) in the pre-letermovir cohort and 27 (interquartile range, 25-34) in the post-letermovir cohort. In a weighted model, there was no association between the pre-versus post-letermovir cohort and HHV-6 detection (adjusted hazard ratio, 1.08; 95% CI, 0.44-2.62). DISCUSSION Despite a large decrease in broad-spectrum antivirals after the introduction of letermovir prophylaxis in CMV-seropositive allogeneic HCT recipients, there was no evidence for increased clinically detected HHV-6 reactivation and disease.
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Affiliation(s)
- Eleftheria Kampouri
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Danniel Zamora
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA
| | - Erika S Kiem
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Winnie Liu
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Sarah Ibrahimi
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Rachel L Blazevic
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Erika A Lovas
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Louise E Kimball
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Meei-Li Huang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Keith R Jerome
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Masumi Ueda Oshima
- Department of Medicine, University of Washington, Seattle, WA, USA; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Marco Mielcarek
- Department of Medicine, University of Washington, Seattle, WA, USA; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Danielle M Zerr
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Michael J Boeckh
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Elizabeth M Krantz
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Joshua A Hill
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA, USA.
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3
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Baleguli V, Cho YM, Horn J, Parris A. Human Herpesvirus 6 (HHV-6) Encephalitis in a Non-Transplant Patient With Polymyositis. Cureus 2021; 13:e19314. [PMID: 34900488 PMCID: PMC8648291 DOI: 10.7759/cureus.19314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2021] [Indexed: 11/13/2022] Open
Abstract
Human herpesvirus 6 (HHV-6) was initially labeled as a human B lymphotropic virus because it was isolated in patients diagnosed with lymphoproliferative disorders. There are two variants of HHV-6: HHV-6A and HHV-6B. A considerable majority of recorded primary infections and reactivation events are primarily due to HHV-6B. We report a case of HHV-6 encephalitis reactivation in a 75-year-old Caucasian diabetic female with a past medical history of polymyositis treated with prednisone for a long time who presented with generalized weakness and drowsiness. She developed her symptoms after contact with her grandchildren, who recently had viral-like symptoms treated with antibiotics. Magnetic resonance imaging (MRI) of the brain without contrast showed 14 mm high transverse relaxation time (T2)/fluid-attenuated inversion recovery (FLAIR) signal intensity focus on the left temporal lobe, suspicious for primary versus metastatic neoplasm. Cerebrospinal fluid analysis found that protein concentration was 75 mg/dl, glucose concentration 55 mg/dl, white blood cell count was 22/mm3, with a lymphocytic predominance. Meningitis/encephalitis polymerase chain reaction (PCR) panel detected HHV-6. She was discharged after treatment with ganciclovir for 14 days. It is crucial to recognize HHV-6 infections in immunocompromised patients who present with a T2/FLAIR signal intensity focus in the left temporal lobe. In a hospital setting, rapid HHV-6 encephalitis testing is important to make a correct diagnosis to avoid any delay to prevent further morbidity and mortality.
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Affiliation(s)
- Vidya Baleguli
- Internal Medicine, Northeast Georgia Medical Center, Gainesville, USA
| | - Young Min Cho
- Internal Medicine, Northeast Georgia Medical Center, Gainesville, USA
| | - Jon Horn
- Radiology, Northeast Georgia Medical Center, Gainesville, USA
| | - Addison Parris
- Internal Medicine, Northeast Georgia Medical Center, Gainesville, USA
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Ward KN, Hill JA, Hubacek P, de la Camara R, Crocchiolo R, Einsele H, Navarro D, Robin C, Cordonnier C, Ljungman P. Guidelines from the 2017 European Conference on Infections in Leukaemia for management of HHV-6 infection in patients with hematologic malignancies and after hematopoietic stem cell transplantation. Haematologica 2019; 104:2155-2163. [PMID: 31467131 PMCID: PMC6821622 DOI: 10.3324/haematol.2019.223073] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/27/2019] [Indexed: 01/15/2023] Open
Abstract
Of the two human herpesvirus 6 (HHV-6) species, human herpesvirus 6B (HHV-6B) encephalitis is an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplant. Guidelines for the management of HHV-6 infections in patients with hematologic malignancies or post-transplant were prepared a decade ago but there have been no other guidelines since then despite significant advances in the understanding of HHV-6 encephalitis, its therapy, and other aspects of HHV-6 disease in this patient population. Revised guidelines prepared at the 2017 European Conference on Infections in Leukaemia covering diagnosis, preventative strategies and management of HHV-6 disease are now presented.
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Affiliation(s)
- Katherine N Ward
- Division of Infection and Immunity, University College London, London, UK
| | - Joshua A Hill
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Petr Hubacek
- Department of Medical Microbiology and Department of Paediatric Haematology and Oncology 2 Medical Faculty of Charles University and Motol University Hospital, Prague, Czech Republic
| | | | | | - Hermann Einsele
- Medizinische Klinik und Poliklinik II, Julius Maximilians Universität, Würzburg, Germany
| | - David Navarro
- Microbiology Service, Hospital Clínico Universitario, Instituto de Investigación INCLIVA and Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain
| | - Christine Robin
- Department of Haematology, Henri Mondor Hospital, Assistance Publique-Hopitaux de Paris, Université Paris-Est Créteil, Créteil, France
| | - Catherine Cordonnier
- Department of Haematology, Henri Mondor Hospital, Assistance Publique-Hopitaux de Paris, Université Paris-Est Créteil, Créteil, France
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5
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Clinical significance of cancer-related fatigue in multiple myeloma patients. Int J Hematol 2018; 108:580-587. [DOI: 10.1007/s12185-018-2516-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 08/04/2018] [Accepted: 08/06/2018] [Indexed: 01/29/2023]
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Abstract
Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.
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Affiliation(s)
- Abdullah A Al-Badr
- College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Tariq D S Ajarim
- College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia
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Camus V, Bouwyn JP, Chamseddine A, Lenain P, Ahtoy P, Stamatoullas A, Lanic H, Lemasle E, Contentin N, Cassuto O, Leprêtre S, Dubois S, Tilly H, Jardin F. Human herpesvirus-6 acute limbic encephalitis after unrelated umbilical cord blood transplantation successfully treated with ganciclovir. Bone Marrow Transplant 2015; 50:1385-7. [PMID: 26146808 DOI: 10.1038/bmt.2015.159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- V Camus
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - J-P Bouwyn
- Department of Neurology, Charles Nicolle University Hospital, Rouen, France
| | - A Chamseddine
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - P Lenain
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - P Ahtoy
- Department of Neurology, Charles Nicolle University Hospital, Rouen, France
| | - A Stamatoullas
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - H Lanic
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - E Lemasle
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - N Contentin
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - O Cassuto
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - S Leprêtre
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - S Dubois
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - H Tilly
- Department of Haematology, Centre Henri Becquerel, Rouen, France
| | - F Jardin
- Department of Haematology, Centre Henri Becquerel, Rouen, France
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8
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Prichard MN, Whitley RJ. The development of new therapies for human herpesvirus 6. Curr Opin Virol 2014; 9:148-53. [PMID: 25462447 DOI: 10.1016/j.coviro.2014.09.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/25/2014] [Accepted: 09/26/2014] [Indexed: 11/18/2022]
Abstract
Human herpesvirus 6 (HHV-6) infections are typically mild and in rare cases can result in encephalitis. A common theme among all the herpesviruses, however, is the reactivation upon immune suppression. HHV-6 commonly reactivates in transplant recipients. No therapies are approved currently for the treatment of these infections, although small studies and individual case reports have reported intermittent success with drugs such as cidofovir, ganciclovir, and foscarnet. In addition to the current experimental therapies, many other compounds have been reported to inhibit HHV-6 in cell culture with varying degrees of efficacy. Recent advances in the development of new small molecule inhibitors of HHV-6 will be reviewed with regard to their efficacy and spectrum of antiviral activity. The potential for new therapies for HHV-6 infections will also be discussed, and they will likely arise from efforts to develop broad spectrum antiviral therapies for DNA viruses.
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Affiliation(s)
- Mark N Prichard
- University of Alabama at Birmingham, Department of Pediatrics, Children's Harbor Building 128, 1600 7th Avenue South, Birmingham, AL 35233-1711, United States
| | - Richard J Whitley
- University of Alabama at Birmingham, Department of Pediatrics, Division of Infectious Diseases, Children's Harbor Building 308, 1600 7th Avenue South, Birmingham, AL 35233-1711, United States.
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9
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Hornig J, McGregor A. Design and development of antivirals and intervention strategies against human herpesviruses using high-throughput approach. Expert Opin Drug Discov 2014; 9:891-915. [DOI: 10.1517/17460441.2014.922538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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10
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Prichard MN, Frederick SL, Daily S, Borysko KZ, Townsend LB, Drach JC, Kern ER. Benzimidazole analogs inhibit human herpesvirus 6. Antimicrob Agents Chemother 2011; 55:2442-5. [PMID: 21300829 PMCID: PMC3088228 DOI: 10.1128/aac.01523-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/28/2011] [Indexed: 11/20/2022] Open
Abstract
Several benzimidazole nucleoside analogs, including 1H-β-D-ribofuranosyl-2-bromo-5,6-dichlorobenzimidazole (BDCRB) and 1H-β-L-ribofuranosyl-2-isopropylamino-5,6-dichlorobenzimidazole (maribavir [MBV]), inhibit the replication of human cytomegalovirus. Neither analog inhibited the related betaherpesvirus human herpesvirus 6 (HHV-6). Additional analogs of these compounds were evaluated against both variants of HHV-6, and two L-analogs of BDCRB had good antiviral activity against HHV-6A, as well as more modest inhibition of HHV-6B replication.
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Affiliation(s)
- Mark N Prichard
- University of Alabama School of Medicine, 1600 6th Avenue South, 128 Children's Harbor Building, Birmingham, AL 35233, USA.
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11
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Chatzidimitriou D, Gavriilaki E, Sakellari I, Diza E. Hematopoietic cell transplantation and emerging viral infections. J Med Virol 2010; 82:528-38. [PMID: 20087928 PMCID: PMC7166846 DOI: 10.1002/jmv.21696] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2009] [Indexed: 12/11/2022]
Abstract
Viral infections remain important causes of morbidity and mortality in hematopoietic cell transplant recipients. More recent developments in preparative regimens and graft manipulations, as well as the control of well-recognized post-transplant infections by the introduction of prophylaxis and preemptive strategies, have influenced the timing and the epidemiology of infections. As new pathogens, such as human metapneumovirus (HMPV), human bocavirus, human coronaviruses HCoV-NL63 and HCoV-HKU1, human herpesviruses HHV-6 and HHV-7, and polyomaviruses, have emerged, it is fundamental to determine the significance of the newly discovered viruses and their role in the transplantation field. This article summarizes recent data on epidemiology and laboratory diagnosis of new pathogens, as well as clinical features and management of the associated infectious complications. J. Med. Virol. 82:528-538, 2010. (c) 2010 Wiley-Liss, Inc.
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Affiliation(s)
- D Chatzidimitriou
- 2nd Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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12
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Vinnard C, Barton T, Jerud E, Blumberg E. A report of human herpesvirus 6-associated encephalitis in a solid organ transplant recipient and a review of previously published cases. Liver Transpl 2009; 15:1242-6. [PMID: 19790143 DOI: 10.1002/lt.21816] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Human herpesvirus 6 (HHV-6) is a common pathogen among children, classically presenting as fever and rash that resolve without specific therapy (exanthem subitum or roseola infantum). Also identified as a pathogen in hematopoietic cell transplant and solid organ transplant (SOT) recipients, it has been recognized as a cause of limbic encephalitis, characterized by confusion and amnesia, with magnetic resonance imaging findings of T2 hyperintensity of the amygdala and hippocampus. We report a case of limbic encephalitis associated with HHV-6 infection in a liver transplant recipient, and we review previously reported cases of HHV-6 encephalitis in SOT recipients.
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Affiliation(s)
- Christopher Vinnard
- Division of Infectious Diseases, University of Pennsylvania, Philadelphia, PA 19146, USA.
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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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