Did you mean: human herpesvirus
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Clinical Microbiology Reviews Apr 2015Human herpesvirus 6 (HHV-6) is a widespread betaherpesvirus which is genetically related to human cytomegalovirus (HCMV) and now encompasses two different species:... (Review)
Review
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.
Topics: Antiviral Agents; DNA, Viral; Herpesvirus 6, Human; Humans; Roseolovirus Infections
PubMed: 25762531
DOI: 10.1128/CMR.00122-14 -
Neurology(R) Neuroimmunology &... Mar 2021The aim of this study was to analyze the clinical, radiologic, and biological features associated with human herpesvirus 6 (HHV-6) encephalitis in immunocompetent and...
OBJECTIVE
The aim of this study was to analyze the clinical, radiologic, and biological features associated with human herpesvirus 6 (HHV-6) encephalitis in immunocompetent and immunocompromised hosts to establish which clinical settings should prompt HHV-6 testing.
METHODS
We performed a retrospective research in the virology database of Fondazione IRCCS Policlinico San Matteo (Pavia, Italy) for all patients who tested positive for HHV-6 DNA in the CSF and/or in blood from January 2008 to September 2018 and separately assessed the number of patients meeting the criteria for HHV-6 encephalitis in the group of immunocompetent and immunocompromised hosts.
RESULTS
Of the 926 patients tested for HHV-6 during the period of interest, 45 met the study criteria. Among immunocompetent hosts (n = 17), HHV-6 encephalitis was diagnosed to 4 infants or children presenting with seizures or mild encephalopathy during primary HHV-6 infection (CSF/blood replication ratio <<1 in all cases). Among immunocompromised hosts (n = 28), HHV-6 encephalitis was diagnosed to 7 adolescents/adults with hematologic conditions presenting with altered mental status (7/7), seizures (3/7), vigilance impairment (3/7), behavioral changes (2/7), hyponatremia (2/7), and anterograde amnesia (1/7). Initial brain MRI was altered only in 2 patients, but 6 of the 7 had a CSF/blood replication ratio >1.
CONCLUSIONS
The detection of a CSF/blood replication ratio >1 represented a specific feature of immunocompromised patients with HHV-6 encephalitis and could be of special help to establish a diagnosis of HHV-6 encephalitis in hematopoietic stem cell transplant recipients lacking radiologic evidence of limbic involvement.
Topics: Adolescent; Adult; Antiviral Agents; Encephalitis, Viral; Female; Hematopoietic Stem Cell Transplantation; Herpesvirus 6, Human; Humans; Immunocompromised Host; Male; Retrospective Studies; Roseolovirus Infections; Seizures; Young Adult
PubMed: 33587722
DOI: 10.1212/NXI.0000000000000942 -
Epilepsia Open Dec 2021We investigated the association between human herpesvirus 6 (HHV-6) and mesial temporal sclerosis (MTS) in 87 patients who had surgery for drug-resistant epilepsy....
We investigated the association between human herpesvirus 6 (HHV-6) and mesial temporal sclerosis (MTS) in 87 patients who had surgery for drug-resistant epilepsy. Fifty-four had MTS, 22 focal cortical dysplasia (FCD), four tumors, three vascular malformations, and three a history of encephalitis. We extracted DNA from fresh brain tissue immediately after surgery and performed viral detection with quantitative real-time polymerase chain reaction (PCR) or digital droplet PCR specific for HHV-6A and HHV-6B. Tissue was studied with standard clinical techniques, including hematoxylin and eosin, glial fibrillary acidic protein, and NeuN stains. Twenty-nine of 54 patients with MTS, six of 23 with focal cortical dysplasia (FCD), and one of three with a history of encephalitis were positive for HHV-6 (P < .02). Febrile seizure history was not associated with HHV-6 detection. Patients with MTS had significantly lower seizure onset age than those with other pathologies. Thirteen patients had positron emission tomography with [11C]PBR28, a marker for reactive astrocytes and activated microglia; there was a trend for HHV-6-positive patients to have higher binding in their seizure foci, suggesting inflammation. Our study supports a potential role for HHV-6 in the etiology of MTS.
Topics: DNA, Viral; Epilepsy; Herpesvirus 6, Human; Humans; Real-Time Polymerase Chain Reaction; Tomography, X-Ray Computed
PubMed: 34324277
DOI: 10.1002/epi4.12531 -
Microbiology Spectrum Jun 2016Human roseoloviruses include three different species, human herpesviruses 6A, 6B, and 7 (HHV-6A, HHV-6B, HHV-7), genetically related to human cytomegalovirus. They... (Review)
Review
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.
Topics: Antiviral Agents; Cidofovir; Cytosine; DNA, Viral; Foscarnet; Ganciclovir; Herpesvirus 6, Human; Herpesvirus 7, Human; Humans; Immunocompromised Host; Organophosphonates; Roseolovirus Infections; Transplant Recipients; Virus Latency
PubMed: 27337451
DOI: 10.1128/microbiolspec.DMIH2-0007-2015 -
Nature Nov 2023Cell therapies have yielded durable clinical benefits for patients with cancer, but the risks associated with the development of therapies from manipulated human cells...
Cell therapies have yielded durable clinical benefits for patients with cancer, but the risks associated with the development of therapies from manipulated human cells are understudied. For example, we lack a comprehensive understanding of the mechanisms of toxicities observed in patients receiving T cell therapies, including recent reports of encephalitis caused by reactivation of human herpesvirus 6 (HHV-6). Here, through petabase-scale viral genomics mining, we examine the landscape of human latent viral reactivation and demonstrate that HHV-6B can become reactivated in cultures of human CD4 T cells. Using single-cell sequencing, we identify a rare population of HHV-6 'super-expressors' (about 1 in 300-10,000 cells) that possess high viral transcriptional activity, among research-grade allogeneic chimeric antigen receptor (CAR) T cells. By analysing single-cell sequencing data from patients receiving cell therapy products that are approved by the US Food and Drug Administration or are in clinical studies, we identify the presence of HHV-6-super-expressor CAR T cells in patients in vivo. Together, the findings of our study demonstrate the utility of comprehensive genomics analyses in implicating cell therapy products as a potential source contributing to the lytic HHV-6 infection that has been reported in clinical trials and may influence the design and production of autologous and allogeneic cell therapies.
Topics: Humans; CD4-Positive T-Lymphocytes; Clinical Trials as Topic; Gene Expression Regulation, Viral; Genomics; Herpesvirus 6, Human; Immunotherapy, Adoptive; Infectious Encephalitis; Receptors, Chimeric Antigen; Roseolovirus Infections; Single-Cell Gene Expression Analysis; Viral Load; Virus Activation; Virus Latency
PubMed: 37938768
DOI: 10.1038/s41586-023-06704-2 -
Clinical Infectious Diseases : An... Sep 2018A review of 15 patients who tested positive for human herpesvirus 6 (HHV-6) on the FilmArray Meningitis/Encephalitis panel revealed that the majority were unlikely to...
A review of 15 patients who tested positive for human herpesvirus 6 (HHV-6) on the FilmArray Meningitis/Encephalitis panel revealed that the majority were unlikely to have HHV-6 encephalitis. Criteria to assist interpretation of HHV-6 positive results are presented.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Encephalitis, Viral; Female; Herpesvirus 6, Human; Humans; Immunocompromised Host; Infant; Infant, Newborn; Male; Meningitis; Middle Aged; Molecular Diagnostic Techniques; Roseolovirus Infections
PubMed: 29635334
DOI: 10.1093/cid/ciy288 -
Viruses Jul 2017Human 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... (Review)
Review
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.
Topics: Chromosomes, Human; DNA Methylation; DNA, Viral; Genome, Viral; Herpesvirus 6, Human; Humans; Plasmids; Roseolovirus Infections; Telomere; Virus Activation; Virus Integration; Virus Latency
PubMed: 28737715
DOI: 10.3390/v9070194 -
Viruses Aug 2022Beyond their pulmonary disease, many COVID-19 patients experience a complex constellation of characteristics, including hyperinflammatory responses, autoimmune...
Beyond their pulmonary disease, many COVID-19 patients experience a complex constellation of characteristics, including hyperinflammatory responses, autoimmune disorders, and coagulopathies. However, the pathogenesis of these aspects of COVID-19 is obscure. More than 90% of people are latently infected with the lymphotropic herpesviruses Epstein-Barr Virus (EBV) and/or Human Herpesvirus-6 (HHV-6). Some of the inflammatory features of COVID-19 resemble clinical syndromes seen during EBV and HHV-6 infection, and these latent viruses can be reactivated by inflammatory mediators. We hypothesized that EBV and HHV-6 reactivation might be a common feature of early COVID-19, particularly in patients with more inflammation. We tested for EBV and HHV-6 reactivation in 67 patients acutely hospitalized with COVID-19 using previously validated quantitative PCR assays on the plasma. In our cohort, we found that 15/67 (22.4%) patients had detectable EBV and 3/67 (4.5%) had detectable HHV-6. This frequency of activation is somewhat more than the frequency reported for some healthy cohorts, such as blood donors and other healthy control cohorts. There was no association between EBV or HHV-6 and markers indicative of more inflammatory disease. We conclude that EBV and HHV-6 activation at about day 7 of hospitalization occurred in a modest fraction of our cohort of COVID-19 patients and was not associated with high levels of inflammation. In the modest fraction of patients, EBV and HHV-6 reactivation could contribute to some features of acute disease and pre-disposition to post-acute sequelae in a subset of patients.
Topics: COVID-19; Epstein-Barr Virus Infections; Herpesvirus 4, Human; Herpesvirus 6, Human; Herpesvirus 8, Human; Humans; Inflammation; Inflammation Mediators
PubMed: 36146679
DOI: 10.3390/v14091872 -
Clinical Microbiology and Infection :... Apr 2016Human herpesvirus 6 (HHV-6) comprises two separate viruses, HHV-6A and HHV-6B, although this distinction is not commonly made. HHV-6B is ubiquitous in the population... (Review)
Review
Human herpesvirus 6 (HHV-6) comprises two separate viruses, HHV-6A and HHV-6B, although this distinction is not commonly made. HHV-6B is ubiquitous in the population with primary infection usually occurring in early childhood, and often resulting in febrile illness. HHV-6B is also recognized as a pathogen in the immunocompromised host, particularly in transplant recipients. HHV-6A is less well characterized and may have a more restricted prevalence. Both viruses are unique among the human herpesviruses in that the entire viral genome can be found integrated into the telomeric regions of host cell chromosomes. Approximately 1% of persons have inherited integrated viral sequences through the germline, and these individuals characteristically have very high viral loads in blood and other sample types. Emerging evidence suggests that HHV-6A and HHV-6B chromosomal integration may not just be an uncommon biological observation, but more likely a characteristic of the replication properties of these viruses. The integrated viral genome appears capable of excision from the chromosomal site and potentially allows viral replication. The clinical consequences of inherited chromosomally integrated HHV-6 have yet to be fully appreciated.
Topics: Herpesvirus 6, Human; Humans; Infectious Disease Transmission, Vertical; Roseolovirus Infections; Virus Integration
PubMed: 26802216
DOI: 10.1016/j.cmi.2015.12.022 -
Biomolecules Nov 2020The human herpesvirus 6 (HHV-6) -A and -B are two dsDNA beta-herpesviruses infectingalmost the entire worldwide population. These viruses have been implicated in... (Review)
Review
The human herpesvirus 6 (HHV-6) -A and -B are two dsDNA beta-herpesviruses infectingalmost the entire worldwide population. These viruses have been implicated in multipleneurological conditions in individuals of various ages and immunological status, includingencephalitis, epilepsy, and febrile seizures. HHV-6s have also been suggested as playing a role inthe etiology of neurodegenerative diseases such as multiple sclerosis and Alzheimer's disease. Theapparent robustness of these suggested associations is contingent on the accuracy of HHV-6detection in the nervous system. The effort of more than three decades of researching HHV-6 in thebrain has yielded numerous observations, albeit using variable technical approaches in terms oftissue preservation, detection techniques, sample sizes, brain regions, and comorbidities. In thisreview, we aimed to summarize current knowledge about the entry routes and direct presence ofHHV-6 in the brain parenchyma at the level of DNA, RNA, proteins, and specific cell types, inhealthy subjects and in those with neurological conditions. We also discuss recent findings relatedto the presence of HHV-6 in the brains of patients with Alzheimer's disease in light of availableevidence.
Topics: Brain; Disease; Herpesvirus 6, Human; Humans
PubMed: 33172107
DOI: 10.3390/biom10111520