Human Herpes Virus-6 (HHV-6) Reactivation after Hematopoietic Cell Transplant and Chimeric Antigen Receptor (CAR)- T Cell Therapy: A Shifting Landscape.

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.

A case of human herpesvirus 6 encephalitis following pediatric hematopoietic stem cell transplantation: early diagnosis and treatment matters.

Human herpesvirus 6 (HHV-6) is one of the life-threatening infectious complications with significant morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Clinically, the diagnosis of HHV-6 encephalitis can be challenging due to a lack of specific symptoms and definitive diagnostic tests. We report a pediatric HSCT recipient who developed late-onset HHV-6 encephalitis without typical radiographic findings. The routine viral infection monitoring protocol contributed to the prompt diagnosis of HHV-6 encephalitis and early therapeutic intervention. The patient was treated successfully without any neurological complications attributable to HHV-6 encephalitis. HHV-6 encephalitis should remain in the differential diagnosis as an important but treatable disease, even for several months after HSCT and even without radiographic findings. Whenever HHV-6 encephalitis is suspected, antivirals should be initiated promptly to prevent its complications.

Prevention and treatment of temporal lobe epilepsy: lessons from hepatitis B story!

Temporal lobe epilepsy (TLE) is the most common type of drug-resistant epilepsy and hippocampal sclerosis (HS) is the most common pathological substrate of TLE. Considering the significant consequences of uncontrolled seizures (e.g. increased morbidity and mortality), epilepsy prevention remains a necessity that potentially could save many lives. Human herpes virus-6 (HHV-6) has been linked to TLE in humans. The relationship between HHV-6 and HS-TLE could be attributed to a neuro-inflammatory cascade triggered by the infection, involving direct neuronal damage and production of several pro-inflammatory cytokines under certain conditions that are still incompletely understood. Hepatitis B virus (HBV) infection is another chronic viral infection with a life-long latency. HBV infection is linked to various clinical conditions, including liver cirrhosis. There are currently three ways to fight HBV infection and its consequences; primary prevention (by vaccination), secondary prevention (by drug therapy), and tertiary prevention (by liver transplantation). Considering the similarities between the natural histories of HHV-6 and HBV infections, and also the successful strategies which are currently available to fight HBV infection and its long-term consequences, here, we propose three strategies to fight HHV-6 and its possible long-term consequence (i.e. HS-TLE): Primary prevention: by developing vaccines to prevent HHV-6 infection; Secondary prevention: by considering trials of antiviral drugs to treat HHV-6 infection, when it happens in the childhood to hopefully prevent its long-term consequences; and, Tertiary prevention: by stem cell therapy for drug-resistant epilepsy.

Human herpesvirus 6 in transplant recipients: an update on diagnostic and treatment strategies.

PURPOSE OF REVIEW: The current review article focuses on recent advances in the approach to the diagnosis and treatment of human herpesvirus 6B (HHV-6B) in hematopoietic cell and solid organ transplant recipients. RECENT FINDINGS: Over the past few years, key studies have broadened our understanding of best practices for the prevention and treatment of HHV-6B encephalitis after transplantation. Moreover, important data have been reported that support a potential role of HHV-6B reactivation in the development of acute graft-versus-host disease and lower respiratory tract disease in transplant recipients. Finally, increasing recognition of inherited chromosomally integrated HHV-6 (iciHHV-6) and an expanding array of diagnostic tools have increased our understanding of the potential for complications related to viral reactivation originating from iciHHV-6 in donors or recipients. SUMMARY: Recent advances in diagnostic tools, disease associations, and potential treatments for HHV-6B present abundant opportunities for improving our understanding and management of this complex virus in transplant recipients.

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.

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.

[How to manage EBV reactivation and EBV-PTLD, CMV and human herpesvirus 6 reactivation and infection after allogeneic stem cell transplantation: A report of the SFGM-TC (update)]. / Conduite à tenir devant une réactivation EBV et un syndrome lymphoprolifératif à EBV, une réactivation ou infection à CMV et à HHV-6 après allogreffe de cellules souches hématopoïétiques : recommandations de la SFGM-TC (mises à jour).

The French society of bone marrow transplantation and cell therapy (SFGM-TC) organizes annually workshops in the attempt to harmonize clinical practices between different francophone transplantation center. Here, we report our recommendations regarding the management of Epstein Barr virus reactivation and lymphoproliferative disorders, cytomegalovirus (CMV) and human herpes virus 6 (HHV6) after allogeneic stem cell transplantation.

Pericarditis Associated With Human Herpesvirus-6 Reactivation in a Patient After Unrelated Cord Blood Transplant.

A 53-year-old woman with myelodysplastic syndrome received a cord blood transplant because she had frequent episodes of febrile neutropenia. As a conditioning regimen for transplant, she received 12 Gy total body irradiation, intravenous cytosine arabinoside 3 g/m2 every 12 hours on days -5 and -4, and cyclophosphamide 60 mg/kg/day on days -3 and -2. She received tacrolimus and short-term methotrexate treatment as prophylaxis for graft-versus-host disease. Her cardiac function was normal before transplant. She developed acute heart failure with a mild pericardial effusion 11 days after transplant, but her failure improved with a diuretic, vasodilator, and inotropic agent. She complained of dyspnea, and chest auscultation revealed pericardial friction rubs on day 28. Massive pericardial effusion was detected by echocardiography and pericarditis was diagnosed. The pericardial space was drained by pericardiocentesis. The pericardial fluid was exudative, but no bacteria or fungi were cultured. On viral polymerase chain reaction examination, human herpesvirus-6 was detected at a level of 3 × 104 copies/mL in the pericardial effusion, but not in the peripheral blood. With conservative treatment alone, that did not include antiviral therapy, her symptoms disappeared on day 56. We conclude that human herpesvirus-6 reactivation may have been associated with her pericarditis.

Early human herpes virus type 6 reactivation in umbilical cord blood allogeneic stem cell transplantation.

Human herpes virus type 6 can reactivate in patients after allogeneic stem cell transplantation and has been associated with serious sequelae such as delayed engraftment and an increased risk of developing acute graft-versus-host disease (GVHD). This study investigated human herpes virus type 6 (HHV-6) reactivation within 60 days of transplantation in stem cell transplants utilizing single umbilical cord blood, double umbilical cord blood, or umbilical cord blood plus haploidentical stem cells. Of 92 patients, 60 (65%) had HHV-6 reactivation. Reactivation was not significantly influenced by any patient characteristics, disease characteristics, or by stem cell source (umbilical cord blood only versus haploidentical plus umbilical cord blood). We did not observe any impact of HHV-6 reactivation on neutrophil or platelet count recovery or on relapse-free survival. HHV-6 reactivation was associated with subsequent development of prerelapse acute GVHD (HR = 3.00; 95% CI, 1.4 to 6.4; p = 0.004).

Cerebral Vasculitis in X-linked Lymphoproliferative Disease Cured by Matched Unrelated Cord Blood Transplant.

UNLABELLED: Vasculitis occurs rarely in association with X-linked lymphoproliferative disease (XLP). There are four published cases of non-EBV XLP-associated cerebral vasculitis reported, none of whom have survived without major cognitive impairment. CASE: A 9-year old boy initially presented aged 5 years with a restrictive joint disease. He subsequently developed dysgammaglobulinemia, episodic severe pneumonitis, aplastic anaemia, gastritis and cerebral vasculitis. A diagnosis of XLP was made, based on flow cytometric analysis and the identification of a novel mutation in SH2D1A, c.96G>C. No peripheral blood lymphocyte clonal proliferation was identified and he was EBV negative, although human herpes virus-7 (HHV7) was detected repeatedly in his cerebrospinal fluid. He underwent a reduced intensity unrelated umbilical cord blood transplant, but failed to engraft. A second 5/6 matched cord gave 100 % donor engraftment. Complications included BK virus-associated haemorrhagic cystitis, a possible NK-cell mediated immune reconstitution syndrome and post-transplant anti-glomerular basement membrane disease, the latter treated with cyclophosphamide and rituximab. At +450 days post-transplant he is in remission from his vasculitis and anti-glomerular basement membrane disease, and HHV-7 has remained undetectable. CONCLUSION: This is the second published description of joint disease in XLP, and only the fourth case of non-EBV associated cerebral vasculitis in XLP, as well as being the first to be successfully treated for this manifestation. This case raises specific questions about vasculitis in XLP, in particular the potential relevance of HHV-7 to the pathogenesis.

Impact of Human Herpesvirus-6 Reactivation on Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation.

Human herpesvirus-6 (HHV-6) is known to reactivate after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and may be associated with development of acute graft-versus-host disease (GVHD) and nonrelapse mortality (NRM). However, the clinical significance of HHV-6 reactivation after allo-HSCT remains unclear. Therefore, we conducted a retrospective analysis to elucidate the impact of HHV-6 reactivation on transplantation outcomes. Of 236 patients who underwent allo-HSCT, 138 (58.5%) developed HHV-6 reactivation and 98 (41.5%) did not. Univariate analysis indicated that at 3 years, patients with HHV-6 reactivation had significantly higher NRM (27.7% versus 13.7%, P = .003) and worse overall survival (42.1% versus 59.0%, P = .008) than those without reactivation. In multivariate analysis, HHV-6 reactivation was associated with higher incidence of acute GVHD (hazard ratio [HR], 1.87; P = .01), cytomegalovirus reactivation (HR, 2.24; P < .001), and NRM (HR, 2.73; P = .007). Subgroup analysis stratified according to conditioning intensity indicated that a significant impact of HHV-6 reactivation on acute GVHD was observed only in patients who received myeloablative conditioning (MAC). These results indicate that HHV-6 reactivation was associated with development of acute GVHD, cytomegalovirus reactivation, and NRM. Furthermore, adverse impact of HHV-6 reactivation on transplantation outcomes was prominent in the setting of MAC.

[Chromosomally integrated human herpesvirus-6 requiring differential diagnosis of reactivation after allogeneic hematopoietic stem cell transplantation].

Human herpesvirus-6 (HHV-6) is known to cause critical encephalitis, as a central nervous system infection, in some hematopoietic stem cell transplantation (HSCT) recipients. Chromosomally integrated human herpesvirus-6 (CIHHV-6) persistently shows HHV-6 DNA in blood, but this does not necessarily suggest active infection. The true clinical significance in HSCT is not clear. The prevalence of CIHHV-6 in Japan is reportedly 0.21%. We herein report two HSCTs: from a CIHHV-6-positive donor to a negative recipient and from a negative donor to a positive recipient. In the CIHHV-6-positive donor case, the recipient's plasma, which had been negative for HHV-6 before HSCT, became positive after transplantation and the level then remained high, although the subject was asymptomatic. In the CIHHV-6-positive recipient case, the patient's plasma viral load was high just after transplantation, although the subject was asymptomatic, and the load gradually decreased after engraftment. Antivirals had no effect on the viral load in either case. We should consider CIHHV-6 when the HHV-6 DNA load in blood persists asymptomatically after HSCT, to avoid misdiagnosis of reactivated HHV-6 infection and overuse of antivirals. It is also useful to monitor HHV-6 DNA in blood before HSCT, to distinguish HHV-6 reactivation from CIHHV-6.

Human herpesvirus-6 encephalitis after allogeneic hematopoietic cell transplantation: what we do and do not know.

Human herpesvirus-6 (HHV-6) encephalitis following allogeneic hematopoietic cell transplantation is a serious and often fatal complication accompanying reactivation of HHV-6B. Incidence varies among studies, but is reportedly 0-11.6% after bone marrow or PBSC transplantation and 4.9-21.4% after umbilical cord blood transplantation, typically around 2-6 weeks post transplant. Symptoms are characterized by memory loss, loss of consciousness and seizures. Magnetic resonance imaging (MRI) typically shows bilateral signal abnormalities in the limbic system. This complication is considered to represent acute encephalitis caused by direct virally induced damage to the central nervous system, but our understanding of the etiologies and pathogenesis is still limited. The mortality rate attributable to this pathology remains high, and survivors are often left with serious sequelae such as impaired memory and epilepsy. Despite the poor prognosis, no validated treatments or preventative measures have been established. Establishment of preventative strategies represents an important challenge. This article reviews the current knowledge of the clinical features, incidence, pathogenesis and treatment of HHV-6 encephalitis, and discusses issues needing clarification in the future to overcome this serious complication.

Diagnostic Clues to Human Herpesvirus 6 Encephalitis and Wernicke Encephalopathy After Pediatric Hematopoietic Cell Transplantation.

Human herpesvirus 6 (HHV6) encephalitis and Wernicke encephalopathy are treatable yet frequently undiagnosed causes of encephalopathy in pediatric recipients of allogeneic and autologous hematopoietic cell transplantation. Here we review representative cases of both conditions to highlight specific and relevant neurologic features that prompted effective diagnosis and treatment. Two patients with confusion accompanied by seizures, memory changes, or specific visual hallucinations and HHV6 detectable by polymerase chain reaction (PCR) in cerebrospinal fluid had improvement in viral load with ganciclovir or foscarnet treatment. Two patients had confusion, ataxia, or ocular changes and low serum thiamine levels, which resolved with parenteral thiamine. In all cases, definitive diagnosis and treatment were facilitated by a high index of suspicion and search for specific pathognomonic neurologic deficits accompanying the confusional state. It is critical to clinically differentiate these 2 conditions from other common neurologic syndromes occurring after transplant, allowing potentially improved patient outcomes by prompt diagnosis and effective treatment.

Immune response to HHV-6 and implications for immunotherapy.

Most adults remain chronically infected with HHV-6 after resolution of a primary infection in childhood, with the latent virus held in check by the immune system. Iatrogenic immunosuppression following solid organ transplantation (SOT) or hematopoetic stem cell transplantation (HSCT) can allow latent viruses to reactivate. HHV-6 reactivation has been associated with increased morbidity, graft rejection, and neurological complications post-transplantation. Recent work has identified HHV-6 antigens that are targeted by the CD4+ and CD8+ T cell response in chronically infected adults. T cell populations recognizing these targets can be expanded in vitro and are being developed for use in autologous immunotherapy to control post-transplantation HHV-6 reaction.

Roseoloviruses: unmet needs and research priorities: perspective.

The human roseoloviruses, human herpesviruses 6A (HHV-6A), HHV-6B, and HHV-7, are highly prevalent viruses that typically cause fever/rash illnesses such as roseola during early life primary infections. They also cause significant neurologic disease and complications following stem cell and solid organ transplantation, and have suggestive but less certain etiologic associations with other neurologic diseases and immunologic disorders. The US National Institute of Allergy and Infectious Diseases recently sponsored a workshop (Roseoloviruses: Clinical Impact, Interventions, and Research Needs) to discuss disease associations, novel biology, and the many unmet research needs related to Roseoloviruses. This perspective is a distillation of the workshop's presentations and discussions, with a focus on the more general research priorities that emerged.

Human herpesvirus 6B immediate-early I protein contains functional HLA-A*02, HLA-A*03, and HLA-B*07 class I restricted CD8(+) T-cell epitopes.

Human herpesvirus 6B (HHV-6B) is a ubiquitous pathogen with frequent reactivation observed in immunocompromised patients such as BM transplant (BMT) recipients. Adoptive immunotherapy is a promising therapeutic avenue for the treatment of opportunistic infections, including herpesviruses. While T-cell immunotherapy can successfully control CMV and EBV reactivations in BMT recipients, such therapy is not available for HHV-6 infections, in part due to a lack of identified protective CD8(+) T-cell epitopes. Our goal was to identify CD8(+) T-cell viral epitopes derived from the HHV-6B immediate-early protein I and presented by common human leukocyte Ag (HLA) class I alleles including HLA-A*02, HLA-A*03, and HLA-B*07. These epitopes were functionally tested for their ability to induce CD8(+) T-cell expansion and kill HHV-6-infected autologous cells. Cross-reactivity of specific HHV-6B-expanded T cells against HHV-6A-infected cells was also confirmed for a conserved epitope presented by HLA-A*02 molecule. Our findings will help push forward the field of adoptive immunotherapy for the treatment and/or the prevention of HHV-6 reactivation in BMT recipients.

Human herpesvirus 6 reactivation before engraftment is strongly predictive of graft failure after double umbilical cord blood allogeneic stem cell transplantation in adults.

Our main objective was to determine new factors associated with engraftment and single-unit predominance after double umbilical cord blood (UCB) allogeneic stem-cell transplantation. Engraftment occurred in 78% of cases in this retrospective study including 77 adult patients. Three-year overall survival, disease-free survival, relapse incidence, and nonrelapse mortality were 55 ± 6%, 44 ± 6%, 33 ± 5%, and 23 ± 4%, respectively. In multivariate analysis, Human herpesvirus 6 reactivation during aplasia (hazard ratio [HR] = 2.63; 95% confidence interval [CI]: 1.64-4.17; p < 0.001), younger recipient age (<53 years) (HR = 1.97; 95% CI: 1.16-3.35; p = 0.012), and lower human leukocyte antigen matching between the two units (3 of 6 or 4 of 6) (HR = 2.09; 95% confidence interval: 1.22-3.59; p = 0.013) were the three factors independently associated with graft failure. Also, factors independently predicting the losing UCB unit were younger age of the UCB unit (odds ratio [OR] = 1.01; 95% CI: 1-1.02; p = 0.035), lower CD34(+) cell dose contained in the UCB unit (≤ 0.8 × 10(5)/kg) (OR = 2.55; 95% CI: 1.05-6.16; p = 0.04), and presence of an ABO incompatibility between the UCB unit and the recipient (OR = 2.53; 95% CI: 1.15-5.53; p = 0.02). Thus, Human herpesvirus 6 reactivation during aplasia, lower unit-unit human leukocyte antigen matching, and younger UCB unit age, as new unfavorable predictive factors, may represent new parameters to take into account after double UCB allogeneic stem-cell transplantation in adults. These results need to be confirmed prospectively, as they may influence unit selections and patient outcomes.

[Unresolved problems and the prospects for research in area of the multiple sclerosis: virologic, immunologic and therapeutic aspects].

Multiple sclerosis--important and unsolved problem of modern neurology. Despite a great deal of publications, in the modern theory of multiple sclerosis there remain many unresolved problems, without solving of which no further advances in the diagnosis and treatment can be possible. The present work elucidates blind spots in pathogenesis of the disease to indicate the most perspective directions of research, the results of which would allow the optimization of existing diagnostic and therapeutic algorithms. Microbial triggers, immunopathological mechanisms, association with immunodeficiencies, efficacy of the immunotherapy and side effects of the immunosuppressants as well as additional antimicrobial treatment are discussed.

[How I manage respiratory syncytial virus, human herpesvirus 6 and adenovirus reactivation or infection after allogeneic stem cell transplantation: a report of the SFGM-TC]. / Conduite à tenir devant une réactivation ou une infection à virus respiratoire syncytial, herpèsvirus 6 et adénovirus après allogreffe de cellules souches hématopoïétiques.

In the attempt to harmonize clinical practices between different French transplantation centers, the French Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC) set up the third annual series of workshops which brought together practitioners from all member centers and took place in October 2012 in Lille. Here we report our results and recommendations regarding the management of virus respiratory syncytial virus (RSV), human herpes virus 6 (HHV6) or adenovirus allogeneic Stem Cell Transplantation.