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

Symptomatic central nervous system tuberculosis and human herpesvirus-6 coinfection with associated hydrocephalus managed with endoscopic third ventriculostomy: A case report and review of human herpesvirus-6 neuropathology

Background

Human herpesvirus 6 (HHV-6) is a double-stranded DNA virus well established in the clinical literature to cause the near-universal childhood infection roseola infantum (exanthema subitum/sixth disease). Primary HHV-6 infection has been reported to cause meningoencephalitis in pediatric patients, although generally in the immunocompromised.

Case Description

The authors treated an immunocompetent 18-month-old female who transferred to our institution for a higher level of care given concerns for meningitis in the setting of decreased level of arousal (Glasgow Coma Scale 12), and bradycardia 9 days after the onset of nasal congestion, fatigue, and repeated bouts of emesis. Outside hospital cerebrospinal fluid (CSF) studies were notable for hypoglycorrhachia, elevated protein, elevated nucleated cells with a mononuclear predominance, and a meningitis polymerase chain reaction panel that was positive only for HHV-6. Brain magnetic resonance imaging with and without contrast revealed a basal cistern predominant leptomeningeal enhancement pattern as well as moderate ventriculomegaly with associated periventricular edema concerning acute communicating hydrocephalus. Considering the CSF studies, neuroimaging, and recent travel history to Mexico, central nervous system (CNS) tuberculosis (TB) was the leading suspicion, and antimicrobial therapy was initiated for this presumptive diagnosis with culture data only proving the TB suspicion correct after nearly 2 months in culture. Anti-viral therapy was initially not felt to be necessary as the HHV-6 was interpreted as incidental and not a cause of symptomatic meningitis in our immunocompetent host. The patient's hydrocephalus was treated with temporary CSF diversion followed by performance of an endoscopic third ventriculostomy. Despite appropriate hydrocephalus management, clinical improvement ultimately seemed to correlate with the initiation of antiviral therapy.

Conclusion

The authors present this case and review the literature on HHV-6-associated CNS infections with the goal of informing the neurosurgeon about this often clinically underestimated pathogen.

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.

Case report: Acute HHV6B encephalitis/myelitis post CAR-T cell therapy in patients with relapsed/refractory aggressive B-cell lymphoma

Background

The development of chimeric antigen receptor (CAR)-T cell therapy has revolutionized treatment outcomes in patients with lymphoid malignancies. However, several studies have reported a relatively high rate of infection in adult patients following CD19-targeting CAR T-cell therapy, particularly in the first 28 days. Notably, acute human herpesvirus 6 B (HHV6B) reactivation occurs in up to two-thirds of allogeneic hematopoietic stem cell transplantation patients.

Case presentations

Herein, we describe a report of HHV6B encephalitis/myelitis in three patients with relapsed/refractory diffuse large B-cell lymphoma post CAR T-cell therapy. All three patients received multiple lines of prior treatment (range: 2-9 lines). All patients presented with fever that persisted for at least 2 weeks after CAR-T cell infusion (CTI). Both the onset time and duration were similar to those of the cytokine release syndrome (CRS); nevertheless, the CRS grades of the patients were low (grade 1 or 2). Delirium and memory loss after CTI were the earliest notable mental presentations. Neurological manifestations progressed rapidly, with patients experiencing varying degrees of impaired consciousness, seizures, and coma. Back pain, lumbago, lower limb weakness and uroschesis were also observed in Patient 3, indicating myelitis. High HHV6B loads were detected in all Cerebral spinal fluid (CSF) samples using metagenomic next-generation sequencing (mNGS). Only one patient required high-activity antivirals and IgG intravenous pulse treatment finally recovered, whereas the other two patients died from HHV6B encephalitis.

Conclusion

Considering its fatal potential, HHV6B encephalitis/myelitis should be urgently diagnosed post CAR-T cell-based therapy. Furthermore, hematologists should differentially diagnose these conditions from CRS or other immunotherapy-related neurotoxicities as early as possible. The results of this study demonstrate the potential of mNGS in the early diagnosis of HHV6B infection, particularly when the organism is difficult to culture.

Viral meningoencephalitis in pediatric solid organ or hematopoietic cell transplant recipients: a diagnostic and therapeutic approach

Neurologic complications, both infectious and non-infectious, are frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. Up to 46% of HCT and 50% of SOT recipients experience a neurological complication, including cerebrovascular accidents, drug toxicities, as well as infections. Defects in innate, adaptive, and humoral immune function among transplant recipients predispose to opportunistic infections, including central nervous system (CNS) disease. CNS infections remain uncommon overall amongst HCT and SOT recipients, compromising approximately 1% of total cases among adult patients. Given the relatively lower number of pediatric transplant recipients, the incidence of CNS disease amongst in this population remains unknown. Although infections comprise a small percentage of the neurological complications that occur post-transplant, the associated morbidity and mortality in an immunosuppressed state makes it imperative to promptly evaluate and aggressively treat a pediatric transplant patient with suspicion for viral meningoencephalitis. This manuscript guides the reader through a broad infectious and non-infectious diagnostic differential in a transplant recipient presenting with altered mentation and fever and thereafter, elaborates on diagnostics and management of viral meningoencephalitis. Hypothetical SOT and HCT patient cases have also been constructed to illustrate the diagnostic and management process in select viral etiologies. Given the unique risk for various opportunistic viral infections resulting in CNS disease among transplant recipients, the manuscript will provide a contemporary review of the epidemiology, risk factors, diagnosis, and management of viral meningoencephalitis in these patients.

Identifying CNS infections in transplantation and immunomodulatory therapy

Opportunistic central nervous system (CNS) infections are a significant cause of morbidity and mortality in immunocompromized patients, including those undergoing transplantation and receiving immunomodulatory therapy. Particularly in these individuals, the clinical presentation of these infections may have atypical patterns, emphasizing the need to consider various diagnostic possibilities, including noninfectious conditions. Quick and accurate identification, along with prompt treatment, is crucial for improving patient outcomes. Therefore, understanding which pathogens are likely to cause infection based on factors such as timing post-transplantation, specific organ transplant, and the mechanism of action of immunomodulatory medications is essential. This review will provide a detailed description of the types of infections that may arise in the context of transplantation and immunomodulatory therapy.

Internationally standardized respiratory viral load testing with limited resources: A derivative-of-care calibration strategy for SARS-CoV-2

Introduction

SARS-CoV-2 has demonstrated that, in targeted circumstances, viral quantification within respiratory specimens can valuably inform patient management, as well as research. Nevertheless, the pandemic has illustrated concomitant challenges for obtaining high-quality (and broadly comparable) respiratory viral loads. This includes a critical need for standardization and calibration, even though the necessary resources may not always be available for emergent pathogens and non-bloodstream specimens.

Methods

To these ends, we describe a novel strategy for implementing quantitative SARS-CoV-2 testing with International Unit-based calibration. Earlier in the course of the pandemic-when analytic resources were far more limited-select residual SARS-CoV-2 positive specimens from routine care in our diagnostic laboratory were pooled to formulate a clinically realistic secondary standard of high volume and analyte concentration, which was cross-calibrated to the primary SARS-CoV-2 standard of the World Health Organization.

Results

The resultant calibrators were integrated into the original CDC RT-qPCR assay for SARS-CoV-2, whose (now broadened) performance characteristics were defined to generate a test appropriate for both clinical and research use. This test allowed for the quantification of virus in respiratory specimens down to a validated lower limit of quantification of 103.4 IU/ml.

Conclusions

By self-formulating calibrators from this derivative-of-care secondary standard, we successfully validated respiratory viral loads without the commercial availability (at that time) of quantitative assays or calibrators. As the SARS-CoV-2 pandemic continues to decline-and even beyond this pathogen-this strategy may be applicable for laboratories seeking to implement viral load testing for nontraditional specimen types despite limited resources.

Evaluation of an automated system for the quantitation of human Herpesvirus-6 DNA from clinical specimens

Background

Quantitation of human herpesvirus-6 (HHV-6) DNA in clinical specimens is important for the diagnosis and management of HHV-6-associated infection and reactivation in immunocompromised patients, particularly transplant recipients.

Methods

The analytical performance of the Altona RealStar ASR HHV-6 qPCR on the semi-automated AltoStar AM16 system was assessed using HHV-6 reference material in plasma and cerebral spinal fluid (CSF). Qualitative and quantitative agreement was determined using 123 clinical EDTA plasma specimens tested using a laboratory-developed HHV-6 qPCR.

Results

The 95% Lower Limit of Detection was 20 IU/mL [95% confidence interval (CI): 10 to 29] in plasma and 78 IU/mL (95% CI: 55 to 146) in CSF. The assay was linear from 7.0 to 2.0 log10 IU/mL in both matrices. Overall agreement of the RealStar ASR HHV-6 qPCR on the AltoStar AM16 with a laboratory-developed test was 95.9% (95% CI: 90.8 to 98.7). Passing-Bablok analysis of specimens quantifiable by both methods and at levels >1000 copies/mL revealed a regression line of Y = 1.00*X-0.20, with neither systematic (95% CI Y-intercept: -0.66 to 0.26) nor proportional (95% CI slope: 0.89 to 1.10) bias compared to the reference.

Conclusions

The RealStar ASR HHV-6 qPCR on the AltoStar AM16 provides accurate quantitation for clinical monitoring of HHV-6 in immunocompromised hosts.

Time course of skin rash, computed tomography findings, and viral load in a rheumatoid arthritis patient with severe varicella pneumonia

Varicella-zoster virus (VZV) infection in adults or immunocompromised patients has a more severe presentation compared to the mild disease in children. To the best of our knowledge, no reports have described the clinical course of VZV pneumonia focusing on time course of skin rash, chest computed tomography (CT) findings, and viral load. Furthermore, no reports have described the reactivation of human herpes virus 6 (HHV-6) in VZV pneumonia. Here, we report a case of severe VZV pneumonia that resulted in reactivation of HHV-6 in a patient with rheumatoid arthritis (RA). A 66-year-old female treated for RA was admitted to our hospital with papules. Her chest CT showed granular infiltrates, micronodules, and ground-glass opacities. The day after admission, because the typical skin rashes and chest CT findings were observed, she was diagnosed with VZV pneumonia and treated with acyclovir. Her skin rash then crusted over five days and entered the healing process, whereas it took approximately two weeks for her respiratory condition and chest CT findings to improve. In addition, VZV deoxyribonucleic acid (DNA) gradually decreased with treatment. On the 34th day of admission, VZV DNA was not found in the serum sample but remained in the sputum sample. Furthermore, although reactivation of HHV-6 was observed, viremia resolved without treatment. Clinicians should be able to recognize the differences in the improvement of skin rashes, respiratory status, and chest CT findings. In addition, treatment for HHV-6 reactivation should be carefully determined for each case.

Current Perspectives on the Management of Herpesvirus Infections in Solid Organ Transplant Recipients

Solid organ transplant recipients (SOTRs) are at high risk of human herpesvirus (HHV)-related morbidity and mortality due to the use of immunosuppressive therapy. We aim to increase awareness and understanding of HHV disease burden in SOTRs by providing an overview of current prevention and management strategies as described in the literature and guidelines. We discuss challenges in both prevention and treatment as well as future perspectives.

Pigmentary retinopathy and nodular granuloma associated with acute retinal necrosis from varicella zoster virus and human herpes virus type 6: Case report

RATIONALE

Acute retinal necrosis (ARN) caused by human herpes virus type 6 (HHV-6) is uncommon. We described a case of consecutive bilateral ARN, which was found to be a coinfection of varicella zoster virus (VZV) and HHV-6 in a 50-year-old woman, not well responded with systemic acyclovir. We showed the atypical findings with corresponding fundus and optical coherence tomography imaging.

PATIENT CONCERNS

She presented with anterior segment inflammation with peripheral retinitis and vasculitis in the left eye with disease progression despite of initial antiviral treatment, end up with retinal detachment. The right eye, subsequently, developed focal retinitis.

DIAGNOSIS

ARN was diagnosed by clinical fundus picture, confirmed by polymerase chain reaction (PCR).

INTERVENTIONS

Initially, she was treated with intravenous acyclovir and intravitreal ganciclovir for left eye. Retinal necrosis progressed, followed by retinal detachment. Pars plana vitrectomy with silicone oil was performed. The right eye, subsequently, developed focal retinitis. Medication was switched to intravenous ganciclovir and then oral valganciclovir.

OUTCOMES

Retinitis was resolved, generalized hyperpigmentation appeared as a salt-and-pepper appearance in the right eye. The left eye presented preretinal deposits on silicone-retina interphase along retinal vessels. Spectral-domain optical coherence tomography (SD-OCT) showed multiple hyperreflective nodules on retinal surface.

LESSONS

ARN from coinfection of VZV and HHV-6 is rare. Preretinal granulomas and generalized hyperpigmentation could be one of the HHV-6 features. HHV-6 should be in the differential diagnosis for ARN. It responds well to systemic ganciclovir.

How I prevent viral reactivation in high-risk patients

Preventing viral infections at an early stage is a key strategy for successfully improving transplant outcomes. Preemptive therapy and prophylaxis with antiviral agents have been successfully used to prevent clinically significant viral infections in hematopoietic cell transplant recipients. Major progress has been made over the past decades in preventing viral infections through a better understanding of the biology and risk factors, as well as the introduction of novel antiviral agents and advances in immunotherapy. High-quality evidence exists for the effective prevention of herpes simplex virus, varicella-zoster virus, and cytomegalovirus infection and disease. Few data are available on the effective prevention of human herpesvirus 6, Epstein-Barr virus, adenovirus, and BK virus infections. To highlight the spectrum of clinical practice, here we review high-risk situations that we handle with a high degree of uniformity and cases that feature differences in approaches, reflecting distinct hematopoietic cell transplant practices, such as ex vivo T-cell depletion.

Longitudinal Detection of Twenty DNA and RNA Viruses in Allogeneic Hematopoietic Stem Cell Transplant Recipients Plasma

Metagenomics revealed novel and routinely overlooked viruses, representing sources of unrecognized infections after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aim to describe DNA and RNA virus prevalence and kinetics in allo-HSCT recipients' plasma for one year post HSCT. We included 109 adult patients with first allo-HSCT from 1 March 2017 to 31 January 2019 in this observational cohort study. Seventeen DNA and three RNA viral species were screened with qualitative and/or quantitative r(RT)-PCR assays using plasma samples collected at 0, 1, 3, 6, and 12 months post HSCT. TTV infected 97% of patients, followed by HPgV-1 (prevalence: 26-36%). TTV (median 3.29 × 10⁵ copies/mL) and HPgV-1 (median 1.18 × 10⁶ copies/mL) viral loads peaked at month 3. At least one Polyomaviridae virus (BKPyV, JCPyV, MCPyV, HPyV6/7) was detected in >10% of patients. HPyV6 and HPyV7 prevalence reached 27% and 12% at month 3; CMV prevalence reached 27%. HSV, VZV, EBV, HHV-7, HAdV and B19V prevalence remained <5%. HPyV9, TSPyV, HBoV, EV and HPg-V2 were never detected. At month 3, 72% of patients had co-infections. TTV and HPgV-1 infections were highly prevalent. BKPyV, MCPyV and HPyV6/7 were frequently detected relative to classical culprits. Further investigation is needed into associations between these viral infections and immune reconstitution or clinical outcomes.

Human herpesvirus 6 (HHV-6) associated permanent hyponatremia in umbilical cord blood transplant recipient

Long-term neurocognitive deficits after human herpesvirus-6 (HHV-6) infection are common in stem-cell transplant recipients, but SIADH (Syndrome of inappropriate antidiuretic hormone secretion) with persistent hyponatremia is rare. A 51-year-old woman presented with somnolence, hyponatremia (121 mmol/L) and HHV-6 viremia (80,330 copies/ml) on day +22 post umbilical cord blood transplant (UCBT). With waterrestriction, tolvaptan and combination of foscarnet and ganciclovir, patient's hyponatremia and HHV-6 viremia improved. On day +94 UCBT, hyponatremia and HHV-6 viremia recurred. Foscarnet was restarted and continued until day +269 UCBT due to multiple HHV-6 recurrences with persistent hyponatremia. At day +712, patient remains on water-restriction, tolvaptan for continuous hyponatremia from SIADH.

Acute autonomic dysregulation due to HHV-6 encephalitis in an immunocompromised patient: a case report and literature review

Human herpesvirus-6 (HHV-6), in particularly HHV-6B, can reactivate in immunocompromised patients. Especially after stem cell transplantation, reactivation of HHV-6 can cause complications, such as limbic encephalitis. We present a case of a 61-year-old man with B-cell non-Hodgkin lymphoma. He presented with subacute lethargy, confusion and hyperhidrosis. Following this, we will give a short review of the literature considering clinical and technical features as well as treatment options.

Autoimmune Neutropenia Associated With HHV-6 Virus Infection: A Case Report

Background

Autoimmune neutropenia (AIN) is divided into primary and secondary forms. The former is more prevalent in children and is usually a self-limiting disease. Secondary AIN is more common in adults and often occurs in the setting of another autoimmune disorder or secondary to infections, malignancies or medications. Several viral and bacterial pathogens were described to trigger AIN. Here we report a case of AIN in an adult woman associated with human herpesvirus-6 (HHV-6) infection.

Case Presentation

We report a case of AIN in an adult woman associated with HHV-6 infection. The patient presented to the emergency department with fever and painful genital ulcers. Upon arrival, her laboratory workup demonstrated severe neutropenia and elevated inflammatory markers. She was hospitalized and underwent a thorough infectious, hematological, autoimmune and inflammatory workup. Malignancy was also excluded using an advanced whole body radiological scan. Serological tests confirmed the presence of both acute and chronic types of HHV-6 antibodies, at very high titers. Polymerase chain reaction demonstrated a numerous copies of the virus in the patient’s blood. Specific immunofluorescence test confirmed the diagnosis of autoimmune neutropenia.

Conclusion

Secondary AIN is a rare disease that may affect all range of ages. The adult type is a challenging disorder that has different etiologies and may be triggered by a variable infectious pathogen. The finding of HHV-6 as a possible culprit pathogen may warrant physicians into widening the evaluation and include HHV-6 in the analysis.

Infectious risks in patients treated with extracorporeal photopheresis for graft-versus-host disease: A retrospective cohort study

BACKGROUND

Infections are common with significant mortality and morbidity in patients with graft-versus-host disease (GvHD). Extracorporeal photopheresis (ECP) is an advantageous treatment option for patients with GvHD because it is not immunosuppressive. The objective of this study was to assess the rate of infections and to determine risk factors in patients with GvHD.

MATERIALS AND METHODS

In a single-center cohort, we retrospectively collected data on infectious episodes by evaluating the clinical records of patients with GvHD treated by ECP since 2011.

RESULTS

A total of 47 patients were included in this study. At ECP initiation, there were 10 patients with acute GvHD and 37 with chronic GvHD. At the final follow-up, 200 infectious episodes were diagnosed in 91.5% of patients with an average follow-up of 25.9 months (ie, 1.97 infections per patient per year). Most episodes had positive outcomes as there was no death related to infections, and only six infections required long-term treatment. Higher dose of corticosteroids at the initiation of ECP was significantly associated with a shorter onset of the first infection (hazard ratio [HR] = 2.05; 95% confidence interval [CI] [1.17, 3.57]; P = .013). Unrelated donor transplants were significantly associated with a lower rate of infection (HR = 0.61; 95% CI [0.39, 0.95]; P = .028).

CONCLUSION

The results of our study suggest that ECP is associated with a low infection rate and an optimal clinical efficacy. Thus, ECP is still a suitable treatment for GvHD. Yet, a future study with a larger cohort will be necessary to deepen the identification of risk factors for infection.

Herpesviridae in critically ill hematology patients: HHV-6 is associated with worse clinical outcome

PURPOSE

Although viral infections are frequent among patients with hematological malignancies (HM), data about herpesviridae in critically ill hematology patients are scarce. We aimed at determining the impact of herpesviridae reactivation/infection in this population.

MATERIAL AND METHODS

We performed a single center retrospective study including all consecutive adult hematology patients admitted to our comprehensive cancer center ICU on a 6-year period. Clinical characteristics, microbiological findings, especially virus detection and outcome were recorded.

RESULTS

Among the 364 included patients, HHV-6 was the predominant retrieved herpesviridae (66 patients, 17.9%), followed by HSV1/2 (41 patients, 11.3%), CMV (38 patients, 10.4%), EBV (24 patients, 6.6%) and VZV (3 patients). By multivariable analysis, HHV-6 reactivation was independently associated with hospital mortality (OR, 2.35; 95% CI, 1.03-5.34; P = 0.042), whereas antiviral prophylaxis during ICU stay had a protective effect (OR, 0.41; 95% CI, 0.18-0.95; P = 0.037). HHV-6 pneumonitis was independently associated with 1-year mortality (OR, 6.87; 95% CI, 1.09-43.3; P = 0.04).

CONCLUSIONS

Among critically ill hematology patients, HHV-6 reactivation and pneumonitis are independent risk factors for hospital and 1-year mortality, respectively. Impact of prevention and treatment using agents active against HHV-6 should be assessed to define a consensual diagnostic and therapeutic strategy.

Central nervous system infections after solid organ transplantation

PURPOSE OF REVIEW

Significant advances to our understanding of several neuroinfectious complications after a solid organ transplant (SOT) have occurred in the last few years. Here, we review the central nervous system (CNS) infections that are relevant to SOT via a syndromic approach with a particular emphasis on recent updates in the field.

RECENT FINDINGS

A few key studies have advanced our understanding of the epidemiology and clinical characteristics of several CNS infections in SOT recipients. Risk factors for poor prognosis and protective effects of standard posttransplant prophylactic strategies have been better elucidated. Newer diagnostic modalities which have broad clinical applications like metagenomic next-generation sequencing, as well as those that help us better understand esoteric concepts of disease pathogenesis have been studied. Finally, several studies have provided newer insights into the treatment of these diseases.

SUMMARY

Recent findings reflect the steady progress in our understanding of CNS infections post SOT. They provide several avenues for improvement in the prevention, early recognition, and therapeutic outcomes of these diseases.

Evasion of the Host Immune Response by Betaherpesviruses

The human immune system boasts a diverse array of strategies for recognizing and eradicating invading pathogens. Human betaherpesviruses, a highly prevalent subfamily of viruses, include human cytomegalovirus (HCMV), human herpesvirus (HHV) 6A, HHV-6B, and HHV-7. These viruses have evolved numerous mechanisms for evading the host response. In this review, we will highlight the complex interplay between betaherpesviruses and the human immune response, focusing on protein function. We will explore methods by which the immune system first responds to betaherpesvirus infection as well as mechanisms by which viruses subvert normal cellular functions to evade the immune system and facilitate viral latency, persistence, and reactivation. Lastly, we will briefly discuss recent advances in vaccine technology targeting betaherpesviruses. This review aims to further elucidate the dynamic interactions between betaherpesviruses and the human immune system.

Guidelines for Infection Prophylaxis, Monitoring and Therapy in Cord Blood Transplantation

As an alternative stem cell source, cord blood (CB) has many advantages. However, delayed engraftment, lack of transferred immunity, and a significant incidence of acute graft-versus-host disease renders CB transplant (CBT) recipients at high risk of infectious complications. This guidance written by CBT and infectious disease experts outlines evidence-based recommendations for the prevention and treatment of opportunistic infections in adult patients undergoing CBT. Topics addressed include bacterial, fungal, viral, pneumocystis jirovcii and toxoplasmosis prophylaxis, suggested PCR monitoring for viruses, therapy for the most commonly encountered infections after CBT. We review key concepts including the recent important role of letermovir in the prevention of CMV reactivation. In instances where there is a paucity of data, practice recommendations are provided, including the duration of antimicrobial prophylaxis.

Association of Inherited Chromosomally Integrated Human Herpesvirus 6 with Neurologic Symptoms and Management after Allogeneic Hematopoietic Cell Transplantation

Reactivation of human herpesvirus 6 (HHV-6) after allogeneic hematopoietic cell transplantation (HCT) is associated with neurologic complications, but the impact of donor and/or recipient inherited chromosomally integrated HHV-6 (iciHHV-6) on post-HCT central nervous system (CNS) symptoms and diagnostic and therapeutic interventions is not well understood. The aims of the present study were (1) to compare the cumulative incidence of CNS symptoms in the first 100 days following allogeneic HCT among patients with donor and/or recipient iciHHV-6 (iciHHV-6^pos)with that of patients with neither donor nor recipient iciHHV-6 (iciHHV-6^neg) and (2) to assess the role of HHV-6 detection in driving potentially unnecessary interventions in iciHHV-6^pos patients. We performed a retrospective matched cohort study of 87 iciHHV-6^pos and 174 iciHHV-6^neg allogeneic HCT recipients. HHV-6 testing was performed at the discretion of healthcare providers, who were unaware of iciHHV-6 status. The cumulative incidence of CNS symptoms was similar in iciHHV-6^pos (n = 37; 43%) and iciHHV-6^neg HCT recipients (n = 81; 47%; P = .63). HHV-6 plasma testing was performed in similar proportions of iciHHV-6^pos (n = 6; 7%) and iciHHV-6^neg (9%) patients and was detected in all tested iciHHV-6^pos HCTs and 2 (13%) iciHHV-6^neg HCTs. This resulted in more frequent HHV-6-targeted antiviral therapy after iciHHV-6^pos HCT (odds ratio, 12.8; 95% confidence interval, 1.5 to 108.2) with associated side effects. HHV-6 plasma detection in 2 iciHHV-6^pos patients without active CNS symptoms prompted unnecessary lumbar punctures. The cumulative incidence of CNS symptoms was similar after allogeneic HCT involving recipients or donors with and without iciHHV-6. Misattribution of HHV-6 detection as infection after iciHHV-6^pos HCT may lead to unnecessary interventions. Testing for iciHHV-6 may improve patient management.

Presence of viremia during febrile neutropenic episodes in patients undergoing chemotherapy for malignant neoplasms

The importance of viral infections as a leading cause of morbidity and mortality is well documented in severely immunosuppressed patients undergoing allogeneic stem cell transplantation. By contrast, viral infections generally receive less attention in patients with malignant disorders undergoing chemotherapy, where the onset of neutropenic fever is mostly associated with bacterial or fungal infections, and screening for viral infections is not routinely performed. To address the occurrence of invasive viral infections in a clinical setting commonly associated with less pronounced immunosuppression, we have prospectively screened 237 febrile neutropenic episodes in pediatric (n = 77) and adult (n = 69) patients undergoing intensive chemotherapy, primarily for treatment of acute leukemia. Serial peripheral blood specimens were tested by RQ-PCR assays for the presence and quantity of the clinically relevant viruses CMV, EBV, HHV6 and HAdV, commonly reactivated in highly immunocompromised patients. Viremia was documented in 36 (15%) episodes investigated, including the detection of HHV6 (n = 14), EBV (n = 15), CMV (n = 6), or HAdV (n = 1). While low or intermediate levels of viremia (<10⁴ virus copies/mL) were commonly associated with bacterial or fungal co-infection, viremia at higher levels (>10⁴ copies/mL) was documented in patients without evidence for other infections, raising the possibility that at least in some instances the onset of fever may have been attributable to the virus detected. The observations suggest that viral infections, potentially resulting from reactivation, might also play a clinically relevant role in patients receiving chemotherapy for treatment of malignant neoplasms, and routine screening for viremia in this clinical setting might be warranted.

Risk Factor and Long-Term Outcome Analyses for Acute Limbic Encephalitis and Calcineurin Inhibitor-Induced Encephalopathy in Adults following Allogeneic Hematopoietic Cell Transplantation

Post-transplantation acute limbic encephalitis (PALE) is a rare, severe inflammatory disorder in the bilateral limbic system, including the hippocampus. To date, only a few studies have reported details, including risk factors for PALE; however, further clinical evidence of PALE, especially in cerebrospinal fluid human herpesvirus 6-negative cases, is warranted. In addition, data are sparse regarding the risk factors for calcineurin inhibitor (CNI)-induced encephalopathy (CNIE) following allogeneic hematopoietic cell transplantation (allo-HCT) in adults. Therefore, we examined the risk factors for and clinical details of PALE and CNIE. We retrospectively analyzed consecutive patients who underwent allo-HCT between January 2005 and November 2017. A total of 485 patients age 46 years (median) were eligible. In total, 14 PALE cases and 11 CNIE cases were identified. Multivariable analyses identified older age, use of an HLA-mismatched unrelated donor (URD), graft-versus-host disease (GVHD) prophylaxis with CNI and mycophenolate mofetil, and grade II-IV acute GVHD as significantly associated with an increased risk of PALE. In 13 patients who received high-dose methylprednisolone (mPSL) therapy, 6 (46%) responded to mPSL therapy, and 3 (23%) achieved complete remission at day 90 after mPSL administration. Furthermore, myelodysplastic syndrome (MDS), HLA-mismatched URD, and grade II-IV acute GVHD were significantly associated with an increased risk of CNIE. The 5-year nonrelapse mortality rate was 50% in PALE and 63% in CNIE, suggesting a very poor prognosis. In conclusion, this study provides evidence that HLA-mismatched URD and acute GVHD may independently contribute to the development of PALE, possibly in part through HLA-mismatch-derived alloimmune responses. Other than acute GVHD, we have identified MDS and HLA-mismatched URD as novel predictors of CNIE after allo-HCT.

Variation in human herpesvirus 6B telomeric integration, excision, and transmission between tissues and individuals

Human herpesviruses 6A and 6B (HHV-6A/6B) are ubiquitous pathogens that persist lifelong in latent form and can cause severe conditions upon reactivation. They are spread by community-acquired infection of free virus (acqHHV6A/6B) and by germline transmission of inherited chromosomally integrated HHV-6A/6B (iciHHV-6A/6B) in telomeres. We exploited a hypervariable region of the HHV-6B genome to investigate the relationship between acquired and inherited virus and revealed predominantly maternal transmission of acqHHV-6B in families. Remarkably, we demonstrate that some copies of acqHHV-6B in saliva from healthy adults gained a telomere, indicative of integration and latency, and that the frequency of viral genome excision from telomeres in iciHHV-6B carriers is surprisingly high and varies between tissues. In addition, newly formed short telomeres generated by partial viral genome release are frequently lengthened, particularly in telomerase-expressing pluripotent cells. Consequently, iciHHV-6B carriers are mosaic for different iciHHV-6B structures, including circular extra-chromosomal forms that have the potential to reactivate. Finally, we show transmission of an HHV-6B strain from an iciHHV-6B mother to her non-iciHHV-6B son. Altogether, we demonstrate that iciHHV-6B can readily transition between telomere-integrated and free virus forms.

Donor-Derived CD4+ T Cells and Human Herpesvirus 6B Detection After Allogeneic Hematopoietic Cell Transplantation

We sought to determine whether donor-derived human herpesvirus (HHV) 6B-specific CD4+ T-cell abundance is correlated with HHV-6B detection after allogeneic hematopoietic cell transplantation. We identified 33 patients who received HLA-matched, non-T-cell-depleted, myeloablative allogeneic hematopoietic cell transplantation and underwent weekly plasma polymerase chain reaction testing for HHV-6B for 100 days thereafter. We tested donor peripheral blood mononuclear cells for HHV-6B-specific CD4+ T cells. Patients with HHV-6B detection above the median peak viral load (200 copies/mL) received approximately 10-fold fewer donor-derived total or HHV-6B-specific CD4+ T cells than those with peak HHV-6B detection at ≤200 copies/mL or with no HHV-6B detection. These data suggest the importance of donor-derived immunity for controlling HHV-6B reactivation.

Human herpesvirus 6B encephalitis in a liver transplant recipient: A case report and review of the literature

Human herpesvirus 6B (HHV‐6B) encephalitis in a liver transplant recipient is rarely reported. In this report, we presented a case of HHV‐6B encephalitis in a liver transplant recipient and reviewed the relevant literature. A 56‐year‐old man was admitted to the intensive care unit (ICU) with an acute headache and intermittent convulsion 17 days after liver transplantation. Next‐generation sequencing (NGS) of the cerebrospinal fluid (CSF) revealed 30691 sequence reads of HHV‐6B and real‐time polymerase chain reaction (real‐time PCR) of the CSF detected HHV‐6B DNA at 12 000 copies/mL, so the patient was diagnosed with HHV‐6B encephalitis and received ganciclovir treatment promptly. The condition of the patient improved well and returned to the general ward with no neurologic deficits. This case indicated that adequate awareness, early diagnosis, and timely treatment are crucial to a good prognosis of HHV‐6B encephalitis after liver transplantation.