Surveillance of active human herpesvirus 6 infection in chinese patients after hematopoietic stem cell transplantation with 3 different methods

Human herpesvirus 6 and central nervous system disease in oncology patients: A retrospective case series and literature review

BACKGROUND

Human herpesvirus 6 (HHV-6) can reactivate with immunosuppression and cause central nervous system (CNS) dysfunction. Much of the literature describes cases after hematopoietic stem cell transplantation (HSCT), ranging from encephalitis to a post-transplant acute limbic encephalitis syndrome (PALE). Outside of HSCT, studies of HHV-6 encephalitis are limited to case reports.

OBJECTIVES

This study was designed to review HHV-6 CNS infection, and evaluate all patients admitted to MD Anderson Cancer Center between March 2016 and December 2018 with detectable HHV-6 DNA in the cerebrospinal fluid (CSF).

STUDY DESIGN

Patients with HHV-6 DNA detected in the CSF using the Viracor or Biofire® Meningitis Encephalitis Panel platforms and no other identified etiology were identified and demographic features, known risk factors, imaging findings, CSF analysis, treatments and patient outcomes were extracted from medical records.

RESULTS

725 patients underwent HHV-6 testing during the study timeframe, with 19 cases (2.6 %) of HHV-6 mediated CNS disease identified. Most patients, 13/19 (68 %), had undergone HSCT with median time to presentation of 31 days after transplant. Survival at 240 days after transplant was 62 %. CSF had lymphocyte predominance and nearly all patients had peripheral lymphopenia. Other at risk populations identified included patients who received chimeric antigen receptor (CAR) T-cell therapy and biologic immunotherapy. Notable discordance among testing platforms was found in 5/9 (55 %) instances.

CONCLUSIONS

In addition to HSCT patients, HHV-6 reactivation leading to CNS disease also occurs in settings such as following adoptive T cell therapy or biologic immunotherapy. Significant diagnostic discordance exists between testing platforms.

Human herpesvirus 6B reactivation and delirium are frequent and associated events after cord blood transplantation

Human herpesvirus 6B (HHV-6B) frequently reactivates after cord blood transplantation (CBT). We previously reported an association between HHV-6B reactivation and delirium after hematopoietic cell transplantation. In this prospective study, 35 CBT recipients underwent twice-weekly plasma PCR testing for HHV-6 and thrice-weekly delirium assessment until day 84. There was a quantitative association between HHV-6B reactivation and delirium in univariable (odds ratio, 2.88; 95% confidence interval (CI), 0.97-8.59) and bivariable models. In addition, intensified prophylaxis with high-dose valacyclovir mitigated HHV-6B reactivation (adjusted hazard ratio, 0.39; 95% CI, 0.14-1.08). Larger trials are needed to explore the utility of HHV-6B prophylaxis after CBT.

Cord-blood hematopoietic stem cell transplant confers an increased risk for human herpesvirus-6-associated acute limbic encephalitis: a cohort analysis

Human herpesvirus-6 (HHV-6) frequently reactivates after allogeneic hematopoietic stem cell transplantation (HSCT); its most severe manifestation is the syndrome of posttransplantation acute limbic encephalitis (HHV-6-PALE). The epidemiology, risk factors, and characteristics of HHV-6-PALE after unrelated cord-blood transplantation (UCBT) are not well characterized. We analyzed 1344 patients undergoing allogeneic HSCT between March 2003 and March 2010 to identify risk factors and characteristics of HHV-6-PALE. The cohort included 1243 adult-donor HSCT and 101 UCBT recipients. All patients diagnosed with HHV-6-PALE had HHV-6 DNA in cerebrospinal fluid (CSF) specimens in addition to symptoms and studies indicating limbic encephalitis. Nineteen cases (1.4%) of HHV-6-PALE were identified during this study: 10 after UCBT (9.9%) and 9 after adult-donor HSCT (0.7%), for an incidence rate of 1.2 cases/1000 patient-days compared to 0.08 cases/1000 patient-days (P < .001), respectively. Risk factors for HHV-6-PALE on multivariable Cox modeling were UCBT (adjusted hazard ratio [aHR], 20.0; 95% confidence interval [CI], 7.3-55.0; P < .001), time-dependent acute graft-versus-host disease (aGVHD) grades II to IV (aHR, 7.5; 95% CI, 2.8-19.8; P < .001), and adult-mismatched donor (aHR, 4.3; 95% CI, 1.1-17.3; P = .04). Death from HHV-6-PALE occurred in 50% of affected patients undergoing UCBT and no recipients of adult-donor cells. Patients receiving UCBT have increased risk for HHV-6-PALE and greater morbidity from this disease.

Human herpesvirus 6 encephalitis

Human herpesvirus (HHV) 6, the etiologic agent of roseola, is nearly universally acquired during childhood. The virus establishes lifelong infection, including within the central nervous system (CNS), and replicates within several CNS cell types. HHV-6 has been linked to CNS disease during primary infection, including febrile seizures and possibly hippocampal injury. HHV-6 may also be associated with neurologic disease later in life, particularly in transplant patients. Recent reports offer evidence that HHV-6 reactivation may underlie a characteristic limbic encephalitis syndrome following hematopoietic cell transplant; the cardinal features of this syndrome include memory loss, insomnia, electroencephalographic evidence of temporal lobe seizure activity, MRI signal intensity abnormalities of the mesial temporal lobe, and the syndrome of inappropriate release of antidiuretic hormone. HHV-6 DNA is frequently detectable by nucleic acid amplification tests in the cerebrospinal fluid and peripheral blood upon symptom onset, which may provide a screening strategy in high-risk patients. Possible associations of HHV-6 with meningoencephalitis, mesial temporal lobe epilepsy, and multiple sclerosis in apparently immunocompetent hosts are under investigation.

The Impact of Human Herpesvirus 6B Reactivation on Early Complications following Allogeneic Hematopoietic Stem Cell Transplantation

Although human herpesvirus 6 (HHV-6) has been considered an important opportunistic and potentially fatal pathogen for allogeneic hematopoietic stem cell transplantation (HSCT), the clinical significance of HHV-6 reactivation remains controversial. In this study, we monitored HHV-6 DNAemia in 72 consecutive allogeneic HSCT recipients by real-time quantitative polymerase chain reaction. A total of 680 peripheral blood specimens were collected from the recipients before HSCT or at weekly intervals after HSCT. As the predominant variant, HHV-6B was detectable at least once in 47.2% (34/72) of HSCT recipients on the median day 21 (range, 7-84 days); HHV-6A reactivation occurred in only 1 recipient (1.4%). Detectable HHV-6B reactivation was associated with increased probability of skin rash by day 30 after HSCT (hazard ratio [HR], 3.68; 95% confidence interval [CI], 1.24-10.92; P = .019), cytomegalovirus (CMV) antigenemia (HR, 2.35; 95%CI, 1.32-4.19; P = .004), and hemorrhagic cystitis (HC) (HR, 2.59; 95%CI, 0.96-6.98; P = .061) by day 100 after HSCT. Neutrophil and platelet engraftment, mortality for 100 days after HSCT were not affected by HHV-6B reactivation. In conclusion, HHV-6 reactivation is a common event, and this study demonstrates a correlation between HHV-6B infection and CMV reactivation, early rash, and possibly increased incidence of HC after transplantation.