A report of human herpesvirus 6-associated encephalitis in a solid organ transplant recipient and a review of previously published cases

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.

HHV-6 Infection in a 19-Year-Old Liver Transplant Recipient - Much More Than Roseola!

Human herpesvirus 6 (HHV-6) infections, most commonly occurring during childhood, are frequently mild and self-limited. However, immunosuppression due to transplantation may cause reactivation of HHV-6 with manifestations ranging from fever and skin exanthem to pneumonitis, hepatitis, encephalitis, and myelitis. Because these infections may be devastating for liver transplant recipients leading to transplant organ fibrosis and failure, it is imperative that internists recognize the manifestations, establish early diagnosis, institute appropriate therapy, and make timely referrals to transplant specialists. We present a case of a 19-year-old liver transplant recipient with HHV-6 viremia, encephalopathy, and hepatitis. The patient's symptoms improved with ganciclovir and intravenous immunoglobulin treatment, serum HHV-6 copies gradually decreased, and she was discharged with outpatient follow-up. After approximately one month of antiviral therapy, the patient's viral load was undetectable. Early recognition of HHV-6 viremia, appropriate laboratory assessment, and early institution of therapy is important for internal medicine physicians to decrease morbidity and mortality in liver transplant recipients.

Approach to Neurologic Complications in the Immunocompromised Patient

Neurologic complications are common in immunocompromised patients, including those with advanced human immunodeficiency virus, transplant recipients, and patients on immunomodulatory medications. In addition to the standard differential diagnosis, specific pathogens and other conditions unique to the immunocompromised state should be considered in the evaluation of neurologic complaints in this patient population. A thorough understanding of these considerations is critical to the inpatient neurologist in contemporary practice, as increasing numbers of patients are exposed to immunomodulatory therapies. In this review, we provide a chief complaint-based approach to the clinical presentations and diagnosis of both infectious and noninfectious complications particular to immunocompromised patients.

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.

Neurologic Infections in Patients on Immunomodulatory and Immunosuppressive Therapies

PURPOSE OF REVIEW

Both broadly immunosuppressive medications and selective immunomodulatory agents that act on particular components of the immune system are increasingly used in the treatment of neurologic and non-neurologic diseases. These therapies predispose patients to particular infections, some of which may affect the nervous system. Therefore, familiarity with the clinical and radiologic features of neurologic infections associated with specific immunomodulatory therapies is of importance for the practicing neurologist. This article reviews these neuroinfectious conditions, as well as other neurologic complications unique to transplant recipients and other patients who are immunocompromised.

RECENT FINDINGS

Diagnosis of infectious pathogens in patients who are immunocompromised may be particularly challenging because a decreased immune response can lead to atypical imaging or laboratory findings. Next-generation sequencing and other novel diagnostic modalities may improve the rate of early identification of neurologic infections in patients who are immunocompromised and ultimately ameliorate outcomes in this vulnerable population.

SUMMARY

A broad range of bacterial, viral, fungal, and parasitic infections of the nervous system can complicate solid organ and hematopoietic cell transplantation as well as other forms of immunocompromise. In addition to neurologic infections, such patients are at risk of neurotoxic and neuroinflammatory complications related to immunomodulatory and immunosuppressive therapies. Early recognition of infectious and noninfectious complications of immunocompromise is essential to guide appropriate treatment, which can include antimicrobial therapy and, in some cases, withdrawal of the predisposing medication with a transition to an alternative regimen.

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.

Human herpesvirus 6 encephalitis in a patient treated with everolimus for renal cell carcinoma

INTRODUCTION

Everolimus is a mammalian target of rapamycin inhibitor and is approved as second-line treatment or beyond for renal cell carcinoma. We report a case of a 75-year-old male treated with everolimus for metastatic renal cell carcinoma, after sunitinib treatment, who was diagnosed with human herpesvirus 6 encephalitis.

CASE REPORT

After 39 months of everolimus, 10 mg per day, our patient was admitted with fever, consciousness disorders and a partial epileptic crisis. Laboratory tests revealed lymphopenia (170 lymphocytes/mm³), and polymerase chain reaction in cerebrospinal fluid was positive for human herpesvirus 6. Brain magnetic resonance imaging study demonstrated hippocampal abnormality and a pontine lesion.

MANAGEMENT AND OUTCOME

The patient stopped everolimus treatment indefinitely. He received ganciclovir initially intravenously, with a rapid clinical improvement, as well as polyvalent immunoglobulins were given to correct hypogammaglobulinemia. Two months later, antiviral therapy was switched to oral ganciclovir, which was never stopped. A new lumbar puncture was performed one month after the initiation of antiviral treatment, which did not reveal human herpesvirus 6 DNA anymore.

DISCUSSION

Human herpesvirus 6 encephalitis is more common in hematopoietic stem cell transplant recipients and HIV patients. This is the first case probably associated to everolimus treatment. In contrast to most patients diagnosed with this infection, who either die or develop neurologic sequelae, our patient almost fully recovered two months later.

Chromatin Profiles of Chromosomally Integrated Human Herpesvirus-6A

Human herpesvirus-6A (HHV-6A) and 6B (HHV-6B) are two closely related betaherpesviruses that are associated with various diseases including seizures and encephalitis. The HHV-6A/B genomes have been shown to be present in an integrated state in the telomeres of latently infected cells. In addition, integration of HHV-6A/B in germ cells has resulted in individuals harboring this inherited chromosomally integrated HHV-6A/B (iciHHV-6) in every cell of their body. Until now, the viral transcriptome and the epigenetic modifications that contribute to the silencing of the integrated virus genome remain elusive. In the current study, we used a patient-derived iciHHV-6A cell line to assess the global viral gene expression profile by RNA-seq, and the chromatin profiles by MNase-seq and ChIP-seq analyses. In addition, we investigated an in vitro generated cell line (293-HHV-6A) that expresses GFP upon the addition of agents commonly used to induce herpesvirus reactivation such as TPA. No viral gene expression including miRNAs was detected from the HHV-6A genomes, indicating that the integrated virus is transcriptionally silent. Intriguingly, upon stimulation of the 293-HHV-6A cell line with TPA, only foreign promoters in the virus genome were activated, while all HHV-6A promoters remained completely silenced. The transcriptional silencing of latent HHV-6A was further supported by MNase-seq results, which demonstrate that the latent viral genome resides in a highly condensed nucleosome-associated state. We further explored the enrichment profiles of histone modifications via ChIP-seq analysis. Our results indicated that the HHV-6 genome is modestly enriched with the repressive histone marks H3K9me3/H3K27me3 and does not possess the active histone modifications H3K27ac/H3K4me3. Overall, these results indicate that HHV-6 genomes reside in a condensed chromatin state, providing insight into the epigenetic mechanisms associated with the silencing of the integrated HHV-6A genome.

Human herpesvirus 6, 7, and 8 in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HHV-6A, HHV-6B, HHV-7, and HHV-8 in the pre- and post-transplant period. The majority of HHV-6 (A and B) and HHV-7 infections in transplant recipients are asymptomatic; symptomatic disease is reported infrequently across organs. Routine screening for HHV-6 and 7 DNAemia is not recommended in asymptomatic patients, nor is prophylaxis or preemptive therapy. Detection of viral nucleic acid by quantitative PCR in blood or CSF is the preferred method for diagnosis of HHV-6 and HHV-7 infection. The possibility of chromosomally integrated HHV-6 DNA should be considered in individuals with persistently high viral loads. Antiviral therapy should be initiated for HHV-6 encephalitis and should be considered for other manifestations of disease. HHV-8 causes Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman disease and is also associated with hemophagocytic syndrome and bone marrow failure. HHV-8 screening and monitoring may be indicated to prevent disease. Treatment of HHV-8 related disease centers on reduction of immunosuppression and conversion to sirolimus, while chemotherapy may be needed for unresponsive disease. The role of antiviral therapy for HHV-8 infection has not yet been defined.

Human Herpesvirus 6B in the Transplant Recipient: When to Worry, When to Act

Human herpesvirus 6B (HHV-6B) is a ubiquitous pathogen that infects most individuals before the age of three years. HHV-6B reactivates in approximately 40% of transplant recipients where it has been associated with a number of important outcomes, especially in allogeneic transplant recipients. This article will review the epidemiology, clinical manifestations, diagnosis, and treatment of HHV-6B infection.

Fatal outcome after reactivation of inherited chromosomally integrated HHV-6A (iciHHV-6A) transmitted through liver transplantation

HHV-6A and HHV-6B are found as inherited and chromosomally integrated forms (iciHHV-6A and -6B) into all germinal and somatic cells and vertically transmitted in a Mendelian manner in about 1% of the population. They were occasionally shown to be horizontally transmitted through hematopoietic stem cell transplantation. Here, we present a clinical case of horizontal transmission of iciHHV-6A from donor to recipient through liver transplantation. Molecular analysis performed on three viral genes (7.2 kb) in the recipient and donor samples supports transmission of iciHHV-6A from the graft. Transmission was followed by reactivation, with high viral loads in several compartments. The infection was uncontrollable, leading to severe disease and death, despite antiviral treatments and the absence of resistance mutations. This case highlights the fact that physicians should be aware of the possible horizontal transmission of iciHHV-6 and its consequences in case of reactivation in immunocompromised patients.

HHV-6 in liver transplantation: A literature review

Human herpesvirus 6 (HHV-6A and HHV-6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV-6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV-6 remains the gold standard for diagnosis of end-organ disease. HHV-6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV-6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue-invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV-6 (ciHHV-6), in either the recipient or the donor organ, may create confusion about systemic HHV-6 infection. Recipients with inherited ciHHV-6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV-6 infections in liver transplant recipients.

Cytomegalovirus and Other β-Herpesviruses

Cytomegalovirus (CMV), human herpes virus (HHV)-6, and HHV-7 are ubiquitous β-herpesviruses that can cause opportunistic infection and disease in kidney transplant recipients. Active CMV infection and disease are associated with acute allograft failure and death, and HHV-6 and HHV-7 replication are associated with CMV disease. CMV prevention strategies are used commonly after kidney transplantation, and include prophylaxis with antiviral medications and preemptive treatment upon the detection of asymptomatic viral replication in blood. Both approaches decrease CMV disease and allograft rejection, but CMV prophylaxis is preferred for high-risk patients because it is easy to administer and may be more effective in real-world settings. CMV disease commonly occurs even with current preventive strategies, whereas HHV-6 and HHV-7 diseases are rare. The clinical manifestations of CMV, HHV-6, and HHV-7 are nonspecific, and laboratory confirmation is essential to establishing diagnoses. Although nucleic acid testing has supplanted other diagnostic modalities given its high sensitivity and specificity, histopathologic examination sometimes is necessary to identify disease definitively. Ganciclovir and valganciclovir are the treatments of choice for CMV and HHV-6, and foscarnet can be used to treat HHV-7. Treatment duration should be informed by the initial severity of disease, and subsequent clinical and virologic responses.

Infectious encephalitis: Management without etiological diagnosis 48hours after onset

Introduction

The etiological diagnosis of infectious encephalitis is often not established 48 hours after onset. We aimed to review existing literature data before providing management guidelines.

Method

We performed a literature search on PubMed using filters such as “since 01/01/2000”, “human”, “adults”, “English or French”, and “clinical trial/review/guidelines”. We also used the Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”.

Results

With Mesh search terms “encephalitis/therapy” and “encephalitis/diagnosis”, we retrieved 223 and 258 articles, respectively. With search terms “encephalitis and corticosteroid”, we identified 38 articles, and with “encephalitis and doxycycline” without the above-mentioned filters we identified 85 articles. A total of 210 articles were included in the analysis.

Discussion

Etiological investigations must focus on recent travels, animal exposures, age, immunodeficiency, neurological damage characteristics, and potential extra-neurological signs. The interest of a diagnosis of encephalitis for which there is no specific treatment is also to discontinue any empirical treatments initially prescribed. Physicians must consider and search for autoimmune encephalitis.

Neurologic complications of transplantation

Major neurologic morbidity, such as seizures and encephalopathy, complicates 20-30% of organ and stem cell transplantation procedures. The majority of these disorders occur in the early posttransplant period, but recipients remain at risk for opportunistic infections and other nervous system disorders for many years. These long-term risks may be increasing as acute survival increases, and a greater number of "sicker" patients are exposed to long-term immunosuppression. Drug neurotoxicity accounts for a significant proportion of complications, with posterior reversible leukoencephalopathy syndrome, primarily associated with calcineurin inhibitors (i.e., cyclosporine and tacrolimus), being prominent as a cause of seizures and neurologic deficits. A thorough evaluation of any patient who develops neurologic symptoms after transplantation is mandatory, since reversible and treatable conditions could be found, and important prognostic information can be obtained.

Treatment of alpha and beta herpesvirus infections in solid organ transplant recipients

INTRODUCTION

Human herpesviruses frequently cause infections in solid organ transplant (SOT) recipients. Areas covered: We provide an overview of the clinical impact of alpha and beta herpesviruses and highlight the mechanisms of action, pharmacokinetics, clinical indications, and adverse effects of antiviral drugs for the management of herpes simplex virus, varicella zoster virus and cytomegalovirus. We comprehensively evaluated key clinical trials that led to drug approval, and served as the foundation for management guidelines. We further provide an update on investigational antiviral agents for alpha and beta herpesvirus infections after SOT. Expert commentary: The therapeutic armamentarium for herpes infections is limited by the emergence of drug resistance. There have been major efforts for discovery of new drugs against these viruses, but the results of early-phase clinical trials have been less than encouraging. We believe, however, that more antiviral drug options are needed given the adverse side effects associated with current antiviral agents, and the emergence of drug-resistant virus populations in SOT recipients. Likewise, optimized use and strategies are needed for existing and novel antiviral drugs against alpha and beta-herpesviruses in SOT recipients.

The Putative Role of Viruses, Bacteria, and Chronic Fungal Biotoxin Exposure in the Genesis of Intractable Fatigue Accompanied by Cognitive and Physical Disability

Patients who present with severe intractable apparently idiopathic fatigue accompanied by profound physical and or cognitive disability present a significant therapeutic challenge. The effect of psychological counseling is limited, with significant but very slight improvements in psychometric measures of fatigue and disability but no improvement on scientific measures of physical impairment compared to controls. Similarly, exercise regimes either produce significant, but practically unimportant, benefit or provoke symptom exacerbation. Many such patients are afforded the exclusionary, non-specific diagnosis of chronic fatigue syndrome if rudimentary testing fails to discover the cause of their symptoms. More sophisticated investigations often reveal the presence of a range of pathogens capable of establishing life-long infections with sophisticated immune evasion strategies, including Parvoviruses, HHV6, variants of Epstein-Barr, Cytomegalovirus, Mycoplasma, and Borrelia burgdorferi. Other patients have a history of chronic fungal or other biotoxin exposure. Herein, we explain the epigenetic factors that may render such individuals susceptible to the chronic pathology induced by such agents, how such agents induce pathology, and, indeed, how such pathology can persist and even amplify even when infections have cleared or when biotoxin exposure has ceased. The presence of active, reactivated, or even latent Herpes virus could be a potential source of intractable fatigue accompanied by profound physical and or cognitive disability in some patients, and the same may be true of persistent Parvovirus B12 and mycoplasma infection. A history of chronic mold exposure is a feasible explanation for such symptoms, as is the presence of B. burgdorferi. The complex tropism, life cycles, genetic variability, and low titer of many of these pathogens makes their detection in blood a challenge. Examination of lymphoid tissue or CSF in such circumstances may be warranted.

Roseoloviruses in transplant recipients: clinical consequences and prospects for treatment and prevention trials

Roseoloviruses frequently reactivate in transplant recipients. We review the impact of Roseoloviruses in transplant recipients and highlight research priorities. Human herpesvirus 6A (HHV-6A) and HHV-6B were recently classified as distinct species with important differences. Both viruses can result in inherited chromosomally integrated HHV-6, which may cause complications after transplant. HHV-6B is the primary species associated with disease and appears to have pleiotropic effects on the central nervous system. Small preemptive and prophylactic studies have not shown a statistically significant impact on HHV-6 disease. Although Roseoloviruses are associated with diverse complications in transplant patients, studies providing strong evidence for a causal role are lacking. Trials focusing on prevention and treatment will be important to inform the significance of Roseolovirus reactivation.

Encephalitis caused by human herpesvirus-6B in pancreas-after-kidney transplantation

Human herpesvirus-6 (HHV-6) is a common pathogen among children, classically presenting with fever and rash that resolves without specific therapy. HHV-6 can be reactivated in the immunosuppressed patient. After bone marrow and solid organ transplantation, HHV-6 has been linked to various clinical syndromes, including undifferentiated febrile illness, encephalitis, myelitis, hepatitis, pneumonitis, and bone marrow suppression. However, HHV-6 encephalitis after pancreatic transplant has rarely been reported. Early diagnosis and treatment of HHV-6 encephalitis may be important for affected patients. We report the case of a 53-year-old pancreas-after-kidney transplant recipient who initially presented with high fever and confusion 3 weeks after operation. We managed to save the patient's life and preserve the pancreas graft function. We also review previously reported cases of HHV-6B encephalitis in solid organ transplant recipients.

Coinfection of human herpesviruses 6A (HHV-6A) and HHV-6B as demonstrated by novel digital droplet PCR assay

The human herpesviruses HHV-6A and HHV-6B have been associated with various neurologic disorders partly due to the detection of elevated viral DNA levels in patients compared to controls. However the reported frequency of these viruses varies widely, likely reflecting differences in PCR methodologies used for detection. Digital droplet PCR (ddPCR) is a third generation PCR technology that enables the absolute quantification of target DNA molecules. Mounting evidence of the biological differences between HHV-6A and HHV-6B has led to their recent reclassification as separate species. As it is now especially relevant to investigate each virus, our objectives were to first design a multiplex HHV-6A and HHV-6B ddPCR assay and then to investigate the incidence of HHV-6A and HHV-6B coinfection in samples from healthy donors and patients with MS, a disease in which HHV-6 is thought to play a role. In our assessment of healthy donors, we observed a heretofore-underappreciated high frequency of coinfection in PBMC and serum, and found that our assay precisely detects both HHV-6A and HHV-6B chromosomally integrated virus, which has important implications in clinical settings. Interestingly, upon comparing the saliva from MS patients and healthy donors, we detected a significantly elevated frequency of coinfection in MS saliva; increased detection of HHV-6A in MS patients is consistent with other studies suggesting that this viral species (thought to be more neurotropic than HHV-6B) is more prevalent among MS patients compared to healthy donors. As the biology and disease associations between these two viral species differ, identifying and quantifying both species of HHV-6 may provide clinically relevant information, as well as enhance our understanding of the roles of each in health and disease.

Acute hepatitis with periportal confluent necrosis associated with human herpesvirus 6 infection in liver transplant patients

OBJECTIVES

To correlate human herpesvirus 6 (HHV-6) viral load with pathologic features in graft acute hepatitis of unknown origin.

METHODS

Liver frozen samples from 26 patients with graft hepatitis of unknown origin were available for HHV-6 DNA quantification.

RESULTS

In 10 (38.5%) of 26 liver samples, HHV-6 DNA was detectable, with a median viral load of 3.84 log10 copies/10⁶ cells. Confluent periportal necrosis was observed in 4 of 10 patients and associated with high viral load. These 4 patients responded to antiviral therapy. Mild unspecific hepatitis was observed in 4 patients with low intragraft viral load and in 2 patients with high viral load in a context of deep immunosuppression. Patients with HHV-6-negative graft hepatitis disclosed lobular necrotico-inflammatory activity without periportal necrosis.

CONCLUSIONS

Our study provides data supporting the pathogenic role of HHV-6 for liver allografts. The presence of confluent periportal necrosis could be a clue for prompt diagnosis of HHV-6-induced graft hepatitis.

Viral and paraneoplastic encephalitis in a patient with liver transplant with unilateral temporoparietal lobe abnormalities: a diagnostic challenge

We report a patient who recently had a liver transplant presented with increasing confusion and intermittent hallucinations. MRI of the brain revealed diffuse left temporal and parietal lobe swelling with cortical diffusion restriction suggestive of possible infectious aetiology, although stroke was also possible given the presence of left posterior cerebral arteries with fetal origin in the anterior circulation. An EEG demonstrated subclinical seizures, for which he was placed on an antiepileptic medication. Routine laboratory testing, lumbar puncture, serum and cerebrospinal fluid testing for viral and paraneoplastic encephalitis, and brain biopsy were performed on our patient. Our clinical diagnosis was viral encephalitis, and positive N-type voltage-gated calcium channel antibody titres were suggestive of paraneoplastic limbic encephalitis. Treatment with antiviral and antiepileptic medications for subclinical seizures resulted in the improvement of his mental status, language output and motor functioning.

Human herpesviruses 6, 7 and 8 in solid organ transplant recipients

Human herpesviruses (HHV) 6 and 7 are ubiquitous infections that reactivate commonly in transplant recipients. However, clinical diseases due to these viruses are reported only in 1% of solid organ transplant recipients. Fever, rash and bone marrow suppression are the most common manifestations, but symptoms of tissue invasive disease may be observed. Treatment of HHV-6 and HHV-7 disease includes antiviral therapy and cautious reduction in immunosuppression. HHV-8 is an oncogenic gamma-herpesvirus that causes Kaposi's sarcoma, Castleman's disease and primary effusion lymphomas in transplant recipients. Nonmalignant diseases such as bone marrow suppression and multiorgan failure have also been associated with HHV-8. Reduction in immunosuppression is the first line treatment of HHV-8 infection. Other alternatives for treatment, especially for HHV-8 diseases not responsive to immuno-minimization strategies, are surgery and chemotherapy. Sirolimus has been shown to be a beneficial component for the treatment of Kaposi's sarcoma and the role of antivirals for HHV-8 infection is being investigated.

Monitoring of active human herpes virus 6 infection in Iranian patients with different subtypes of multiple sclerosis

Background. Recently, it has been suggested that human herpes virus 6 (HHV6) may play a role in the pathogenesis of multiple sclerosis (MS). Our purpose is to determine the incidence of reactivated HHV6 in MS patients. Methods. Viral sequence analyzed by qPCR in the peripheral blood mononuclear cells (PBMCs), serum, and saliva samples of different subtypes of MS patients (n = 78) and healthy controls (n = 123). HHV6 IgG and IgM antibody levels measured by ELISA technique in the plasma samples of both groups. Likewise, cerebrospinal fluid (CSF) samples of some MS patients (n = 38) were analyzed for viral sequence. Results. Results demonstrate increased levels of anti-HHV6-IgG (78.2% versus 76.4% in controls; P = NS), and IgM (34.6% versus 6.5% in controls; P < 0.05) in MS patients. Furthermore, RRMS and SPMS patients showed relatively higher anti-HHV6 IgG and IgM compared to PPMS (P < 0.001). Moreover, load of cell-free viral DNA was higher in RRMS and SPMS patients and detected in 60.2% (47/78) of MS patients, compared with 14.6% (18/123) of healthy controls (P < 0.001). Moreover, load of cell-free viral DNA was higher in RRMS and SPMS patients and detected in 60.2% (47/78) of MS patients, compared with 14.6% (18/123) of healthy controls (P < 0.001). Conclusions. The results extend the observation of an increased frequency of systemic reactivated HHV6 infection in MS patients with developed stages of disease.

Human herpesvirus 6 (HHV-6) disease in the setting of transplantation

PURPOSE OF REVIEW

Human herpesvirus 6 (HHV-6) frequently reactivates after solid-organ and hematopoietic cell transplantation (HCT), and it has been associated with important outcomes in these settings. In 1-2% of recipients or donors, HHV-6 was inherited through chromosomal integration. Although HHV-6 chromosomal integration has not been associated with disease, the resulting very high levels of HHV-6 DNA in human tissue and blood samples can be challenging to interpret in the transplant setting. This review addresses the recent findings regarding the clinical outcomes associated with HHV-6 as well as diagnostic and therapeutic concerns.

RECENT FINDINGS

The evidence supports a causal association between HHV-6 and central nervous system disease. New studies have further characterized the impact of HHV-6 on the central nervous system. In addition, new studies have explored the associations between HHV-6 and other important outcomes. The implications of integrated HHV-6 in transplant recipients remain undefined, though the possibility of an association with organ rejection has been suggested. New exploratory data exist regarding the safety of antiviral prophylactic and preemptive strategies.

SUMMARY

Our understanding of the full clinical impact of HHV-6 in the transplant population remains incomplete. A large antiviral trial would not only help to further define causality between HHV-6 associated clinical outcomes but also start to define preventive strategies.

Human herpesvirus 6 and cytomegalovirus in ileocolonic mucosa in inflammatory bowel disease

OBJECTIVES

Reactivation of a latent cytomegalovirus (CMV) may occur in inflammatory bowel disease (IBD). Data of human herpesvirus 6 (HHV-6)--a close relative to CMV--in active IBD are scarce. The aim of this study was to detect HHV-6 and CMV antigens in the mucosa of active and inactive IBD.

MATERIAL AND METHODS

79 IBD patients (47 ulcerative colitis (UC) and 32 Crohn's disease (CD)) were recruited and endoscopic and histological disease activity was scored. Control group consisted of 15 non-IBD patients with normal colonoscopy. Immunohistochemical stainings for HHV-6B and CMV antigens were performed on biopsy specimens from the ileum and colorectum. The intensity of HHV-6B and CMV expression was graded as negative, mild, moderate, or intense.

RESULTS

HHV-6B antigen was positive in 35 (44%) and CMV in 64 (81%). Of controls, 6 (40%) were mildly positive for HHV-6 and 6 (40%) for CMV. In IBD, both CMV and HHV-6B intensity correlated with endoscopic disease severity (CMV p = 0.010 and HHV-6 p = 0.048). Simultaneous HHV-6B and CMV antigen expression occurred in 29 (37%) and associated with endoscopic activity (p = 0.006) and to a number of immunosuppressives (p = 0.033). A significant difference in HHV-6B positivity was found between endoscopically active and inactive UC (p = 0.040). Both CMV and HHV-6B intensity correlated with histological severity in the rectal biopsy specimens (for CMV p = 0.040 and for HHV-6B p = 0.027).

CONCLUSIONS

Both viruses occurred ubiquitously in the IBD mucosa. Coexistence of viruses was common and associated with disease activity and use of immunosuppressives. HHV-6B intensity correlated with endoscopic severity in UC.

Detection of HHV-6 in over a thousand samples: new types of infection revealed by an analysis of positive results

BACKGROUND

Clinical manifestations of human herpesvirus-6 (HHV-6) have not been clearly defined, and the role of HHV-6 in human disease remains to be fully elucidated.

OBJECTIVE

To determine the frequency of HHV-6 infections at Rennes Teaching Hospital and to describe all possible symptoms of such infections.

STUDY DESIGN

We systematically analyzed in a retrospective study all the samples between May 2003 and December 2004 from patients with HHV-6 by polymerase chain reaction (PCR). Clinical records of patients with positive HHV-6 PCR were recorded. Diagnosis of HHV-6 infection was accepted if all other possible diagnoses had been eliminated.

RESULTS

Over the study period, 1591 PCRs were performed from various tissues, including blood, cerebrospinal fluid, ascitis and tissue biopsies. Forty-three samples from 25 patients tested positive (3%). We describe three groups of clinical manifestations of HHV-6 infection. The first group consisted of neurological complications (32% of patients), including convulsions, encephalitis and chronic psychiatric disorders in immunocompetent patients. The second group consisted of clinical problems relating to gastrointestinal tract, which was found in 9 of our patients (36%). All of these patients were immunocompromised. Four of them presented colitis, and one of them died one month after liver transplantation because of this colitis. The last group of clinical symptoms was associated with maternal-fetal infection leading to abortion following HHV-6 seroconversion during pregnancy.

CONCLUSION

Three clinical types of HHV-6 infections are described: neurological manifestations including encephalitis in non-immunocompromised patients, digestive problems in immunosuppressed patients and severe maternal-fetal infection.

Emerging viruses in transplantation

PURPOSE OF REVIEW

Several viruses have recently gained importance for the transplant recipient. The purpose of this review is to give an update on emerging viruses in transplantation.

RECENT FINDINGS

BK virus-associated nephropathy (BKVAN) causes graft loss after kidney transplantation. Immunosuppression lowering strategies have now been shown to have benefit in decreasing the incidence of BKVAN. Guidelines for screening, prevention, and therapy have also been developed. Another polyomavirus, JC virus, is a cause of progressive multifocal leukoencephalopathy and has also gained prominence due to the increasing use of monoclonal antibodies in transplant recipients. The significance of human herpesvirus-6 and -7 continues to be debated in the literature, and new data is available on their association with clinical disease. Finally, newly discovered respiratory viruses, such as human metapneumovirus, bocavirus, KI and WU viruses, have also been described in transplant recipients. Human metapneumovirus appears to cause significant respiratory disease whereas the significance of bocavirus, KI and WU viruses in transplant recipients remains uncertain.

SUMMARY

Viral infections, such as polyomaviruses, human herpesvirus-6 and -7 and respiratory viruses, are emerging as causes of significant disease in transplantation. Antiviral options for these viruses are limited, and decreasing immunosuppression is the cornerstone of therapy.