Emergence of late cytomegalovirus central nervous system disease in hematopoietic stem cell transplant recipients

Dynamic findings of brain magnetic resonance imaging in a haploidentical hematopoietic stem cell transplantation recipient with cytomegalovirus ventriculoencephalitis: a case report and systematic review

Our case demonstrated unique cytomegalovirus (CMV) encephalitis post-haploidentical donor hematopoietic stem cell transplantation (HID-HSCT), with early findings on diffusion-weighted brain magnetic resonance imaging (MRI) in the absence of any neurologic symptoms. A 54-year-old Chinese man with acute lymphoblastic leukemia (Philadelphia chromosome-negative) underwent HID-HSCT. After HSCT, the patient developed CMV viremia and severe acute graft-versus-host disease. Recurrence of CMV viremia was observed. On day 129, brain MRI was performed to determine the cause for the intermittent fever. Diffusion-weighted imaging (DWI) revealed several bright spots in the cortex of the frontal lobes and anterior angle of the left lateral ventricle. Subsequently, he developed transplant-associated thrombotic microangiopathy, posterior reversible encephalopathy syndrome, and enlargement of lesions alongside the ventricular wall on a brain MRI series. Metagenomic next-generation sequencing (NGS) of the cerebrospinal fluid (CSF) led to the final diagnosis of CMV encephalitis. Although ganciclovir combined with foscarnet was administered, the patient's consciousness deteriorated, followed by respiratory failure. The patient died on day 198. Additionally, we performed a systematic review to comprehensively analyze this disease. Regarding treatment, immunological therapies, including virus-specific T cells from a third donor and CMV-cytotoxic T lymphocytes, may be more effective. This case report and systematic review underscores the complexities of managing CMV ventriculoencephalitis in HSCT recipients and emphasizes the importance of early diagnosis by brain MRI and CSF polymerase chain reaction or NGS and ongoing research in improving outcomes.

Clinical significance of late CMV disease in adult patients who underwent allogeneic stem cell transplant

INTRODUCTION

Late cytomegalovirus (CMV) disease, which was defined as CMV disease occurring >100 days post-transplant, remains an important complication among allogeneic stem cell transplant recipients, even now that the prophylactic strategy using ganciclovir preemptive therapy has been established. Due to the recent expansion of donor sources and conditioning regimens, it is therefore appropriate to reevaluate the incidence, risk factors, and clinical impacts of late CMV disease.

METHODS

This study included the 1295 adult patients, who underwent transplant for the first time from 2008 to 2015, without underlying disease relapse or CMV disease within 100 days post-transplant. There were no restrictions on underlying diseases or transplant procedures.

RESULTS

During the median follow-up period of 48.4 months, 21 patients developed late CMV disease and the 5-year cumulative incidence of late CMV disease was 1.6%. By multivariate analysis, haploidentical related donor, adult T-cell leukemia lymphoma, and preemptive therapy before 100 days post-transplant were extracted as independent risk factors. Late CMV disease negatively affected transplant outcomes, and was identified as an independent risk factor for the non-relapse mortality rate (hazard ratio 3.83, p < 0.001) and overall survival rate (hazard ratio 4.01, p < 0.001). Although 17 of 21 patients with late CMV disease died, the main causes of death were not related to CMV, except in three patients with CMV pneumonia.

CONCLUSIONS

Although the incidence of late CMV disease is low in transplant recipients, this complication negatively affects clinical courses. Therefore, transplant recipients with these risk factors should be more carefully managed.

Cutaneous presentation of disseminated cytomegalovirus infection in a non-transplant patient with hematological malignancy: A case report

RATIONALE

Cytomegalovirus (CMV) disease is relatively uncommon in nontransplant hematological patients. Moreover, cutaneous manifestations of CMV diseases have scarcely been reported and are probably under-recognized.

PATIENT CONCERNS

We describe a patient with large B-cell lymphoma who developed a band-form, erythematous lesion over his left abdomen soon after the second course of rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone chemotherapy.

DIAGNOSES

The lesion was initially mistaken for bacterial cellulitis or herpes zoster and was histologically confirmed as cutaneous CMV infection. Subsequent work-up also detected CMV viremia and the presence of CMV meningoencephalitis.

INTERVENTIONS

The patient was treated with ganciclovir plus CMV immune globulin followed by foscarnet.

OUTCOMES

Although the patient's cutaneous lesion resolved, his cognitive impairment did not recover, and he developed a fatal multi-organ failure 1 month later.

LESSONS

Cutaneous CMV disease can herald multisystem involvement and an unfavorable prognosis in immunocompromised hosts. It should be ruled out with biopsy in patients with hematological malignancy who have cutaneous lesions refractory to antibacterial therapy.

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.

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.

Standard treatment-refractory cytomegalovirus encephalitis unmasked by immune reconstitution inflammatory syndrome and successfully treated with virus-specific hyperimmune globulin

Objectives

Cytomegalovirus (CMV)‐related encephalitis is a rare but potentially life‐threatening complication of CMV infection in immunocompromised patients. The high mortality rate is associated with deficient immune system reconstitution after hematopoietic stem cell transplant (HSCT) and poor bioavailability of antiviral drugs in cerebrospinal fluid (CSF). CMV‐related central nervous system (CNS) infection may occur with aspecific symptoms, without evidence of either blood viral load or magnetic resonance imaging (MRI) signs of encephalitis.

Methods

Here, we describe a 10‐year‐old girl who underwent an allogeneic HSCT and subsequently developed CMV encephalitis. Because of the absence of CMV antigen in the blood, the diagnosis of encephalitis was proposed only after a delay, following the onset of immune reconstitution inflammatory syndrome (IRIS). Two months of combined dual antiviral therapy with ganciclovir and foscarnet proved ineffective against CMV and caused significant bone marrow and renal toxicity. To avoid further toxicity, the girl was given daily treatment with CMV‐hyperimmune globulins alone.

Results

After three weeks, the CSF viral load dropped significantly and was undetectable within three more weeks. In the meantime, the renal impairment resolved, and there was a complete bone marrow recovery.

Conclusion

We suggest that this patient succeeded in achieving CMV CSF clearance with high dose of CMV‐hyperimmune globulin, given alone, because of the ability of immunoglobulins to penetrate the blood–brain barrier (BBB).

Donor CMV-specific cytotoxic T lymphocytes successfully treated drug-resistant cytomegalovirus encephalitis after allogeneic hematopoietic stem cell transplantation

Background: Cytomegalovirus (CMV) infection of the central nervous system (CNS) is a rare but life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT).Cases presentation: Two patients with drug-resistant CMV encephalitis after allo-HSCT were successfully treated with donor CMV-specific cytotoxic T lymphocytes (CTLs). In the first case, a 27-year-old male who received haploidentical transplantation to treat T-cell acute lymphoblastic leukemia (T-ALL), developed CMV encephalitis during the time of the ganciclovir maintenance treatment. After intravenous foscarnet and donor CMV-specific CTLs, CMV-DNA of CSF became undetectable and the abnormal signs of brain magnetic resonance imaging (MRI) were limited. Another case, a 57-year-old female with acute myeloid leukemia (AML) who underwent haploidentical transplantation, also developed CMV encephalitis during the maintenance treatment of the ganciclovir. After administering donor CMV-specific CTLs intrathecally, the CMV load of the CSF decreased.Conclusions: The intravenous/intratheca administration of donor CMV-specific CTLs may be a safe and effective treatment for CMV encephalitis, especially for patients who suffered from drug-resistant CMV infection.

Resistant or refractory cytomegalovirus infections after hematopoietic cell transplantation: diagnosis and management

PURPOSE OF REVIEW

Refractory or resistant cytomegalovirus (CMV) infections are challenging complications after hematopoietic cell transplantation (HCT). Most refractory or resistant CMV infections are associated with poor outcomes and increased mortality. Prompt recognition of resistant or refractory CMV infections, understanding the resistance pathways, and the treatment options in HCT recipients are imperative.

RECENT FINDINGS

New definitions for refractory and resistant CMV infections in HCT recipients have been introduced for future clinical trials. Interestingly, refractory CMV infections are more commonly encountered in HCT recipients when compared with resistant CMV infections. CMV terminase complex mutations in UL56, UL89, and UL51 could be associated with letermovir resistance; specific mutations in UL56 are the most commonly encountered in clinical practice. Finally, brincidofovir, maribavir, letermovir, and CMV-specific cytotoxic T-cell therapy expanded our treatment options for refractory or resistant CMV infections.

SUMMARY

Many advances have been made to optimize future clinical trials for management of refractory or resistant CMV infections, and to better understand new resistance mechanisms to novel drugs. New drugs or strategies with limited toxicities are needed to improve outcomes of difficult to treat CMV infections in HCT recipients.

Compartmentalization of a Multidrug-Resistant Cytomegalovirus UL54 Mutant in a Stem Cell Transplant Recipient with Encephalitis

We report a case of cytomegalovirus encephalitis in a hematopoietic stem cell transplant recipient. A previously uncharacterized V787E mutation in UL54 was identified in cerebrospinal fluid but not plasma specimens. For the V787E recombinant virus, the half maximal effective concentrations for ganciclovir, foscarnet, and cidofovir were 8.6-, 3.4- and 2.9-fold higher than for wild-type virus, and the replicative capacity was lower. The introduction of a bulkier and negatively charged glutamate residue at position 787 could destabilize the finger domain of UL54 DNA polymerase. Viral genotyping of cerebrospinal fluid is warranted in subjects with cytomegalovirus encephalitis, owing to the low penetration of antivirals in this compartment.

The Cytomegalovirus Protein Kinase pUL97:Host Interactions, Regulatory Mechanisms and Antiviral Drug Targeting

Human cytomegalovirus (HCMV) expresses a variety of viral regulatory proteins that undergo close interaction with host factors including viral-cellular multiprotein complexes. The HCMV protein kinase pUL97 represents a viral cyclin-dependent kinase ortholog (vCDK) that determines the efficiency of HCMV replication via phosphorylation of viral and cellular substrates. A hierarchy of functional importance of individual pUL97-mediated phosphorylation events has been discussed; however, the most pronounced pUL97-dependent phenotype could be assigned to viral nuclear egress, as illustrated by deletion of the UL97 gene or pharmacological pUL97 inhibition. Despite earlier data pointing to a cyclin-independent functionality, experimental evidence increasingly emphasized the role of pUL97-cyclin complexes. Consequently, the knowledge about pUL97 involvement in host interaction, viral nuclear egress and additional replicative steps led to the postulation of pUL97 as an antiviral target. Indeed, validation experiments in vitro and in vivo confirmed the sustainability of this approach. Consequently, current investigations of pUL97 in antiviral treatment go beyond the known pUL97-mediated ganciclovir prodrug activation and henceforward include pUL97-specific kinase inhibitors. Among a number of interesting small molecules analyzed in experimental and preclinical stages, maribavir is presently investigated in clinical studies and, in the near future, might represent a first kinase inhibitor applied in the field of antiviral therapy.

Cytomegalovirus retinitis in children and adolescents with acute leukemia following allogeneic hematopoietic stem cell transplantation

Cytomegalovirus retinitis (CMVR) may occur after allogeneic hematopoietic stem cell transplantation (HSCT). However, little is known about its incidence, strategies for ophthalmic surveillance, and timely implementation of adequate antiviral treatment in pediatric allogeneic HSCT recipients. We provide a retrospective analysis of the epidemiology and clinical features of CMVR in pediatric allogeneic HSCT patients transplanted at our center over a 16-year period. Two patients of this cohort with leukemia are presented. Our analysis is supplemented by a systematic review on pediatric patients with leukemia and CMVR in the setting of allogeneic HSCT. The overall incidence of CMVR in our cohort was 1% (4/338) and 14.2% (3/21) in leukemic patients. In published cases, CMVR occurred at a median of 143 days after transplantation, and, in the majority of patients, was preceded by CMV detection in blood by a median of 93 days. Continued immune suppression following engraftment likely triggers CMVR. Preemptive treatment with ganciclovir as standard is usually successful. Foscarnet is used in case of resistance to ganciclovir or drug-induced granulocytopenia. Overall, CMVR after HSCT in pediatric leukemic patients is rare, but a potentially higher vulnerability of this population for involvement of the eye warrants a standardized ophthalmological examination plan.

Betaherpesvirus Complications and Management During Hematopoietic Stem Cell Transplantation

Two of the four betaherpesviruses, Cytomegalovirus (CMV) and human herpesvirus 6B (HHV-6B), play an important role in opportunistic infections in hematopoietic stem cell transplant (HSCT) recipients. These viruses are ubiquitous in humans and can latently infect mononuclear lymphocytes, complicating the diagnosis of the diseases they cause. Although the detection of viral DNA in a patient's peripheral blood by real-time PCR is widely used for monitoring viral infection, it is insufficient for the diagnosis of virus-associated disease. Theoretically, end-organ disease should be confirmed by detecting either viral antigen or significant amounts of viral DNA in a tissue sample obtained from the involved organ; however, this is often difficult to perform in clinical practice. The frequency of CMV-associated diseases has decreased gradually as a result of the introduction of preemptive or prophylactic treatments; however, CMV and HHV-6B infections remain a major problem in HSCT recipients. Measurement of viral DNA load in peripheral blood or plasma using real-time PCR is commonly used for monitoring these infections. Additionally, recent data suggest that an assessment of host immune response, particularly cytotoxic T-cell response, may be a reliable tool for predicting these viral infections. The antiviral drugs ganciclovir and foscarnet are used as first-line treatments; however, it is well known that these drugs have side effects, such as bone marrow suppression and nephrotoxicity. Further research is required to develop less-toxic antiviral drugs.

Epigenetically repressing human cytomegalovirus lytic infection and reactivation from latency in THP-1 model by targeting H3K9 and H3K27 histone demethylases

Human Cytomegalovirus (hCMV) infects a broad range of the population and establishes life-long latency in the infected individuals. Periodically the latently infected virus can reactivate and becomes a significant cause of morbidity and mortality in immunocompromised individuals. In latent infection, the viral genome is suppressed in a heterochromatic state and viral gene transcription is silenced. Upon reactivation, the repressive chromatin is remodeled to an active form, allowing viral lytic gene transcription, initiated by the expression of viral Immediate Early (IE) genes. During this process, a number of histone modification enzymes, including histone demethylases (HDMs), play important roles in driving IE expression, but the mechanisms involved are not fully understood. To get a better understanding of these mechanisms, we focused on two HDMs, KDM4 and KDM6, which reverse the repressive histone H3-lysine 9 and lysine 27 methylation, respectively. Our studies show that in lytic infection, both demethylases are important in the activation of viral IE gene expression. Simultaneous disruption of both via genetic or chemical methods leads to severely impaired viral IE gene expression and viral replication. Additionally, in an experimental latency-reactivation model in THP-1 cells, the KDM6 family member JMJD3 is induced upon viral reactivation and its knockdown resulted in reduced IE gene transcription. These findings suggest pharmacological inhibition of these HDMs may potentially block hCMV lytic infection and reactivation, and control the viral infection associated diseases, which are of significant unmet medical needs.

How I treat resistant cytomegalovirus infection in hematopoietic cell transplantation recipients

Cytomegalovirus (CMV) infection is a significant complication in hematopoietic cell transplantation (HCT) recipients. Four antiviral drugs are used for preventing or treating CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. With prolonged and repeated use of these drugs, CMV can become resistant to standard therapy, resulting in increased morbidity and mortality, especially in HCT recipients. Antiviral drug resistance should be suspected when CMV viremia (DNAemia or antigenemia) fails to improve or continue to increase after 2 weeks of appropriately dosed and delivered antiviral therapy. CMV resistance is diagnosed by detecting specific genetic mutations. UL97 mutations confer resistance to ganciclovir and valganciclovir, and a UL54 mutation confers multidrug resistance. Risk factors for resistance include prolonged or previous anti-CMV drug exposure or inadequate dosing, absorption, or bioavailability. Host risk factors include type of HCT and degree of immunosuppression. Depending on the genotyping results, multiple strategies can be adopted to treat resistant CMV infections, albeit no randomized clinical trials exist so far, after reducing immunosuppression (if possible): ganciclovir dose escalation, ganciclovir and foscarnet combination, and adjunct therapy such as CMV-specific cytotoxic T-lymphocyte infusions. Novel therapies such as maribavir, brincidofovir, and letermovir should be further studied for treatment of resistant CMV.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Cytomegalovirus infection in the bone marrow transplant patient

Cytomegalovirus (CMV) infection is an important contributor to the morbidity and mortality associated with bone marrow transplantation (BMT). Infection may lead to CMV disease involving multiple organs such as pneumonia, gastroenteritis, retinitis, central nervus system involvement and others. CMV seropositivity is an important risk factor and approximately half of BMT recipients will develop clinically significant infection most commonly in the first 100 d post-transplant. The commonly used tests to diagnose CMV infection in these patients include the pp65 antigenemia test and the CMV DNA polymerase chain reaction (PCR) assay. Because of its greater sensitivity and lesser turnaround time, the CMV PCR is nowadays the preferred test and serves as a main guide for pre-emptive therapy. Methods of CMV prevention include use of blood products from seronegative donors or leukodepleted products. Prophylaxis or pre-emptive therapy strategies for CMV prevention may be used post-transplant with the latter becoming more common. The commonly used antivirals for pre-emptive therapy and CMV disease management include intravenous gancyclovir and foscarnet. The role of intravenous immunoglobulin, although used commonly in CMV pneumonia is not clear.

Cytomegalovirus infection in transplant recipients

Cytomegalovirus infection is a frequent complication after transplantation. This infection occurs due to transmission from the transplanted organ, due to reactivation of latent infection, or after a primary infection in seronegative patients and can be defined as follows: latent infection, active infection, viral syndrome or invasive disease. This condition occurs mainly between 30 and 90 days after transplantation. In hematopoietic stem cell transplantation in particular, infection usually occurs within the first 30 days after transplantation and in the presence of graft-versus-host disease. The major risk factors are when the recipient is cytomegalovirus seronegative and the donor is seropositive as well as when lymphocyte-depleting antibodies are used. There are two methods for the diagnosis of cytomegalovirus infection: the pp65 antigenemia assay and polymerase chain reaction. Serology has no value for the diagnosis of active disease, whereas histology of the affected tissue and bronchoalveolar lavage analysis are useful in the diagnosis of invasive disease. Cytomegalovirus disease can be prevented by prophylaxis (the administration of antiviral drugs to all or to a subgroup of patients who are at higher risk of viral replication) or by preemptive therapy (the early diagnosis of viral replication before development of the disease and prescription of antiviral treatment to prevent the appearance of clinical disease). The drug used is intravenous or oral ganciclovir; oral valganciclovir; or, less frequently, valacyclovir. Prophylaxis should continue for 90 to 180 days. Treatment is always indicated in cytomegalovirus disease, and the gold-standard drug is intravenous ganciclovir. Treatment should be given for 2 to 3 weeks and should be continued for an additional 7 days after the first negative result for viremia.

Cytomegalovirus diseases after hematopoietic stem cell transplantation: a mini-review

Cytomegalovirus (CMV) infection remains a significant complication after hematopoietic stem cell transplantation (HSCT) and may have a deleterious impact on the overall outcome after transplantation. In addition to the direct effects of CMV infection, tissue-invasive CMV diseases may be associated with increased risk of graft versus host disease, myelosuppression, and invasive bacterial and fungal infections. Because of these direct and indirect adverse effects, prevention of CMV infection, mostly through pre-emptive therapy, is one of the essential strategies that may improve outcomes of HSCT recipients. Management of CMV infection relies mainly on intravenous (IV) antiviral therapy with ganciclovir and foscarnet, with or without IV polyclonal immunoglobulins. Although viral resistance remains rare, better tolerated antiviral agents with less serious side effects are needed, and a few will be evaluated in phase III clinical trials in the near future.

Temporal and spatial compartmentalization of drug-resistant cytomegalovirus (CMV) in a child with CMV meningoencephalitis: implications for sampling in molecular diagnosis

We describe a case of antiviral-resistant cytomegalovirus meningoencephalitis occurring after hematopoietic stem cell transplantation. Antiviral-resistant cytomegalovirus was identified in blood 16 months earlier. However, wild-type cytomegalovirus was evidenced in blood when the meningoencephalitis was diagnosed. Treatment of meningoencephalitis should be adapted to all previously identified resistance mutations in any compartment.

Differential outcome of neurological HCMV infection in two hematopoietic stem cell transplant recipients

BACKGROUND

Human cytomegalovirus (HCMV) infection of the central nervous system (CNS) is a rare but life threatening condition which may follow hematopoietic stem cell transplantation. Diagnosis, monitoring and treatment approaches rely on anecdotal reports.

CASE PRESENTATIONS

The different outcomes of HCMV CNS disease in an adult and a pediatric T-cell depleted hematopoietic stem cell transplant (HSCT) recipient are reported. In the first case, HCMV encephalitis emerged in the context of simultaneous impairment of the T- and B-cell immunity. Antiviral treatment only reduced viral load in peripheral blood and the patient died. In the second case, an HCMV radiculopathy was observed and antiviral treatment was adjusted on the basis of intrathecal drug level. In addition, donor HCMV-specific cytotoxic T lymphocytes (CTLs) were infused. Viral load in the CNS decreased and the patient recovered from the acute event. In neither case were drug-resistant HCMV variants observed in blood or CNS samples.

CONCLUSIONS

T-cell depleted HSCT appears a predisposing condition for CNS HCMV infection since never observed in other HSCT recipients at our center in the last 15 years. Intensive diagnostic approaches and timely aggressive combination treatments might improve clinical outcome in these patients.

Regulatory roles of protein kinases in cytomegalovirus replication

Viral replication is a complex process relying on a network of interacting viral and cellular proteins, in which particularly protein kinases play an important regulatory role. The specific phosphorylation of substrate proteins induces activation, inactivation, or other functional modification and thus determines virus-host cell interregulation. During herpesviral infections, both viral and cellular protein kinases are expressed and provide activities crucial for the efficiency of virus replication. The protein kinase pUL97 encoded by human cytomegalovirus (HCMV) is a multifunctional regulatory enzyme which exerts strong regulatory effects on early and late steps of the viral replication cycle. A number of interacting proteins and substrates of pUL97 have been described, including retinoblastoma (Rb) protein, nuclear lamins and viral pUL69. Recently, it was demonstrated that pUL97 has structural and functional resemblance to cyclin-dependent protein kinases (CDKs) and thus represents a CDK ortholog. pUL97 can phosphorylate and inactivate Rb, resulting in a stimulation of cell cycle progression. In addition, the association of pUL97 activity with nucleocytoplasmic export of viral capsids has been demonstrated by several investigators. We could show that pUL97 is able to phosphorylate nuclear lamins and to contribute to the HCMV-induced reorganization of the nuclear lamina. On the basis of very recent findings, it is becoming increasingly clear that pUL97 is a component of a multiprotein nuclear egress complex (NEC). The NEC contains a small number of egress proteins involved in the recruitment of protein kinases, such as pUL97 and cellular protein kinase C (PKC), to specific sites of the nuclear lamina. Current information about the composition, function, and regulatory complexity of the NEC leads to a mechanistic concept which may set the key features of HCMV nuclear egress in a new light.

Compartmentalization of acyclovir-resistant varicella zoster virus: implications for sampling in molecular diagnostics

BACKGROUND

Acyclovir resistance of varicella zoster virus (VZV) may arise in stem cell transplant (SCT) recipients with VZV disease and is usually a result of mutations in VZV thymidine kinase (TK), which is the target protein of acyclovir. Early detection of such mutations is necessary to enable timely therapy adaptation, for example, to foscarnet. We aimed to investigate whether TK mutations arise over time, and what sample types might be the most useful for this method.

METHODS

Spatially and temporally distinct samples from 3 SCT recipients with VZV disease unresponsive to acyclovir treatment were retrospectively investigated for the presence of TK mutations by polymerase chain reaction and sequence analysis.

RESULTS

In all 3 patients, a mutation in the VZV TK coding region was found resulting in an amino acid substitution. TK mutations were not only temporally but also spatially compartmentalized. In particular, plasma samples frequently showed wild-type TK sequences, whereas cerebrospinal fluid or skin vesicle fluid acquired on the same day contained mutant sequences.

CONCLUSIONS

This study shows the importance of careful sampling for molecular diagnostics of acyclovir resistance in VZV disease. All affected body sites should be sampled and plasma samples may not be representative for the viral mutation status.

Mass spectrometry-based comparative sequencing to detect ganciclovir resistance in the UL97 gene of human cytomegalovirus

BACKGROUND

Persistent infections with herpesviruses such as human cytomegalovirus (HCMV) frequently occur after solid organ or stem cell transplantation, and are due to either failure of the host to immunologically control the virus or emerging resistance of the virus to the antiviral drug(s) used. Antiviral therapy can be guided by viral drug susceptibility testing based on screening for known resistance-inducing mutations in the viral genome. Mass spectrometry-based comparative sequence analysis (MSCSA) might be advantageous for this purpose because of its suitability for semi-automation.

OBJECTIVES

The applicability of MSCSA to detect sequence polymorphisms and drug resistance-inducing mutations in the HCMV genome was investigated.

STUDY DESIGN

We analyzed the 3' part of the HCMV UL97 gene, which encodes the kinase that is activated by the commonly used anti-HCMV drug ganciclovir. Sequences obtained by MSCSA of material from HCMV-infected patients (43 samples) and the HCMV type strain were compared to conventional cycle sequencing results.

RESULTS

In 94.1% of all samples the results obtained by MSCSA of the UL97 gene were identical to those from conventional cycle sequencing. The threshold to detect mutant sequences in a mixture with wild-type material was 20% using either technique. Furthermore, MSCSA was successfully applied to study the development of drug resistance in a patient who developed encephalitis due to ganciclovir-resistant HCMV.

CONCLUSIONS

MSCSA was found to be equally accurate compared to conventional cycle sequencing in the analysis of UL97 of HCMV.

Human cytomegalovirus UL97 kinase and nonkinase functions mediate viral cytoplasmic secondary envelopment

Previous studies have revealed critical roles for the human cytomegalovirus (HCMV) UL97 kinase in viral nuclear maturation events. We have shown recently that UL97 affects the morphology of the viral cytoplasmic assembly compartment (AC) (M. Azzeh, A. Honigman, A. Taraboulos, A. Rouvinski, and D. G. Wolf, Virology 354:69-79, 2006). Here, we employed a comprehensive ultrastructural analysis to dissect the impact of UL97 on cytoplasmic steps of HCMV assembly. Using UL97 deletion (ΔUL97) and kinase-null (K355M) mutants, as well as the UL97 kinase inhibitor NGIC-I, we demonstrated that the loss of UL97 kinase activity resulted in a unique combination of cytoplasmic features: (i) the formation of pp65-rich aberrant cytoplasmic tegument aggregates, (ii) distorted intracytoplasmic membranes, which replaced the normal architecture of the AC, and (iv) a paucity of cytoplasmic tegumented capsids and dense bodies (DBs). We further showed that these abnormal assembly intermediates did not result from impaired nuclear capsid maturation and egress per se by using 2-bromo-5,6-dichloro-1-(β-d-ribofuranosyl) benzimidizole (BDCRB) to induce the artificial inhibition of nuclear maturation and the nucleocytoplasmic translocation of capsids. The specific abrogation of UL97 kinase activity under low-multiplicity-of-infection conditions resulted in the improved release of extracellular virus compared to that of ΔUL97, despite similar rates of viral DNA accumulation and similar effects on nuclear capsid maturation and egress. The only ultrastructural correlate of the growth difference was a higher number of cytoplasmic DBs, tegumented capsids, and clustered viral particles observed upon the specific abrogation of UL97 kinase activity compared to that of ΔUL97. These combined findings reveal a novel role for UL97 in HCMV cytoplasmic secondary envelopment steps, with a further distinction of kinase-mediated function in the formation of the virus-induced AC and a nonkinase function enhancing the efficacy of viral tegumentation and release.

CMV central nervous system disease in stem-cell transplant recipients: an increasing complication of drug-resistant CMV infection and protracted immunodeficiency

We report on two patients with no active GVHD and on moderate doses of immunosuppressive drugs who unexpectedly developed fatal CMV meningoencephalitis after umbilical cord blood transplantation. A review of these two cases along with nine other cases of CMV central nervous system (CNS) disease after allogeneic SCT that were mostly reported within the last 8 years suggests that this severe complication of CMV infection may be increasing. CMV CNS disease after allogeneic SCT is a late-onset disease (median time of onset, 210 days) and is usually manifested as encephalitis in the absence of other sites of CMV disease. The development of CMV CNS disease is associated with risk factors (T-cell depletion, anti-thymocyte globulin, umbilical cord blood transplantation) that cause severe and protracted T-cell immunodeficiency (8 of 11 cases), a history of recurrent CMV viremia treated with multiple courses of preemptive ganciclovir or foscarnet therapy (11 of 11 cases), and ganciclovir-resistant CMV infection (11 of 11 cases). Despite therapy with a combination of antiviral drugs (ganciclovir, foscarnet and cidofovir), mortality is high (10 of 11 cases). Given this high mortality, extended prophylaxis with current or novel antiviral drugs and strategies to enhance CMV immunity need to be considered in high-risk patients.

Molecular targets for antiviral therapy of cytomegalovirus infections

Human cytomegalovirus infections are still associated with severe morbidity and mortality in immunocompromised individuals, despite the availability of five drugs that are currently licensed for antiviral therapy. Furthermore, human cytomegalovirus is the most frequent cause of congenital infections for which antiviral treatment options are very limited. Thus, the need for a potent, safe and well-tolerated antiviral drug remains. This review focuses on target molecules that are implicated in the development of innovative anticytomegaloviral approaches, such as viral immediate-early and DNA replication proteins, as well as regulatory protein kinases. Special emphasis is given to promising host factors, in particular the receptor tyrosine kinase PDGF and cyclin-dependent protein kinases, since a combined targeting of viral and cellular factors that are critical for viral replication may alleviate the emergence of drug-resistant virus variants.

Analysis of human cytomegalovirus-encoded microRNA activity during infection

MicroRNAs (miRNAs) are expressed in a wide variety of organisms, ranging from plants to animals, and are key posttranscriptional regulators of gene expression. Virally encoded miRNAs are unique in that they could potentially target both viral and host genes. Indeed, we have previously demonstrated that a human cytomegalovirus (HCMV)-encoded miRNA, miR-UL112, downregulates the expression of a host immune gene, MICB. Remarkably, it was shown that the same miRNA also downregulates immediate-early viral genes and that its ectopic expression resulted in reduced viral replication and viral titers. The targets for most of the viral miRNAs, and hence their functions, are still unknown. Here we demonstrate that miR-UL112 also targets the UL114 gene, and we present evidence that the reduction of UL114 by miR-UL112 reduces its activity as uracil DNA glycosylase but only minimally affects virus growth. In addition, we show that two additional HCMV-encoded miRNAs, miR-US25-1 and miR-US25-2, reduce the viral replication and DNA synthesis not only of HCMV but also of other viruses, suggesting that these two miRNAs target cellular genes that are essential for virus growth. Thus, we suggest that in addition to miR-UL112, two additional HCMV miRNAs control the life cycle of the virus.

Case report: persistent cytomegalovirus (CMV) infection after haploidentical hematopoietic stem cell transplantation using in vivo alemtuzumab: emergence of resistant CMV due to mutations in the UL97 and UL54 genes

Addition of in vivo alemtuzumab to the conditioning regimen enabled 2- or 3-locus-mismatched hematopoietic stem cell transplantation with an acceptable incidence of graft-versus-host-disease. However, the procedure was associated with a high incidence of cytomegalovirus (CMV) reactivation. Although preemptive therapy with ganciclovir prevented successfully severe CMV diseases and CMV-related mortality, a patient developed persistent positive CMV antigenemia for more than 1 year after transplantation and CMV disease, despite the use of ganciclovir and foscarnet. The in vitro susceptibility assay showed that the clinical isolate was resistant to foscarnet, moderately resistant to ganciclovir, but sensitive to cidofovir. Therefore, cidofovir was administered. CMV antigenemia became negative within 2 weeks and never developed again. Nucleotide sequence of the UL54 and UL97 of the clinical isolate showed 4 amino acid substitutions (V11L, Q578H, S655L, and G874R) in UL54 and 2 mutations (A140V and A594V) in UL97 compared with the Towne and AD169 strains. Ganciclovir resistance was suspected to be caused by both A594V of UL97 and Q578H of UL54, whereas foscarnet resistance was due mainly to Q578H of UL54. In conclusion, the in vitro susceptibility assay as well as nucleotide sequence of clinical isolate is important to choose appropriate antiviral agents for patients who have persistent CMV reactivation after stem cell transplantation.

Cytomegalovirus UL97 mutations in the era of ganciclovir and maribavir

Mutations in the human CMV UL97 kinase gene are a major mechanism of viral resistance to two anti-CMV drugs, ganciclovir (GCV) and maribavir (MBV). GCV, the most widely used and established therapy for CMV, is a substrate for the UL97 kinase. Well-characterised GCV-resistance mutations at UL97 codons 460, 520 and 590-607 impair the phosphorylation of GCV that is necessary for its antiviral activity, presumably by altering substrate recognition. In contrast, MBV is an inhibitor of the UL97 kinase and is the first new CMV therapy to reach later stage clinical trials in many years. No MBV-resistant CMV isolates have yet been detected in clinical trials, but after culture propagation under drug, UL97 mutations that confer moderate to high-level MBV resistance have been identified at codons 353, 397, 409 and 411. These mutations are located upstream of the GCV-resistance mutations and are close to the ATP-binding and catalytic domains common to all kinases, consistent with MBV acting as a small molecule ATP-competitive kinase inhibitor. So far, no UL97 mutations are known to confer resistance to both GCV and MBV.

Artesunate as a potent antiviral agent in a patient with late drug-resistant cytomegalovirus infection after hematopoietic stem cell transplantation

This is the first report of treatment of cytomegalovirus infection with artesunate, for a stem cell transplant recipient with a newly identified foscarnet-resistant and ganciclovir-resistant DNA polymerase L776M mutation. Artesunate treatment resulted in a 1.7-2.1-log reduction in viral load by treatment day 7, with a viral half-life of 0.9-1.9 days, indicating a highly effective block in viral replication.

Viral monitoring and successful treatment of a ganciclovir-resistant cytomegalovirus infection in a heart transplant recipient

We reported a ganciclovir (GCV)-resistant cytomegalovirus (CMV) infection in a heart transplant recipient. Genotypic and phenotypic susceptibility assays demonstrated an A594V mutation in the UL97 phosphotransferase gene and GCV IC(50)>96 microM. Low GCV concentration exposure, immunosuppressive treatment, donor-positive/recipient-negative CMV serostatus, viral reactivations within antiviral prophylaxis or treatment, contributed to GCV-resistant strain selection.

Extralymphatic virus sanctuaries as a consequence of potent T-cell activation

T helper cells can support the functions of CD8(+) T cells against persistently infecting viruses such as murine lymphocytic choriomeningitis virus (LCMV), cytomegalovirus, hepatitis C virus and HIV. These viruses often resist complete elimination and remain detectable at sanctuary sites, such as the kidneys and other extralymphatic organs. The mechanisms underlying this persistence are not well understood. Here we show that mice with potent virus-specific T-cell responses have reduced levels and delayed formation of neutralizing antibodies, and these mice fail to clear LCMV from extralymphatic epithelia. Transfer of virus-specific B cells but not virus-specific T cells augmented virus clearance from persistent sites. Virus elimination from the kidneys was associated with the formation of IgG deposits in the interstitial space, presumably from kidney-infiltrating B cells. CD8(+) T cells in the kidneys of mice that did not clear virus from this site were activated but showed evidence of exhaustion. Thus, we conclude that in this model of infection, site-specific virus persistence develops as a consequence of potent immune activation coupled with reductions in virus-specific neutralizing antibodies. Our results suggest that sanctuary-site formation depends both on organ anatomy and on the induction of different adaptive immune effector mechanisms. Boosting T-cell responses alone may not reduce virus persistence.

Surveillance of cytomegalovirus (CMV) DNAemia in pediatric allogeneic stem cell transplantation: incidence and outcome of CMV infection and disease

Cytomegalovirus (CMV) remains a serious problem after hematopoietic stem cell transplantation (HSCT). To investigate the incidence of CMV infection and outcome we retrospectively analyzed 70 consecutive pediatric allogeneic HSCTs monitored by CMV polymerase chain reaction (PCR), with at least 1-year follow-up or until death. All patients at risk for CMV infection (CMV-seropositive patients and CMV-seronegative recipients transplanted from CMV-seropositive donors) received hyperimmune anti-CMV globulins whereas in the group of HSCT patients with both donor and recipient CMV negativity, polyvalent immunoglobulins were given, both at a dose of 400 mg/kg. All patients received acyclovir at prophylactic doses for at least 6 months. Patients were monitored twice a week by CMV PCR. Patients with 2 positive results for CMV DNAemia received ganciclovir for 14 days and continued until 2 consecutive negative results were obtained. The incidence of CMV DNAemia was 12.8% (9/70) in the whole group, with significant higher risk for patients with CMV-seropositive recipient status, 8 out of 22 (36%), vs. patients with seronegative status, 1 out of 48 (2%) (P=0.0002). Three out of 9 patients with DNAemia developed CMV disease despite adequate preemptive treatment. The transplant-related mortality was higher in the CMV-seropositive recipient group (P=0.05). Age, use of hyperimmune anti-CMV globulins at a high dose, and the low incidence of graft-versus-host disease might be contributing factors to this low incidence.

Pulmonary complications of haematopoietic cell transplantation in children

Paediatric haematopoietic cell transplantation has experienced significant advances in the last few decades. However, pulmonary complications are an important limitation to the efficacy of this intervention, contributing to post-transplantation morbidity and mortality. Such complications persist even in experienced centres and occur in adult and paediatric recipients. This review identifies the paediatric pulmonary complications that are commonly seen following haematopoietic cell transplantation and addresses both infectious and non-infectious aetiologies and their clinical manifestations, evaluation, and potential therapy. Ultimately, improvement in outcomes will require attention to immunosuppression as well as traditional diagnostic procedures and treatment. This article aims to review the current state of pulmonary complications post-transplantation, to examine the impact of our recent advances and changes in treatment, and to identify potential future therapies and hypothesise what role these might have on long-term survival.

The emergence of cytomegalovirus resistance to ganciclovir therapy in kidney transplant recipients

Transplant recipients that have not been previously exposed to the cytomegalovirus (CMV) are highly susceptible to viral diseases while under immunosuppression therapy. CMV disease requires prolonged therapy, facilitating the emergence of resistant strains. Persistence of positive antigenemia represents clinical evidence of the presence of resistant strains, although its frequency is unknown. These strains may present amino acid deletions or substitutions in conserved regions of the UL97 protein, point mutations in the DNA polymerase (UL54), or both. In this study we aimed to analyze the prevalence of mutations associated with ganciclovir resistance in transplant recipients. Fifteen kidney transplant recipients and four kidney-pancreas transplant recipients, with a positive and oscillating CMV viremia detected by sequential antigenemia test, were enrolled. The UL97 gene was amplified by Nested-PCR and enzymatically digested in samples of these patients in order to detect mutations in the most common codons, such as 460 (M460V), 594 (A594V) and 595(L595S/F). The end-product fragments were further sequenced. Nine (47.4%) out of 19 patients presented with mutations in UL97 at codons L595S (55.6%), A594V (11.1%), A595F/A594V (11.1%) and L595S/A594V (22.2%). None presented with mutation at the M460V codon. Renal transplant patients with oscillation in viral load for more than 2 weeks might have developed viral resistance to anti-drug therapy. Its detection might aid physicians in their clinical plan of tapering the patient's immunosuppression.

Guillain-Barre syndrome associated with cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation

The association between cytomegalovirus (CMV) infection and the development of Guillain-Barré syndrome (GBS) in the setting of allogeneic hematopoietic stem cell transplantation (alloSCT) has been reported only occasionally. We describe here a 23-year-old patient diagnosed with acute myelogenous leukemia who underwent a partially HLA-mismatched alloSCT and soon after developed GBS along with a CMV infection. Serum autoantibodies to several ganglioside antigens were concomitantly detected. Despite therapy with ganciclovir and plasma exchanges, the patient's clinical condition rapidly deteriorated, and he died 3 weeks later with persisting CMV antigenemia. Although a coincidental association cannot be excluded, it could be speculated that a pathogenetic link exists between the 2 disorders. In this sense, molecular mimicry between viral antigens and neural host tissues could be postulated as the hypothetical mechanism underlying the triggering of the autoimmune disease in the present case.

Inhibition of the NKp30 activating receptor by pp65 of human cytomegalovirus

Human cytomegalovirus, a chief pathogen in immunocompromised people, can persist in a healthy immunocompetent host throughout life without being eliminated by the immune system. Here we show that pp65, the main tegument protein of human cytomegalovirus, inhibited natural killer cell cytotoxicity by an interaction with the activating receptor NKp30. This interaction was direct and specific, leading to dissociation of the linked CD3zeta from NKp30 and, consequently, to reduced killing. Thus, pp65 is a ligand for the NKp30 receptor and demonstrates a unique mechanism by which an intracellular viral protein causes general suppression of natural killer cell cytotoxicity by specific interaction with an activating receptor.

How evolution of mutations conferring drug resistance affects viral dynamics and clinical outcomes of cytomegalovirus-infected hematopoietic cell transplant recipients

Infection with cytomegalovirus (CMV) remains a significant cause of morbidity and mortality among hematopoietic cell transplant (HCT) recipients. We describe two pediatric HCT recipients who developed persistent and severe drug-resistant CMV infections. CMV resistance to foscarnet and ganciclovir was detected after only 6 and 11 weeks of therapy, respectively. Viral pol mutations associated with drug resistance in these patients included T838A (a novel mutation) and D588N, which were shown by marker transfer to confer foscarnet and multidrug resistance, respectively. Each of these mutations significantly reduced in vitro replication of CMV, suggesting that they may decrease viral fitness. This finding was further supported by the disappearance of mutations upon withdrawal of antiviral pressure in one patient. Novel antivirals or combination therapy may be required for the treatment of drug-resistant CMV in HCT recipients and perhaps in other severely immunocompromised patients.

Emergence and compartmentalization of fatal multi-drug-resistant cytomegalovirus infection in a patient with autosomal-recessive severe combined immune deficiency

The authors describe a patient with autosomal-recessive severe combined immunodeficiency (SCID) with severe, multiorgan cytomegalovirus (CMV) disease. In the face of appropriate therapy, the patient developed a 100-fold gradient in viral load across the blood-brain barrier. Disseminated disease, including pneumonitis, contributed to a fatal outcome. Serial genotypic analyses revealed multiple UL97 and UL54 (DNA polymerase) mutations that conferred phenotypic resistance to all currently licensed systemic CMV antivirals.

Natural polymorphism of cytomegalovirus DNA polymerase lies in two nonconserved regions located between domains delta-C and II and between domains III and I

We described the natural polymorphism of cytomegalovirus DNA polymerase in 42 unrelated isolates susceptible to ganciclovir, foscarnet, and cidofovir. All variations, including an eight-amino-acid deletion, were located between domains delta-C and II and between domains III and I, suggesting that these specific residues are not involved in enzymatic functions.

Recent advances in the prevention of CMV infection and disease after hematopoietic stem cell transplantation

Cytomegalovirus (CMV) remains an important pathogen in hematopoietic stem cell transplant (HCT) recipients in the current era of antiviral prophylaxis and preemptive therapy, despite the almost complete elimination of CMV disease during the first 3 months after transplantation. Pretransplant CMV serostatus of the donor and/or recipient remains an important risk factor for poor post-transplant outcome, especially in highly immunodeficient patients (e.g. recipients of ex vivo or in vivo T-cell depletion). Prevention of late CMV disease continues to be a challenge in selected high-risk populations, and indirect immunomodulatory effects of CMV (e.g. invasive bacterial and fungal infections) appear to contribute to the poor outcome. The risk of developing antiviral resistance remains low in most patients; however, in a setting of intense immunosuppression (e.g. after transplantation from a haploidentical donor) the incidence may be as high as 8%. Transfusion-transmitted CMV infection can be reduced by the provision of seronegative or leukocyte-depleted blood products; however, a small risk of 1-2% of CMV disease remains. Surveillance and preemptive therapy is effective in preventing transfusion-related CMV disease. The development of new drugs and immunologic strategies (adoptive transfer of CMV-specific T-cells and donor/recipient vaccination strategies) are important goals for the elimination of the negative impact of CMV in the HCT setting.

Late cytomegalovirus polyradiculopathy following haploidentical CD34+-selected hematopoietic stem cell transplantation

A 55-year-old man with acute myeloid leukemia in second relapse presented 4 months after haploidentical CD34+-selected hematopoietic stem cell transplantation (HSCT) with symmetric, progressive neurological deficits of the lower extremities. Although there was no molecular evidence for drug resistance in the cerebral-spinal fluid, antiviral combination therapy failed to control the rapidly progressing CMV polyradiculopathy (PRP) and encephalitis, which were confirmed by autopsy studies. Late CMV PRP as an unusual manifestation of CMV disease should be kept in mind in patients with suggestive neurological symptoms after HSCT.