JC virus DNA load in patients with and without progressive multifocal leukoencephalopathy

Biomarkers for progressive multifocal leukoencephalopathy: emerging data for use of JC virus DNA copy number in clinical trials

Progressive multifocal leukoencephalopathy is a rare but devastating demyelinating disease caused by the JC virus (JCV), for which no therapeutics are approved. To make progress towards addressing this unmet medical need, innovations in clinical trial design are needed. Quantitative JCV DNA in CSF has the potential to serve as a valuable biomarker of progressive multifocal leukoencephalopathy disease and treatment response in clinical trials to expedite therapeutic development, as do neuroimaging and other fluid biomarkers such as neurofilament light chain. Specifically, JCV DNA in CSF could be used in clinical trials as an entry criterion, stratification factor, or predictor of clinical outcomes. Insights from the investigation of candidate biomarkers for progressive multifocal leukoencephalopathy might inform approaches to biomarker development for other rare diseases.

Polyomavirus Wakes Up and Chooses Neurovirulence

JC polyomavirus (JCPyV) is a human-specific polyomavirus that establishes a silent lifelong infection in multiple peripheral organs, predominantly those of the urinary tract, of immunocompetent individuals. In immunocompromised settings, however, JCPyV can infiltrate the central nervous system (CNS), where it causes several encephalopathies of high morbidity and mortality. JCPyV-induced progressive multifocal leukoencephalopathy (PML), a devastating demyelinating brain disease, was an AIDS-defining illness before antiretroviral therapy that has "reemerged" as a complication of immunomodulating and chemotherapeutic agents. No effective anti-polyomavirus therapeutics are currently available. How depressed immune status sets the stage for JCPyV resurgence in the urinary tract, how the virus evades pre-existing antiviral antibodies to become viremic, and where/how it enters the CNS are incompletely understood. Addressing these questions requires a tractable animal model of JCPyV CNS infection. Although no animal model can replicate all aspects of any human disease, mouse polyomavirus (MuPyV) in mice and JCPyV in humans share key features of peripheral and CNS infection and antiviral immunity. In this review, we discuss the evidence suggesting how JCPyV migrates from the periphery to the CNS, innate and adaptive immune responses to polyomavirus infection, and how the MuPyV-mouse model provides insights into the pathogenesis of JCPyV CNS disease.

[Reactivation of latent viruses in Neurology]

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

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.

Two susceptible HLA-DRB1 alleles for multiple sclerosis differentially regulate anti-JC virus antibody serostatus along with fingolimod

Background

Progressive multifocal leukoencephalopathy (PML) caused by JC virus (JCV) is a rare but serious complication of some disease-modifying drugs used to treat multiple sclerosis (MS). Japanese MS patients treated with fingolimod were reported to be 10 times more likely to develop PML than equivalent patients in other countries. The strongest susceptibility human leukocyte antigen (HLA) class II alleles for MS are distinct between races (DRB1*15:01 for Caucasians and DRB1*04:05 and DRB1*15:01 for Japanese); therefore, we investigated whether HLA class II alleles modulate anti-JCV antibody serostatus in Japanese MS patients with and without fingolimod.

Methods

We enrolled 128 Japanese patients with MS, in whom 64 (50%) were under fingolimod treatment at sampling, and examined the relationship between HLA class II alleles and anti-JCV antibody serostatus. Serum anti-JCV antibody positivity and index were measured using a second-generation two-step assay and HLA-DRB1 and -DPB1 alleles were genotyped.

Results

HLA-DRB1*15 carriers had a lower frequency of anti-JCV antibody positivity (57% vs 78%, p = 0.015), and lower antibody index (median 0.42 vs 1.97, p = 0.037) than non-carriers. Among patients without HLA-DRB1*15, DRB1*04 carriers had a higher seropositivity rate than non-carriers (84% vs 54%, p = 0.030), and DPB1*04:02 carriers had a higher anti-JCV antibody index than non-carriers (3.20 vs 1.34, p = 0.008) although anti-JCV antibody-positivity rates did not differ. Patients treated with fingolimod had a higher antibody index than other patients (1.46 vs 0.64, p = 0.039) and treatment period had a positive correlation with antibody index (p = 0.018). Multivariate logistic regression analysis revealed that age was positively associated, and HLA-DRB1*15 was negatively associated with anti-JCV antibody positivity (odds ratio [OR] = 1.06, p = 0.006, and OR = 0.37, p = 0.028, respectively). Excluding HLA-DRB1*15-carriers, DRB1*04 was an independent risk factor for the presence of anti-JCV antibody (OR = 5.50, p = 0.023).

Conclusions

HLA-DRB1*15 is associated with low anti-JCV antibody positive rate and low JCV antibody index, and in the absence of DRB1*15, DRB1*04 carriers are associated with a high antibody positive rate in Japanese, suggesting the effects of two susceptible HLA-DRB1 alleles on anti-JCV antibody serostatus differ.

JCPyV NCCR analysis in PML patients with different risk factors: exploring common rearrangements as essential changes for neuropathogenesis

Background

During severe immunosuppression or treatment with specific biological drugs, human polyomavirus JC (JCPyV) may establish a lytic infection in oligodendrocytes, leading to progressive multifocal leukoencephalopathy (PML). Beyond AIDS, which represents the most common predisposing condition, several biological drugs have been associated to the development of PML, such as natalizumab, fingolimod and dimethyl fumarate, which have been showed to increase the risk of PML in the multiple sclerosis (MS) population. JCPyV non-coding control region (NCCR) can be found in two different forms: a virulent neurotropic pathogenic form and a latent non-pathogenic form. The neurotropic forms contain a rearranged NCCR and are typically found in the cerebrospinal fluid, brain or blood of PML patients.

Case presentation

We sequenced and critically examined JCPyV NCCR from isolates detected in the cerebrospinal fluid of four newly diagnosed progressive multifocal leukoencephalopathy patients: two HIV-positive and two HIV-negative multiple sclerosis patients. More complex NCCR rearrangements were observed in the two HIV-positive patients compared to the HIV-negative multiple sclerosis patients with PML.

Conclusions

The comparison of HIV-positive and HIV-negative MS patients with PML, allowed us to evidence the presence of a common pattern of JCPyV NCCR rearrangement, characterized by the deletion of the D-block, which could be one of the initial rearrangements of JCPyV NCCR needed for the development of PML.

Diagnostic and Prognostic Value of JC Virus DNA in Plasma in Progressive Multifocal Leukoencephalopathy

Background

Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease caused by the polyomavirus JC (John Cunningham; JCV) that affects patients with impaired immune systems. While JCV-DNA detection in cerebrospinal fluid (CSF) is diagnostic of PML, the clinical significance of plasma JCV-DNA is uncertain.

Methods

We retrospectively analyzed plasma samples from PML patients that were drawn close to disease onset and from controls without PML. In PML patients, we compared plasma JCV-DNA detection and levels to clinical and laboratory parameters, and patient survival.

Results

JCV-DNA was detected in plasma of 49/103 (48%) patients with PML (20/24, 83%, human immunodeficiency virus [HIV] negative; 29/79, 37%, HIV-positive) and of 4/144 (3%) controls without PML (0/95 HIV-negative; 4/49, 8%, HIV-positive), yielding a diagnostic sensitivity and specificity of 48% and 97% (83% and 100% in HIV-negative; 37% and 92% in HIV-positive), respectively. Among 16 PML patients with undetectable CSF JCV-DNA, 4 (25%) had detectable plasma JCV-DNA. Plasma JCV-DNA levels were independently associated with CSF levels (P < .0001) and previous corticosteroid treatment (P = .012). Higher plasma JCV-DNA levels were associated with disease progression in HIV-negative patients (P = .005); in HIV-positive patients, there was an increased risk of progression only in those treated with combination antiretroviral therapy (cART; P < .0001).

Conclusions

Testing JCV-DNA in plasma might complement PML diagnosis, especially when CSF is unavailable or JCV-DNA not detectable in CSF. In addition, JCV-DNA plasma levels could be useful as a marker of disease progression in both HIV-negative and cART-treated, HIV-positive PML patients.

An overview on human polyomaviruses biology and related diseases

In recent years, the Polyomaviridae family grew rapidly, thanks to the introduction of high-throughput molecular techniques. To date, 14 polyomaviruses have been identified in humans but the association with human diseases has been established only for few of them. BKPyV has been associated with nephropathy in kidney transplant patients and hemorrhagic cystitis in hematopoietic stem cell transplant patients; JCPyV to progressive multifocal leukoencephalopathy, mainly in HIV-positive patients; Merkel cell polyomavirus to Merkel cell carcinoma; Trichodysplasia spinulosa polyomavirus to the rare skin disease Trichodysplasia spinulosa; human polyomaviruses 6 and 7 to pruritic rash. Immunocompromised patients are at risk of developing disease. Here, we summarized and discussed the scientific literature concerning the human polyomaviruses biology, seroprevalence and association with human diseases.

Advances in preventing adverse events during monoclonal antibody management of multiple sclerosis

INTRODUCTION

Decades of pharmacological research in Multiple Sclerosis (MS) led to the development of therapeutic Monoclonal Antibodies (MAbs) with many different mechanisms of action (MoA), potentially able to improve disability outcome but also determining a more complex management of patients. Areas covered: When clinicians select MS treatments, they should consider adverse events (AEs) on individual basis to minimize patients' risks. Some AEs are common and can be easily handled, but rare complications should also be taken into account. The aim of this review is to summarize existing evidence and provide practical recommendations for the management of therapeutic MAbs in MS. Expert opinion: The introduction of MAbs revolutionized MS treatment with an improvement in effectiveness. Unfortunately, this has been coupled with a more complex array of AEs needing a tighter surveillance strategy. A close interaction between general practitioners, neurologists, and other specialists is the key for a safer use of such effective drugs.

JC virus infection of meningeal and choroid plexus cells in patients with progressive multifocal leukoencephalopathy

JC virus (JCV) can cause a lytic infection of oligodendrocytes and astrocytes in the central nervous system (CNS) leading to progressive multifocal leukoencephalopathy (PML). JCV can also infect meningeal and choroid plexus cells causing JCV meningitis (JCVM). Whether JCV also infects meningeal and choroid plexus cells in PML patients and other immunosuppressed individuals with no overt symptoms of meningitis remains unknown. We therefore analyzed archival formalin-fixed, paraffin-embedded brain samples from PML patients, and HIV-seropositive and seronegative control subjects by immunohistochemistry for the presence of JCV early regulatory T Ag and JCV VP1 late capsid protein. In meninges, we detected JCV T Ag in 11/48 (22.9%) and JCV VP1 protein in 8/48 (16.7%) PML patients. In choroid plexi, we detected JCV T Ag in 1/7 (14.2%) and JCV VP1 protein in 1/8 (12.5%) PML patients. Neither JCV T Ag nor VP1 protein could be detected in meninges or choroid plexus of HIV-seropositive and HIV-seronegative control subjects without PML. In addition, examination of underlying cerebellar cortex of PML patients revealed JCV-infected cells in the molecular layer, including GAD 67+ interneurons, but not in HIV-seropositive and HIV-seronegative control subjects without PML. Our findings suggest that productive JCV infection of meningeal cells and choroid plexus cells also occurs in PML patients without signs or symptoms of meningitis. The phenotypic characterization of JCV-infected neurons in the molecular layer deserves further study. This data provides new insight into JCV pathogenesis in the CNS.

Remarkable improvement in progressive multifocal leukoencephalopathy following acute pyelonephritis with bacteremia

Progressive multifocal leukoencephalopathy (PML) is caused by John Cunningham (JC) virus in immunocompromized patients such as those with human immunodeficiency virus (HIV) infection, hematological malignancy, autoimmune disorder, and immunodeficiency disorder as well as those undergoing chemotherapy or immunosuppressive therapy. No effective treatments have been established for PML, which commonly causes severe neurological sequelae. We describe the first case of PML in a patient without HIV infection who exhibited remarkable improvement following acute pyelonephritis with Escherichia coli bacteremia.

A loop-mediated isothermal amplification assay for the detection and quantification of JC polyomavirus in cerebrospinal fluid: a diagnostic and clinical management tool and technique for progressive multifocal leukoencephalopathy

Background

JC polyomavirus (JCV) is the causative agent of progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the central nervous system in immunosuppressed patients. PML usually has a poor prognosis. Detection and quantification of the JCV genome in cerebrospinal fluid (CSF) is an efficacious tool for the diagnosis and management of PML, for which proper therapeutic interventions are required.

Methods

A loop-mediated isothermal amplification (LAMP) assay was applied for the quantitative detection of JCV. The LAMP assay was evaluated for the efficacy in diagnosis of PML in comparison with the TaqMan-based quantitative real-time PCR (qPCR) assay using 153 CSF specimens collected from patients with suspected PML.

Results

The LAMP assay showed no cross-reactivity against other polyomavirus plasmids, viral DNA, and viral RNA, which causes encephalitis, and detected 1 copy of the standard DNA per reaction. Among 50 qPCR-positives, 42 specimens (containing JCV genome ranged from 3.2 × 10⁰ to 3.2 × 10⁶ copies/reaction) showed positive reactions and 8 specimens (containing 0.9 to 19.9 copies/reaction) showed negative in the LAMP assay. Furthermore, 3 of 103 qPCR-negative specimens showed positive reactions in the LAMP assay. The sensitivity, specificity, positive predictive value, and negative predictive values of the LAMP assay were 84% (42/50), 97% (100/103), 93% (42/45), and 93% (100/108), respectively. The kappa statistic was 0.83. The JCV loads determined by the LAMP assay showed a strong positive correlation with those determined by the qPCR assay for 33 specimens with copy numbers of ≥1 copies/reaction (r = 0.89). Additionally, the LAMP assay could monitor the JCV genome copy number in CSF for sequential samples equivalently to qPCR assay.

Conclusions

The newly developed LAMP assay is highly specific against JCV and detect the JCV genome in the sample DNA containing 20 or more copies of JCV genome per reaction with 100% sensitivity (n = 29), which corresponds to ≥3 × 10³ copies/mL of CSF. The LAMP assay is useful for the diagnosis and offers valuable information for the evaluation and management of PML in the clinical setting.

Amebic Encephalitis in a Patient with Chronic Lymphocytic Leukemia on Ibrutinib Therapy

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in Western countries. A common first-line therapy offered to qualifying patients includes ibrutinib, an oral covalent inhibitor of Bruton's tyrosine kinase. Treatment of CLL with ibrutinib therapy is generally well tolerated; however, serious opportunistic infections are being reported in patients treated with ibrutinib. In this report, we present a patient with CLL on ibrutinib therapy who developed rapidly declining neurological status concerning for the central nervous system (CNS) process related to his immunocompromised status. Despite multiple testing modalities, no evidence was found to explain the acute changes the patient was experiencing, and he had no improvement with common antimicrobial coverage. The patient ultimately expired, and autopsy of the brain revealed granulomatous amebic encephalitis due to opportunistic infection by Acanthamoeba species. As evidenced by this case, ibrutinib therapy, despite being generally well tolerated, has the potential to predispose patients to opportunistic infections like amebic encephalitis. Amebic encephalitis is a highly lethal CNS infection, and it is important for clinicians to recognize early on the potential for infection in patients on ibrutinib therapy presenting with CNS symptoms.

Progressive multifocal leukoencephalopathy after allogeneic stem cell transplantation: Case report and review of the literature

Progressive multifocal leukoencephalopathy (PML) is a rare, yet typically fatal complication of allogeneic stem cell transplantation. It is caused by reactivation of the John Cunningham (JC) virus in an immunocompromised host. This report describes an unfortunate case of PML in a recipient of an allogeneic stem cell transplant for acute myelogenous leukemia. The JC virus was undetectable in the patient's cerebrospinal fluid by polymerase chain reaction (PCR); however, a positive diagnosis was made after a brain biopsy. This and other published cases demonstrate that recipients of allogeneic stem cells can develop PML. Moreover, early diagnosis of the disease is often difficult and, as demonstrated in this case, screening with PCR does not appear to have strong diagnostic significance. With no effective treatment presently available, restoration of immune function is the only intervention that can affect prognosis. Further prospective studies are needed to understand the pathophysiology and treatment of this disease.

Definition and characterization of novel HLA-*A02-restricted CD8+ T cell epitopes derived from JCV polyomavirus with clinical relevance

Human JC and BK polyomaviruses (JCV/BKV) can establish a latent infection without any clinical symptoms in healthy individuals. In immunocompromised hosts infection or reactivation of JCV and BKV can cause lethal progressive multifocal leukoencephalopathy (PML) and hemorrhagic cystitis, respectively. Vaccination with JCV/BKV derived antigen epitope peptides or adoptive transfer of virus-specific T cells would constitute an elegant approach to clear virus-infected cells. Furthermore, donor leukocyte infusion (DLI) is another therapeutic approach which could be helpful for patients with JCV/BKV infections.So far, only few immunodominant T cell epitopes of JCV and BKV have been described and therefore is a fervent need for the definition of novel epitopes. In this study, we identified novel T cell epitopes by screening libraries of overlapping peptides derived from the major capsid protein VP1 of JCV. Virus like particles (VLPs) were used to confirm naturally processing. Two human leucocyte antigen (HLA)-A*02-restricted epitopes were characterized by fine mapping with overlapping peptides and nonamer peptide sequences were identified. Cytokine release profile of the epitope-specific T cells was analyzed by enzyme-linked immunospot (ELISPOT) assays and by flow cytometry. We demonstrated that T cell responses were of polyfunctional nature with the potential of epitope-specific killing and cross-reactivity between JCV and BKV. These novel epitopes might constitute a new potential tool to design effective diagnostic and therapeutic approaches against both polyomaviruses.

Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a relatively common complication of HIV disease. In this chapter changes to the epidemiology are discussed along with an update in its pathogenesis and treatment. Immune reconstitution inflammatory syndrome is increasingly frequent in PML; accordingly management strategies and prognosis are detailed.

Diagnosis and Treatment of Progressive Multifocal Leukoencephalopathy Associated with Multiple Sclerosis Therapies

Progressive multifocal leukoencephalopathy (PML) is a rare, but serious, complication encountered in patients treated with a select number of disease-modifying therapies (DMTs) utilized in treating multiple sclerosis (MS). PML results from a viral infection in the brain for which the only demonstrated effective therapy is restoring the perturbed immune system-typically achieved in the patient with MS by removing the offending therapeutic agent or, in the case of HIV-associated PML, treatment with highly active antiretroviral therapies. Other therapies for PML remain either ineffective or experimental. Significant work to understand the virus and host interaction has been undertaken, but lack of an animal model for the disorder has significantly hindered progress, especially with respect to development of treatments. Strategies to limit risk of PML with natalizumab, a drug that carries a uniquely high risk for the development of the disorder, have been developed. Identifying factors such as positive JC virus antibody status that increase PML risk, at least in theory, should decrease the incidence rate of the disease. Whether other risk factors for PML can be identified and validated or unique strategies should be employed in association with other DMTs that predispose to PML and whether this has a salutary effect on outcome remains to be demonstrated. Identifying PML early, then promptly eliminating drug in the case of natalizumab-associated PML has demonstrated better outcomes, but the complication of PML continues to carry significant morbidity and mortality. While the scientific community has yet to identify targeted therapy with proven efficacy against JCV or PML there are several candidates being studied.

Polyomaviruses

Over the last 10 years, the number of identified polyomaviruses has grown to more than 35 subtypes, including 13 in humans. The polyomaviruses have similar genetic makeup, including genes that encode viral capsid proteins VP1, 2, and 3 and large and small T region proteins. The T proteins play a role in viral replication and have been implicated in viral chromosomal integration and possible dysregulation of growth factor genes. In humans, the Merkel cell polyomavirus has been shown to be highly associated with integration and the development of Merkel cell cancers. The first two human polyomaviruses discovered, BKPyV and JCPyV, are the causative agents for transplant-related kidney disease, BK commonly and JC rarely. JC has also been strongly associated with the development of progressive multifocal leukoencephalopathy (PML), a rare but serious infection in untreated HIV-1-infected individuals and in other immunosuppressed patients including those treated with monoclonal antibody therapies for autoimmune diseases systemic lupus erythematosus, rheumatoid arthritis, or multiple sclerosis. The trichodysplasia spinulosa-associated polyomavirus (TSAPyV) may be the causative agent of the rare skin disease trichodysplasia spinulosa. The remaining nine polyomaviruses have not been strongly associated with clinical disease to date. Antiviral therapies for these infections are under development. Antibodies specific for each of the 13 human polyomaviruses have been identified in a high percentage of normal individuals, indicating a high rate of exposure to each of the polyomaviruses in the human population. PCR methods are now available for detection of these viruses in a variety of clinical samples.

Copy Number Heterogeneity of JC Virus Standards

Quantitative PCR is a diagnostic mainstay of clinical virology, and accurate quantitation of viral load among labs requires the use of international standards. However, the use of multiple passages of viral isolates to obtain sufficient material for international standards may result in genomic changes that complicate their use as quantitative standards. We performed next-generation sequencing to obtain single-nucleotide resolution and relative copy number of JC virus (JCV) clinical standards. Strikingly, the WHO international standard and the Exact v1/v2 prototype standards for JCV showed 8-fold and 4-fold variation in genomic coverage between different loci in the viral genome, respectively, due to large deletions in the large T antigen region. Intriguingly, several of the JCV standards sequenced in this study with large T antigen deletions were cultured in cell lines immortalized using simian virus 40 (SV40) T antigen, suggesting the possibility of transcomplementation in cell culture. Using a cutoff 5% allele fraction for junctional reads, 7 different rearrangements were present in the JC virus sequences present in the WHO standard across multiple library preparations and sequencing runs. Neither the copy number differences nor the rearrangements were observed in a clinical sample with a high copy number of JCV or a plasmid control. These results were also confirmed by the quantitative real-time PCR (qPCR), droplet digital PCR (ddPCR), and Sanger sequencing of multiple rearrangements. In summary, targeting different regions of the same international standard can result in up to an 8-fold difference in quantitation. We recommend the use of next-generation sequencing to validate standards in clinical virology.

Polyomavirus Persistence

Mammalian polyomaviruses are characterized by establishing persistent infections in healthy hosts and generally causing clinical disease only in hosts whose immune systems are compromised. Despite the fact that these viruses were discovered decades ago, our knowledge of the mechanisms that govern viral persistence and reactivation is limited. Whereas mouse polyomavirus has been studied in a fair amount of detail, our understanding of the human viruses in particular is mostly inferred from experiments aimed at addressing other questions. In this review, we summarize the state of our current knowledge, draw conclusions when possible, and suggest areas that are in need of further study.

Progressive Multifocal Leukoencephalopathy in a HIV Negative, Immunocompetent Patient

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease most common in immunodeficient patients. It occurs due to reactivation of the John Cunningham Virus (JCV) and carries a poor prognosis, with a median life expectancy of 6 months. We report a case of a 66-year-old man with a history of HCV related cirrhosis (HCV) and hepatocellular carcinoma (HCC) who was found to have PML in the setting of a negative viral load in the CSF and a CD4+ >200. He initially presented with two weeks of mild confusion and word-finding difficulty concerning for hepatic encephalopathy. An MRI was notable for extensive T2/FLAIR hyperintensity signal in the left temporal lobe. Brain biopsy was positive for JCV. PML is rare in immunocompetent individuals, especially in the setting of a negative viral load. It is possible, however, that transient states of immunosuppression may have been responsible in this case. Although viral load was reported as negative, virus may still have been detected but was below the quantifiable threshold. It is important for clinicians to note that a negative result does not necessarily exclude the possibility of PML, and care should be taken to review lab values on viral load in closer detail.

Isolation of a monoclonal antibody that recognizes the origin binding domain of JCV, but not SV40, large T-antigen

Within immunocompromised populations, the JC polyomavirus is the cause of the often-fatal disease Progressive Multifocal Leukoencephalopathy (PML). JC virus encodes a protein, termed T-antigen (T-ag), which is essential for its replication and pathogenicity. Previous studies of JCV T-ag have, in general, used antibodies raised against SV40 T-ag. Unfortunately, SV40 T-ag is also detected in humans and therefore there have been concerns about cross-reactivity. To address this issue, we have isolated a monoclonal antibody that binds to the JCV, but not the SV40, T-ag origin-binding domain (OBD). Furthermore, the region on the surface of the JCV T-ag OBD that is recognized by the "anti-JCV OBD mAb" has been mapped. We also demonstrate that the "anti-JCV OBD mAb" will be a useful reagent for standard techniques (e.g., Westerns blots and ELISAs). Finally, we note that additional monoclonal Abs that are specific for the T-ags encoded by the other human polyomaviruses could be generated by adopting the approach described herein.

Safety and diagnostic value of brain biopsy in HIV patients: a case series and meta-analysis of 1209 patients

Early brain biopsy may be indicated in HIV patients with focal brain lesion. This study aimed to evaluate and compare the safety and diagnostic value of brain biopsy in HIV patients in the pre-highly active antiretroviral therapy (HAART) versus post-HAART era via meta-analysis. Appropriate studies were identified per search criteria. The local database was retrospectively reviewed to select a similar patient cohort. Patient demographics, brain biopsy technique, histopathology and patient outcomes were extracted from each study. Study-specific outcomes were combined per random-effects model. Outcomes were compared between the pre-HAART and post-HAART era. Correlations between outcomes and baseline characteristics were assessed via meta-regression analysis. The proportions of histopathological diagnosis were tabulated and compared between the pre- and post-HAART era. Survival analysis was performed for patients in the post-HAART era. A total of 26 studies (including the local database) with 1209 patients were included in this meta-analysis. The most common indications for brain biopsy were diagnosis unlikely to be toxoplasmosis (n=8, 42.1%), focal brain lesion (n=5, 26.3%) or both (n=3, 15.8%). The weighted proportions for diagnostic success were 92% (95% CI 90.0% to 93.8%), change in management 57.7% (45.9% to 69.1%) and clinical improvement 36.6% (26.3% to 47.5%). Morbidity and mortality were 5.7% (3.6% to 8.3%) and 0.9% (0.3% to 1.9%), respectively. Diagnostic success rate was significantly higher in the post-HAART than the pre-HAART era (97.5% vs 91.9%, p=0.047). The odds ratio (OR) for diagnostic success in patients with contrast-enhanced lesions was 2.54 ((1.25 to 5.15), p<0.01). The median survival for HIV patients who underwent biopsy in the post-HAART era was 225 days (90-2446). Brain biopsy in HIV patients is safe with high diagnostic yield. Early brain biopsy should be considered in patients without classic presentation of toxoplasmosis encephalitis.

Opportunistic Neurologic Infections in Patients with Acquired Immunodeficiency Syndrome (AIDS)

Infections of the central nervous system (CNS) in individuals with human immunodeficiency virus (HIV) remain a substantial cause of morbidity and mortality despite the introduction of highly active antiretroviral therapy (HAART) especially in the resource-limited regions of the world. Diagnosis of these infections may be challenging because findings on cerebrospinal fluid (CSF) analysis and brain imaging are nonspecific. While brain biopsy provides a definitive diagnosis, it is an invasive procedure associated with a relatively low mortality rate, thus less invasive modalities have been studied in recent years. Diagnosis, therefore, can be established based on a combination of a compatible clinical syndrome, radiologic and CSF findings, and understanding of the role of HIV in these infections. The most common CNS opportunistic infections are AIDS-defining conditions; thus, treatment of these infections in combination with HAART has greatly improved survival.

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.

Progressive neurologic dysfunction in a psoriasis patient treated with dimethyl fumarate

Progressive multifocal leukoencephalopathy (PML) has recently been described in psoriasis or multiple sclerosis patients treated with fumaric acid esters (fumarates), who had developed severe and long-standing lymphocytopenia (<500/mm(3) ). We report a psoriasis patient who presented with progressive neurologic dysfunction and seizures after 2.5 years of fumarate therapy. Despite absolute lymphocyte counts remaining between 500-1000/mm(3) , his CD4(+) and CD8(+) T-cell counts were markedly low. MRI showed right hemispheric and brainstem lesions and JC virus DNA was undetectable in his cerebrospinal fluid. Brain biopsy revealed typical features of PML as well as JC virus-infected neurons. Clinicians should consider PML in the differential diagnosis of fumarate-treated patients presenting with brain lesions or seizures even in the absence of severe lymphocytopenia.

Synthetic antibodies and peptides recognizing progressive multifocal leukoencephalopathy-specific point mutations in polyomavirus JC capsid viral protein 1

Polyomavirus JC (JCV) is the causative agent of progressive multifocal leukoencephalopathy (PML), a rare and frequently fatal brain disease that afflicts a small fraction of the immune-compromised population, including those affected by AIDS and transplantation recipients on immunosuppressive drug therapy. Currently there is no specific therapy for PML. The major capsid viral protein 1 (VP1) involved in binding to sialic acid cell receptors is believed to be a key player in pathogenesis. PML-specific mutations in JCV VP1 sequences present at the binding pocket of sialic acid cell receptors, such as L55F and S269F, abolish sialic acid recognition and might favor PML onset. Early diagnosis of these PML-specific mutations may help identify patients at high risk of PML, thus reducing the risks associated with immunosuppressive therapy. As a first step in the development of such early diagnostic tools, we report identification and characterization of affinity reagents that specifically recognize PML-specific mutations in VP1 variants using phage display technology. We first identified 2 peptides targeting wild type VP1 with moderate specificity. Fine-tuning via selection of biased libraries designed based on 2 parental peptides yielded peptides with different, yet still moderate, bindinspecificities. In contrast, we had great success in identifying synthetic antibodies that recognize one of the PML-specific mutations (L55F) with high specificity from the phage-displayed libraries. These peptides and synthetic antibodies represent potential candidates for developing tailored immune-based assays for PML risk stratification in addition to complementing affinity reagents currently available for the study of PML and JCV.

Atypical progressive multifocal leukoencephalopathy in a patient with antisynthetase syndrome

Antisynthetase syndrome is a disorder belonging to the dermatomyositis/polymyositis group, with high rates of morbidity and mortality. We herein present the case of a 71-year-old man who was diagnosed with antisynthetase syndrome and treated with rituximab. Almost three years later, the patient showed right-sided hemiparesis that ultimately progressed to complete hemiplegia and advancing cognitive deterioration with a poor clinical outcome. The neuropathological diagnosis was progressive multifocal leukoencephalopathy. Treatment with rituximab for antisynthetase syndrome itself plays a fundamental role in the development of infectious complications.

Inter- and intralaboratory comparison of JC polyomavirus antibody testing using two different virus-like particle-based assays

JC polyomavirus (JCPyV) can cause progressive multifocal leukoencephalopathy (PML), a debilitating, often fatal brain disease in immunocompromised patients. JCPyV-seropositive multiple sclerosis (MS) patients treated with natalizumab have a 2- to 10-fold increased risk of developing PML. Therefore, JCPyV serology has been recommended for PML risk stratification. However, different antibody tests may not be equivalent. To study intra- and interlaboratory variability, sera from 398 healthy blood donors were compared in 4 independent enzyme-linked immunoassay (ELISA) measurements generating >1,592 data points. Three data sets (Basel1, Basel2, and Basel3) used the same basic protocol but different JCPyV virus-like particle (VLP) preparations and introduced normalization to a reference serum. The data sets were also compared with an independent method using biotinylated VLPs (Helsinki1). VLP preadsorption reducing ≥35% activity was used to identify seropositive sera. The results indicated that Basel1, Basel2, Basel3, and Helsinki1 were similar regarding overall data distribution (P = 0.79) and seroprevalence (58.0, 54.5, 54.8, and 53.5%, respectively; P = 0.95). However, intra-assay intralaboratory comparison yielded 3.7% to 12% discordant results, most of which were close to the cutoff (0.080 < optical density [OD] < 0.250) according to Bland-Altman analysis. Introduction of normalization improved overall performance and reduced discordance. The interlaboratory interassay comparison between Basel3 and Helsinki1 revealed only 15 discordant results, 14 (93%) of which were close to the cutoff. Preadsorption identified specificities of 99.44% and 97.78% and sensitivities of 99.54% and 95.87% for Basel3 and Helsinki1, respectively. Thus, normalization to a preferably WHO-approved reference serum, duplicate testing, and preadsorption for samples around the cutoff may be necessary for reliable JCPyV serology and PML risk stratification.

Application of human and animal viral microbial source tracking tools in fresh and marine waters from five different geographical areas

Integrated river basin management planning to mitigate the impacts of economic, demographic and climate change is an important issue for the future protection of water resources. Identifying sources of microbial contamination via the emerging science of Microbial Source Tracking (MST) plays a key role in risk assessment and the design of remediation strategies. Following an 18-month surveillance program within the EU-FP7-funded VIROCLIME project, specific MST tools were used to assess human markers such as adenoviruses (HAdV) and JC polyomaviruses (JCPyV) and porcine and bovine markers such as porcine adenoviruses (PAdV) and bovine polyomaviruses (BPyV) via quantification with real-time PCR to analyze surface water collected from five sites within different climatic zones: the Negro River (Brazil), Glafkos River (Greece), Tisza River (Hungary), Llobregat River (Spain) and Umeälven River (Sweden). The utility of the viral MST tools and the prevalence and abundance of specific human and animal viruses in the five river catchments and adjacent seawater, which is impacted by riverine contributions from the upstream catchments, were examined. In areas where no sanitation systems have been implemented, sewage can directly enter surface waters, and river water exhibited high viral loads; HAdV and JCPyV could be detected at mean concentrations of 10(5) and 10(4) Genome Copies/Liter (GC/L), respectively. In general, river water samples upstream of urban discharges presented lower human viral loads than downstream sampling sites, and those differences appeared to increase with urban populations but decrease in response to high river flow, as the elevated river water volume dilutes microbial loads. During dry seasons, river water flow decreases dramatically, and secondary effluents can represent the bulk of the riverine discharge. We also observed that ice cover that formed over the river during the winter in the studied areas in North Europe could preserve viral stability due to the low temperatures and/or the lack of solar inactivation. Porcine and bovine markers were detected where intensive livestock and agricultural activities were present; mean concentration values of 10(3) GC/L indicated that farms were sometimes unexpected and important sources of fecal contamination in water. During spring and summer, when livestock is outdoors and river flows are low, animal pollution increases due to diffuse contamination and direct voiding of feces onto the catchment surface. The field studies described here demonstrate the dynamics of fecal contamination in all catchments studied, and the data obtained is currently being used to develop dissemination models of fecal contamination in water with respect to future climate change scenarios. The results concerning human and animal targets presented in this study demonstrate the specificity and applicability of the viral quantitative parameters developed to widely divergent geographical areas and their high interest as new indicators of human and animal fecal contamination in water and as MST tools.

JC virus reactivation during prolonged natalizumab monotherapy for multiple sclerosis

OBJECTIVE

To determine the prevalence of JC virus (JCV) reactivation and JCV-specific cellular immune response during prolonged natalizumab treatment for multiple sclerosis (MS).

METHODS

We enrolled 43 JCV-seropositive MS patients, including 32 on natalizumab monotherapy >18 months, 6 on interferon β-1a monotherapy >36 months, and 5 untreated controls. We performed quantitative real-time polymerase chain reaction in cerebrospinal fluid (CSF), blood, and urine for JCV DNA, and we determined JCV-specific T-cell responses using enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining (ICS) assays, ex vivo and after in vitro stimulation with JCV peptides.

RESULTS

JCV DNA was detected in the CSF of 2 of 27 (7.4%) natalizumab-treated MS patients who had no symptoms or magnetic resonance imaging-detected lesions consistent with progressive multifocal leukoencephalopathy. JCV DNA was detected in blood of 12 of 43 (27.9%) and in urine of 11 of 43 (25.6%) subjects without a difference between natalizumab-treated patients and controls. JC viral load was higher in CD34(+) cells and in monocytes compared to other subpopulations. ICS was more sensitive than ELISpot. JCV-specific T-cell responses, mediated by both CD4(+) and CD8(+) T lymphocytes, were detected more frequently after in vitro stimulation. JCV-specific CD4(+) T cells were detected ex vivo more frequently in MS patients with JCV DNA in CD34(+) (p = 0.05) and B cells (p = 0.03).

INTERPRETATION

Asymptomatic JCV reactivation may occur in CSF of natalizumab-treated MS patients. JCV DNA load is higher in circulating CD34(+) cells and monocytes compared to other mononuclear cells, and JCV in blood might trigger a JCV-specific CD4(+) T-cell response. JCV-specific cellular immune response is highly prevalent in all JCV-seropositive MS patients, regardless of treatment.

Immune reconstitution after allogeneic hematopoietic stem cell transplantation is associated with selective control of JC virus reactivation

JC virus (JCV) causes progressive multifocal leukoencephalopathy (PML) in immunocompromised patients. The mechanism of JCV reactivation and immunity in a transplanted immune system remains unclear. We prospectively studied 30 patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) and collected blood and urine samples before HSCT and 3, 6, and 12 to 18 months after HSCT. Before HSCT, JCV DNA was detected in 7 of 30 urine, 5 of 30 peripheral blood mononuclear cells (PBMC) and 6 of 30 plasma samples. Although JC viruria remained stable after HSCT with detection in 5 of 21 samples, viremia was detected in only 1 of 22 plasma and none of 22 PBMC samples 12 to 18 months after HSCT. Prevalence of anti-JCV IgG was 83% before HSCT and decreased to 72% at 12 to 18 months. Anti-JCV IgM was rarely detected. JCV-specific CD4(+) and CD8(+) T cell responses increased 12 to 18 months after HSCT. Although JC viruria correlated directly with detection of anti-JCV IgG, the cellular immune response to JCV measured by ELISpot was inversely correlated with anti-JCV IgG response. The diagnosis of acute myelogenous leukemia and age group were 2 independent patient factors associated with significantly reduced cellular immune responses to JCV. This prospective study in HSCT patients provides a model of interactions between the host immune response and viral activation in multiple compartments during the recovery of the immune system.

Analytical characterization of an assay designed to detect and identify diverse agents of disseminated viral infection

BACKGROUND

Diverse viruses often reactivate in or infect cancer patients, patients with immunocompromising infections or genetic conditions, and transplant recipients undergoing immunosuppressive therapy. These infections can disseminate, leading to death, transplant rejection, and other severe outcomes.

OBJECTIVES

To develop and characterize an assay capable of inclusive and accurate identification of diverse potentially disseminating viruses directly from plasma specimens.

STUDY DESIGN

We developed a PCR/electrospray ionization mass spectrometry (PCR/ESI-MS) assay designed to simultaneously detect and identify adenovirus, enterovirus, polyomaviruses JC and BK, parvovirus B19, HSV-1, HSV-2, VZV, EBV, CMV, and herpesviruses 6-8 in plasma specimens. The assay performance was characterized analytically, and the results from clinical plasma samples were compared to the results obtained from single-analyte real time PCR tests currently used in clinical practice.

RESULTS

The assay demonstrated sensitivity and specificity to diverse strains of the targeted viral families and robustness to interfering substances and potentially cross reacting organisms. The assay yielded 94% sensitivity when testing clinical plasma samples previously identified as positive using standard-of-care real-time PCR tests for a single target virus (available samples included positive samples for 11 viruses targeted by the assay).

CONCLUSIONS

The assay functioned as designed, providing simultaneous broad-spectrum detection and identification of diverse agents of disseminated viral infection. Among 156 clinical samples tested, 37 detections were made in addition to the detections matching the initial clinical positive results.

Immune surveillance and response to JC virus infection and PML

The ubiquitous human polyomavirus JC virus (JCV) is the established etiological agent of the debilitating and often fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Most healthy individuals have been infected with JCV and generate an immune response to the virus, yet remain persistently infected at subclinical levels. The onset of PML is rare in the general population, but has become an increasing concern in immunocompromised patients, where reactivation of JCV leads to uncontrolled replication in the CNS. Understanding viral persistence and the normal immune response to JCV provides insight into the circumstances which could lead to viral resurgence. Further, clues on the potential mechanisms of reactivation may be gleaned from the crosstalk among JCV and HIV-1, as well as the impact of monoclonal antibody therapies used for the treatment of autoimmune disorders, including multiple sclerosis, on the development of PML. In this review, we will discuss what is known about viral persistence and the immune response to JCV replication in immunocompromised individuals to elucidate the deficiencies in viral containment that permit viral reactivation and spread.

Natalizumab and progressive multifocal leukoencephalopathy: migrating towards safe adhesion molecule therapy in multiple sclerosis

Natalizumab, a humanized monoclonal antibody against alpha4beta1 integrin, was shown in clinical trials to dramatically reduce the relapse rate, development of new magnetic resonance imaging (MRI) lesions and progression of disability in patients with relapsing multiple sclerosis. Following its expedited approval, sales of the drug were discontinued owing to the emergence of two cases of progressive multifocal leukoencephalopathy (PML), a rare but deadly viral infection of the central nervous system (CNS) associated with immunosuppression. Owing to the effect of natalizumab on central nervous system leukocyte recruitment, the emergence of PML has been attributed to diminished immunosurveillance. The lack of additional opportunistic or CNS infections among natalizumab-treated patients, however, suggests that alternate mechanisms may contribute to the infectious risk. This review examines how the inhibition of alpha4beta1-mediated adhesion might establish a unique milieu for the development of PML and how future approaches to selective adhesion molecule therapy in multiple sclerosis might avoid a similar fate.

Continued declining incidence and improved survival of progressive multifocal leukoencephalopathy in HIV/AIDS patients in the current era

To evaluate the situation and perspectives of progressive multifocal leukoencephalopathy (PML) in human immunodeficiency virus (HIV)-infected patients, we investigated changes in the incidence, causes, and long-term outcome of this disease in 72 acquired immunodeficiency syndrome (AIDS) patients who were diagnosed with PML from 1996 to 2011. Patients were classified according to the date of diagnosis in the first (1996-2000, n = 35), second (2001-2006, n = 26), and recent or third highly active antiretroviral therapy (HAART) period (2007-2011, n = 11). Overall, the incidence of PML decreased from 14.8 cases/1,000 patients/year in 1996 to 2.6 in 2005 and 0.8 in 2011, and nearly two-thirds of recent cases (64 %) were observed in HIV patients not attending clinical visits. The baseline median CD4+ count was higher in recently PML-diagnosed patients (77 vs. 86 vs. 101 cells/mm(3); p < 0.01), and this fact was associated with a cerebrospinal fluid (CSF) inflammatory profile (from 11 to 31 to 55 %, p = 0.007) and with a significantly longer survival (attributable death, 54 vs. 35 vs. 36 %, respectively, p < 0.01). Thus, the overall 1-year and 3-year survival rates were 55 and 50 %, respectively, increasing to 79 % at 1 year for patients with CD4+ count above 100 cells/mm(3) at diagnosis. In a Cox regression analysis, an older age (hazard ratio, HR 0.76), a baseline CD4+ count above 100 cells/mm(3) (HR 0.33), and a CSF inflammatory profile (HR 0.12) were significantly associated with a longer survival. The clinical presentation and outcome of PML in AIDS patients continue to change dramatically. Now, a declining incidence and long-term survival is observed.

JC virus antibody status underestimates infection rates

OBJECTIVE

JC virus (JCV) seropositivity is a risk factor for progressive multifocal leukoencephalopathy (PML) in patients on natalizumab. Accordingly, the JCV serological antibody test is of paramount importance in determining disease risk.

METHODS

We tested the accuracy of the JCV serum antibody test by comparing the results of JCV serology to JCV viruria and viremia in 67 patients enrolled in a single-center, retrospective cohort study. Bodily fluids (urine and blood) were assessed for JCV DNA by real time quantitative polymerase chain reaction 6 to 47 months (mean = 26.1 months) before JCV antibody testing. In 10 individuals, blood and urine samples were obtained on 2 separate occasions at 6-month intervals.

RESULTS

Forty (59.7%) of the 67 patients were JCV seropositive. Of 27 JCV seronegative patients, 10 (37%) had JCV viruria. Urine JCV DNA copy numbers were significantly higher in the seropositive group (mean log copy number = 5.93, range = 1.85-9.21) than the seronegative group (mean log copy number = 2.41, range = 1.85-5.43; p = 0.0026). Considering all body fluid test results, 50 (74.6%) of the 67 patients were previously infected with JCV.

INTERPRETATION

The false-negative rate of the JCV serology in this study was 37%; therefore, JCV serostatus does not appear to identify all patients infected with JCV. Thus, a negative JCV antibody result should not be conflated with absence of JCV infection. This discordance may be important in understanding JCV biology, risk for PML, and PML pathogenesis.

Progressive multifocal leukoencephalopathy with gastrointestinal disease in a pediatric kidney transplant recipient

PML is a demyelinating disease of the central nervous system caused by infection with JCV. Several cases of PML in bone marrow and solid organ transplant recipients have been reported in recent years. JCV has been isolated from the gastrointestinal mucosa of immunocompromised patients, but there are no published reports of PML associated with symptomatic gastrointestinal involvement in kidney transplant recipients. We report a case of a nine-yr-old girl with a kidney transplant who developed a severe gastrointestinal illness causing pseudo-obstruction in association with PML. JCV was suspected as the causative agent in this patient by the detection of high JCV titer through PCR analysis of the cerebrospinal fluid and blood and positive staining for simian virus 40 in the colon. JCV intestinal infection should be considered in kidney transplant recipients presenting with intestinal pseudo-obstruction.

HIV-associated progressive multifocal leukoencephalopathy: longitudinal study of JC virus non-coding control region rearrangements and host immunity

John Cunningham virus (JCV), the etiological agent of progressive multifocal leukoencephalopathy (PML), contains a hyper-variable non-coding control region usually detected in urine of healthy individuals as archetype form and in the brain and cerebrospinal fluid (CSF) of PML patients as rearranged form. We report a case of HIV-related PML with clinical, immunological and virological data longitudinally collected. On admission (t0), after 8-week treatment with a rescue highly active antiretroviral therapy (HAART), the patient showed a CSF-JCV load of 16,732 gEq/ml, undetectable HIV-RNA and an increase of CD4+ cell count. Brain magnetic resonance imaging (MRI) showed PML-compatible lesions without contrast enhancement. We considered PML-immune reconstitution inflammatory syndrome as plausible because of the sudden onset of neurological symptoms after the effective HAART. An experimental JCV treatment with mefloquine and mirtazapine was added to steroid boli. Two weeks later (t1), motor function worsened and MRI showed expanded lesions with cytotoxic oedema. CSF JCV-DNA increased (26,263 gEq/ml) and JCV viremia was detected. After 4 weeks (t2), JCV was detected only in CSF (37,719 gEq/ml), and 8 weeks after admission (t3), JC viral load decreased in CSF and JCV viremia reappeared. The patient showed high level of immune activation both in peripheral blood and CSF. He died 4 weeks later. Considering disease progression, combined therapy failure and immune hyper-activation, we finally classified the case as classical PML. The archetype variant found in CSF at t0/t3 and a rearranged sequence detected at t1/t2 suggest that PML can develop from an archetype virus and that the appearance of rearranged genotypes contribute to faster disease progression.

Detection of JC virus-specific immune responses in a novel humanized mouse model

Progressive Multifocal Leukoencephalopathy (PML) is an often fatal disease caused by the reactivation of the JC virus (JCV). Better understanding of viral-host interactions has been hampered by the lack of an animal model. Engrafting NOD/SCID/IL-2-Rg (null) mice with human lymphocytes and thymus, we generated a novel animal model for JCV infection. Mice were inoculated with either a PML isolate, JCV Mad-4, or with JCV CY, found in the kidney and urine of healthy individuals. While mice remained asymptomatic following inoculation, JCV DNA was occasionally detected in both the blood and the urine compartments. Mice generated both humoral and cellular immune responses against JCV. Expressions of immune exhaustion marker, PD-1, on lymphocytes were consistent with response to infection. Using this model we present the first in vivo demonstration of virological and immunological differences between JCV Mad-4 and CY. This model may prove valuable for studying JCV host immune responses.

Detection and quantification of classic and emerging viruses by skimmed-milk flocculation and PCR in river water from two geographical areas

Molecular techniques and virus concentration methods have shown that previously unknown viruses are shed by humans and animals, and may be transmitted by sewage-contaminated water. In the present study, 10-L river-water samples from urban areas in Barcelona, Spain and Rio Janeiro, Brazil, have been analyzed to evaluate the viral dissemination of human viruses, validating also a low-cost concentration method for virus quantification in fresh water. Three viral groups were analyzed: (i) recently reported viruses, klassevirus (KV), asfarvirus-like virus (ASFLV), and the polyomaviruses Merkel cell (MCPyV), KI (KIPyV) and WU (WUPyV); (ii) the gastroenteritis agents noroviruses (NoV) and rotaviruses (RV); and (iii) the human fecal viral indicators in water, human adenoviruses (HAdV) and JC polyomaviruses (JCPyV). Virus detection was based on nested and quantitative PCR assays. For KV and ASFLV, nested PCR assays were developed for the present study. The method applied for virus concentration in fresh water samples is a one-step procedure based on a skimmed-milk flocculation procedure described previously for seawater. Using spiked river water samples, inter- and intra-laboratory assays showed a viral recovery rate of about 50% (20-95%) for HAdV, JCPyV, NoV and RV with a coefficient of variation ≤ 50%. HAdV and JCPyV were detected in 100% (12/12) of the river samples from Barcelona and Rio de Janeiro. Moreover, NoV GGII was detected in 83% (5/6) and MCPyV in 50% (3/6) of the samples from Barcelona, whereas none of the other viruses tested were detected. NoV GGII was detected in 33% (2/6), KV in 33% (2/6), ASFLV in 17% (1/6) and MCPyV in 50% (3/6) of the samples from Rio de Janeiro, whereas KIPyV and WUPyV were not detected. RV were only analyzed in Rio de Janeiro and resulted positive in 67% (4/6) of the samples. The procedure applied here to river water represents a useful, straightforward and cost-effective method that could be applied in routine water quality testing. The results of the assays expand our understanding of the global distribution of the viral pathogens studied here and their persistence in the environment.

Quantification of human and animal viruses to differentiate the origin of the fecal contamination present in environmental samples

Many different viruses are excreted by humans and animals and are frequently detected in fecal contaminated waters causing public health concerns. Classical bacterial indicator such as E. coli and enterococci could fail to predict the risk for waterborne pathogens such as viruses. Moreover, the presence and levels of bacterial indicators do not always correlate with the presence and concentration of viruses, especially when these indicators are present in low concentrations. Our research group has proposed new viral indicators and methodologies for determining the presence of fecal pollution in environmental samples as well as for tracing the origin of this fecal contamination (microbial source tracking). In this paper, we examine to what extent have these indicators been applied by the scientific community. Recently, quantitative assays for quantification of poultry and ovine viruses have also been described. Overall, quantification by qPCR of human adenoviruses and human polyomavirus JC, porcine adenoviruses, bovine polyomaviruses, chicken/turkey parvoviruses, and ovine polyomaviruses is suggested as a toolbox for the identification of human, porcine, bovine, poultry, and ovine fecal pollution in environmental samples.

Central Nervous System Infections

Central nervous system (CNS) infections—i.e., infections involving the brain (cerebrum and cerebellum), spinal cord, optic nerves, and their covering membranes—are medical emergencies that are associated with substantial morbidity, mortality, or long-term sequelae that may have catastrophic implications for the quality of life of affected individuals. Acute CNS infections that warrant neurointensive care (ICU) admission fall broadly into three categories—meningitis, encephalitis, and abscesses—and generally result from blood-borne spread of the respective microorganisms. Other causes of CNS infections include head trauma resulting in fractures at the base of the skull or the cribriform plate that can lead to an opening between the CNS and the sinuses, mastoid, the middle ear, or the nasopharynx. Extrinsic contamination of the CNS can occur intraoperatively during neurosurgical procedures. Also, implanted medical devices or adjunct hardware (e.g., shunts, ventriculostomies, or external drainage tubes) and congenital malformations (e.g., spina bifida or sinus tracts) can become colonized and serve as sources or foci of infection. Viruses, such as rabies, herpes simplex virus, or polioviruses, can spread to the CNS via intraneural pathways resulting in encephalitis. If infection occurs at sites (e.g., middle ear or mastoid) contiguous with the CNS, infection may spread directly into the CNS causing brain abscesses; alternatively, the organism may reach the CNS indirectly via venous drainage or the sheaths of cranial and spinal nerves. Abscesses also may become localized in the subdural or epidural spaces. Meningitis results if bacteria spread directly from an abscess to the subarachnoid space. CNS abscesses may be a result of pyogenic meningitis or from septic emboli associated with endocarditis, lung abscess, or other serious purulent infections. Breaches of the blood–brain barrier (BBB) can result in CNS infections. Causes of such breaches include damage (e.g., microhemorrhage or necrosis of surrounding tissue) to the BBB; mechanical obstruction of microvessels by parasitized red blood cells, leukocytes, or platelets; overproduction of cytokines that degrade tight junction proteins; or microbe-specific interactions with the BBB that facilitate transcellular passage of the microorganism. The microorganisms that cause CNS infections include a wide range of bacteria, mycobacteria, yeasts, fungi, viruses, spirochaetes (e.g., neurosyphilis), and parasites (e.g., cerebral malaria and strongyloidiasis). The clinical picture of the various infections can be nonspecific or characterized by distinct, recognizable clinical syndromes. At some juncture, individuals with severe acute CNS infections require critical care management that warrants neuro-ICU admission. The implications for CNS infections are serious and complex and include the increased human and material resources necessary to manage very sick patients, the difficulties in triaging patients with vague or mild symptoms, and ascertaining the precise cause and degree of CNS involvement at the time of admission to the neuro-ICU. This chapter addresses a wide range of severe CNS infections that are better managed in the neuro-ICU. Topics covered include the medical epidemiology of the respective CNS infection; discussions of the relevant neuroanatomy and blood supply (essential for understanding the pathogenesis of CNS infections) and pathophysiology; symptoms and signs; diagnostic procedures, including essential neuroimaging studies; therapeutic options, including empirical therapy where indicated; and the perennial issue of the utility and effectiveness of steroid therapy for certain CNS infections. Finally, therapeutic options and alternatives are discussed, including the choices of antimicrobial agents best able to cross the BBB, supportive therapy, and prognosis.

The long and evolving relationship between viruses and multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disorder of unknown etiology, possibly caused by a virus or is virus-triggered. Several viruses, including herpesviruses, were suggested as etiologic agents or risk factors for exacerbation in the course of illness but none have been shown to be irrefutably linked. Recently the interest of researchers and clinicians in the association between viruses and MS was reawakened by the development of progressive multifocal leukoencephalopathy, a demyelinating and fatal disease caused by JC polyomavirus replication, in natalizumab-treated MS patients. In this review, we will illustrate the evidence underlying the viral hypothesis for MS pathogenesis and will review the main features of the potential viral candidates. We will also describe the risks associated with newer MS therapies and with viral/bacterial vaccinations.