Genetic changes in JC virus possibly associated with progressive multifocal leukoencephalopathy]

Progressive multifocal leukoencephalopathy (PML) is a fetal demyelinating disease in the central nervous system. PML was once a rare disease, but it is now relatively common among AIDS (acquired immunodeficiency syndrome) patients. The immunological state of patients mainly contributes to the pathogenesis of PML. Genetic changes of the etiological agent, however, may also be involved in the development and progression of the disease. The major genetic changes possibly associated with PML include the regulatory region rearrangement and the VP1 loop mutation. Both changes have been identified as genetic changes usually occurring in JCV (JCvirus) DNAs from the brain and cerebrospinal fluid of PML patients. Although it remained to be clarified how these changes are involved in the pathogenesis of PML, accumulating evidence suggests that the VP1 loop mutation is associated with the progression of PML. Here we overview studies (mainly those performed by ourselves) on these genetic changes.     

Fatal ruxolitinib-related JC virus meningitis

We report a possible association between ruxolitinib and JC virus meningitis. A 72-year-old man with myelofibrosis started treatment with ruxolitinib. Fourteen days later, the patient presented to the emergency department with fever and nausea. HIV test was negative. Ruxolitinib was suspended. Symptoms progressed with neck stiffness, cognitive impairment, and motor aphasia. CSF was positive for JC virus. MRI showed nonspecific abnormal findings. Five days after the clinical debut, the patient died. The clinical picture, MRI imaging, and positive JC virus PCR in CSF strongly suggest ruxolitinib-related JC virus meningitis.     

Recent progress in the research field on triplet repeat diseases]

At present, 8 inherited neurodegenerative disorders (e.g. Huntington disease, Machado-Joseph disease, etc.) are identified to be caused by the polyglutamine-coding CAG triplet expansions in the responsible genes. These disorders commonly demonstrate dominant inheritance, if autosomal, and late onset of their manifestations. Interestingly, the longer expansions result in earlier onset and more severe clinical manifestations. Proteins containing expanded polyglutamine repeats appear to precipitate by self-aggregation, and as a result produce a core disease-related phenotype: neuronal cell death or degeneration. Given that polyglutamine aggregation might be central in neurodegeneration, the parameters that determine the feasibility of the polyglutamines to aggregate would determine the age of onset and the clinical severity. These parameters are postulated to be the concentration and the length of polyglutamines, which is supported by clinical and experimental observations. The stronger neuronal degenerations are always accompanied by the longer polyglutamine stretches and by the higher concentration of the expanded polyglutamines. In other neurodegenerative disorders, such as Alzheimer disease, prion disease, Parkinson disease and amyotrophic lateral sclerosis, precipitation of abnormal proteins is also now considered to play a key role. These observations might lead to the elucidation of universal mechanisms for neurodegeneration and to treatments effective for many neurodegenerative disorders.     

JC virus agnoprotein colocalizes with tubulin

The human polyomavirus JC (JCV) encodes an agnoprotein that consists of 71 amino acid residues, with a molecular weight of approximately 8 kDa, from the late protein coding region. The agnoprotein of JCV shares 50% to 60% homology with those of simian virus 40 (SV40) and BK virus (BKV), and the carboxyl-terminal region of JCV agnoprotein is relatively unique. By using specific antibody to the carboxyl-terminal region of JCV agnoprotein, the authors have demonstrated that JCV agnoprotein expressed in the JCV-infected cells, where it localized predominantly in the perinuclear region of the cytoplasm, and colocalizes with the cellular cytoskeletal protein, tubulin. The results suggest that JCV agnoprotein may play a role in the stability of microtubules and the preservation of JCV infected cells via an interaction with tubulin.     

JC virus agnoprotein colocalizes with tubulin

The human polyomavirus JC (JCV) encodes an agnoprotein that consists of 71 amino acid residues, with a molecular weight of approximately 8 kDa, from the late protein coding region. The agnoprotein of JCV shares 50% to 60% homology with those of simian virus 40 (SV40) and BK virus (BKV), and the carboxyl-terminal region of JCV agnoprotein is relatively unique. By using specific antibody to the carboxyl-terminal region of JCV agnoprotein, the authors have demonstrated that JCV agnoprotein expressed in the JCV-infected cells, where it localized predominantly in the perinuclear region of the cytoplasm, and colocalizes with the cellular cytoskeletal protein, tubulin. The results suggest that JCV agnoprotein may play a role in the stability of microtubules and the preservation of JCV infected cells via an interaction with tubulin.     

Recent advances in limb-girdle muscular dystrophy research]

In our laboratory, limb-girdle muscular dystrophy (LGMD) accounted for 20% of all patients with muscular dystrophy. To determine the incidence of various forms of LGMD phenotypes, we looked for mutations in the calpain 3 gene and, for deficiencies in dysferlin and sarcoglycan by immunohistochemical studies with specific antibodies on muscle biopsies from patients with probable autosomal recessive inheritance (LGMD2), which were mostly sporadic cases of LGMD. Fourteen of 276 (5%) patients examined had sarcoglycan complex deficiency (sarcoglycanopathy) and 21 of 80 (26%) had mutations in the calpain 3 gene. Although we have not performed gene analysis in all patients, 10 of 64 (15%) patients examined had no apparent immunoreactivity against the dysferlin antibody. Thus, approximately 46% of LGMD2 patients had the above 3 distinct disorders, but in 54% the causative defects remain unknown.     

Role of the environment in the transmission of JC virus

JC virus is etiologically associated with a fatal demyelinating disease known as PML. JCV produces persistent infections in the kidney and is excreted in the urine of healthy individuals and in the urine of PML patients. The characteristics of the JCV excreted in the environment have been studied by analyzing sewage samples from divergent geographical areas. The intergenic region of JCV strains detected in the sewage of Barcelona (Spain), Ume? (Sweden), Nancy (France), Pretoria (South Africa), Patras (Greece), Cairo (Egypt), Washington, D.C. (USA), and diverse areas of Northern India has been sequenced, and the phylogenetic analysis showed their relationships with JCV strains previously described in urine or clinical samples in these geographic areas. The JCV regulatory region of the JCV DNA detected in sewage presented archetypal or archetypal-like regulatory regions with the exception of one of the twenty clones obtained from a sewage sample of the area of Washington, D.C. that presented a tandem repeated structure. Infectivity studies showed that archetypal JCV present in the urine of a pregnant woman productively infected SVG cells. Also JC viral particles showed considerable stability in sewage at 20 degrees C and in front of treatments with acidic pH and trypsin. The high prevalence of JCV in urine and in sewage and the stability of the viral particles observed suggests that contaminated water, food, and fomites could be the vehicles of JCV transmission through the oral route. Virions partially degraded or noninfectious could be a source of JCV DNA and may represent an additional mechanism of entry of viral genes into cells.     

Role of the environment in the transmission of JC virus

JC virus is etiologically associated with a fatal demyelinating disease known as PML. JCV produces persistent infections in the kidney and is excreted in the urine of healthy individuals and in the urine of PML patients. The characteristics of the JCV excreted in the environment have been studied by analyzing sewage samples from divergent geographical areas. The intergenic region of JCV strains detected in the sewage of Barcelona (Spain), Umeå (Sweden), Nancy (France), Pretoria (South Africa), Patras (Greece), Cairo (Egypt), Washington, D.C. (USA), and diverse areas of Northern India has been sequenced, and the phylogenetic analysis showed their relationships with JCV strains previously described in urine or clinical samples in these geographic areas. The JCV regulatory region of the JCV DNA detected in sewage presented archetypal or archetypal-like regulatory regions with the exception of one of the twenty clones obtained from a sewage sample of the area of Washington, D.C. that presented a tandem repeated structure. Infectivity studies showed that archetypal JCV present in the urine of a pregnant woman productively infected SVG cells. Also JC viral particles showed considerable stability in sewage at 20°C and in front of treatments with acidic pH and trypsin. The high prevalence of JCV in urine and in sewage and the stability of the viral particles observed suggests that contaminated water, food, and fomites could be the vehicles of JCV transmission through the oral route. Virions partially degraded or noninfectious could be a source of JCV DNA and may represent an additional mechanism of entry of viral genes into cells.     

Atypical presentations and course of JC virus infection

Journal of NeuroVirology - There is increasing evidence that the spectrum of human polyomavirus 2 (JCV) CNS disease includes novel syndromes other than progressive multifocal leukoencephalopathy...     

Rarity of JC virus DNA sequences and early proteins in human gliomas and medulloblastomas: the controversial role of JC virus in human neurooncogenesis

JC virus (JCV), the agent of progressive multifocal leucoencephalopathy (PML), exerts an oncogenic effect in several laboratory animal models. Moreover, JCV genomic DNA and early viral protein T-antigen have been detected in various types of human central nervous system (CNS) neoplasms. To further explore this association we have studied paraffin-embedded brain biopsy tissue from 60 neoplasms (55 gliomas and five medulloblastomas) and 15 reactive gliosis cases for the presence of JCV DNA sequences and proteins. Four post mortem cases of HIV-associated PML were used as positive controls. Samples were assessed by polymerase chain reaction (PCR) amplification of early (large T antigen) and late (virion protein 3) sequences and immunohistochemistry (IHC) with both PAb 2024 and anti-SV40 large T antigen monoclonal antibodies. Five cases (three neoplasms and two reactive gliosis instances) showed low viral DNA levels when PCR-tested for VP3 or large T, while no case was immunoreactive for any of the two antibodies used. The four PML cases yielded positive results with both PCR and IHC. Additionally, IHC with both antibodies was applied to a tissue micro-array including 109 CNS tumours and 21 reactive gliosis samples. No immunoreactivity was detected in any of these tissue micro-array samples. The rarity of JCV DNA sequences and early proteins in our brain tumours enriches the controversy over the role of JCV in human neurooncogenesis, whose clarification is in need of further molecular and epidemiologic studies.     

Involvement of cell membrane factors in JC virus infection

At present it remains unknown if the JC virus (JCV), the causative agent of progressive multifocal leukoencephalopathy, employs specific cellular receptors or cell membrane factors for viral entry. To investigate this, we have examined the cell-specific replication of a chimeric JCV, which contains the control region (CR) cloned from JCI and the coding sequences of the prototype Mad-1 virus. We examined and compared the hemagglutination (HA) titers produced during viral multiplication following microinjection, transfection with chloramphenicol acetyl-transferase (CAT) assays, and inoculation using a permissive cell line IMR-32 and three non-permissive cell lines COS-7, CV-1, and A431. Virus microinjected into cells proliferated well in both IMR-32 and COS-7, but not in the non-permissive CV-1 and A431 cell lines. When cells were infected with the chimeric JCV, the HA titers were high in IMR-32, low in COS-7, and negative in the other cell lines. Chloramphenicol acetyltransferase assays demonstrated that the CR was active in IMR-32, COS-7, and CV-1, and inactive in A431 cells. The results suggest that not only nuclear, but also cell membrane factors play an important role in the susceptibility of cells to JCV infection.