Traffic of JC virus from sites of initial infection to the brain: the path to progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disorder of the human brain caused by infection with the human polyomavirus, JC. Up to 80% of humans express serum antibodies to JC virus (JCV), yet considerably fewer people develop PML-predominantly those under immunosuppressive conditions. Recent research showed JCV infection in multiple tissues throughout the body, suggesting sites for viral latency. These observations allow the proposal of pathways that JCV may use from sites of initial infection to the brain. Results from investigations into cell-surface receptors, intracellular DNA-binding proteins, and variant viral regulatory regions also suggest mechanisms that may regulate cellular susceptibility to JCV infection. Together, these data elucidate how JCV may establish infection in various cell types, persist latently or become reactivated, and ultimately reach the brain to cause PML.     

Differential expression of mRNAs for JC virus large and small tumor antigens in brain tissues from progressive multifocal leukoencephalopathy patients with and without AIDS.

JC virus (JCV) causes progressive multifocal leukoencephalopathy (PML), the fatal demyelinating infection of oligodendrocytes, in up to 5% of AIDS patients. An intron-differential RNA PCR was developed to study the expression of alternately spliced JCV early mRNAs in brain tissues from PML patients with and without AIDS and in JCV-induced hamster brain tumors. The method utilizes primers that span the large tumor (T) and small tumor (t) antigen introns allowing amplification of specific cDNAs in the presence of contaminating viral genomic DNA. Hybridization with specific junctional probes and DNA sequence analysis confirmed the identity of the PCR products. Sequencing showed that JCV early mRNA is alternatively spliced as previously predicted by analogy to simian virus 40. Large T antigen mRNA was detected in all the brain tissues from PML patients with and without AIDS. The expression of small t antigen mRNA varied depending upon the association of PML with AIDS and upon other unknown factors. Of the 12 PML/AIDS brain tissue samples, 11 (92%) expressed small t antigen mRNA, whereas only 8 of 13 (62%) brain samples from patients with PML alone showed detectable levels of small t antigen mRNA. Human immunodeficiency virus 1 proviral DNA was detected in 10 of 12 PML/AIDS brain samples. The results indicate that alternative splicing of JCV early mRNA is regulated in the human brain and that the production of small t antigen may not be essential for the pathogenesis of PML.     

JC病毒研究进展

JC病毒为小双链DNA病毒,在人群中广泛感染,只有一种血清型,可分为30多个基因型。JC病毒可垂直传播,也可通过呼吸道、消化道传播。严重免疫抑制患者感染JC病毒后可引起进行性多灶性脑白质病(progressive multifocal leukoen-cephalopathy,PML),而CD4+、CD8+T淋巴细胞对感染后是否发病起关键作用。JC病毒对培养细胞和实验动物有很强的致癌潜能,与人类肿瘤存在一定关联性。对感染者的尿液、脑脊液、血液及病变组织进行JC病毒DNA检测和对活组织进行原位杂交及免疫组化检测等为确定JC病毒感染的主要手段,而抗体检测并非确证存在活动性PML的可靠方法。目前没有针对JC病毒有效的抗病毒药物,应用高效抗反转录病毒治疗来获得免疫重建是治疗HIV/AIDS患者感染JC病毒引起PML最好的方法。     

Leg weakness in a lung transplant patient

Progressive multifocal leukoencephalopathy (PML) is associated with JC polyomavirus (JCV) infection of central nervous system oligodendrocytes resulting in demyelinization and progressive focal neurologic deficits. Reactivation of dormant JCV occurs in the setting of immunosuppression, most commonly in patients with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) or hematological malignancies. PML has also been reported in solid organ transplant recipients. We report the case of a 61‐year‐old man after bilateral lung transplantation for chronic hypersensitivity pneumonitis who presented with leg weakness, cognitive decline, and expressive aphasia at 5 months post transplantation. Magnetic resonance imaging and brain biopsy were consistent with PML. Treatment attempt with cytarabine was unsuccessful, and immunomodulation resulted in recurrent grade A3 rejection. The difficulty of managing PML in lung transplant patients is highlighted by the lack of directed therapy and risk of graft rejection or failure with attempts at decreasing immunosuppression.     

Subclinical central nervous system infection with JC virus in patients with AIDS.

Immunocompromised patients, particularly those with AIDS, develop progressive multifocal leukoencephalopathy (PML) due to central nervous system infection with JC virus (JCV). It is unknown whether JCV infection in the central nervous system can occur in the absence of PML symptoms. To address this question, autopsy specimens from patients with AIDS were examined. The brains of a group of patients without AIDS or central nervous system disease were also examined. JCV DNA was detected by the polymerase chain reaction in brain tissue from 4 (31%) of 13 human immunodeficiency virus (HIV)-positive patients. JCV was also detected in 1 elderly HIV-negative patient but not in the 11 other control brains. JCV was not detected in 22 myocardial specimens obtained at autopsy from HIV-negative patients nor 10 peripheral blood specimens from HIV-positive patients. The presence of JCV in brains of patients without clinically evident PML suggests that JCV may be present in the central nervous system without clinical disease.     

Detection of Toxoplasma gondii, Epstein-Barr virus, and JC virus DNAs in the cerebrospinal fluid in acquired immunodeficiency syndrome patients with focal central nervous system complications.

OBJECT: Toxoplasmic encephalitis (TE), primary central nervous system lymphoma (PCNSL) and progressive multifocal leukoencephalopathy (PML) are major central nervous system (CNS) diseases in patients with acquired immunodeficiency syndrome (AIDS). We assessed the diagnostic value of polymerase chain reaction (PCR) in the detection of DNAs of Toxoplasma gondii (T. gondii), Epstein-Barr virus (EBV) and JC virus (JCV) in the cerebrospinal fluid (CSF). METHODS: We compared the PCR results with those of pathological findings at autopsy. PATIENTS OR MATERIALS: The present study included 23 autopsies representing those in whom CSF samples were obtained before death while the patient was hospitalized or at autopsy. RESULTS: The threshold levels for PCR detection were 4 tachyzoites of T. gondii, 5-15 genomes of EBV and 10 genomes of JCV. We identified T. gondii DNA in 4 out of 5 autopsy-defined cases of TE, EBV DNA in 5 out of 5 cases with PCNSL, and JCV DNA in 2 out of 2 cases with PML. The specificity of PCR was 100% in TE, 78% in PCNSL, and 100% in PML. CONCLUSION: Although the number of cases was relatively small in this study, PCR correctly identified T. gondii DNA in those cases in which PML or PCNSL was the sole clinical diagnosis. Our results indicate that PCR examination of CSF is a clinically useful tool for the diagnosis of focal brain lesions in patients with AIDS.     

Progressive multifocal leukoencephalopathy in a patient with multiple myeloma

Progressive multifocal leukoencephalopathy (PML) is a neurological disease that affects immunodeficient patients. We describe here a case of 64-year-old man with IgD type multiple myeloma (MM) who developed progressive neurological symptoms. T₂-weighted magnetic resonance imaging of the brain showed a hyperintense non-enhancing lesion in the left frontal lobe, and analysis of the cerebrospinal fluid by polymerase chain reaction revealed the presence of John Cunningham virus (JCV) DNA. Histopathological analysis of the autopsy brain specimen with in situ hybridization assay revealed the presence of JCV DNA in the nuclei of oligodendroglia. PML in a patient with MM is rare. However, this case report suggests that PML should be suspected and relevant diagnostic examinations should be performed when MM patients present with neurological symptoms.     

Human cytomegalovirus induces JC virus DNA replication in human fibroblasts.

JC virus, a human papovavirus, is the causative agent of the demyelinating brain disease progressive multifocal leucoencephalopathy (PML). PML is a rare but fatal disease which develops as a complication of severe immunosuppression. Latent JC virus is harbored by many asymptomatic carriers and is transiently reactivated from the latent state upon immunosuppression. JC virus has a very restricted host range, with human glial cells being the only tissue in which it can replicate at reasonable efficiency. Evidence that latent human cytomegalovirus is harbored in the kidney similar to latent JC virus led to the speculation that during episodes of impaired immunocompetence, cytomegalovirus might serve as helper virus for JC virus replication in otherwise nonpermissive cells. We show here that cytomegalovirus infection indeed leads to considerable JC virus DNA replication in cultured human fibroblasts that are nonpermissive for the replication of JC virus alone. Cytomegalovirus-mediated JC virus replication is dependent on the JC virus origin of replication and T antigen. Ganciclovir-induced inhibition of cytomegalovirus replication is associated with a concomitant inhibition of JC virus replication. These results suggest that reactivation of cytomegalovirus during episodes of immunosuppression might lead to activation of latent JC virus, which would enhance the probability of subsequent PML development. Ganciclovir-induced repression of both cytomegalovirus and JC virus replication may form the rational basis for the development of an approach toward treatment or prevention of PML.     

JC virus genotypes in France: molecular epidemiology and potential significance for progressive multifocal leukoencephalopathy

JC virus (JCV) induces progressive multifocal leukoencephalopathy (PML), especially in human immunodeficiency virus (HIV)-infected patients. Although JCV genotypes have primarily been associated with geographic patterns, a distinctive neuropathogenicity was recently attributed to genotype 2. A multicenter study was conducted to describe the distribution of JCV genotypes in France and to investigate correlations between genotypes and PML. Genotypes were determined by sequencing 494 bp in the VP1 capsid gene. Peripheral JCV was studied in 65 urine samples from 43 HIV-infected patients and from 22 control subjects. Genotypes 1, 4, 2, and 3 were detected in 52.3%, 30.8%, 12.3%, and 4.6% of the samples, respectively. In 56 brain or cerebrospinal fluid samples, PML-associated JCV of genotypes 1, 2, 4, and 3 was found in 66%, 19.7%, 8.9%, and 5.4%, respectively. Infection with JCV genotypes 1 or 2 was correlated with PML (odds ratio, 3.29). On the other hand, infection with JCV genotype 4 could represent a lower risk for PML.     

Progressive multifocal leukoencephalopathy (PML) development is associated with mutations in JC virus capsid protein VP1 that change its receptor specificity

Progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease caused by JC virus (JCV) infection of oligodendrocytes, may develop in patients with immune disorders following reactivation of chronic benign infection. Mutations of JCV capsid viral protein 1 (VP1), the capsid protein involved in binding to sialic acid cell receptors, might favor PML onset. Cerebrospinal fluid sequences from 37/40 PML patients contained one of several JCV VP1 amino acid mutations, which were also present in paired plasma but not urine sequences despite the same viral genetic background. VP1-derived virus-like particles (VLPs) carrying these mutations lost hemagglutination ability, showed different ganglioside specificity, and abolished binding to different peripheral cell types compared with wild-type VLPs. However, mutants still bound brain-derived cells, and binding was not affected by sialic acid removal by neuraminidase. JCV VP1 substitutions are acquired intrapatient and might favor JCV brain invasion through abrogation of sialic acid binding with peripheral cells, while maintaining sialic acid-independent binding with brain cells.     

Infliximab and the risk of latent viruses reactivation in active Crohn's disease

BACKGROUND: Infliximab is used for refractory Crohn's disease but there are concerns regarding long-term safety. Recently, JC-polyomavirus (JCV) was studied after 3 cases of progressive multifocal leukoencephalopathy (PML) were found after treatment with natalizumab. The aim of this study was to investigate the short-term effect of infliximab on reactivation of several harmful latent viruses. METHODS: Sixty consecutive patients scheduled for infliximab induction course were prospectively enrolled. Blood samples were taken before each infliximab infusion at 0, 2, 6, and 14 weeks. Specific polymerase chain reaction (PCR) analyses were performed to detect JCV, Epstein-Barr virus (EBV), human herpes virus-6, (HHV-6), -7, -8, and cytomegalovirus (CMV). RESULTS: Indications to infliximab were luminal and fistulizing disease in 49 and 15 cases, respectively. Clinical improvement and remission were achieved in 54 (90%) and 39 (65%) of patients, respectively, at 6 weeks. No patient was JCV-positive at any timepoint. EBV serology was positive for 59/60 patients (98%); EBV-PCR tests were transiently positive (>40 copies/10(5) Peripheral blood mononuclear cells, PBMC) in 4 (7%) patients after infliximab, but in each case were negative at subsequent timepoints. All patients were negative for HHV-6, -7, and -8 at all timepoints. CMV serology was positive in 42 patients (70%), but no CMV-PCR-positive patient was observed. There was no association between concomitant treatments or clinical characteristics and viral status. CONCLUSIONS: Our results support the safety of short-term infliximab treatment with respect to latent virus reactivation. The long-term effects of infliximab, particularly for the issue of lymphoproliferative disorders, warrants further studies with larger populations, but so far data are reassuring.     

JC virus meningitis in a patient with systemic lupus erythematosus

The human neurotropic JC virus (JCV) is most commonly acquired during childhood, and, because no clinical illness has been associated with primary infection, is presumed to be asymptomatic. In the immunocompromised host, JCV is responsible for progressive multifocal leukoencephalopathy (PML). We describe a patient with longstanding systemic lupus erythematosus who presented with acute meningitis without encephalitis or PML. JCV was the only pathogen found in the cerebrospinal fluid suggesting a primary infection or symptomatic reactivation. Our observation demonstrates the expanding clinical importance of JCV in autoimmune diseases, and diagnostic tests for JCV should be included in the investigative work-up for meningitis or encephalitis in these patients.     

Improvement of Progressive Multifocal Leukoencephalopathy After Cidofovir Therapy in a Patient with a Destructive Polyarthritis

Abstract The human neurotropic JC virus (JCV) is responsible for progressive multifocal leukoencephalopathy (PML), an infectious demyelinating brain disease with major morbidity and mortality, usually refractory to treatment. We describe a PML in a 67-year-old woman with a destructive polyarthritis associated with anti-JO1 antibodies treated with corticosteroids. Although glucocorticoid therapy was maintained, administration of cidofovir improved the neurological condition. Our observation demonstrates the expanding clinical importance of JCV in systemic rheumatic diseases, particularly when immunosuppressive agents are used, and neurological symptoms or white matter changes on central nervous system imaging should arouse the suspicion of PML.     

In vitro activation of human herpesviruses 6 and 7 from latency.

Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are prevalent lymphotropic viruses that infect more than 80% of children at infancy or during early childhood. Infection ranges from asymptomatic to severe disease. HHV-6B causes exanthem subitum. The virus can be recovered from peripheral blood mononuclear cells during the acute phase of exanthem subitum, but the host remains latently infected throughout life. In immunocompromised patients undergoing kidney, liver, or bone marrow transplantation latent HHV-6B is reactivated, at times causing severe or fatal disease. Here, we describe the establishment of an in vitro system for reactivation of HHV-6B and HHV-7 from latency. HHV-7 is reactivated from latently infected peripheral blood mononuclear cells by T-cell activation. HHV-6B could not be reactivated under similar conditions; however, the latent HHV-6B could be recovered after the cells were infected with HHV-7. Once reactivated, the HHV-6B genomes became prominent and the HHV-7 disappeared. We conclude that HHV-7 can provide a transacting function(s) mediating HHV-6 reactivating from latency. Understanding the activation process is critical for the development of treatments to control the activation of latent viruses so as to avoid these sometimes life threatening infections in transplant recipients.     

Progressive multifocal leucoencephalopathy in a patient with systemic lupus erythematosus treated with rituximab

SIR, Progressive multifocal leucoencephalopathy (PML) is a rarebut usually fatal demyelinating disease of the brain causedby JC papovavirus (JCV). At least 50–75% of the adultpopulation are seropositive for JCV. When JCV reactivation occurs,focal plaques develop in central nervous system white matter.Viral proliferation causes lysis of oligodendrocytes and thereforerapid demyelination [1]. Rituximab is a relatively novel therapyfor systemic lupus erythematosus (SLE) and PML has not previouslybeen reported in a patient with SLE treated with rituximab. The patient was     

Polyomavirus JC-targeted T-cell therapy for progressive multiple leukoencephalopathy in a hematopoietic cell transplantation recipient

Progressive multifocal leukoencephalopathy (PML) associated with polyomavirus JC (JCV) infection has been reported to be usually fatal in allogeneic hematopoietic SCT (HSCT) recipients. We present the case of a 19-year-old HSCT patient diagnosed with JCV-associated PML after prolonged immunosuppression for severe GVHD. No short-term neurological improvement was observed after antiviral treatment and discontinuation of immunosuppressive therapy. Donor-derived JCV Ag-specific CTLs were generated in vitro after stimulation with 15-mer peptides derived from VP1 and large T viral proteins. After adoptive CTL infusion, virus-specific cytotoxic cells were shown in the peripheral blood, JCV-DNA was cleared in the cerebrospinal fluid and the patient showed remarkable improvement. Adoptive T-lymphocyte therapy with JCV-specific CTLs was feasible and had no side effects. This case suggests that adoptive transfer of JCV-targeted CTLs may contribute to restore JCV-specific immune competence and control PML in transplanted patients.     

BKV-DNA and JCV-DNA in CSF of Patients with Suspected Meningitis or Encephalitis

Abstract. Background: Few studies have looked for the polyoma viruses JC or BK virus in the central nervous system (CNS) of patients without neurological symptoms or with neurological symptoms other than progressive multifocal leukoencephalopathy (PML). PCR-microplate hybridization method was employed for the detection of BKV-DNA or JCV-DNA in cerebrospinal fluid (CSF) specimens from patients with suspected meningitis or encephalitis. Materials and Methods: A total of 181 CSF specimens from 151 patients with suspected meningitis or encephalitis was examined for BKV or JCV using PCR-microplate hybridization method. None of the patients had (clinically diagnosed) PML. A control group consisting of 20 CSF specimens from normal subject was also included. Results: BKV DNA was found in five out of 131 (3.8%) and JCV DNA in two out of 131 (1.5%) of the patients with suspected meningitis or encephalitis by PCR ELISA. BKV or JCV DNA was not detected in CSF samples of any of 19 HIVpositive patients. BKV and JCV DNAs were detected respectively in two CSF samples in which Mycobacterium tuberculosis (TB) PCR was also positive. Another patient who was positive for JCV PCR died with a diagnosis of cerebral lymphoma. Among the BK virus infected patients there was a patient with a previous history of hemolytic uremia and acute renal failure. Neither BKV nor JCV DNA was found in any of the 20 CSF samples from normal patients undergoing lumbar puncture for myelography as a part of an investigation of lower back pain. Conclusion: These results suggest that BK virus may be associated with neurological diseases either in immunocompetent or immunocompromised patients. Detection of BKV and JCV DNA in the CSF of the patients suspected to have either meningitis or encephalitis suggests that these viruses may have an etiological role. Thus, diagnostic tests for BK and JC viruses should be included in the investigative program for meningitis or encephalitis patients.     

Critical role of JC virus-specific CD4 T-cell responses in preventing progressive multifocal leukoencephalopathy

BACKGROUND: JC virus (JCV) is ubiquitous among the general population. However, only individuals with severely impaired immunity, mainly AIDS patients, develop progressive multifocal leukoencephalopathy (PML). Here, we examined the role of specific CD4 T cells in the control of JCV infection. METHODS AND DESIGN: JCV-specific CD4 T-cell responses were investigated by assaying peripheral blood mononuclear cell proliferation in response to the purified virus. Four groups of individuals without PML were examined: 14 HIV-seronegative healthy donors and 25 HIV-infected patients without PML, separated into urinary JCV excretors (active infection) and non-excretors, according to JCV PCR on urine. Two groups of patients with PML were also studied: 14 HIV-infected patients with active PML; and 10 PML survivors on effective and prolonged antiretroviral therapy. All of the patients were PCR-positive for JCV in the cerebrospinal fluid at the time of diagnosis of PML. RESULTS: No significant anti-JCV CD4 T-cell proliferation was found in any of the non-excretors tested. All nine healthy donors and seven of the 13 non-PML HIV-infected patients with urinary JCV excretion had positive JCV-specific CD4 T-cell responses. No significant response was found in the 14 patients with active PML, while nine of the 10 PML survivors had positive responses. Restoration of JCV-specific CD4 T-cell responses was associated with JCV clearance from the cerebrospinal fluid. CONCLUSION: JCV-specific CD4 T-cell responses appear to play a critical role in the control of JCV infection, preventing PML development. Such responses can be restored in PML survivors following effective and prolonged antiretroviral therapy.     

Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy is a subacute demyelinating disease that occurs in patients with defects in cell-mediated immunity, including those with AIDS and lymphoproliferative disorders. It is caused by reactivation of JC virus (JCV), which infects 70% to 90% of the population by adulthood, but remains latent in normal hosts. Once reactivated, JCV infects oligodendrocytes and astrocytes, with resultant cell lysis, leading to focal areas of demyelination and necrosis in cerebral white matter causing focal neurologic deficits and characteristic findings on MRI. Polymerase chain reaction for the detection of JCV is a sensitive and specific test, replacing brain biopsy as the initial diagnostic test in the appropriate clinical setting. Historically, the prognosis of progressive multifocal leukoencephalopathy is poor, with most patients dying within 6 months of diagnosis. Antiviral medications targeted against JCV have shown little success. However, with the use of highly active antiretroviral therapy, survival of AIDS patients with progressive multifocal leukoencephalopathy has improved.