Exploring JC polyomavirus sequences and human gene expression in brain tissue of patients with progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a rare neurological condition associated with reactivation of dormant JC polyomavirus (JCPyV). In this study, we characterized gene expression and JCPyV rearrangements in PML brain tissue. Infection of white matter astrocytes and oligodendrocytes as well as occasional brain cortex neurons was shown. PML brain harbored exclusively rearranged JCPyV variants. Viral transcripts covered the whole genome on both strands. Strong differential expression of human genes associated with neuroinflammation, blood-brain-barrier permeability and neurodegenerative diseases was shown. Pathway analysis revealed wide immune activation in PML brain. The study provides novel insights into the pathogenesis of PML.

JC Polyomavirus Modifies the Expression of Human microRNAs in Progressive Multifocal Leukoencephalopathy Brain.

Progressive multifocal leukoencephalopathy (PML) is a severe neurological condition caused by reactivation of JC polyomavirus (JCPyV) in immunosuppression. Asymptomatic JCPyV persists in peripheral tissues. Upon reactivation, neurotropic rearrangements may emerge, and the virus gains access to the brain. To assess the mechanisms of PML pathogenesis, brain tissue material from PML patients was collected for small RNA sequencing. Upregulation of 8 microRNAs (miRNAs) in PML brain was validated using quantitative microRNA polymerase chain reaction (PCR). Bioinformatics tools were utilized to identify major associations of the upregulated miRNAs: neuroinflammation and blood-brain barrier disruption. The results indicate involvement of human miRNA regulation in PML pathogenesis.

Human papillomavirus self-sampling with mRNA testing benefits routine screening.

High risk human papillomavirus (hrHPV) based screening provides the possibility of vaginal self-sampling as a tool to increase screening attendance. In order to evaluate the impact and feasibility of opt-in self-sampling in the Finnish setting, we invited a randomized population of 5350 women not attending screening after age group invitation or after reminder, to attend HPV self-sampling-based screening in the autumn of 2018 in Helsinki. Out of those, 1282 (24.0%) expressed their interest and ordered the sampling package. Eventually 787 women (14.7% of the total invited population) took part in screening, 770 women by providing a vaginal sample within 2 months from invitation and 17 by providing a pap smear in the laboratory. Self-taken samples were collected in Aptima Multitest vials and tested using the Aptima HPV mRNA assay. A high proportion, 158/770 (20.5%) of the samples were positive in the Aptima HPV assay. One hundred and forty-one samples were further submitted to Aptima HPV Genotyping and extended genotyping by a Luminex based assay. Of those, 23 samples (16.3%) were HPV 16 positive and 7 (5.0%) were positive for HPV 18/45; extended genotyping revealed multiple high-risk and low-risk HPV genotypes. At follow-up seven cases of high-grade squamous intraepithelial lesion (HSIL) were diagnosed, which represents 4.4% of HPV positive women and 0.9% of screened women, whereas the rate was 0.5% in routine screening. Our findings suggest that self-sampling with HPV mRNA testing is a feasible approach to improve screening efficacy in a high-risk population among original nonattendees.

Overtreatment rate after immediate local excision of suspected cervical intraepithelial neoplasia: A prospective cohort study.

OBJECTIVE: The gold standard of cervical intraepithelial neoplasia (CIN) treatment is large loop excision of the transformation zone (LLETZ) after histopathological diagnosis from punch biopsies. In addition, treatment may be appropriate at initial colposcopy. Our objective was to study the applicability of immediate treatment strategy according to clinical parameters. METHODS: We conducted a prospective cohort study among patients referred to colposcopy at Helsinki University Hospital, Finland, between January 2014, and September 2018 (ISRCTN10933736). Patients treated with LLETZ, either after biopsies or immediately at initial colposcopy, were included. The main outcome measure was overtreatment (OT) rate defined as normal or low-grade histopathological findings in LLETZ specimen within both treatment groups. RESULTS: A total of 572 patients treated with LLETZ were included: 360 treated after biopsies and 212 treated immediately at initial colposcopy. When LLETZ was performed immediately after high-grade referral cytology and with colposcopic impression of high-grade disease, the overtreatment (OT) rate was 10.0% (95% CI 9.10 to 17.2), whereas when LLETZ was done after biopsy-confirmed high-grade lesions, the OT rate was 18.9% (95% CI 14.7 to 23.7), resulting in risk difference (RD) -8.91% (95% CI -16.0 to -1.82). Among HPV16/18 positive patients the OT rate was 8.22% (95% CI 3.08 to 17.0) for immediate treatment, resulting in RD of -10.7% (95% CI -18.3 to -3.04) compared to LLETZ after biopsies. CONCLUSIONS: Immediate LLETZ does not result in overtreatment when applied on selected cases, especially after high-grade referral cytology and when high-grade lesion is also colposcopically suspected.

BetaHPV E6 and E7 colocalize with NuMa in dividing keratinocytes.

Human papillomaviruses (HPVs) of genus betapapillomavirus (betaHPV) are implicated in skin carcinogenesis, but their exact role in keratinocyte transformation is poorly understood. We show an interaction of HPV5 and HPV8 oncoproteins E6 and E7 with the nuclear mitotic apparatus protein 1 (NuMA). Binding of E6 or E7 to NuMA induces little aneuploidy, cell cycle alterations, or aberrant centrosomes. Intracellular localization of NuMA is not altered by E6 and E7 expression in 2D cultures. However, the localization profile is predominantly cytoplasmic in 3D organotypic skin models. Both viral proteins colocalize with NuMA in interphase cells, while only E7 colocalizes with NuMA in mitotic cells. Intriguingly, a small subset of cells shows E7 at only one spindle pole, whereas NuMA is present at both poles. This dissimilar distribution of E7 at the spindle poles may alter cell differentiation, which may in turn be relevant for betaHPV-induced skin carcinogenesis.

BK polyomavirus viremia and antibody responses of pediatric kidney transplant recipients in Finland.

BACKGROUND: BKPyV is an important cause of premature graft failure after KT. Most clinical studies describe BKPyV infection in adult KT patients. We studied the prevalence of post-transplant BKPyV viremia, serology, and graft function in pediatric KT recipients. METHODS: Forty-six pediatric patients transplanted between 2009 and 2014 were followed up for BKPyV DNAemia by plasma PCR for median 2.3 (range: 1-6) years. BKPyV-specific antibodies were retrospectively analyzed using virus-like particle ELISA. GFR was measured annually by 51 Cr-EDTA clearance, and serum samples were screened for DSAs by Luminex assay. RESULTS: BKPyV viremia was demonstrated in nine patients at a median of 6 months post-KT. Early BKPyV viremia at 3 months post-KT associated with decreased concomitant GFR and tendency for decreased subsequent graft function. Three of nine patients with BKPyV viremia developed DSA, all against class II antigens. PyVAN developed to four patients and responded to judicious reduction in IS. One graft was lost later due to ABMR. BKPyV-IgG was found in 18 of 31 patients (58%) tested at transplantation, and seven recipients seroconverted after transplantation with a significant increase in IgG levels with IgM. Finally, BKPyV-IgG was detectable in 31 of 40 patients (78%) at the end of the study. CONCLUSIONS: Post-transplant BKPyV viremia in pediatric KT patients may alter graft function and contribute to progression of chronic allograft injury. BKPyV-IgG predicts past exposure. Low or absent BKPyV-specific antibody levels were seen pretransplant in 42% of tested patients, but were not predictive of prolonged replication or poor outcome.

Single-Molecule Sequencing Revealing the Presence of Distinct JC Polyomavirus Populations in Patients With Progressive Multifocal Leukoencephalopathy.

Background: Progressive multifocal leukoencephalopathy (PML) is a fatal disease caused by reactivation of JC polyomavirus (JCPyV) in immunosuppressed individuals and lytic infection by neurotropic JCPyV in glial cells. The exact content of neurotropic mutations within individual JCPyV strains has not been studied to our knowledge. Methods: We exploited the capacity of single-molecule real-time sequencing technology to determine the sequence of complete JCPyV genomes in single reads. The method was used to precisely characterize individual neurotropic JCPyV strains of 3 patients with PML without the bias caused by assembly of short sequence reads. Results: In the cerebrospinal fluid sample of a 73-year-old woman with rapid PML onset, 3 distinct JCPyV populations could be identified. All viral populations were characterized by rearrangements within the noncoding regulatory region (NCCR) and 1 point mutation, S267L in the VP1 gene, suggestive of neurotropic strains. One patient with PML had a single neurotropic strain with rearranged NCCR, and 1 patient had a single strain with small NCCR alterations. Conclusions: We report here, for the first time, full characterization of individual neurotropic JCPyV strains in the cerebrospinal fluid of patients with PML. It remains to be established whether PML pathogenesis is driven by one or several neurotropic strains in an individual.

Archetype JC Polyomavirus (JCPyV) Prevails in a Rare Case of JCPyV Nephropathy and in Stable Renal Transplant Recipients With JCPyV Viruria.

Background: JC polyomavirus (JCPyV) is reactivated in approximately 20% of renal transplant recipients, and it may rarely cause JCPyV-associated nephropathy (JCPyVAN). Whereas progressive multifocal leukoencephalopathy of the brain is caused by rearranged neurotropic JCPyV, little is known about viral sequence variation in JCPyVAN owing to the rarity of this condition. Methods: Using single-molecule real-time sequencing, characterization of full-length JCPyV genomes in urine and plasma samples from 1 patient with JCPyVAN and 20 stable renal transplant recipients with JCPyV viruria was attempted. Sequence analysis of JCPyV strains was performed, with emphasis on the noncoding control region, the major capsid protein gene VP1, and the large T antigen gene. Results: Exclusively archetype strains were identified in urine from the patient with JCPyVAN. Full-length JCPyV sequences were not retrieved from plasma. Archetype strains were found in urine samples from 19 stable renal transplant recipients, with JCPyV quasispecies detected in 5 samples. In a patient with minor graft dysfunction, a strain with an archetype-like noncoding cont rol region was discovered. Individual point mutations were detected in both VP1 and large T antigen genes. Conclusions: Archetype JCPyV was dominant in the patient with JCPyVAN and in stable renal transplant recipients. Archetype rather than rearranged JCPyV seems to drive the pathogenesis of JCPyVAN.

JCPyV microRNA in plasma inversely correlates with JCPyV seropositivity among long-term natalizumab-treated relapsing-remitting multiple sclerosis patients.

Sensitive biomarkers are needed to better manage multiple sclerosis (MS) patients for natalizumab (NTZ)-associated risk of progressive multifocal leukoencephalopathy (PML). A currently used risk stratification algorithm, mainly based on JC polyomavirus (JCPyV) serology, has not led to a reduction of PML incidence. Therefore, this study was designed to evaluate the presence and prevalence of JCPyV miRNAs in plasma of NTZ-treated MS patients, and to explore their biomarker potential for NTZ-associated PML risk assessment. Altogether, 102 plasma samples from 49 NTZ-treated and 28 interferon-beta (IFN-ß)-treated relapsing-remitting MS patients, and 25 healthy controls (HCs) were analyzed for jcv-miR-J1-5p (5p miRNA) and jcv-miR-J1-3p (3p miRNA) expression. The overall detection rate of 5p miRNA was 84% (41/49) among NTZ-treated patients, 75% (21/28) among IFN-ß-treated patients, and 92% (23/25) in HCs. Relative 5p miRNA expression levels were lower in NTZ-treated patients as compared to patients treated with IFN-ß (p = 0.027) but not to HCs. Moreover, 5p miRNA expression inversely correlated with anti-JCPyV antibody index among JCPyV seropositive long-term NTZ-treated patients (r = -0.756; p = 0.002). The overall detection rate of 3p miRNA was low. Our results suggest that JCPyV miRNA in plasma may be linked to the reactivation of persistent JCPyV, to enhanced virus replication, and eventually to the risk of developing PML among NTZ-treated MS patients. However, further study is warranted in a larger data set including samples from PML patients to confirm the clinical relevance of JCPyV miRNA as a sign of/in viral reactivation, and to identify its potential to predict developing PML risk.

Human papillomavirus type 8 E7 protein binds nuclear myosin 1c and downregulates the expression of pre-rRNA.

Our aim was to search for new cellular binding partners for the E6 and E7 oncogenes of beta human papillomaviruses (HPV), whose direct role in skin carcinogenesis has not been thoroughly investigated. By employing glutathione S-transferase pulldown and coimmunoprecipitation, we identified nuclear myosin 1c as a binding partner of HPV 8 E7 protein. As nuclear myosin 1c is an essential component of the RNA polymerase I transcription complex, we studied the effects of HPV 8 E7 protein expression on ribosomal RNA (rRNA) expression. Here we show that the activity of RNA polymerase I is decreased and that pre-rRNA expression is consequently reduced due to HPV 8 E7 expression. However, the expression levels of mature cytoplasmic 18S and 28S rRNA are retained. We propose that by relieving their resources from the energy-consuming process of rRNA transcription, HPV 8 E7 expressing cells might support more efficient virus replication in the differentiating epithelium.

Performance of mRNA- and DNA-based high-risk human papillomavirus assays in detection of high-grade cervical lesions.

INTRODUCTION: The aim was to assess the performance of two commercial assays for the detection of high-risk human papillomavirus (hrHPV): Aptima HPV Assay (Hologic, Inc., Marlborough, MA, USA) which detects mRNA of 14 different hrHPV types, and Hybrid Capture 2 HPV DNA test (HC2; Qiagen, Gaithersburg, MD, USA), which detects the DNA of 13 different hrHPV types. Test performance was compared in the settings of a standard colposcopy clinic, among the regular patient flow. MATERIAL AND METHODS: Two separate cervical cell samples for Aptima and HC2 testing were collected from women referred to colposcopy or a cervical follow-up visit. Altogether, 481 paired samples were analyzed and all positive samples were also tested using the Aptima HPV 16 18/45 Genotype Assay. Results from the two assays were compared directly and with stratification by histology and cytology from the same sampling visit. RESULTS: The overall agreement between HC2 and Aptima assays was 92.9% (Kappa coefficient of 0.855). The sensitivity and specificity of the assays in detecting CIN2+ were 92.5 and 58.2% for HC2, and 94.0 and 59.3% for Aptima, respectively. No significant differences between the assays were found (p-values >0.5). Both assays detected all CIN3 (n = 30) and carcinoma (n = 2) cases. CONCLUSIONS: The mRNA-based Aptima assay and the extensively studied DNA-based HC2 test performed equally well in detecting high-grade cervical lesions. Our data contribute to the growing evidence base indicating that the mRNA-based Aptima assay could be used for the triage of patients with HPV-associated cervical disease.

Individual and Complementary Effects of Human Papillomavirus Oncogenes on Epithelial Cell Proliferation and Differentiation.

Previous studies on human papillomavirus (HPV) type 16 protein functions have established the oncogenic nature of three viral proteins: E5, E6 and E7. Here we have studied the functions of these proteins by functional deletion of the individual E5, E6 or E7, or both E6 and E7 oncogenes in the context of the whole viral genome. These mutants, or the intact wild-type genome, were expressed from the natural viral promoters along with differentiation of epithelial HaCaT cells in three-dimensional collagen raft cultures. High episomal viral copy numbers were obtained using a transfection-based loxp-HPV16-eGFP-N1 vector system. All epithelial equivalents carrying the different HPV type 16 genomes showed pronounced hyperplastic and dysplastic morphology. Particularly the E7 oncogene, with contribution of E6, was shown to enhance cell proliferation. Specifically, the crucial role of E7 in HPV-associated hyperproliferation was clearly manifested. Based on morphological characteristics, immunohistochemical staining for differentiation and proliferation markers, and low expression of E1^E4, we propose that our raft culture models produce cervical intraepithelial neoplasia (CIN)1 and CIN2-like tissue. Our experimental setting provides an alternative tool to study concerted functions of HPV proteins in the development of epithelial dysplasia.

[Polvomaviruses as causative agents of diseases]. / Polyoomavirukset sairauksien aiheuttajina.

The number of polyomaviruses causing infections in humans is as high as thirteen. The BK and JC polyomaviruses and the diseases caused by them are best known. For the present, the Merkel cell polyomavirus is the only human polyomavirus considered to be a causative agent of cancer. Other disease associations of polyomaviruses are also subject to active research. All polyomavirus infections are usually harmless respiratory or intestinal infections of childhood. Polyomaviruses, remain in the body for the rest of life, i.e. they persist as part of the body microbiome. Upon weakening of cell-mediated immunity they can also become reactivated and cause clinical problems.

Expression of toll-like receptors in HPV-positive and HPV-negative oropharyngeal squamous cell carcinoma--an in vivo and in vitro study.

The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has increased over the past decades in many western countries. This trend is mainly attributed to the human papillomavirus (HPV). Cancer-related actions of immunological defense systems are being intensively researched. Human toll-like receptors (TLRs) are a family of pattern recognition receptors that participate in the immunological defense against pathogens, but their actions are also linked to cancer. The expression of TLRs in cervical epithelium alters both during the clearance of HPV infection and the HPV-induced neoplasia, but the expression of TLRs has not been studied in OPSCC. Thirty-five paraffin-embedded, formalin-fixed, squamous cell carcinoma tissue specimens were analyzed for TLRs 2, 3, 4, 5, 7, and 9 and HPV and p16 statuses. The TLR 9 expression was lower in HPV-positive tumors compared with HPV-negative tumors. TLR 7 was expressed in all cancer specimens, but elevated expression was evident in HPV and/or p16-positive tumors. The majority of p16-positive tumors did not express TLR 5, whereas its expression was stronger in p16-negative tumors. The results of in vitro analysis of five human OPSCC cell lines and one human oral tongue squamous cell carcinoma cell line agree with the in vivo trends: low levels of TLR 5 and high levels of TLR 7 in p16-positive OPSCC. Overall, TLR 7 and 9 expression patterns are demonstrated here to relate to the HPV status in vivo and TLR 5 and 7 expression patterns to the p16 status in vivo and in vitro.

Differentiation of highly pathogenic strains of human JC polyomavirus in neurological patients by next generation sequencing.

BACKGROUND: JC polyomavirus (JCPyV) persists asymptomatic in more than half of the human population. Immunocompromising conditions may cause reactivation and acquisition of neurotropic rearrangements in the viral genome, especially in the non-coding control region (NCCR). Such rearranged JCPyV strains are strongly associated with the development of progressive multifocal leukoencephalopathy (PML). METHODS: Using next-generation sequencing (NGS) and bioinformatics tools, the NCCR was characterized in cerebrospinal fluid (CSF; N = 21) and brain tissue (N = 16) samples from PML patients (N = 25), urine specimens from systemic lupus erythematosus patients (N = 2), brain tissue samples from control individuals (N = 2) and waste-water samples (N = 5). Quantitative PCR was run in parallel for diagnostic PML samples. RESULTS: Archetype NCCR (i.e. ABCDEF block structure) and archetype-like NCCR harboring minor mutations were detected in two CSF samples and in one CSF sample and in one tissue sample, respectively. Among samples from PML patients, rearranged NCCRs were found in 8 out of 21 CSF samples and in 14 out of 16 brain tissue samples. Complete or partial deletion of the C and D blocks was characteristic of most rearranged JCPyV strains. From ten CSF samples and one tissue sample NCCR could not be amplified. CONCLUSIONS: Rearranged NCCRs are predominant in brain tissue and common in CSF from PML patients. Extremely sensitive detection and identification of neurotropic viral populations in CSF or brain tissue by NGS may contribute to early and accurate diagnosis, timely intervention and improved patient care.

BK virus viremia in a well-HLA-matched kidney transplant population mainly on low-dose cyclosporine-based immunosuppression.

The incidence and clinical course of polyomavirus-associated nephropathy (PyVAN) in our well-HLA-matched kidney transplant population mainly on low-dose cyclosporine-based triple-drug immunosuppression has not been described in detail. We aimed to characterize our patients with PyVAN and BK virus (BKV) viremia. Among 166 kidney transplantations between January 2007 and February 2011 followed up at Helsinki University Hospital nephrology clinic, 136 were screened for BKV viremia by quantitative analysis of BKV DNA in plasma. PyVAN was diagnosed by biopsy histopathology and SV40 T-antigen detection. BKV viremia or PyVAN were treated by reducing immunosuppression. BKV viremia was detected in 12 (9%) patients. PyVAN was diagnosed in six patients (4%). In the six patients with no PyVAN, four had low-level viremia (<10,000 copies/mL) of short duration (<2 months), one had high-level viremia, and one had sustained low-level viremia. After reduction of immunosuppression, all except one patient were able to clear viremia. No grafts were lost due to PyVAN. Even in a low-risk population, BKV viremia and PyVAN occur, highlighting the importance of monitoring viral loads. Reduction of immunosuppression was successful, and no grafts were lost due to PyVAN.

miRSeqNovel: an R based workflow for analyzing miRNA sequencing data.

We present miRSeqNovel, an R based workflow for miRNA sequencing data analysis. miRSeqNovel can process both colorspace (SOLiD) and basespace (Illumina/Solexa) data by different mapping algorithms. It finds differentially expressed miRNAs and gives conservative prediction of novel miRNA candidates with customized parameters. miRSeqNovel is freely available at http://sourceforge.net/projects/mirseq/files.

Cell culture model predicts human disease: Altered expression of junction proteins and matrix metalloproteinases in cervical dysplasia.

BACKGROUND: Cervical cancer is necessarily caused by human papillomaviruses, which encode three oncogenes manifesting their functions by interfering with a number of cellular proteins and pathways: the E5, E6, and E7 proteins. We have earlier found in our microarray studies that the E5 oncogene crucially affects the expression of cellular genes involved in adhesion and motility of epithelial cells. METHODS: In order to biologically validate our previous experimental findings we performed immunohistochemical staining of a representative set of tissue samples from different grades of high-risk human papillomavirus associated cervical disease as well as normal squamous and columnar cervical epithelium. Three-dimensional collagen raft cultures established from E5-expressing and control epithelial cells were also examined. The expression of p16, matrix metalloproteinase (MMP) -7, MMP-16, cytokeratin (CK) 8/18, laminin, E-cadherin and beta-catenin was studied. RESULTS: In agreement with our previous microarray studies, we found intense staining for E-cadherin and beta-catenin in adherens junctions even in high-grade cervical lesions. Staining for MMP-16 was increased in severe disease as well. No significant change in staining for MMP-7 and cytokeratin 8/18 along with the grade of cervical squamous epithelial disease was observed. CONCLUSIONS: Here we have confirmed, using tissue material from human papillomavirus associated lesions, some of the cellular gene expression modifications that we earlier reported in an experimental system studying specifically the E5 oncogene of papillomaviruses. These findings were partially surprising in the context of cervical carcinogenesis and emphasize that the complexity of carcinogenesis is not yet fully understood. Microarray approaches provide a wide overwiev of gene expression in experimental settings, which may yield biologically valid biomarkers for disease diagnostics, prognosis, and follow-up.

Transmission of human papillomavirus DNA from patient to surgical masks, gloves and oral mucosa of medical personnel during treatment of laryngeal papillomas and genital warts.

The risk of occupational human papillomavirus (HPV) transmission from patient to medical personnel during laser vaporization procedures remains controversial. The purpose of this study was to determine the risk of HPV transmission from the patient to the protective surgical masks, gloves and oral mucosa of medical personnel during the treatment of laryngeal papillomas and genital warts. The study involved five male patients scheduled for the surgical treatment of laryngeal papillomas, and five male patients undergoing carbon dioxide (CO(2)) laser treatment for urethral warts. Oral mucosa specimens were obtained from the study patients and the employees pre- and postoperatively. Samples were collected from the HPV-infected patient tissue, and from the surgical masks and gloves used by the employees. A total of 120 samples were analyzed for the presence of HPV DNA by PCR, using the degenerated MY09/11/HMB01 primers. After the papilloma procedures, the surgeons' gloves tested HPV positive in one of the five cases and those of the surgical nurse in three of the five cases. After the treatment of genital warts, HPV DNA corresponding to the patient tissue specimens was present in all the samples obtained from the surgical gloves of the operators. All oral mucosa samples obtained from 18 different employees tested HPV negative, as did the surgical mask specimens. According to our study, HPV may contaminate protective equipment, most of all surgical gloves, but transmission of HPV DNA to medical personnel is unlikely to occur provided that protective surgical gloves and masks are applied and disposed of properly.

JC polyomavirus DNA detection in clinical practice.

BACKGROUND: There are limited data about the use and clinical value of JC polyomavirus (JCPyV) DNA detection in various clinical indications. METHODS: We reviewed the clinical records of 410 patients from whom cerebrospinal fluid (CSF), plasma, urine, or tissue samples had been collected for JCPyV DNA polymerase chain reaction (PCR) between 2012 and 2018. RESULTS: JCPyV DNA was analyzed in 224 plasma, 190 CSF-, 32 urine and 10 tissue samples. 240 patients had a history of hematopoietic stem cell or solid organ transplantation, 159 had nephrological disease, 90 had hematologic malignancies, 58 had neurological disease, 37 had infectious disease and 23 had AIDS/HIV as underlying disease. Six patients had no underlying disease. The main reasons to take CSF or plasma samples were neurological symptoms of unknown etiology. Most urine samples were taken to monitor kidney transplantation patients. JCPyV DNA PCR contributed to the diagnosis of progressive multifocal leukoencephalopathy in eight patients (2.0%), of which seven had hematologic malignancy as an underlying disease. CONCLUSIONS: JCPyV PCR is most informative among immunosuppressed patients with neurologic symptoms. CSF and brain biopsy are useful when there is clinical suspicion of PML, whereas plasma samples are not useful. The value of plasma samples is a matter of dispute in the screening of JCPyV-associated nephropathy, as BK polyomavirus is the causative agent in most polyomavirus-associated nephropathy cases. JCPyV detection is valuable in case the patient has past, current or planned treatment with immunosuppressive drugs.