Luc Tritsmans

Quasispecies Analysis of JC Virus DNA Present in Urine of Healthy Subjects

JC virus is a human polyomavirus that infects the majority of people without apparent symptoms in healthy subjects and it is the causative agent of progressive multifocal leucoencephalopathy (PML), a disorder following lytic infection of oligodendrocytes that mainly manifests itself under immunosuppressive conditions. A hallmark for JC virus isolated from PML-brain is the presence of rearrangements in the non-coding control region (NCCR) interspersed between the early and late genes on the viral genome. Such rearrangements are believed to originate from the archetype JC virus which is shed in urine by healthy subjects and PML patients. We applied next generation sequencing to explore the non-coding control region variability in urine of healthy subjects in search for JC virus quasispecies and rearrangements reminiscent of PML. For 61 viral shedders (out of a total of 254 healthy subjects) non-coding control region DNA and VP1 (major capsid protein) coding sequences were initially obtained by Sanger sequencing. Deletions between 1 and 28 nucleotides long appeared in ∼24.5% of the NCCR sequences while insertions were only detected in ∼3.3% of the samples. 454 pyrosequencing was applied on a subset of 54 urine samples demonstrating the existence of JC virus quasispecies in four subjects (∼7.4%). Hence, our results indicate that JC virus DNA in urine is not always restricted to one unique virus variant, but can be a mixture of naturally occurring variants (quasispecies) reflecting the susceptibility of the non-coding control region for genomic rearrangements in healthy individuals. Our findings pave the way to explore the presence of viral quasispecies and the altered viral tropism that might go along with it as a potential risk factor for opportunistic secondary infections such as PML.

The miRNA world of polyomaviruses

Polyomaviruses are a family of non-enveloped DNA viruses infecting several species, including humans, primates, birds, rodents, bats, horse, cattle, raccoon and sea lion. They typically cause asymptomatic infection and establish latency but can be reactivated under certain conditions causing severe diseases. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in several cellular processes by binding to and inhibiting the translation of specific mRNA transcripts. In this review, we summarize the current knowledge of microRNAs involved in polyomavirus infection. We review in detail the different viral miRNAs that have been discovered and the role they play in controlling both host and viral protein expression. We also give an overview of the current understanding on how host miRNAs may function in controlling polyomavirus replication, immune evasion and pathogenesis.

Viral miRNAs in plasma and urine divulge JC polyomavirus infection

BackgroundJC polyomavirus (JCPyV) is a widespread human polyomavirus that usually resides latently in its host, but can be reactivated under immune-compromised conditions potentially causing Progressive Multifocal Leukoencephalopathy (PML). JCPyV encodes its own microRNA, jcv-miR-J1.MethodsWe have investigated in 50 healthy subjects whether jcv-miR-J1-5p (and its variant jcv-miR-J1a-5p) can be detected in plasma or urine.ResultsWe found that the overall detection rate of JCPyV miRNA was 74% (37/50) in plasma and 62% (31/50) in urine. Subjects were further categorized based on JCPyV VP1 serology status and viral shedding. In seronegative subjects, JCPyV miRNA was found in 86% (12/14) and 57% (8/14) of plasma and urine samples, respectively. In seropositive subjects, the detection rate was 69% (25/36) and 64% (23/36) for plasma and urine, respectively. Furthermore, in seropositive subjects shedding virus in urine, higher levels of urinary viral miRNAs were observed, compared to non-shedding seropositive subjects (P < 0.001). No correlation was observed between urinary and plasma miRNAs.ConclusionThese data indicate that analysis of circulating viral miRNAs divulge the presence of latent JCPyV infection allowing further stratification of seropositive individuals. Also, our data indicate higher infection rates than would be expected from serology alone.

Circulating human microRNAs are not linked to JC polyomavirus serology or urinary viral load in healthy subjects

BackgroundJC polyomavirus (JCPyV) is a widespread human polyomavirus that usually resides latently in its host. It can be reactivated under immunomodulating conditions and cause Progressive Multifocal Leukoencephalopathy (PML). Circulating microRNAs (miRNAs) are emerging as promising biomarkers for several pathologies. In this study, we have investigated whether circulating miRNAs exist that are differentially expressed between JCPyV seropositive and JCPyV seronegative on the one hand or between JCPyV shedders and JCPyV non-shedders on the other hand.MethodsHuman miRNA expression profiling was performed in a small set of plasma samples obtained from seronegative subjects, seropositive shedders and seropositive non-shedders. A set of 10 miRNAs was selected for further analysis in a larger group of samples.ResultsBased on the plasma profiling experiment of 30 samples, 6 miRNAs were selected that were possibly differentially expressed between seropositive and seronegative subjects and 4 miRNAs were selected that were possibly differentially expressed between shedders and non-shedders. Subsequently, expression of these 10 selected miRNAs was assessed in an independent set of 100 plasma samples. Results indicated that none of them were differentially expressed.ConclusionThis study could not identify circulating human miRNAs that were differentially expressed between plasma from JCPyV seropositive and JCPyV seronegative subjects or between JCPyV shedders and JCPyV non-shedders.

An antibody response to human polyomavirus 15-mer peptides is highly abundant in healthy human subjects

BackgroundHuman polyomaviruses (HPyV) infections cause mostly unapparent or mild primary infections, followed by lifelong nonpathogenic persistence. HPyV, and specifically JCPyV, are known to co-diverge with their host, implying a slow rate of viral evolution and a large timescale of virus/host co-existence. Recent bio-informatic reports showed a large level of peptide homology between JCPyV and the human proteome. In this study, the antibody response to PyV peptides is evaluated.MethodsThe in-silico analysis of the HPyV proteome was followed by peptide microarray serology. A HPyV-peptide microarray containing 4,284 peptides was designed and covered 10 polyomavirus proteomes. Plasma samples from 49 healthy subjects were tested against these peptides.ResultsIn-silico analysis of all possible HPyV 5-mer amino acid sequences were compared to the human proteome, and 1,609 unique motifs are presented. Assuming a linear epitope being as small as a pentapeptide, on average 9.3% of the polyomavirus proteome is unique and could be recognized by the host as non-self. Small t Ag (stAg) contains a significantly higher percentage of unique pentapeptides. Experimental evidence for the presence of antibodies against HPyV 15-mer peptides in healthy subjects resulted in the following observations: i) antibody responses against stAg were significantly elevated, and against viral protein 2 (VP2) significantly reduced; and ii) there was a significant correlation between the increasing number of embedded unique HPyV penta-peptides and the increase in microarray fluorescent signal.ConclusionThe anti-peptide HPyV-antibodies in healthy subjects are preferably directed against the penta-peptide derived unique fraction of the viral proteome.

BACE1 Dynamics Upon Inhibition with a BACE Inhibitor and Correlation to Downstream Alzheimer's Disease Markers in Elderly Healthy Participants

The β-site amyloid-β protein precursor (AβPP) cleaving enzyme-1 (BACE1) is the rate limiting enzyme in the generation of amyloid-β peptide (Aβ) from AβPP, one of the major pathways in Alzheimer’s disease (AD) pathology. Increased BACE1 levels and activity have been reported in the brain of patients with sporadic AD. Therefore, changes of BACE1 levels in the cerebrospinal fluid (CSF) have also been investigated as a possible biomarker of the disease. We analyzed BACE1 levels in CSF of elderly healthy participants before and after chronic treatment with a BACE inhibitor (BACEi) and evaluated the correlation between BACE1 levels and downstream AD markers. Overall, BACE1 CSF levels showed strong correlations to all downstream AD markers investigated. This is the first reported finding that shows BACE1 levels in CSF were well correlated to its end product Aβ1 - 42. As previously described, BACE1 levels were strongly correlated to total-tau and phosphorylated tau levels in CSF. Generally, chronic BACE inhibition did not influence BACE1 CSF protein levels. Follow-up studies including early-stage AD pathophysiology and prodromal AD patients will help to understand the importance of measuring BACE1 routinely in daily clinical practice and AD clinical trials.

Hospital referral of stroke patients: a survey of attitudes in general practice, and consideration of entry times for clinical trials

Two major issues in clinical trials in stroke are the criteria used for the selection of patients expected to benefit from the proposed treatment, and the entry time of those patients. We surveyed 507 Belgian general practitioners (GPs) on their opinions on referral of stroke patients to hospital and also on their actual referral behaviour. The feasibility of a 6-hour entry time was included in the investigation. Stroke is considered to require an urgent response: 88% of GPs visited the patient immediately on concluding that such an event had occurred. The mean time between the onset of the first clinical symptoms and the arrival of the GP at the patients residence was about 30 minutes. Within 6 h of the insult, 95% of the patients referred to hospital had been admitted. Information on the GPs most recent stroke patient revealed that 72.4% of these stroke patients were admitted to hospital. Patients referred to hospital were significantly younger, had a significantly more severe stroke, and were significantly more likely to have had a first stroke and to have lived independently before the insult than patients not admitted to hospital. We think that Belgian GPs need to change their referral behaviour with respect to stroke patients and refer more of those who have suffered more mildly. There is every reason to be optimistic about this re-education, since the patients whom GPs do refer to hospital are referred rapidly enough to profit from a possibly efficacious treatment.

Profiling the dynamics of CSF and plasma Aβ reduction after treatment with JNJ-54861911, a potent oral BACE inhibitor

Safety, tolerability, pharmacokinetics, and pharmacodynamics of a novel β‐site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitor, JNJ‐54861911, were assessed after single and multiple dosing in healthy participants.

Does early improvement predict response to the fast-dissociating D2 receptor antagonist JNJ-37822681 in patients with acute schizophrenia? ☆ ☆

Early predictability of sustained response to atypical antipsychotics in patients with schizophrenia has important implications for clinical decision making. In order to investigate whether early onset of efficacy correlates with week-6 response for the selective fast-dissociating D2 receptor antagonist JNJ-37822681, we analysed data from a 12-week placebo- and active-controlled (olanzapine) study designed to evaluate efficacy and safety of JNJ-37822681. Factors, including baseline Positive and Negative Syndrome Scale (PANSS) total score, waist circumference, weight, body mass index group, number of previous hospitalisations, age at diagnosis, race, sex and age at study entry, and relative (%) change from baseline on day 3 (early improvement) in PANSS total score, were analysed using logistic regression models and receiver operator characteristic (ROC) curve analysis, to predict the week-6 efficacy response (≥ 30% improvement in PANSS total score). Results showed that week-6 response with JNJ-37822681 30 mg bid treatment could be reliably predicted by improvement in PANSS total score on day 3, the number of previous hospitalisations, and race (80% accuracy [ROC area under curve]). Early improvement (day 3) in PANSS score had the highest predictive value as a single factor across all JNJ-37822681 doses. At a specificity of 70%, sensitivity for predicting week-6 response was: 0.60, 0.64, and 0.74 in the 10-, 20-, and 30 mg bid JNJ-37822681 groups, respectively; 0.40 in olanzapine group. Early improvement in PANSS may be a simple and reliable way to predict sustained response with JNJ-37822681 in patients with acute schizophrenia.

Antibodies reacting with JCPyV_VP2 _167-15mer as a novel serological marker for JC polyomavirus infection

BackgroundJC polyomavirus (JCPyV) is a widespread human polyomavirus that usually resides latently in its host, but can be reactivated under immune-compromised conditions potentially causing Progressive Multifocal Leukoencephalopathy (PML). Detection of antibodies against the major capsid protein VP1 currently is the main marker for assessment of infection with JCPyV.MethodsBased on a peptide microarray, peptide JCPyV_VP2_167-15mer was selected and a peptide ELISA was developed for detection of antibodies directed against this peptide. Epitope mapping and computational modelling was performed to further characterize this peptide. In a cohort of 204 healthy subjects it was investigated whether antibodies against JCPyV_VP2_167-15mer were correlated with VP1 serology or urinary viral load.ResultsEpitope mapping of peptide JCPyV_VP2_167-15mer showed that the minimal epitope consisted of L173PALTSQEI181 with amino acids P174, L176 and E180 being essential for antibody recognition. Computational analysis was used to predict that this epitope is located at an exposed domain of the VP2 capsid protein, readily accessible for immune recognition upon infection. No correlation could be observed with JCPyV VP1 antibody levels, or urinary viral load.ConclusionThis work indicates that specific antibodies against JCPyV_VP2_167-15mer might be considered as a novel serological marker for infection with JCPyV.