Diagnosis of Methionine/Valine Variant Creutzfeldt-Jakob Disease by Protein Misfolding Cyclic Amplification

A patient with a heterozygous variant of Creutzfeldt-Jakob disease (CJD) with a methionine/valine genotype at codon 129 of the prion protein gene was recently reported. Using an ultrasensitive and specific protein misfolding cyclic amplification–based assay for detecting variant CJD prions in cerebrospinal fluid, we discriminated this heterozygous case of variant CJD from cases of sporadic CJD

Detection of prions in the plasma of presymptomatic and symptomatic patients with variant Creutzfeldt-Jakob disease

Variant Creutzfeldt-Jakob disease (vCJD) is a human prion disease resulting from the consumption of meat products contaminated by the agent causing bovine spongiform encephalopathy. Evidence supporting the presence of a population of silent carriers that can potentially transmit the disease through blood transfusion is increasing. The development of a blood-screening assay for both symptomatic vCJD patients and asymptomatic carriers is urgently required. We show that a diagnostic assay combining plasminogen-bead capture and protein misfolding cyclic amplification (PMCA) technologies consistently detected minute amounts of abnormal prion protein from French and British vCJD cases in the required femtomolar range. This assay allowed the blinded identification of 18 patients with clinical vCJD among 256 plasma samples from the two most affected countries, with 100% sensitivity [95% confidence interval (CI), 81.5 to 100%], 99.2% analytical specificity (95% CI, 95.9 to 100%), and 100% diagnostic specificity (95% CI, 96.5 to 100%). This assay also allowed the detection of silent carriage of prions 1.3 and 2.6 years before the clinical onset in two blood donors who later developed vCJD. These data provide a key step toward the validation of this PMCA technology as a blood-based diagnostic test for vCJD and support its potential for detecting presymptomatic patients, a prerequisite for limiting the risk of vCJD transmission through blood transfusion

Artificial neural network prediction of clozapine response with combined pharmacogenetic and clinical data.

Although one third to one half of refractory schizophrenic patients responds to clozapine, however, there are few evidences currently that could predict clozapine response before the use of the medication. The present study aimed to train and validate artificial neural networks (ANN) , using clinical and pharmacogenetic data, to predict clozapine response in schizophrenic patients. Five pharmacogenetic variables and five clinical variables were collated from 93 schizophrenic patients taking clozapine, including 26 responders. ANN analysis was carried out by training the network with data from 75% of cases and subsequently testing with data from 25% of unseen cases to determine the optimal ANN architecture. Then the leave-one-out method was used to examine the generalization of the models. The optimal ANN architecture was found to be a standard feed-forward, fully- connected, back-propagation multilayer perceptron. The overall accuracy rate of ANN was 83.3%, which is higher than that of logistic regression (LR) (70.8%). By using the area under the receiver operating characteristics curve as a measure of performance, the ANN outperformed the LR (0.821 + /- 0.054 versus 0.579 +/- 0.068; p < 0. 001). The ANN with only genetic variables outperformed the ANN with only clinical variables (0.805 +/- 0.056 versus 0.647 +/- 0.066; p = 0.046). The gene polymorphisms should play an important role in the prediction. Further validation of ANN analysis is likely to provide decision support for predicting individual response

Prion amplification techniques for the rapid evaluation of surface decontamination procedures.

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Rapid Diagnostic Test for Hepatitis B Virus Viral Load Based on Recombinase Polymerase Amplification Combined with a Lateral Flow Read-Out

International audienceHepatitis B (HBV) infection is a major public health concern. Perinatal transmission of HBV from mother to child represents the main mode of transmission. Despite the existence of effective immunoprophylaxis, the preventive strategy is inefficient in neonates born to mothers with HBV viral loads above 2 × 105 IU/mL. To prevent mother-to-child transmission, it is important to identify highly viremic pregnant women and initiate antiviral therapy to decrease their viral load. We developed a simple innovative molecular approach avoiding the use of automatic devices to screen highly viremic pregnant women. This method includes rapid DNA extraction coupled with an isothermal recombinase polymerase amplification (RPA) combined with direct visual detection on a lateral flow assay (LFA). We applied our RPA-LFA approach to HBV DNA-positive plasma samples with various loads and genotypes. We designed a triage test by adapting the analytical sensitivity to the recommended therapeutic decision threshold of 2 × 105 IU/mL. The sensitivity and specificity were 98.6% (95% CI: 92.7–99.9%) and 88.2% (95% CI: 73.4–95.3%), respectively. This assay performed excellently, with an area under the ROC curve value of 0.99 (95% CI: 0.99–1.00, p < 0.001). This simple method will open new perspectives in the development of point-of-care testing to prevent HBV perinatal transmission

Prion amplification techniques for the rapid evaluation of surface decontamination procedures.

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Magnetic Field-Enhanced Agglutination Readout Combined With Isothermal Reverse Transcription Recombinase Polymerase Amplification for Rapid and Sensitive Molecular Detection of Dengue Virus

International audienceAmong the numerous molecular diagnostic methods, isothermal reverse transcription recombinase polymerase amplification (RT-RPA) is a simple method that has high sensitivity and avoids the use of expensive instruments. However, detection of amplified genomes often requires a fluorescence readout on costly readers or migration on a lateral flow strip with a subjective visual reading. Aiming to establish a new approach to rapidly and sensitively detect viruses, we combined RT-RPA with a magnetic field-enhanced agglutination (MFEA) assay and assessed the ability of this method to detect the dengue virus (DENV). Magnetization cycles accelerated the capture of amplified DENV genomes between functionalized magnetic nanoparticles by a fast chaining process to less than 5 min; the agglutination was quantified by simple turbidimetry. A total of 37 DENV RNA + and 30 DENV RNA − samples were evaluated with this combined method. The sensitivity and specificity were 89.19% (95% CI, 72.75–100.00%) and 100% (95% CI, 81.74–100.00%), respectively. This approach provides a solution for developing innovative diagnostic assays for the molecular detection of emerging infections

Earliest detection of prion seeding activity in blood of human PRP transgenic mice infected with vCJD

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Diagnosis of Variant Creutzfeldt - Jakob Disease in life Using Protein Misfolding Cyclic Amplification (PMCA).

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Diagnosis of Variant Creutzfeldt - Jakob Disease in life Using Protein Misfolding Cyclic Amplification (PMCA).

International audienc