Role of prion protein glycosylation in replication of human prions by protein misfolding cyclic amplification.

Prion diseases are transmissible neurological disorders associated with the presence of abnormal, disease-related prion protein (PrPD). The detection of PrPD in the brain is the only definitive diagnostic evidence of prion disease and its identification in body fluids and peripheral tissues are valuable for pre-mortem diagnosis. Protein misfolding cyclic amplification (PMCA) is a technique able to detect minute amount of PrPD and is based on the conversion of normal or cellular PrP (PrPC) to newly formed PrPD, sustained by a self-templating mechanism. Several animal prions have been efficiently amplified by PMCA, but limited results have been obtained with human prions with the exception of variant-Creutzfeldt-Jakob-disease (vCJD). Since the total or partial absence of glycans on PrPC has been shown to affect PMCA efficiency in animal prion studies, we attempted to enhance the amplification of four major sporadic-CJD (sCJD) subtypes (MM1, MM2, VV1, and VV2) and vCJD by single round PMCA using partially or totally unglycosylated PrPC as substrates. The amplification efficiency of all tested sCJD subtypes underwent a strong increase, inversely correlated to the degree of PrPC glycosylation and directly related to the matching of the PrP polymorphic 129 M/V genotype between seed and substrate. This effect was particularly significant in sCJDMM2 and sCJDVV2 allowing the detection of PK-resistant PrPD (resPrPD) in sCJDMM2 and sCJDVV2 brains at dilutions of 6 × 107 and 3 × 106. vCJD, at variance with the tested sCJD subtypes, showed the best amplification with partially deglycosylated PrPC substrate reaching a resPrPD detectability at up to 3 × 1016 brain dilution. The differential effect of substrate PrPC glycosylations suggests subtype-dependent PrPC-PrPD interactions, strongly affected by the PrPC glycans. The enhanced PMCA prion amplification efficiency achieved with unglycosylated PrPC substrates may allow for the developing of a sensitive, non-invasive, diagnostic test for the different CJD subtypes based on body fluids or easily-accessible-peripheral tissues.

A minimally invasive biomarker for sensitive and accurate diagnosis of Parkinson's disease.

Seeding activities of disease-associated α-synuclein aggregates (αSynD), a hallmark of Parkinson's disease (PD), are detectable by seed amplification assay (αSyn-SAA) and being developed as a diagnostic biomarker for PD. Sensitive and accurate αSyn-SAA for blood or saliva would greatly facilitate PD diagnosis. This prospective diagnostic study conducted αSyn-SAA analyses on serum and saliva samples collected from patients clinically diagnosed with PD or healthy controls (HC). 124 subjects (82 PD, 42 HC) donated blood and had extensive clinical assessments, of whom 74 subjects (48 PD, 26 HC) also donated saliva at the same visits. An additional 57 subjects (35 PD, 22 HC) donated saliva and had more limited clinical assessments. The mean ages were 69.21, 66.55, 69.58, and 64.71 years for PD serum donors, HC serum donors, PD saliva donors, and HC saliva donors, respectively. αSynD seeding activities in either sample type alone or both sample types together were evaluated for PD diagnosis. Serum αSyn-SAA data from 124 subjects showed 80.49% sensitivity, 90.48% specificity, and 0.9006 accuracy (AUC of ROC); saliva αSyn-SAA data from 131 subjects attained 74.70% sensitivity, 97.92% specificity, and 0.8966 accuracy. Remarkably, the combined serum and saliva αSyn-SAA from 74 subjects with both sample types achieved better diagnostic performance: 95.83% sensitivity, 96.15% specificity, and 0.98 accuracy. In addition, serum αSynD seeding activities correlated inversely with Montreal Cognitive Assessment in males and positively with Hamilton Depression Rating Scale in females and in the < 70 age group, whereas saliva αSynD seeding activities correlated inversely with age at diagnosis in males and in the < 70 age group. Our data indicate that serum and saliva αSyn-SAA together can achieve high diagnostic accuracy for PD comparable to that of CSF αSyn-SAA, suggesting their potential utility for highly sensitive, accurate, and minimally invasive diagnosis of PD in routine clinical practice and clinical studies.

A minimally Invasive Biomarker for Sensitive and Accurate Diagnosis of Parkinson's Disease.

Importance: Parkinson's disease (PD), the second most common neurodegenerative disease, is pathologically characterized by intraneuronal deposition of misfolded alpha-synuclein aggregates (αSyn D ). αSyn D seeding activities in CSF and skin samples have shown great promise in PD diagnosis, but they require invasive procedures. Sensitive and accurate αSyn D seed amplification assay (αSyn-SAA) for more accessible and minimally invasive samples (such as blood and saliva) are urgently needed for PD pathological diagnosis in routine clinical practice. Objective: To develop a sensitive and accurate αSyn-SAA biomarker using blood and saliva samples for sensitive, accurate and minimally invasive PD diagnosis. Design Setting and Participants: This prospective diagnostic study evaluates serum and saliva samples collected from patients clinically diagnosed with PD or healthy controls (HC) without PD at an academic Parkinson's and Movement Disorders Center from February 2020 to March 2024. Patients diagnosed with non-PD parkinsonism were excluded from this analysis. A total of 124 serum samples (82 PD and 42 HC) and 131 saliva samples (83 PD and 48 HC) were collected and examined by αSyn-SAA. Out of the 124 serum donors, a subset of 74 subjects (48 PD and 26 HC) also donated saliva samples during the same visits. PD patients with serum samples had a mean age of 69.21 years (range 44-88); HC subjects with serum samples had a mean age of 66.55 years (range 44-81); PD patients with saliva samples had a mean age of 69.58 years (range 49-87); HC subjects with saliva samples had a mean age of 64.71 years (range 30-81). Main Outcomes and Measures: Serum and/or saliva αSyn D seeding activities from PD and HC subjects were measured by αSyn-SAA using the Real-Time Quaking-Induced Conversion (RT-QuIC) platform. These PD patients had extensive clinical assessments including MDS-UPDRS. For a subset of PD and HC subjects whose serum and saliva samples were both collected during the same visits, the αSyn D seeding activities in both samples from the same subjects were examined, and the diagnostic accuracies for PD based on the seeding activities in either sample alone or both samples together were compared. Results: RT-QuIC analysis of αSyn D seeding activities in the 124 serum samples revealed a sensitivity of 80.49%, a specificity of 90.48%, and an accuracy of 0.9006 (AUC of ROC, 95% CI, 0.8472-0.9539, p <0.0001) for PD diagnosis. RT-QuIC analysis of αSyn D seeding activity in 131 saliva samples revealed a sensitivity of 74.70%, a specificity of 97.92%, and an accuracy of 0.8966 (AUC of ROC, 95% CI, 0.8454-0.9478, p <0.0001). When aSyn D seeding activities in the paired serum-saliva samples from the subset of 48 PD and 26 HC subjects were considered together, sensitivity was 95.83%, specificity was 96.15%, and the accuracy was 0.98 (AUC of ROC, 95% CI, 0.96-1.00, p <0.001), which are significantly better than when αSyn D seeding activities in either serum or saliva were used alone. For the paired serum-saliva samples, when specificity was set at 100% by elevating the αSyn-SAA cutoff values, a sensitivity of 91.7% and an accuracy of 0.9457 were still attained. Detailed correlation analysis revealed that αSyn D seeding activities in the serum of PD patients were correlated inversely with Montreal Cognitive Assessment (MoCA) score ( p =0.04), positively with Hamilton Depression Rating Scale (HAM-D) ( p =0.03), and weakly positively with PDQ-39 cognitive impairment score ( p =0.07). Subgroup analysis revealed that the inverse correlation with MoCA was only seen in males ( p =0.013) and weakly in the ≥70 age group ( p =0.07), and that the positive correlation with HAM-D was only seen in females ( p =0.04) and in the <70 age group ( p =0.01). In contrast, αSyn D seeding activities in the saliva of PD patients were inversely correlated with age at diagnosis ( p =0.02) and the REM sleep behavior disorder (RBD) status ( p =0.04), but subgroup analysis showed that the inverse correlation with age at diagnosis was only seen in males ( p =0.04) and in the <70 age group ( p =0.01). Conclusion and Relevance: Our data show that concurrent RT-QuIC assay of αSyn D seeding activities in both serum and saliva can achieve high diagnostic accuracies comparable to that of CSF αSyn-SAA, suggesting that αSyn D seeding activities in serum and saliva together can potentially be used as a valuable biomarker for highly sensitive, accurate, and minimally invasive diagnosis of PD in routine clinical practice. αSyn D seeding activities in serum and saliva of PD patients correlate differentially with some clinical characteristics and in an age and sex-dependent manner. KEY POINTS: Question: Are αSyn D seeding activities in serum and saliva together a more sensitive and accurate diagnostic PD biomarker than αSyn D seeding activities in either sample type alone? Are αSyn D seeding activities in either serum or saliva correlated with any clinical characteristics? Findings: Examinations of αSyn D seeding activities in 124 serum samples and 131 saliva samples from PD and heathy control subjects show that αSyn D seeding activities in both serum and saliva samples together can provide significantly more sensitive and accurate diagnosis of PD than either sample type alone. αSyn D seeding activities in serum or saliva exhibit varied inverse or positive correlations with some clinical features in an age and sex-dependent manner. Meaning: αSyn D seeding activities in serum and saliva together can potentially be used as a valuable pathological biomarker for highly sensitive, accurate, and minimally invasive PD diagnosis in routine clinical practice and clinical studies, and αSyn D seeding activities in serum or saliva correlate with some clinical characteristics in an age and sex-dependent manner, suggesting some possible clinical utility of quantitative serum/saliva αSyn-SAA data.

Two distinct conformers of PrPD type 1 of sporadic Creutzfeldt-Jakob disease with codon 129VV genotype faithfully propagate in vivo.

Current classifications of sporadic Creutzfeldt-Jakob disease (sCJD) identify five subtypes associated with different disease phenotypes. Most of these histopathological phenotypes (histotypes) co-distribute with distinct pairings of methionine (M)/valine (V) genotypes at codon 129 of the prion protein (PrP) gene and the type (1 or 2) of the disease-associated PrP (PrPD). Types 1 and 2 are defined by the molecular mass (~ 21 kDa and ~ 19 kDa, respectively) of the unglycosylated isoform of the proteinase K-resistant PrPD (resPrPD). We recently reported that the sCJDVV1 subtype (129VV homozygosity paired with PrPD type 1, T1) shows an electrophoretic profile where the resPrPD unglycosylated isoform is characterized by either one of two single bands of ~ 20 kDa (T120) and ~ 21 kDa (T121), or a doublet of ~ 21-20 kDa (T121-20). We also showed that T120 and T121 in sCJDVV have different conformational features but are associated with indistinguishable histotypes. The presence of three distinct molecular profiles of T1 is unique and raises the issue as to whether T120 and T121 represent distinct prion strains. To answer this question, brain homogenates from sCJDVV cases harboring each of the three resPrPD profiles, were inoculated to transgenic (Tg) mice expressing the human PrP-129M or PrP-129V genotypes. We found that T120 and T121 were faithfully replicated in Tg129V mice. Electrophoretic profile and incubation period of mice challenged with T121-20 resembled those of mice inoculated with T121 and T120, respectively. As in sCJDVV1, Tg129V mice challenged with T121 and T120 generated virtually undistinguishable histotypes. In Tg129M mice, T121 was not replicated while T120 and T121-20 generated a ~ 21-20  kDa doublet after lengthier incubation periods. On second passage, Tg129M mice incubation periods and regional PrP accumulation significantly differed in T120 and T121-20 challenged mice. Combined, these data indicate that T121 and T120 resPrPD represent distinct human prion strains associated with partially overlapping histotypes.

Decrease in Skin Prion-Seeding Activity of Prion-Infected Mice Treated with a Compound Against Human and Animal Prions: a First Possible Biomarker for Prion Therapeutics.

Previous studies have revealed that the infectious scrapie isoform of prion protein (PrPSc) harbored in the skin tissue of patients or animals with prion diseases can be amplified and detected through the serial protein misfolding cyclic amplification (sPMCA) or real-time quaking-induced conversion (RT-QuIC) assays. These findings suggest that skin PrPSc-seeding activity may serve as a biomarker for the diagnosis of prion diseases; however, its utility as a biomarker for prion therapeutics remains largely unknown. Cellulose ethers (CEs, such as TC-5RW), widely used as food and pharmaceutical additives, have recently been shown to prolong the lifespan of prion-infected mice and hamsters. Here we report that in transgenic (Tg) mice expressing hamster cellular prion protein (PrPC) infected with the 263K prion, the prion-seeding activity becomes undetectable in the skin tissues of TC-5RW-treated Tg mice by both sPMCA and RT-QuIC assays, whereas such prion-seeding activity is readily detectable in the skin of untreated mice. Notably, TC-5RW exhibits an inhibitory effect on the in vitro amplification of PrPSc in both skin and brain tissues by sPMCA and RT-QuIC. Moreover, we reveal that TC-5RW is able to directly decrease protease-resistant PrPSc and inhibit the seeding activity of PrPSc from chronic wasting disease and various human prion diseases. Our results suggest that the level of prion-seeding activity in the skin may serve as a useful biomarker for assessing the therapeutic efficacy of compounds in a clinical trial of prion diseases and that TC-5RW may have the potential for the prevention/treatment of human prion diseases.

Generation of human chronic wasting disease in transgenic mice.

Chronic wasting disease (CWD) is a cervid prion disease caused by the accumulation of an infectious misfolded conformer (PrPSc) of cellular prion protein (PrPC). It has been spreading rapidly in North America and also found in Asia and Europe. Although bovine spongiform encephalopathy (i.e. mad cow disease) is the only animal prion disease known to be zoonotic, the transmissibility of CWD to humans remains uncertain. Here we report the generation of the first CWD-derived infectious human PrPSc by elk CWD PrPSc-seeded conversion of PrPC in normal human brain homogenates using in vitro protein misfolding cyclic amplification (PMCA). Western blotting with human PrP selective antibody confirmed that the PMCA-generated protease-resistant PrPSc was derived from the human PrPC substrate. Two lines of humanized transgenic mice expressing human PrP with either Val or Met at the polymorphic codon 129 developed clinical prion disease following intracerebral inoculation with the PMCA-generated CWD-derived human PrPSc. Diseased mice exhibited distinct PrPSc patterns and neuropathological changes in the brain. Our study, using PMCA and animal bioassays, provides the first evidence that CWD PrPSc can cross the species barrier to convert human PrPC into infectious PrPSc that can produce bona fide prion disease when inoculated into humanized transgenic mice.

Publisher Correction: Early preclinical detection of prions in the skin of prion-infected animals.

The original version of this Article contained errors in the author affiliations. Affiliation 2 incorrectly read 'Department of Neurology, The First Hospital of Jilin University, Changchun 130021 Jilin Province, China.'Affiliation 5 incorrectly read 'Department of Otolaryngology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061 Shanxi Province, China'Affiliation 9 incorrectly read 'State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China.'This has now been corrected in both the PDF and HTML versions of the Article.

Early preclinical detection of prions in the skin of prion-infected animals.

A definitive pre-mortem diagnosis of prion disease depends on brain biopsy for prion detection currently and no validated alternative preclinical diagnostic tests have been reported to date. To determine the feasibility of using skin for preclinical diagnosis, here we report ultrasensitive serial protein misfolding cyclic amplification (sPMCA) and real-time quaking-induced conversion (RT-QuIC) assays of skin samples from hamsters and humanized transgenic mice (Tg40h) at different time points after intracerebral inoculation with 263K and sCJDMM1 prions, respectively. sPMCA detects skin PrPSc as early as 2 weeks post inoculation (wpi) in hamsters and 4 wpi in Tg40h mice; RT-QuIC assay reveals earliest skin prion-seeding activity at 3 wpi in hamsters and 20 wpi in Tg40h mice. Unlike 263K-inoculated animals, mock-inoculated animals show detectable skin/brain PrPSc only after long cohabitation periods with scrapie-infected animals. Our study provides the proof-of-concept evidence that skin prions could be a biomarker for preclinical diagnosis of prion disease.

The molecular diversity of different isolates of Beauveria bassiana (Bals.) Vuill. as assessed using intermicrosatellites (ISSRs).

Inter-microsatellite PCR (ISSR-PCR) markers were used to identify and to examine the genetic diversity of eleven Beauveria bassiana isolates with different geographic origins. The variability and the phylogenetic relationships between the eleven strains were analyzed using 172 ISSR-PCR markers. A high level of polymorphism (near 80%) was found using these molecular markers. Seven different isolates showed exclusive bands, and ISSR primer 873 was able to distinguish between all the strains. The dendrogram obtained with these markers is robust and in agreement with the geographical origins of the strains. All the isolates from the Caribbean region were grouped together in a cluster, while the other isolates grouped in the other cluster. The similarity exhibited between the two clusters was less than 50%. This value of homology shows the high genetic variability detected between the isolates from the Caribbean region and the other isolates. ISSR-PCR markers provide a quick, reliable and highly informative system for DNA fingerprinting, and allowed the identification of the different B. bassiana isolates studied.

Protein misfolding cyclic amplification of infectious prions.

Prions are proteinaceous infectious agents responsible for the transmission of prion diseases. The lack of a procedure for cultivating prions in the laboratory has been a major limitation to the study of the unorthodox nature of this infectious agent and the molecular mechanism by which the normal prion protein (PrP(C)) is converted into the abnormal isoform (PrP(Sc)). Protein misfolding cyclic amplification (PMCA), described in detail in this protocol, is a simple, fast and efficient methodology to mimic prion replication in the test tube. PMCA involves incubating materials containing minute amounts of infectious prions with an excess of PrP(C) and boosting the conversion by cycles of sonication to fragment the converting units, thereby leading to accelerated prion replication. PMCA is able to detect the equivalent of a single molecule of infectious PrP(Sc) and propagate prions that maintain high infectivity, strain properties and species specificity. A single PMCA assay takes little more than 3 d to replicate a large amount of prions, which could take years in an in vivo situation. Since its invention 10 years ago, PMCA has helped to answer fundamental questions about this intriguing infectious agent and has been broadly applied in research areas that include the food industry, blood bank safety and human and veterinary disease diagnosis.

Allelic frequencies of the 15 STR loci included in the AmpFlSTR Identifiler PCR Amplification Kit in an autochthonous sample from Spain.

The aim of this study was to estimate the allelic frequencies of the 15 STR loci included in the AmpFlSTR Identifiler PCR Amplification Kit in a sample of 342 unrelated Caucasian individuals autochthonous from Spain to be used for forensic purposes and population studies. The combined power of discrimination and the combined power of exclusion for all of the 15 loci were 5.68x10(-18) and 0.9999964, respectively. According to the obtained data, the D18S51 locus may be considered the most informative among the tested loci.

Chromosomal location of 46 new RAPD markers in rye (Secale cereale L.).

The polymerase chain reaction (PCR) was used to locate RAPD markers using disomic wheat-rye addition lines in order to develop a set of molecular markers distributed on the seven rye chromosomes. We carried out RAPD amplifications on genomic DNA of wheat 'Chinese Spring' (CS), rye 'Imperial' (I), the amphiploid wheat-rye and the seven disomic wheat-rye addition lines (1R-7R) using 140 different 10-mer oligonucleotides. Forty six new RAPD markers were located on the seven rye chromosomes and all the disomic wheat-rye addition lines were identified on the basis of their amplification patterns. The number of RAPD bands located on 1R, 2R, 3R, 4R, 5R, 6R and 7R chromosomes were 5, 8, 11, 8, 8, 10 and 6, respectively. The seven wheat-rye addition lines can be distinguished using only the following three 10-mer oligonucleotides: OPA16, OPF19 and GEN3-605, the other RAPD primers being useful for this purpose. The use of these RAPDs as a source of molecular markers that could be linked to interesting genes or other important agronomic traits is discussed.