Detection of Pathognomonic Biomarker PrPSc and the Contribution of Cell Free-Amplification Techniques to the Diagnosis of Prion Diseases

Abstract

Transmissible spongiform encephalopathies or prion diseases are rapidly progressive neurodegenerative diseases, the clinical manifestation of which can resemble other promptly evolving neurological maladies. Therefore, the unequivocal ante-mortem diagnosis is highly challenging and was only possible by histopathological and immunohistochemical analysis of the brain at necropsy. Although surrogate biomarkers of neurological damage have become invaluable to complement clinical data and provide more accurate diagnostics at early stages, other neurodegenerative diseases show similar alterations hindering the differential diagnosis. To solve that, the detection of the pathognomonic biomarker of disease, PrP Sc , the aberrantly folded isoform of the prion protein, could be used. However, the amounts in easily accessible tissues or body fluids at pre-clinical or early clinical stages are extremely low for the standard detection methods. The solution comes from the recent development of in vitro prion propagation techniques, such as Protein Misfolding Cyclic Amplification (PMCA) and Real Time-Quaking Induced Conversion (RT-QuIC), which have been already applied to detect minute amounts of PrP Sc in different matrixes and make early diagnosis of prion diseases feasible in a near future. Herein, the most relevant tissues and body fluids in which PrP Sc has been detected in animals and humans are being reviewed, especially those in which cell-free prion propagation systems have been used with diagnostic purposes.

Exploring the Potential of Biomarkers for Early Diagnosis and Management of Sporadic Creutzfeldt - Jakob disease; A Review

“…Other potential biomarkers, such as blood, urine, and saliva, have also been investigated for their potential use in diagnosing and monitoring sCJD. One potential biomarker is the prion protein, which can be detected in blood (54). However, the sensitivity and specificity of this method are currently not high enough for clinical use.…”

Transmission, Strain Diversity, and Zoonotic Potential of Chronic Wasting Disease

“…These assays have a rather low sensitivity and cannot be performed in live animals. In recent years, in vitro prion-replication assays, including PMCA and RT-QuIC, have been extensively used to detect prions in biological fluids of different animal species, including CWD [ 113 , 114 , 115 , 116 , 117 , 118 ]. These assays rely on mimicking in vitro the mechanism of prion replication to amplify minute amounts of PrP Sc at expenses of large quantities of PrP C using a cyclic-amplification procedure involving cycles of incubation and fragmentation.…”

Development of molecular tools for diagnosis of Alzheimer’s disease that are based on detection of amyloidogenic proteins

“…ThT binds to cross-β structures, thus detecting oligomers and fibrils that are in the amyloid conformation [ 66 ]. PMCA and RT-QuIC protocols are routinely employed for detection of the PrP-based prion in the meat and body liquids of domestic animals, as well as in natural environments [ 67 ]. RT-QuIC protocol for the detection of PrP aggregates in CSF has also been implemented into clinical practice for diagnostics of sporadic CJD in humans by The National CJD Research & Surveillance Unit (NCJRSU) in UK, and demonstrated 92% sensitivity and 100% specificity [ 68 ].…”