Blood-based Nano-QuIC: Accelerated and Inhibitor-resistant Detection of Misfolded α-synuclein

Abstract

AbstractA hallmark of α-synucleinopathies including Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy, is the misfolding and aggregation of α-synuclein in tissues and biological fluids. Real-time quaking-induced conversion (RT-QuIC) is a protein amplification assay providing ultrasensitive detection of disease-associated misfolded proteins yet is currently limited to invasive sample types such as cerebrospinal fluid for clinical use. More accessible sample types, especially blood, contain inhibitors that interfere with the RT-QuIC assay. Here, we show that Nanoparticle-enhanced Quaking-induced Conversion (Nano-QuIC) can greatly accelerate the detection and improves sensitivity of detection of misfolded alpha-synuclein spiked into extremely complex samples such as human plasma and whole lysed bovine blood compared to RT-QuIC. In spiked human plasma samples, Nano-QuIC showed 100-fold sensitivity improvement while doubling the speed of the reaction. In lysed whole bovine blood, Nano-QuIC detected concentrations of misfolded α-synuclein down to 90 pg/ml while RT-QuIC failed to have any detection due to the presence of strong inhibitors. Crucially, no false positives were observed in human plasma or lysed whole blood with 50 nm silica nanoparticles. This sets the groundwork for noninvasive diagnostic use of Nano-QuIC toward enabling early disease detection and management through blood-based testing.TOC graphic