Visual detection of misfolded alpha-synuclein and prions via capillary-based quaking-induced conversion assay (Cap-QuIC)

Neurodegenerative protein misfolding diseases impact tens of millions of people worldwide, contributing to millions of deaths and economic hardships across multiple scales. The prevalence of neurodegenerative disease is predicted to greatly increase over the coming decades, yet effective diagnostics for such diseases are limited. Most diagnoses come from the observation of external symptoms in clinical settings, which typically manifest during relatively advanced stages of disease, thus limiting potential therapeutic applications. While progress is being made on biomarker testing, the underlying methods largely rely on fragile and expensive equipment that limits their point-of-care potential, especially in developing countries. Here we present Capillary-based Quaking Induced Conversion (Cap-QuIC) as a visual diagnostic assay based on simple capillary action for the detection of neurodegenerative disease without necessitating expensive and complex capital equipment. We demonstrate that Cap-QuIC has the potential to be a detection tool for a broad range of misfolded proteins by successfully distinguishing misfolded versus healthy proteins associated with Parkinson’s disease (α-synuclein) and Chronic Wasting Disease (prions). Additionally, we show that Cap-QuIC can accurately classify biological tissue samples from wild white-tailed deer infected with Chronic Wasting Disease. Our findings elucidate the underlying mechanism that enables the Cap-QuIC assay to distinguish misfolded protein, highlighting its potential as a diagnostic technology for neurodegenerative diseases.