Detection and quantification of CWD prions in fixed paraffin embedded tissues by real-time quaking-induced conversion

Abstract

Traditional diagnostic detection of chronic wasting disease (CWD) relies on immunodetection of misfolded CWD prion protein (PrP CWD) by western blotting, ELISA, or immunohistochemistry (IHC). These techniques require separate sample collections (frozen and fixed) which may result in discrepancies due to variation in prion tissue distribution and assay sensitivities that limit detection especially in early and subclinical infections. Here, we harness the power of real-time quaking induced conversion (RT-QuIC) to amplify, detect, and quantify prion amyloid seeding activity in fixed paraffin-embedded (FPE) tissue sections. We show that FPE RT-QuIC has greater detection sensitivity than IHC in tissues with low PrP CWD burdens, including those that are IHC-negative. We also employ amyloid formation kinetics to yield a semi-quantitative estimate of prion concentration in a given FPE tissue. We report that FPE RT-QuIC has the ability to enhance diagnostic and investigative detection of disease-associated PrP RES in prion, and potentially other, protein misfolding disease states.