Comparison of acetone and sodium phosphotungstic acid precipitation for sample enrichment prior to RT-QuIC for the detection of prion disease.

Transmissible spongiform encephalopathies, or prion diseases, are fatal neurodegenerative diseases that are medically, economically, and ecologically important. In livestock and wildlife, detection to prevent introduction into a new herd or to assess environmental contamination is imperative for disease management. Real time quaking induced conversion (RT-QuIC) is an amplification-based approach with higher sensitivity than traditionally used immunoassays for TSEs and has been used to detect the presence of disease associated prions from various sample types. RT-QuIC also pairs well with upstream sample enrichment methods. In this study we compare sample enrichment by sodium phosphotungstic acid (NaPTA) precipitation, to acetone precipitation. Acetone precipitation is widely used in preparation and analysis of proteins but less commonly used for prion disease samples. This work shows that for brain samples, which typically contain a high amount of disease associated prion protein, acetone and NaPTA provide similar results to unenriched samples. In fecal samples, which have a low abundance of disease associated prion protein, acetone enrichment results in greater sensitivity than either NaPTA or unenriched samples. Acetone enrichment can complement RT-QuIC affording laboratories a rapid sample enrichment approach to improve sensitivity of detection for low abundance prion samples collected from wild and farmed animals.