Prions, the causative agents of transmissible spongiform encephalopathies such as scrapie in sheep and chronic wasting disease (CWD) in members of the deer family, persist and remain infectious in the environment for years. The environmental persistence of prions has contributed to the rapid spread of CWD, which now spans three continents and at least 26 U.S. states. Soil is a likely reservoir of prion infectivity on the landscape, but monitoring efforts are hampered by a lack of high-throughput analytical methods capable of detecting low levels of prions in such complex matrices. To address this gap, we have developed sample preparation methods compatible with analysis by the Real-Time Quaking-Induced Conversion (RT-QuIC) assay. The RT-QuIC assay monitors amyloid formation in a microplate format, rapidly detecting seeding material (<i>viz</i>. prions) at levels comparable to the gold standard bioassay. We found RT-QuIC ineffective at direct detection of prions sorbed to soil particles, likely due to interferences from natural organic matter or soil mineral phases. We evaluated the efficacy of several surfactants for extracting prions from soil particles in the replication-competent conformation. We identified a zwitterionic surfactant with considerable promise. Extraction of soil by this surfactant followed by sample clean up via precipitation allows detection of prions associated with soils varying widely in composition. We report the analytical performance of the method across a range of soils. We expect this high-throughput method will aid CWD management via identification of hotspots of environmental transmission and determination of contamination in captive deer facilities.

High-throughput prion detection in contaminated soils and compost

ACS Fall 2021

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