Prion Partitioning and Persistence in Environmental Waters

Chronic wasting disease (CWD) is a fatal neurodegenerative disease affecting cervids. CWD is caused by infectious prions, which can enter the environment through bodily fluids or the carcasses of infected animals. Prions can be stored, remain infectious in both soil and water for many years, and transported hydrologically, possibly expanding the geographic range of CWD transmission. In order to better predict hydrological prion transport, we investigated how CWD prion protein (PrP^CWD) partitions and persists in environmental waters. We performed PrP^CWD spike experiments with water samples containing fine sediments from two locations within a CWD-contaminated site, at which contamination sources were removed one year prior. Samples were filtered after spiking, and filtrates and sediments were tested separately for PrP^CWD using real-time quaking-induced conversion (RT-QuIC). Unspiked filtrates tested negative for PrP^CWD, while unspiked sediments were positive, indicating PrP^CWD persistence in environmental sediments for at least one year. Spiked sediments were positive immediately after spiking and throughout 28 days of incubation. Spiked filtrates were largely negative immediately after spiking and remained negative for 28 days, with some inconsistent positives from one sampling location. Our results indicate that PrP^CWD readily partitions to the sediment fraction of environmental waters, suggesting that hydrological prion transport is sediment-facilitated.