Chronic wasting disease (CWD) is an emerging prion disease affecting cervids including deer, elk, and moose. It has an expanding geographical range in both North America and Europe. CWD is detrimental to the cervid population with the incidence that can exceed 50% in free-ranging deer and a poorly defined zoonotic potential including humans. Soil is likely to serve as a significant environmental reservoir for CWD prions released from secretions/excreta of infected animals and decomposed CWD carcasses. CWD can persist in the environment and environmental transmission of CWD has been observed. Transitional metals, especially manganese and copper, can bind prions and were found to impact prion properties, e.g., prion conversion capacity. However, the effects of copper and manganese on the persistence of CWD prions in the environment are unclear. In this study, we investigated whether copper and/or manganese could alter prion resistance to environmental degradation. A rodent prion (hamster-adapted transmissible mink encephalopathy, HY TME) or natural elk CWD prion isolates were incubated with CuCl₂ or MnCl₂ at 0.05, 0.5, or 5 mM (final concentration) for 1 week or 1 month at both room and elevated (40°C) temperatures. All treated samples were subjected to proteinase K (PK) digestion to assess the relative resistance of PrP^Sc to degradation. It was observed that both HY TME and CWD PrP^Sc became less resistant to PK digestion when incubated with CuCl₂ depending on metal concentration and incubation conditions, whereas the ones incubated with MnCl₂ were less or not impacted regarding PK resistance. The results indicate a decreased stability of PrP^Sc when associated with copper. These PrP^Sc-metal mixtures will be subjected to simulated weathering conditions such as repeated cycles of drying and wetting to further elucidate the effects of copper and manganese on prion persistence in the environment. Prion infectivity will also be evaluated.

Hui Li

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