Cellular PrP^CWD deposition identified at the maternal-foetal interface of chronic wasting disease-infected cervids

Vertical transmission has been identified as a viable route of transmission in the spread of chronic wasting disease (CWD), yet demonstration of trafficking mechanism(s) at the maternal-foetal interface has been limited. Conventional assays, including immunohistochemistry (IHC), Western blot and ELISA, often fail to detect low concentrations of the aberrant prion protein (PrP^CWD). Contemporary in vitro amyloid conversion assays can detect low concentrations of prion seeding activity but lack the ability to localize prion seeds within specific cellular structures of tissues. In this study, we developed an enhanced immunohistochemical approach, as IHC uniquely enables cellular localization, to reveal prion deposition in maternal-foetal tissues from experimentally infected Reeves' muntjac. After confirming improved sensitivity of amplification-IHC (AMP-IHC) in lymphoid tissues, we applied the assay to placentomes and uterine samples, comparing the results to matched tissue sections assessed by conventional IHC. AMP-IHC consistently detected PrP^CWD deposition that was undetected by conventional IHC, including its presence within the uterine glandular epithelium and glandular lumen. These observations provide the first histological evidence depicting prion association with uterine glands - structures responsible for secreting vital nutrients during early pregnancy. The presence of PrP^CWD in these structures supports the hypothesis that the developing conceptus can be exposed to prions in utero. Our findings expand upon earlier studies demonstrating vertical CWD transmission and highlight AMP-IHC as a valuable tool for identifying low-level prion accumulation in tissues where conventional IHC proves insufficient.