Effect of decay on detection of chronic wasting disease (CWD) in lymph nodes using enzyme-linked immunosorbent assay...

Surveillance of wildlife diseases poses multiple challenges, including the availability of samples for testing and, in some situations, issues with suboptimal tissue condition. Chronic wasting disease (CWD) is a prion disease threatening the health of wild and captive cervids that is diagnosed with enzyme-linked immunosorbent assay (ELISA) and/or immunohistochemistry (IHC) of retropharyngeal lymph nodes or obex tissue. IHC uses the three-dimensional structure from fresh preserved tissues to facilitate the detection of accumulated prion proteins PrP^CWD within the tissue architecture. ELISA does not require tissue structure and uses tissue lysates to detect PrP^CWD, but its ability to detect PrP^CWD in degraded diagnostic samples is unknown. We thus examined how lymph node decomposition at 4°C and 27°C for up to 12 months affects the ability of ELISA to detect CWD prions in known CWD-positive lymph nodes from wild white-tailed deer (Odocoileus virginianus) in Illinois, USA. We found that prions remained detectable in 100% of the lymph nodes decayed for 12 months at both temperatures, though the detection percentage in each experimental group varied over time. Our findings are the first to demonstrate that USDA-APHIS approved ELISA assays can be used on extensively degraded lymph nodes for CWD surveillance, enabling testing of tissue in suboptimal conditions using.