Affiliation:
1. Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, Ottawa, ON K2J 4S1, Canada
Abstract
Real-time quaking-induced conversion (RT-QuIC) assays have become a common tool to detect chronic wasting disease (CWD) and are very sensitive provided the assay duration is sufficient. However, a prolonged assay duration may lead to non-specific signal amplification. The wide range of pre-defined assay durations in current RT-QuIC applications presents a need for methods to optimize the RT-QuIC assay. In this study, receiver operating characteristic (ROC) analysis was applied to optimize the assay duration for CWD screening in obex and retropharyngeal lymph node (RLN) tissue specimens. Two different fluorescence thresholds were used: a fixed threshold based on background fluorescence (Tstdev) and a max-point ratio (maximum/background fluorescence) threshold (TMPR) to determine CWD positivity. The optimal assay duration was 33 h for obex and 30 h for RLN based on Tstdev, and 29 h for obex and 32 h for RLN based on TMPR. The optimized assay durations were then evaluated for screening CWD in white-tailed deer from an affected farm. At a replicate level, using the optimized assay durations with TStdev and TMPR, the level of agreement with enzyme-linked immunosorbent assay (ELISA) was significantly higher (p < 0.05) than that when using a 40 h assay duration. These findings demonstrate that the optimization of assay duration via a ROC analysis can improve RT-QuIC assays for screening CWD in white-tailed deer.
Funder
Canadian Food Inspection Agency
Reference31 articles.
1. U.S. Geological Survey (2023, December 15). Wildlife National Health Center Distribution of Chronic Wasting Disease in North America, Available online: https://www.usgs.gov/media/images/distribution-chronic-wasting-disease-north-america-0.
2. U.S. Geological Survey (2024, January 23). Expanding Distribution of Chronic Wasting Disease, Available online: https://www.usgs.gov/centers/nwhc/science/expanding-distribution-chronic-wasting-disease.
3. Pathways of Prion Spread during Early Chronic Wasting Disease in Deer;Hoover;J. Virol.,2017
4. Immediate and Ongoing Detection of Prions in the Blood of Hamsters and Deer Following Oral, Nasal, or Blood Inoculations;Elder;J. Virol.,2015
5. Burgener, K.R., Lichtenberg, S.S., Lomax, A., Storm, D.J., Walsh, D.P., and Pedersen, J.A. (2022). Diagnostic Testing of Chronic Wasting Disease in White-Tailed Deer (Odocoileus virginianus) by RT-QuIC Using Multiple Tissues. PLoS ONE, 17.