Comparison of conventional, amplification and bio-assay detection methods for a chronic wasting disease inoculum pool

• Published in: PloS one Vol. 14; no. 5; p. e0216621
• Main Authors: McNulty, Erin, Nalls, Amy V, Mellentine, Samuel, Hughes, Erin, Pulscher, Laura, Hoover, Edward A, Mathiason, Candace K
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.05.2019; Public Library of Science (PLoS)
• Subjects: Alzheimer's disease; Amplification; Amyloid; Amyloid - analysis; Analysis; Animals; Bioassays; Biological Assay - methods; Biology and Life Sciences; Brain; Brain - metabolism; Brain - pathology; Brain research; Care and treatment; Chronic wasting disease; Control; Correlation analysis; Deer; Deer - metabolism; Disease transmission; Enzyme-linked immunosorbent assay; Enzymes; Genetic engineering; Identification methods; Immunization; Immunoassay; Immunohistochemistry; Immunology; Inoculum; Longitudinal studies; Medical diagnosis; Medical research; Medicine and Health Sciences; Mice; Mice, Transgenic; Nucleic Acid Amplification Techniques - methods; Pathogenesis; Pathology; Prevalence studies (Epidemiology); Prion Proteins - genetics; Prions; Prions - analysis; Prions - genetics; Protein folding; Protein seeding; Proteins; Research and Analysis Methods; Risk factors; Sensitivity analysis; Transgenic animals; Transgenic mice; Transmissible spongiform encephalopathy; Vaccines; Virology; Wasting Disease, Chronic - diagnosis; Wasting Disease, Chronic - transmission; Zoonoses; United States > US; Colorado
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0216621

Longitudinal studies of chronic wasting disease (CWD) in the native host have provided considerable understanding of how this prion disease continues to efficiently spread among cervid species. These studies entail great cost in animal, time and financial support. A variety of methods have emerged including transgenic mouse bioassay, western blot, enzyme-linked immunoassay (ELISA), immunohistochemistry (IHC), serial protein misfolding cyclic amplification (sPMCA) and real time quaking-induced conversion (RT-QuIC), that deepen our understanding of this and other protein misfolding disorders. To further characterize an inoculum source used for ongoing CWD studies and to determine how the readouts from each of these assays compare, we assayed a CWD-positive brain pool homogenate (CBP6) and a mouse dilutional bioassay of this homogenate using the above detection methods. We demonstrate that: (i) amplification assays enhanced detection of amyloid seeding activity in the CWD+ cervid brain pool to levels beyond mouse LD50, (ii) conventional detection methods (IHC and western blot) performed well in identifying the presence of PrPSc in terminal brain tissue yet lack sufficient detection sensitivity to identify all CWD-infected mice, and (iii) the incorporation of amplification assays enhanced detection of CWD-infected mice near the LD50. This cross-platform analysis provides a basis to calibrate the relative sensitivities of CWD detection assays.