title: Quantitative assessment of prion infectivity in tissues and body fluids by real-time quaking-induced conversion.
abstract: Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving the templated conversion of the normal cellular prion protein (PrP(C)) to a pathogenic misfolded conformation. Templated conversion has been modelled in several in vitro assays, including serial protein misfolding amplification, amyloid seeding and real-time quaking-induced conversion (RT-QuIC). As RT-QuIC measures formation of amyloid fibrils in real-time, it can be used to estimate the rate of seeded conversion. Here, we used samples from deer infected with chronic wasting disease (CWD) in RT-QuIC to show that serial dilution of prion seed was linearly related to the rate of amyloid formation over a range of 10(-3) to 10(-8) µg. We then used an amyloid formation rate standard curve derived from a bioassayed reference sample (CWD+ brain homogenate) to estimate the prion seed concentration and infectivity in tissues, body fluids and excreta. Using these methods, we estimated that urine and saliva from CWD-infected deer both contained 1-5 LD50 per 10 ml. Thus, over the 1-2 year course of an infection, a substantial environmental reservoir of CWD prion contamination accumulates.
authors.affiliation: Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Davin M
authors.initials: DM
authors.lastname: Henderson
authors.affiliation: Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Kristen A
authors.initials: KA
authors.lastname: Davenport
authors.affiliation: Department of Diagnostic Medicine and Pathobiology, Kansas State University, College of Veterinary Medicine, Manhattan, KS 66506, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Haley
authors.affiliation: Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Nathaniel D
authors.initials: ND
authors.lastname: Denkers
authors.affiliation: Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Candace K
authors.initials: CK
authors.lastname: Mathiason
authors.affiliation: Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Hoover
mesh_terms: D000682:Amyloid / Q000378:metabolism; D000818:Animals; D001681:Biological Assay / Q000379:methods; D001826:Body Fluids / Q000378:metabolism*; D001921:Brain / Q000378:metabolism / Q000821:virology; D003670:Deer / Q000378:metabolism; D017096:Prion Diseases / Q000378:metabolism; D011328:Prions / Q000378:metabolism*; D012463:Saliva / Q000378:metabolism; D014556:Urine / Q000737:chemistry; D034081:Wasting Disease, Chronic / Q000378:metabolism / Q000652:urine
chemical_list: D000682:Amyloid; D011328:Prions