title: De NovoGeneration of a Unique Cervid Prion Strain Using Protein Misfolding Cyclic Amplification.
abstract: Substantial evidence supports the hypothesis that prions are misfolded, infectious, insoluble, and protease-resistant proteins (PrPRES) devoid of instructional nucleic acid that cause transmissible spongiform encephalopathies (TSEs). Protein misfolding cyclic amplification (PMCA) has provided additional evidence that PrPRes acts as a template that can convert the normal cellular prion protein (PrPC) present in uninfected normal brain homogenate (NBH) into the infectious misfolded PrPRESisoform. Human PrPChas been shown to spontaneously convert to a misfolded pathological state causing sporadic Creutzfeldt-Jakob disease (sCJD). Several investigators have reported spontaneous generation of prions byin vitroassays, including PMCA. Here we tested the rate ofde novogeneration of cervid prions in our laboratory using our standard PMCA protocol and NBH from transgenic mice expressing cervid PrPC(TgCerPrP mice). We generatedde novoprions in rounds 4, 5, and 7 at low cumulative rates of 1.6, 5.0, and 6.7%, respectively. The prions caused infectious chronic wasting disease (CWD) upon inoculation into normal uninfected TgCerPrP mice and displayed unique biochemical characteristics compared to other cervid prion strains. We conclude that PMCA of cervid PrPCfrom normal brain homogenate spontaneously generated a new cervid prion strain. These data support the potential for cervids to develop sporadic CWD.IMPORTANCECWD is the only known TSE that affects free-ranging wildlife, specifically cervids such as elk, deer, moose, caribou, and reindeer. CWD has become endemic in both free-ranging and captive herds in North America, South Korea, and, most recently, northern Europe. The prion research community continues to debate the origins of CWD. Original foci of CWD emergence in Colorado and Wyoming coincident with the sheep TSE scrapie suggest that scrapie prions may have adapted to cervids to cause CWD. However, emerging evidence supports the idea that cervid PrPCmay be more prone to misfolding to the pathological isoform. Here we test the hypothesis that cervid PrPCcan spontaneously misfold to createde novoprions. Whether CWD can arise spontaneously as a sporadic TSE or represents a new TSE caused by cervid-adapted scrapie prions profoundly impacts surveillance and mitigation strategies.Podcast: A podcast concerning this article is available.
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: Crystal
authors.initials: C
authors.lastname: Meyerett-Reid
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: A Christy
authors.initials: AC
authors.lastname: Wyckoff
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: Terry
authors.initials: T
authors.lastname: Spraker
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Pulford
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Bender
authors.affiliation: Prion Research Center at Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, Colorado, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Zabel
keywords: chronic wasting disease; prions; protein misfolding cyclic amplification; spontaneous generation; strains