Humic substances interfere with detection of pathogenic prion protein

Authors

Christen B. Smith, Environmental Chemistry and Technology Program, University of Wisconsin
Clarissa J. Booth, Molecular and Environmental Toxicology Center
Tyler J. Wadzinski, Environmental Chemistry and Technology Program, University of Wisconsin
Giuseppe Legname, Neurobiology Sector, Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Rick Chappell, Departments of Statistics and of Biostatistics & Medical Informatics, University of Wisconsin
Christopher J. Johnson, Prion Research Laboratory, USGS National Wildlife Health Center
Joel A. Pedersen, Environmental Chemistry and Technology Program, University of Wisconsin; Molecular and Environmental Toxicology Center; Department of Soil Science, University of WisconsinFollow

Document Type

Article

Date of this Version

2014

Citation

Soil Biology and Biochemistry 68, 2014

Comments

U.S. Government work

Abstract

Studies examining the persistence of prions (the etiological agent of transmissible spongiform encephalopathies) in soil require accurate quantification of pathogenic prion protein (PrPTSE) extracted from or in the presence of soil particles. Here, we demonstrate that natural organic matter (NOM) in soil impacts PrPTSE detection by immunoblotting. Methods commonly used to extract PrPTSE from soils release substantial amounts of NOM, and NOM inhibited PrPTSE immunoblot signal. The degree of immunoblot interference increased with increasing NOM concentration and decreasing NOM polarity. Humic substances affected immunoblot detection of prion protein from both deer and hamsters. We also establish that after interaction with humic acid, PrPTSE remains infectious to hamsters inoculated intracerebrally, and humic acid appeared to slow disease progression. These results provide evidence for interactions between PrPTSE and humic substances that influence both accurate measurement of PrPTSE in soil and disease transmission.