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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #350603

Research Project: Immunodiagnostics to Detect Prions and Other Important Animal Pathogens

Location: Produce Safety and Microbiology Research

Title: Using mass spectrometry to determine the relative susceptibility of PrP polymorphisms to atypical scrapie

Author
item Silva, Christopher - Chris
item Erickson-Beltran, Melissa
item MARTÍN-BURRIEL, INMACULADA - University Of Zaragoza
item BADIOLA, JUAN JOSÉ - University Of Zaragoza
item REQUENA, JESUS - University Of Santiago De Compostela
item BOLEA, ROSA - University Of Zaragoza

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2018
Publication Date: 5/23/2018
Citation: Silva, C.J., Erickson-Beltran, M.L., Martín-Burriel, I., Badiola, J., Requena, J.R., Bolea, R. 2018. Using mass spectrometry to determine the relative susceptibility of PrP polymorphisms to atypical scrapie. Meeting Abstract. Poster 110. Prion2018, Santiago de Compostela, Spain.

Interpretive Summary: Pathological proteins (prions) convert a normal cellular prion protein into a prion to cause brain disease. Atypical scrapie is a recently discovered sheep fatal prion disease and is thought to arise spontaneously. Each parent of a sheep provides one of the two copies of the gene producing the normal cellular prion. Offspring possessing different normal cellular prion protein genes (heterozygous) produce two different forms (polymorphism) of the normal cellular prion protein. In heterozygous animals prions replicate by using two different normal cellular prion proteins. This allows a comparison of the replication rates of atypical scrapie prions in the same animal. Prion replication is also dependent upon the amount of normal cellular prion protein that an animal produces. The more normal cellular prion protein an animal produces, the faster the prion disease progresses. We isolated the prions from heterozygous sheep naturally (not experimentally) infected with atypical scrapie. We also isolated the normal cellular prion protein from atypical scrapie-infected sheep and from uninfected sheep. We determined the relative amounts of each form of the normal cellular prion protein in each animal. The normal cellular prion protein was present in similar amounts in both the infected and uninfected sheep. This shows that sheep infected with atypical scrapie do not produce more of the normal cellular prion protein than uninfected sheep. In the naturally infected sheep, both forms of the normal cellular prion protein were converted into prions at a similar rate. This suggests that all normal cellular prion protein forms can be converted to atypical scrapie prions and that no form of the normal cellular prion protein will protect sheep from atypical scrapie.

Technical Abstract: A novel form of scrapie was described in 1998 and referred to as Nor98 for the country of origin and date of its discovery. Since then it has been found in numerous countries, including New Zealand and Australia, and has been renamed atypical scrapie. Unlike classical scrapie, the epidemiology of this sheep prion (PrPSc) disease is consistent with a sporadic origin. Even though it may arise spontaneously, atypical scrapie can be experimentally transmitted to other sheep. Atypical scrapie is associated with specific PrPC polymorphisms that are different from those associated with classical scrapie. We used a mass spectrometry-based method to determine the relative amount of each PrP polymorphism present in a sample from a heterozygous animal. The total amount and relative amounts of each PrP polymorphism present in PrPSc and PrPC were determined. Each PrP sample was isolated and digested with chymotrypsin to yield a set of characteristic peptides spanning relevant polymorphisms at positions 136, 141, 154, 171 and 172 of sheep PrPC. 15N-labeled internal standards, derived from chymotrypsin digested 15N-labeled rPrP, were used to quantify PrP polymorphisms (ALRRY and ALHQY or ALRQD or AFRQY) present in heterozygous atypical scrapie-infected or uninfected control sheep. Full length and truncated (C1) natively expressed PrPC isolated from atypical scrapie-infected animals showed both PrP polymorphisms are produced in equal amounts. In addition, similar amounts of PrPC are present in either infected or uninfected animals. The amount of PrPSc isolated from infected heterozygotes was variable, but was composed of significant amounts of both PrP polymorphisms, including the ALRRY polymorphism which is highly resistant to classical scrapie. Atypical scrapie infection does not originate from sheep PrPC overexpression. Atypical scrapie prions replicate at comparable rates, in spite of polymorphisms at positions 141, 154, 171, or 172.