Biochemical typing of pathological prion protein in aging cattle with BSE

Seraina Tester,Torsten Seuberlich,Bianca Haase,Miroslaw Polak,Tosso Leeb,Marcus G Doherr,Valerie Juillerat,Andreas Zurbriggen,Felix Ehrensperger

doi:10.1186/1743-422x-6-64

Seraina Tester, Torsten Seuberlich + Show 7 more

Open Access

https://doi.org/10.1186/1743-422x-6-64

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Journal: Virology journal	Publication Date: May 26, 2009
Citations: 69	License type: cc-by

Affiliation: University of Bern, University of Zurich

Abstract

BackgroundThe broad enforcement of active surveillance for bovine spongiform encephalopathy (BSE) in 2000 led to the discovery of previously unnoticed, atypical BSE phenotypes in aged cattle that differed from classical BSE (C-type) in biochemical properties of the pathological prion protein. Depending on the molecular mass and the degree of glycosylation of its proteinase K resistant core fragment (PrPres), mainly determined in samples derived from the medulla oblongata, these atypical cases are currently classified into low (L)-type or high (H)-type BSE. In the present study we address the question to what extent such atypical BSE cases are part of the BSE epidemic in Switzerland.ResultsTo this end we analyzed the biochemical PrPres type by Western blot in a total of 33 BSE cases in cattle with a minimum age of eight years, targeting up to ten different brain regions. Our work confirmed H-type BSE in a zebu but classified all other cases as C-type BSE; indicating a very low incidence of H- and L-type BSE in Switzerland. It was documented for the first time that the biochemical PrPres type was consistent across different brain regions of aging animals with C-type and H-type BSE, i.e. independent of the neuroanatomical structure investigated.ConclusionTaken together this study provides further characteristics of the BSE epidemic in Switzerland and generates new baseline data for the definition of C- and H-type BSE phenotypes, thereby underpinning the notion that they indeed represent distinct prion disease entities.

Highlights

The broad enforcement of active surveillance for bovine spongiform encephalopathy (BSE) in 2000 led to the discovery of previously unnoticed, atypical BSE phenotypes in aged cattle that differed from classical BSE (C-type) in biochemical properties of the pathological prion protein
BSE cases in aging cattle Since H- and L-type BSE have been identified only in cattle ≥ 8 years of age, we extracted all such animals, in total 37, from our database that includes all confirmed BSE cases in Switzerland from the index case in 1990 until today
That (i) the molecular mass of the unglycosylated moiety of PrPres was conspicuously higher in the zebu as compared to L- and C-type BSE and similar to the Polish H-type BSE control by using the PrPres core-binding monoclonal antibodies (mAb) 6H4 (Figure 1a), (ii) the N-terminal-specific mAb 12B2 readily detected PrPres in the zebu and the H-type BSE control but not in C- and L-type BSE (Figure 1b), (iii) the C-terminal-specific mAb SAF84 revealed a complex banding pattern in the zebu and the H-type BSE control (Figure 1c) and (iv) the diglycosylated PrPres moiety was predominant in C- and H-type BSE and the zebu using mAb 6H4, but not in the L-type control

Summary

Introduction

The broad enforcement of active surveillance for bovine spongiform encephalopathy (BSE) in 2000 led to the discovery of previously unnoticed, atypical BSE phenotypes in aged cattle that differed from classical BSE (C-type) in biochemical properties of the pathological prion protein. Depending on the molecular mass and the degree of glycosylation of its proteinase K resistant core fragment (PrPres), mainly determined in samples derived from the medulla oblongata, these atypical cases are currently classified into low (L)-type or high (H)-type BSE. The origin of BSE still remains under debate and it has been hypothesized that the disease derived from sheep scrapie, human TSEs [8] or from a spontaneous bovine prion disease analogous to sporadic forms of CJD in human [9]. PrPSc but not PrPC partially resists digestion by proteinase K (PK), resulting in an N-terminally truncated prion protein termed PrPres. The latter can be detected immunochemically, e.g. by Western blot (WB), in which it reveals a characteristic banding-pattern that reflects un-, mono- and diglycosylated PrPres- moieties. The apparent molecular masses and relative quantities of these glycoforms are used in biochemical PrPres typing as the criteria to differentiate between prion diseases [11,12]

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