Chronic Wasting Disease of Elk and Deer and Creutzfeldt-Jakob Disease: COMPARATIVE ANALYSIS OF THE SCRAPIE PRION PROTEIN

Zhiliang Xie,Katherine I O'Rourke,Zhiqian Dong,Allen L Jenny,Julie A Langenberg,Ermias D Belay,Lawrence B Schonberger,Robert B Petersen,Wenquan Zou,Qingzhong Kong,Pierluigi Gambetti,Shu G Chen

doi:10.1074/jbc.m509052200

Abstract

Chronic wasting disease (CWD), a transmissible prion disease that affects elk and deer, poses new challenges to animal and human health. Although the transmission of CWD to humans has not been proven, it remains a possibility. If this were to occur, it is important to know whether the "acquired" human prion disease would show a phenotype including the scrapie prion protein (PrP(Sc)) features that differ from those associated with human sporadic prion disease. In this study, we have compared the pathological profiles and PrP(Sc) characteristics in brains of CWD-affected elk and deer with those in subjects with sporadic Creutzfeldt-Jakob disease (CJD), as well as CJD-affected subjects who might have been exposed to CWD, using histopathology, immunohistochemistry, immunoblotting, conformation stability assay, and N-terminal protein sequencing. Spongiform changes and intense PrP(Sc) staining were present in several brain regions of CWD-affected animals. Immunoblotting revealed three proteinase K (PK)-resistant bands in CWD, representing different glycoforms of PrP(Sc). The unglycosylated PK-resistant PrP(Sc) of CWD migrated at 21 kDa with an electrophoretic mobility similar to that of type 1 human PrP(Sc) present in sporadic CJD affecting subjects homozygous for methionine at codon 129 (sCJDMM1). N-terminal sequencing showed that the PK cleavage site of PrP(Sc) in CWD occurred at residues 82 and 78, similar to that of PrP(Sc) in sCJDMM1. Conformation stability assay also showed no significant difference between elk CWD PrP(Sc) and the PrP(Sc) species associated with sCJDMM1. However, there was a major difference in glycoform ratio of PrP(Sc) between CWD and sCJDMM1 affecting both subjects potentially exposed to CWD and non-exposed subjects. Moreover, PrP(Sc) of CWD exhibited a distinct constellation of glycoforms distinguishable from that of sCJDMM1 in two-dimensional immunoblots. These findings underline the importance of detailed PrP(Sc) characterization in trying to detect novel forms of acquired prion disease.

Highlights

From the ‡Institute of Pathology and National Prion Disease Pathology Surveillance Center, Case Western Reserve University, Cleveland, Ohio 44106, §United States Department of Agriculture Agricultural Research Services, Animal Disease Research Unit, Pullman, Washington 99164, ¶United States Department of Agriculture National Veterinary Services Laboratories, Ames, Iowa 50010, ʈWildlife Health Program, Bureau of Wildlife Management, Wisconsin Department of Natural Resources, Madison, Wisconsin 53707, and **National Center for Infectious Diseases, Division of Viral and Rickettsial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333
Consistent with previous studies, we observed that spongiform degeneration involving the neuropil as well as the cell body of neurons is the histopathological hallmark of Chronic wasting disease (CWD) in free-ranging elk, whereas astrogliosis and neuronal loss are generally minimal
Overwhelming evidence indicates that variant Creutzfeldt-Jakob disease (vCJD) is caused by the transmission of bovine spongiform encephalopathy (BSE) to humans [30, 31]

Summary

Introduction

Chronic wasting disease (CWD), a transmissible prion disease that affects elk and deer, poses new challenges to animal and human health. The transmission of CWD to humans has not been proven, it remains a possibility If this were to occur, it is important to know whether the “acquired” human prion disease would show a phenotype including the scrapie prion protein (PrPSc) features that differ from those associated with human sporadic prion disease. PrPSc of CWD exhibited a distinct constellation of glycoforms distinguishable from that of sCJDMM1 in two-dimensional immunoblots These findings underline the importance of detailed PrPSc characterization in trying to detect novel forms of acquired prion disease. Intra-species transmissibility and increased surveillance have contributed to the discovery that geographic distribution and FEBRUARY 17, 2006 VOLUME 281 NUMBER 7

Methods

Results

Conclusion