Molecular Studies on Chronic Wasting Disease, a Transmissible Spongiform Encephalopathy of Deer and Elk

NON-TECHNICAL SUMMARY: Chronic wasting disease (CWD) is a transmissible spongiforrn encephalopathy (TSE) of deer and elk. CWD is endemic in certain regions of the USA, but its origin is unknown. Other forms of TSE include scrapie in sheep goats, bovine spongiform encephalopathy (also known as "mad cow" disease), and Creutzfeldt-Jakob disease (CJD) in humans. Since BSE has been shown to transmit the disease to different animal species and possibly to humans, the potential risk of CWD to wildlife, livestock and humans needs to be vigorously assessed. It is generally accepted that TSE is caused by prions consisted mainly of an abnormal, protease-resistant form of the prion protein (PrP). To study CWD of deer and elk at the molecular level, we will examine the overall biochemical properties and structural features of the abnormal PrP in brains of diseased animals. A combination of it immunological and protein chemical methods will be used to characterize the PrP protein subtypes for the classification of prion strains in CWD of deer and elk. Understanding of the molecular features of PrP in CWD-affected cervids will be necessary to gain insights into the pathogenesis of CWD .This line of research may also help us devise better surveillance strategies and improved measures for minimizing the potential threat of CWD to US agriculture and human health.

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APPROACH: The gel migration pattern of PrP(CWD) following digestion of brain homogenates with proteinase K (PK) will be analyzed using the immunoblotting method. Monoclonal antibody will be used to detect PrP on both the conventional and two-dimensional Western blots. For controls, previously characterized human PrP type 1 and type 2 of cm will serve as references for gel mobility and for classification of PrP variants. Different brain samples from diseased deer and elk will be screened for distinct pattern of PrP(CWD) to assess the molecular heterogeneity of CWD. Representative cases of CWD will be selected for purification of PrP(CWD) from brain tissues. Proteinase K will be used to probe the PrP conformation. The PK cleavage sites, indicative of PrP conformational properties, will be determined by N-terminal microsequencing and by mass spectrometry peptide mapping following enzymatic digestion. The relative signal intensities of the individual N-terminal species will be used to build the conformational profile of PrP(CWD).