Prion diseases are a class of transmissible fatal disorders. In order to identify alterations associated with the pathogenesis of prion diseases, several studies have been conducted involving differential gene expression analysis using cDNA libraries, mRNA differential displays, and gene microarrays. These genomic approaches may be useful for identifying genes that are differentially expressed in prion diseases and that may participate directly or indirectly in the pathogenesis of the disease. In this study, we compared the gene expression profiles of normal and CWD-infected TgElk mice using the GeneFishing differentially expressed gene (DEG) screening system and real-time PCR analysis. DEGs were screened using the ACP-based PCR method with GeneFishing synthesis. In order to validate candidate genes, we used quantitative PCR (qPCR), and eleven DEGs were identified. Five of these eleven DEGs were upregulated and two were downregulated in the CWD mice. The DEGs newly identified in this study may be useful for diagnosing and studying the pathogenesis of prion diseases.

The sensitivities of PrP Sc detection methods, western blotting (WB), immunohistochemistry (IHC) and protein mis-folding cyclic amplification (PMCA) techniques were compared from brains, spleens and blood of mice challenged with PrP Sc of murine-adapted BSE strain 301C. PrP Sc was detected in the spleen from 30 dpi by IHC and at 60 dpi by WB. At 30 dpi, disease-specific signals of PrP Sc was observed in only two follicles of a single spleen. PrP Sc was detected in spleen at 10 dpi with PMCA after 5 rounds of amplification. Clinical signs were obviously shown from 240 dpi, and coincided with first detection of PrP Sc in brains by WB, IHC and PMCA after one round amplification. In addition, PrP Sc was also detected in blood at 60, 180 and 240 dpi with PMCA after 5 rounds of amplification. The FDC-M1 epitope, which appears in immature FDCs, and PrP Sc were detected in follicles first at 30 dpi, whilst the FDC-M2 epitope of mature FDCs was detected at 60 dpi. More FDC-M2 epitope and PrP Sc were detected in follicles as disease progressed. The CD21/35 epitope is expressed on both FDCs and germinal center B cells. The pattern of CD21/35 expressing cells was similar to but less dominant than that of FDCs.

Abnormal prions are infectious agents involved in a neuro-degenerative disease, which occurs naturally such as Chronic Wasting Disease (CWD) in deer and elk, Bovine Spongiform Encephalopathy (BSE) in cattle, Scrapie in sheep and goats and Creutzfeldt-Jakob Disease (CJD) in humans. The cellular prion protein of the elk consists of 233 amino acids (residues 25-257), which represents an autonomous folding unit with three α-helices and two-stranded anti-parallel β-sheets. Here, we demonstrated elk-recPrP (Elk recombinant prion protein) which can be obtained as follows; (1) Cloning of elk PrP gene, (2) Expression of a histidine-tagged full-length elk PrP by induction with IPTG in E. coli and (3) Purification by affinity chromatography using Ni-NTA agarose resin. In Western blot and ELISA analysis, elk-recPrP showed specific activity against anti-PrP monoclonal antibody. Thus, our elk-recPrP would be a useful tool for the understanding of basic structure and mechanism studies of PrPSC formation.