| Transmissible Spongiform Encephalopathies (TSEs) comprise a family of neurodegenerative diseases characterized by the accumulation of misfolded isoform(s) of host encoded prion protein (PrP). The infectious agents in TSEs, commonly referred to as a prions, are believed to be comprised of an infectious isotype of prion protein (Prusiner 1982; Prusiner 1991). Besides having unique proteinaceous infectious agents, TSEs are also unique in that evidence suggests both horizontal and vertical transmission mechanisms are influenced by the PrP genotype of the host; nevertheless, the complete mechanisms for transmission of some TSEs are still unknown (Blattler 2002). The pathologies of many TSE diseases are also uncharacterized. More sensitive and more specific diagnostic assays would provide insights into TSE pathology and transmission mechanisms.;Current diagnostic methods for Transmissible Spongiform Encephalopathies (TSEs), have extremely limited sensitivity, noninvasiveness, and time efficiencies (Raeber and Oesch 2006). The application of several new ultrasensitive immunoassay formats potentially provided a framework to develop a TSE test (Lefebvre 2005). These immunoassays potentially allowed for several important advances including: (1) noninvasivity (the test can be performed on live animals), (2) rapidity (the test can be performed in less than four hours), and (3) sensitivity (the test can potentially detect at picograms per milliliter level which is at least orders of magnitude more sensitive than present or proposed TSE detection methods). Sensitive assays formats including magnetic bead ELISA, bio-bar code assay, and antibody arrays were utilized in an attempt to develop an assay meeting the above requirements. While the preliminary results of the studies with the sensitive assay formats with prion protein were promising, attempts to replicate the results failed due to the variability of the signal. In addition, these formats failed to meet the necessary assay requirements due to the poor sensitivity and specificity of current antibodies as well as the distribution of the different sizes of prion particles which affects binding properties of prion protein to antibodies. In order for this assay format to work, sensitive and specific antibodies need to be engineered specifically for the assay format. Further, a greater understanding of prion protein three dimensional structure would facilitate assay development. |
