Final Activity Report Summary - BRC (Biological Research Center, Hungarian Academy of Sciences) Although the exact nature of the infectious agents, the prions, is not known, the presence of the abnormal form is a generally accepted indication for the on-going progression of the disease process. It constitutes the best surrogate marker so far. One of the major problems in developing a method based on the detection of the abnormal form is that very little structural information is available about the abnormal form which would facilitate the generation of monoclonal antibodies with high sensitivity. The difference between the two forms is conformational only, no alteration in the covalent structure of the forms has been revealed. The abnormal form has an elevated beta-sheet content indicating a dramatic conformational change. It has a high tendency for aggregation and soluble only in detergents and denaturants. However, these treatments also destroy the structure of the abnormal form as indicated by the loss of the beta-sheet content and most importantly, the loss of the infectivity in the sample. The most characteristic feature of the abnormal form is its elevated protease resistance and digestion pattern that is used most frequently for its identification. We developed a method for detection of disease-associated prion protein forms in blood of TSE-affected animals without using protease digestion. The method has been successfully applied to hamster and sheep plasma samples. Contrast to other published approach, our method explores only a simple ELISA step and offers all the advantages (sensitivity, reproducibility, specificity, rapidity, practicability for routine use, amenability to automatisation) known to be associated with an ELISA-based method.
