Molecular analysis of Irish sheep scrapie cases

Different strains of transmissible spongiform encephalopathies in humans an d rodent models are associated with the accumulation of PrPSc of distinct m olecular characteristics. These characteristics include glycosylation profi les, fragment sizes and long-term resistance of PrPSc to proteinase K, The first objective of this study was to determine the applicability of these c riteria to characterize and differentiate sheep scrapie PrPSc and bovine sp ongiform encephalopathy (BSE) PrPSc. PrPSc in sheep scrapie samples from Ir eland had clearly distinct molecular characteristics to PrPSc in cattle BSE samples using a monoclonal antibody (MAb P4) directed to position 89-104 o f ovine PrP using either brain homogenates or semi-purified scrapie-associa ted fibrils. Similar glycoprofiles were found when analysing scrapie PrPSc in six different CNS regions (thoracic spinal cord, thalamus, basal ganglia , mediobasal hypothalamus, medulla oblongata and cortex). While the long-te rm resistance results using a different monoclonal antibody (raised to rumi nant PrP positions 145-163; MAb L42) were similar to the results obtained w ith MAb P4, different glycotyping results were obtained. Given the variatio n in glycosylation patterns using different antibodies, we conclude that st andardization of methodology and antibodies is crucial to the applicability of molecular analysis of ruminant BSE and scrapie samples.