Accomplishments for FY2011: 1) We have studied the structures of prion seeded recombinant PrP fibrils by infrared spectroscopy and solid-state nuclear magnetic resonance spectroscopy and found evidence for parallel-inregister beta sheet conformations in portions of those fibrils. 2) Using a combination of infrared and hydrogen-deuterium exchanges spectroscopies we have discriminated strain-dependent conformations of mouse scrapie prion protein and determined that the effects of glycosylation and GPI-anchoring on the conformations are modest relative to the conformational differences between strains.