A comprehensive understanding of the biology of prion diseases is crucial for risk assessment as regards both humans and animals. To further the communication of the current knowledge and the exchange of diagnostic technologies in the scientific community, a symposium on the 'Characterization and Diagnosis of Prion Diseases' was held from September 23-25, 1999 in Tubingen, Germany. The overwhelming interest and the participation of more than 500 scientists from 26 countries made this symposium the largest meeting ever held in the field. In this Supplementum to Archives of Virology twenty-six...