Researchers at Case Western Reserve University School of Medicine have taken a major step towards understanding how abnormal prion proteins, the suspected cause of mad cow and related diseases, change shape to jump from one animal species to another. In test tube experiments, they were able to make human prion proteins exhibit characteristics of mouse prions or hamster prions through the substitution of either one or two amino acids. Furthermore, they describe how prions may overcome natural transmissibility barriers between two species of mammals. This may happen if prion proteins from one of these two species have been exposed to abnormal prions from a third species.
