1.   But prions can fold in an aberrant shape to become a rogue agent, forcing normal prions to change into the disease-causing shape.

2.   Does a normal prion bind to an abnormal prion and then change its shape?

3.   First, the hypothesis holds, the prions touch normal prion proteins in the brain.

4.   For example, how does the infectious prion alter the normal prion?

5.   Humans and most animals carry normal prions in their bodies, and they do no harm.

6.   If a prion taken from a sick cow cannot convert a normal human prion to the abnormal form, he said, people in Europe will worry less.

7.   Infectious prions are produced when normal prions, for unknown reasons, assume a flattened shape that prevents them from being broken down by the body.

8.   It causes disease, Prusiner said, when it nestles against normal prion proteins and makes them change their shapes.

9.   Mice lacking the gene appear healthy, suggesting that the normal prion protein is not an essential protein in mice.

10.   Normal prion protein is produced by a gene that is widely found in nature.