1.   Prion infection did not reappear for three weeks, the interval used to define a cure in this kind of laboratory experiment.

2.   Since the normal proteins are conjectured to form part of the surface of nerve cells, prion infections show up as brain degenerative diseases.

3.   The researchers stressed that it was impossible to say whether either of these molecules was the critical receptor for prion infection.

4.   The French food safety agency AFSSA said it had carried out tests to assess any risks of prion infection from beef muscle, and all the results were negative.