1.   There are three human prion diseases and four main prion diseases of animals.

2.   He then injected this material into mice genetically altered to produce human prions.

3.   If the new variety of human prion is injected into a cat, yet another disease can be created.

4.   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.

5.   It looks exactly like a CJD-related human prion but it can be more insidious.

6.   The difference between a cow and a human prion might be eight of these building blocks out of hundreds.

7.   They point especially to the fact that no one has been able to convert a normal human prion into a lethal one in a test tube.

8.   But the efficiency of this reaction was much lower than that achieved in human prion protein by the defective prions associated with other forms of CJD, he said.