21.   The old and new prion proteins each latch onto good proteins, and the process continues.

22.   The prion protein, then, would sit on the surface of cells and serve as a portal for a scrapie virus.

23.   The ultimate proof, these critics say, would be to inject an animal with a prion protein and cause disease.

24.   Then they mixed it with unlabeled prion protein isolated from scrapie-infected hamster brains.

25.   We have identified new classes of inhibitors that block the formation of the abnormal prion protein.

26.   After coaxing the prion proteins into forming crystals, they bombarded them with X-rays.

27.   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.

28.   Last month, Dutch researchers said they could detect prion proteins in sheep before symptoms of scrapie, a disease similar to mad cow, appear.

29.   Scientists had prior indications that the inherited fatal insomnia was among the half-dozen human brain diseases caused by the prion protein.

30.   The researchers used a laboratory test that identifies different chemical variants of prion proteins.