1.   Blood can carry misfolded proteins.

2.   According to the prion hypothesis, however, they are caused by misfolded proteins.

3.   But how did Prusiner demonstrate that misfolded proteins could cause disease?

4.   But when this process goes awry, small numbers of misfolded proteins accumulate into tiny spherical particles inside cells.

5.   In each case the misfolded protein is called a prion.

6.   In other cases, the misfolded proteins are transmitted via food, blood transfusions or surgical instruments.

7.   Misfolded proteins are also behind the spongiform encephalopathies, diseases that involve strange, spongelike holes in certain parts of the brain.

8.   Misfolded proteins build up, like trash clogging an alleyway.

9.   Moreover, the theory holds, the misfolded protein acts like a seed crystal, causing other, healthy proteins to misfold and bringing on destruction of brain tissue.

10.   Moreover, studies of prion diseases are shedding light on how seeds of misfolded proteins can corrupt otherwise healthy proteins and propagate disease.