Protein aggregates generated in a test tube were found to infect wild-type hamsters with a disease much like scrapie. Such a demonstration has, in the past, been called the gold standard of "proof" that infectious protein particles, or prions, free of nucleic acids, are the culprit in transmissible spongiform encephalopathies (TSEs). Study coauthor Claudio Soto says this demonstration,1 together with a paper published by Stanley Prusiner's group last summer,2 should allay most doubts. "There is really little room for skepticism."
Soto's group has been using a process that they call protein misfolding cyclic amplification (PMCA), which aids the conversion of the normal cellular proteins, PrPc, into the protease-resistant aggregates, PrPres, associated with TSE pathology. After seeding PrPc with PrPres, the solution is repeatedly incubated and sonicated to break up growing aggregates.
Crucially, however, the PrPres seed comes from infected hamster brain homogenate, while the normal PrPc comes from healthy hamster ...
