I would say that the Vacci-test is the most recent, as Dr. C. Soto, Dr. GP Saborio, Dr. B Permanne together published "Sensitive detection of pathological prion protein by cyclic amplification of protein misfolding, Nature 411:810-813, in 2001.  

Accordingly, to test for malformed proteins with this amplification procedure, you homogenated brain from the appropriate species.