Tissues from a 42-year old patient with the PRNP Q227X mutation (UMCU #S07–176)  and from a 52- year old patient with the PRNP G131V mutation (UMCU #S04–346)  were provided as frozen brain samples from the middle frontal gyrus of the frontal lobe. The frozen tissues were thawed at the Rocky Mountain Laboratory (RML) and prepared as 20% w/v homogenates in PBS using an OMNI tissue homogenizer. Prior to inoculation, 20% brain homogenate aliquots were thawed, sonicated and further diluted to 10% or 1% brain homogenate in PBS for stereotactic microinjection (1ul) or macroinjection (30ul) respectively.