To further explore the biophysical status of PK-sensitive, acutely synaptotoxic PrPSc species from earlier time points of M1000 prion disease we undertook size exclusion chromatography to fractionate ex vivo preparations from PrPSc from brains at 30%, 50%, and 70% of the TSD and compared them with ex vivo PrPSc fractions prepared from 100% of the TSD (positive control), as well as PrPC fractions prepared from sham-infected NBH controls (negative control). Here, PRNP is linked to prion disease.