Immuno-gold localization of prion filaments in scrapie-infected hamster brains

The brains of scrapie-infected hamsters have been examined for the presence of structures antigenically related to the prion protein (PrP 27-30). Glutaraldehyde-perfused hamster brains, 72 days postinfection, were immunostained using rabbit monospecific antisera raised against synthetic peptides corresponding to the N-terminal 13 or 15 amino acids of PrP 27-30, and using rabbit antisera raised against infectious prions or PrP 27-30 purified from scrapie-infected hamster brains. Antisera to the synthetic peptides stained extracellular filaments in agreement with previous immunoperoxidase studies which used affinity-purified PrP 27-30 antibodies; in addition to subependymal and subpial localization, we show ventricular and perivascular staining. Using a colloidal gold-secondary antibody technique, we have demonstrated that the antibodies labeled filaments measuring 7 to 17 nm in diameter. Whereas most of the periventricular and perivascular filaments appeared extracellular, some appeared to be within processes intimately associated with ependymal cells, degenerating membranes of astrocytes, and neurites.