Extracellular PrPsc (gold particles) is on exosome-like vesicles.
Raposo/NAS
But prions originally enter their hosts via the gut and must somehow reach the brain. Now, Benoit Fevrier, Graça Raposo (Institut Curie, Paris, France), and colleagues suggest that prions might travel at least partly via tiny vesicles called exosomes.
Exosomes form when late endosomes invaginate to form small, internal vesicles. The bag of vesicles, or multivesicular body (MVB), can fuse with the plasma membrane to disgorge these vesicles, named exosomes, which then travel to other cells to transmit messages. In the immune system, for example, exosomes transfer peptide-laden MHC proteins.
When the French group looked at the supernatant of PrPsc-infected epithelial and neuroglial cell cultures they found PrPsc....
