Detection of exosomal prions in blood by immunochemistry techniques

In most forms of prion diseases blood is infectious, but the detection by immunochemistry techniques of the only available marker of infection (the misfolded prion protein, PrPTSE) in blood remains elusive. Researchers at the Istituto Superiore di Sanità, Italy developed a novel method for the detection of PrPTSE in blood of prion-infected rodents based on the finding that PrPTSE is associated with plasma exosomes. However, further purification of exosome on sucrose gradient was necessary for removing plasma immunoglobulins, which interfere with PrPTSE masking its detection by immunochemistry. Finally, they report that about 20% of plasma infectivity is associated with exosomes.