Peripherally administrated prions reach the brain at sub-infectious quantities in experimental hamsters.

The mechanisms implicated in prion infection and tissue distribution are not completely understood. In this study we investigated the levels of 263K prions in brain and spleen of Syrian hamsters few days after intra-peritoneal challenge. For this purpose we utilized the PMCA technology which permits to detect as little as few PrP(Sc) molecules. Our results show that peripherally administered prions directly reach the brain, although at levels below the minimum necessary to produce disease. PrP(Sc) remains in the brain several days after administration suggesting inefficient clearance or early replication. Understanding the fate of the infectious agent after administration and its uptake in different organs and fluids may provide useful information to develop strategies to minimize further spreading of prion diseases.