Urinary excretion and blood level of prions in scrapie-infected hamsters

Prions, infectious agents causing transmissible spongiform encephalopathy (TSE), are composed primarily of the pathogenic form (PrP(Sc)) of the host-encoded prion protein. Although very low levels of infectivity have been detected in urine from scrapie-infected rodents, no reports of urinary PrP(Sc) have been substantiated. Studies on the dynamics of urinary PrP(Sc) during infection are needed to ensure the safety of urine-derived biopharmaceuticals and to assess the possible horizontal transmission of prion diseases. Using the protein misfolding cyclic amplification technique, a time-course study of urinary excretion and blood levels of PrP(Sc) was performed in Sc237-infected hamsters and a high rate of PrP(Sc) excretion was found during the terminal stage of the disease. Following oral administration, PrP(Sc) was present in all buffy coat samples examined; it was also present in most of the plasma samples obtained from hamsters in the symptomatic stage. PrP(Sc) was excreted in urine for a few days after oral administration; subsequently, urinary PrP(Sc) was not detected until the terminal disease stage. These results represent the first biochemical detection of PrP(Sc) in urine from TSE-infected animals.