Development of an Assay for the Detection of PrPres in Blood and Urine Based on PMCA Assay and ELISA Methods

The focus of this project was the development of a pre-clinical blood-based TSE diagnostic assay. This is the final report for this project. The assay was developed with plasma from hamsters infected with scrapie 263K and with some modifications the same assay could also be adapted to human plasma. Most of the proposed aims were achieved. We developed and evaluated an immuno-assay for the detection of PrPc and PrPsc from hamster brain and plasma. We conducted a study to determine the PK concentration that preserved plasma infectivity while reducing the level of endogenous PrPc to below the limit of detection of our PrP assay. These studies were designed to assess whether PK can be used as the discrimination method in a PrPsc detection assay. The results indicated that 50-200 mugml PK is an appropriate concentration range to discriminate PrPsc in infected plasma. We also found that urine excreted by infected hamsters harbors infectivity with infectivity titers similar to that of hamster plasma. Urine from pre-clinical hamsters did not show detectable levels of infectivity. Lack of infectivity may be due to technical reasons and it should be repeated. Urine could be a useful alternative to blood in a TSE diagnostic assay.