Development of Bioassays for Prion Infectivity Using Human, Deer, or Elk Cells

Originally believed to be due to a unique viral infection, it is now believed that prion diseases or Transmissible Spongiform Encephalopathies (TSEs) are the result of a new, infectious protein (PrPSc). Definitive antemortem tests for TSEs are lacking, primarily due to an inability to expand the small amounts of infective prion protein found in the blood of asymptomatic individuals. To date, only rodent cell lines have been used to expand murine-adapted scrapie protein. Unfortunately, cell lines from other susceptible species (including deer and elk) are lacking. The two major cell types which appear to concentrate PrPSc during infection are nerve cells and follicular dendritic cells (FDCs). FDCs have the unique ability to concentrate foreign proteins due to a specific interaction with complement components. We have successfully used a magnetic-bead separation based methodology to isolate and culture FDCs from sheep, and have confirmed the utility of these reagents against deer and elk cells. We will establish FDC lines from susceptible deer and elk, and to adapt existing techniques for PrPSc proliferation to propogate Chronic Wasting Disease prion protein (PrPCWD). Phase II efforts would be directed towards development of more sensitive dioagnostic assays for prion infection than are currently available.