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

The human infectivity of Chronic Wasting Disease (CWD) is unclear. Current diagnostics rely upon post-mortem examination and late-term disease. Migratory B cells are emerging as likely candidates for blood-borne infectivity, and therefore, a logical target for sensitive antemortem diagnosis. We have focused on the Follicular Dendritic Cell (FDC)-B cell interaction as a target to expand prions. This approach has been verified using ovine cells infected with scrapie, and during Phase I we have cultured deer and elk FDCs to define an analagous assay for CWD. The goals of Phase II are to optimize this assay in cervid FDC cultures, and to quantify the sensitivity and specificity of prion replication. To accomplish these goals, we will 1) Confirm the applicability of the ovine assay to cervid tissues; 2) Optimize efficiency suitable to a commercial diagnostic test. 3) Define the limits of the system. 4) Define applicability to diagnosis of other tissues 5) Investigate the utility of the assay to evaluate the "species barriers" of CWD. At the conclusion of Phase II, we will deliver a streamlined in vitro culture assay for early blood-based diagnosis of prion disease in cervids, and applicability of the assay to other prion sources and species.