Successful transmission of three mouse-adapted scrapie strains to murine neuroblastoma cell lines overexpressing wild-type mouse prion protein

Propagation of the agents responsible for transmissible spongiform encephal opathies (TSEs) in cultured cells las been achieved for only a few cell lin es. To establish efficient and versatile models for transmission, we develo ped neuroblastoma cell lines overexpressing type A mouse prion protein, MoP rPC-A, and then tested the susceptibility of the cells to several different mouse-adapted scrapie strains. The transfected cell clones expressed up to sixfold-higher levels of PrPC than the untransfected cells. Even after 30 passages, we were able to detect an abnormal proteinase R-resistant form of prion protein, PrPSc, in the agent-inoculated PrP-overexpressing cells, wh ile no PrPSc was detectable in the untransfected cells after 3 passages. Pr oduction of PrPSc in these cells was also higher and more stable than that seen in scrapie-infected neuroblastoma cells (ScN2a). The transfected cells mere susceptible to PrPSc-A strains Chandler, 139A, and 22L but not to PrP Sc-B strains 87V and 22A. We further demonstrate the successful transmissio n of PrPSc from infected cells to other uninfected cells. Our results corro borate the hypothesis that the successful transmission of agents ex vivo de pends on both expression Levels of host PrPC and the sequence of PrPSc. Thi s new ex vivo transmission model will facilitate research into the mechanis m of host-agent interactions, such as the species barrier and strain divers ity, and provides a basis for the development of highly susceptible cell li nes that could be used in diagnostic and therapeutic approaches to the TSEs .