Inability to transmit scrapie by transfection of mouse embryo cells in vitro.

Infectivity of nucleic acid from highly infectious mouse scrapie brains was studied by transfecting the nucleic acid in vitro prior to inoculation into animals. Foetal mouse brain and whole mouse embryo cultures were chosen as the cells used for the transfection. As an internal control, infectious nucleic acid was recovered from bacteriophage phi X174 and whole virus particles were obtained when cultures were transfected with herpes simplex virus DNA. In contrast, none of the animals inoculated with nucleic acid preparations derived from scrapie-infected tissues developed scrapie disease either with or without transfection procedures. These findings (i) show transfection techniques fail to elicit evidence of a scrapie-specific infectious nucleic acid and (ii) confirm the observation that scrapie is not a viroid.