Figure 1.

Makarava et al² test whether overexpression of hamster PrP^C in Tg7 transgenic mice enhances the formation of atypical PrPres or PrP^Sc. After inoculation of Tg7 mice with recombinant hamster PrP fibrils, production of atypical PrPres increases, but PrP^Sc does not appear and the mice remain healthy. During subsequent passages, PrP^Sc gradually replaces atypical PrPres, correlating with the development of clinical symptoms and neuropathology. This latter process is not enhanced by increased levels of hamster PrP^C substrate. The schematic shows Western blot analysis of protease-resistant fragments of PrP from the brains of the mice, which allows distinction of atypical PrPres from PrP^Sc. PrP, prion protein; PrP^C, cellular prion protein; PrPres, alternative self-replicating state of prion protein; PrP^Sc, prion protein scrapie isoform; Tg, transgenic.