Fig 1. Passage history of scrapie sources used in this study.

For the serial passage of scrapie prions in mice, the brain of a single mouse was chosen from the previous passage. The selected mice were named Mo1, Mo2, and Mo3 in Exp. 1 and Mo1′, Mo2′, and Mo3′ in Exp. 2. Mice that clinically and/or pathologically developed L-type disease are shown in grey, while those that developed S-type disease are shown in white. Survival days are indicated underneath each mouse. PrP^Sc-positive and -negative GT1-7 cells are shown in grey and white, respectively.