Summary of the No.13-7 scrapie isolate serial passages.

The original scrapie isolate was passaged four times by the intracranial route in sheep of the ARQ/ARQ genotype prior to its oronasal challenge in WTD. A cerebrum or brainstem sample from a deer with clinical disease was used to oronasally challenge sheep of various genotypes. The first two sheep to develop disease had the VRQ/VRQ genotype (29 MPI) and were challenged with the scrapie agent from deer cerebrum. One ARQ/ARQ sheep challenged with deer cerebrum also developed disease but at 48 MPI. Sheep challenged with the scrapie agent from deer brainstem tested positive for PrP^Sc but with an extended incubation period of 65 MPI. Also shown is the inoculation route from WTD scrapie challenged sheep to Tg338 mice expressing ovine PrP. The mouse passage results can be found in Fig 6 of the current study. The animal figures were created by Corey Summers.