Diagramatic representation of the global outcome of the experiment (excluding ARQ/ARR recipients and environmental controls). A: transmissions with AAS inoculum. B: transmissions with VVC inoculum. Survival times in days (dpi) of AAS and VVC inoculum donors (red and blue squares, respectively), and of ARQ/ARQ (AA, red if Suffolk, orange if Cheviot), VRQ/ARQ (VA, pink, all Cheviot) and VRQ/VRQ (VV, blue, all Cheviot) recipients, challenged by the oral (triangles) or subcutaneous (circles) route. In white, PrPd-positive sheep dying from intercurrent conditions or culled for welfare reasons (all of them Cheviot in the case of AAS inoculum and Suffolk in the case of VVC inoculum). Black circle and triangles, four sheep (two Cheviot and two Suffolk) culled at the end of the experiment which resulted completely negative for PrPd and PrPres by IHC and WB, respectively. Dotted lines split sheep with additional polymorphisms at codons either 112 (MT, Suffolk) or 141 (LF, Cheviot) from MMLL sheep (with no additional polymorphisms). Numbers next to each symbol correspond to sheep identification numbers in Additional file 2.