Susceptibility of GT1–7 cells to mouse-passaged field scrapie isolates with a long incubation

A typical feature of scrapie in sheep and goats is the accumulation of disease-associated prion protein. Scrapie consists of many strains with different biological properties. Nine natural sheep scrapie cases were transmitted to wild-type mice and mouse-passaged isolates were classified into 2 types based on incubation time: short and long. These 2 types displayed a distinct difference in their pathology. We attempted to transmit these mouse-passaged isolates to 2 murine cell lines (GT1–7 and L929) to compare their properties. All of the isolates were transmitted to L929 cells. However, only mouse-passaged field isolates with a long incubation time were transmitted to GT1–7 cells. This specific susceptibility of GT1–7 cells was also confirmed with a primary-passaged isolate that was not completely adapted to the new host species. Characterization of the mechanisms of the specific susceptibility of GT1–7 cells to isolates with a long incubation time may lead to a greater understanding of the differences among prion strains.