Sc237 hamster PrPSc and Sc237-derived mouse PrPSc generated by interspecies in vitro amplification exhibit distinct pathological and biochemical properties in tga20 transgenic mice.

Prions are the infectious agents responsible for transmissible spongiform encephalopathy, and are primarily composed of the pathogenic form (PrP(Sc)) of the host-encoded prion protein (PrP(C)). Recent studies have revealed that protein misfolding cyclic amplification (PMCA), a highly sensitive method for PrP(Sc) detection, can overcome the species barrier in several xenogeneic combinations of PrP(Sc) seed and PrP(C) substrate. Although these findings provide valuable insight into the origin and diversity of prions, the differences between PrP(Sc) generated by interspecies PMCA and by in vivo cross-species transmission have not been described. This study investigated the histopathological and biochemical properties of PrP(Sc) in the brains of tga20 transgenic mice inoculated with Sc237 hamster scrapie prion and PrP(Sc) from mice inoculated with Sc237-derived mouse PrP(Sc), which had been generated by interspecies PMCA using Sc237 as seed and normal mouse brain homogenate as substrate. Tga20 mice overexpressing mouse PrP(C) were susceptible to Sc237 after primary transmission. PrP(Sc) in the brains of mice inoculated with Sc237-derived mouse PrP(Sc) and in the brains of mice inoculated with Sc237 differed in their lesion profiles and accumulation patterns, Western blot profiles, and denaturant resistance. In addition, these PrP(Sc) exhibited distinctive virulence profiles upon secondary passage. These results suggest that different in vivo and in vitro environments result in propagation of PrP(Sc) with different biological properties.