Author(s): Azumi Hirata, Akikazu Sakudo, Kazufumi Takano, Shigenori Kanaya and Yuichi Koga
PrPSc is thought to be the infective agent of TSE, and inactivating the infectivity of PrPSc without using strong reagents is difficult. Although PrPSc is a protease resistant protein, it can be degraded in vitro by the hyperthermophilic protease (Tk-subtilisin) at temperatures above 65ºC through the synergistic effect of heat destabilization of PrP and the high proteolytic activity of the thermostable protease. However, the change in infectivity of the proteasedigested PrPSc is still unknown. Therefore, we used mouse brain homogenate containing PrPSc (SBH) in a bioassay to investigate the loss of infectivity after Tk-subtilisin digestion. Surprisingly, the Tk-subtilisin digested SBH retained a high level of infectivity. Despite this, Tk-subtilisin could still be used for decontamination in highly protein denaturing condition such as in the presence of SDS.
