A novel enzymatic composition effective for prion degradation.

Background and objective of investigation: The infective prion agent (PrPSc) is resistant to common proteases and conventional sterilization processes. Complete destruction of this agent by incineration and alkaline hydrolysis precludes applications such as decontamination of reusable medical instruments, laboratory equipments and specified risk materials. Enzymatic prion degradation is a viable environmentally friendly alternative, but most current methods are limited by operational requirements such as heat pre-treatment of prion material, addition of chemical agents, high temperature incubation and extended digestion time. This study investigates the effects of a biological agent on keratinase degradation of ME7 scrapie prion and aims to constitute an enzymatic composition effective for prion degradation under mild digestion conditions. Method: ME7 scrapie prion brain homogenate (1 %) was digested with the enzymatic composition and constituents of its composition at 50 °C and 65 °C over a time course of 10-120 min. The digested prion samples were evaluated for residual PrPSc signal in vitro by Western blot analysis. Result: The purified keratinase (EF) significantly degraded PrP at 65 °C for 1 h to show typical PrPSc bands whereas the biological agent (BS) on its own did showed no activity toward PrP as determined by Western blot. Interestingly, digestion with the enzymatic composition (EF+BS) resulted in complete loss of PrPSc signal to undetectable levels. A digestion time of 10 min at 65 °C was sufficient to achieve PrPSc degradation to undetectable levels by Western blot analysis. Time-course degradation experiment demonstrated a consistent pattern of increasing disintegration of PrPSc with a significant loss of PrPSc immunoreaction in 2 h when digested at 50 °C. Conclusion: The mild incubation condition of this entirely biological system overcomes the key limitations of currently reported enzymatic methods and hence is potentially useful for decontamination of sensitive medical and laboratory devices and for other applications