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Updated: Aug 6, 2026
Protein Misfolding Cyclic Amplification of Prions
Published on: November 7, 2012
Protein misfolding cyclic amplification as a rapid test for assessment of prion inactivation
Yuichi Murayama1, Miyako Yoshioka, Hiroko Horii
1Prion Disease Research Center, National Institute of Animal Health, Ibaraki, Japan. ymura@affrc.go.jp
Abstract:
Abnormal isoform of prion proteins (PrP(Sc)), which are infectious agents associated with prion diseases, retain infectivity after undergoing routine sterilization processes. A sensitive method to detect the infectivity is a bioassay, and it has been used for assessing prion inactivation. However, the result is obtained after several hundred days. Here, protein misfolding cyclic amplification (PMCA) in which PrP(Sc) can be amplified in vitro was applied for assessing prion inactivation by dry heating and autoclaving. Scrapie-infected hamster brains were inactivated under various conditions, and residual infectivity and PrP(Sc) were detected by the bioassay and PMCA, respectively. The PMCA results were in good agreement with those of the bioassay. In samples autoclaved at temperatures below 150 degrees C, while infected mice died in the bioassay, protease-resistant PrP (PrP(res)) signals were detected in the second or third round of PMCA. Three rounds of PMCA require only 6 days, which means that the PMCA method is much faster than the bioassay.
Insights
Protein misfolding cyclic amplification (PMCA) offers a faster method for detecting prion infectivity after sterilization. This in vitro technique accurately assesses prion inactivation, significantly reducing detection time compared to traditional bioassays.
Area of Science:
- Biochemistry
- Infectious Diseases
- Neuroscience
Background:
- Prion diseases are linked to abnormal prion proteins (PrP(Sc)) that resist standard sterilization.
- Bioassays are the standard for detecting prion infectivity but are time-consuming, taking hundreds of days.
Purpose of the Study:
- To evaluate protein misfolding cyclic amplification (PMCA) as a rapid method for assessing prion inactivation.
- To compare PMCA results with traditional bioassays for prion infectivity detection.
Main Methods:
- Scrapie-infected hamster brains were subjected to dry heating and autoclaving under various conditions.
- Residual prion infectivity was assessed using a bioassay.
- Prion protein (PrP(Sc)) amplification and detection were performed using protein misfolding cyclic amplification (PMCA).
Main Results:
- PMCA results showed good agreement with bioassay findings for prion inactivation.
- Protease-resistant PrP (PrP(res)) signals were detected by PMCA in samples autoclaved below 150°C, where bioassays indicated infectivity.
- PMCA detected residual infectivity within 6 days (three rounds), drastically faster than the bioassay.
Conclusions:
- PMCA is a rapid and reliable method for assessing prion inactivation by heat sterilization.
- PMCA significantly accelerates the detection of residual prion infectivity compared to conventional bioassays.
