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Updated: May 8, 2026
Protein Misfolding Cyclic Amplification of Prions
Published on: November 7, 2012
De novo generation of infectious prions with bacterially expressed recombinant prion protein
Zhihong Zhang1, Yi Zhang, Fei Wang
12Department of Molecular and Cellular Biochemistry, 1645 Neil Ave., Rm. 457A Hamilton Hall, Ohio State University, Columbus, OH 43210, USA. ma.131@osu.edu.
Abstract:
The prion hypothesis is strongly supported by the fact that prion infectivity and the pathogenic conformer of prion protein (PrP) are simultaneously propagated in vitro by the serial protein misfolding cyclic amplification (sPMCA). However, due to sPMCA's enormous amplification power, whether an infectious prion can be formed de novo with bacterially expressed recombinant PrP (rPrP) remains to be satisfactorily resolved. To address this question, we performed unseeded sPMCA with rPrP in a laboratory that has never been exposed to any native prions. Two types of proteinase K (PK)-resistant and self-perpetuating recombinant PrP conformers (rPrP-res) with PK-resistant cores of 17 or 14 kDa were generated. A bioassay revealed that rPrP-res(17kDa) was highly infectious, causing prion disease in wild-type mice with an average survival time of about 172 d. In contrast, rPrP-res(14kDa) completely failed to induce any disease. Our findings reveal that sPMCA is sufficient to initiate various self-perpetuating PK-resistant rPrP conformers, but not all of them possess in vivo infectivity. Moreover, generating an infectious prion in a prion-free environment establishes that an infectious prion can be formed de novo with bacterially expressed rPrP.
Insights
Infectious prions can be created de novo from recombinant prion protein (rPrP) using protein misfolding cyclic amplification (PMCA). However, not all generated rPrP conformers are infectious, as demonstrated in a prion-free environment.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- The prion hypothesis posits that prion diseases are caused by misfolded prion proteins (PrP).
- Serial protein misfolding cyclic amplification (sPMCA) can propagate prion infectivity and pathogenic PrP conformers in vitro.
- It remains unresolved whether infectious prions can form de novo from recombinant PrP (rPrP).
Purpose of the Study:
- To determine if infectious prions can be generated de novo from bacterially expressed recombinant PrP (rPrP) using sPMCA.
- To investigate the infectivity of different proteinase K (PK)-resistant rPrP conformers generated in vitro.
Main Methods:
- Unseeded sPMCA was performed using rPrP in a prion-free laboratory setting.
- Two types of PK-resistant, self-perpetuating rPrP conformers (rPrP-res) with distinct PK-resistant core sizes (17 kDa and 14 kDa) were generated.
- Bioassays were conducted in wild-type mice to assess the infectivity of the generated rPrP-res conformers.
Main Results:
- Two distinct PK-resistant rPrP conformers (rPrP-res) were successfully generated via sPMCA.
- The rPrP-res(17kDa) conformer was highly infectious, inducing prion disease in mice with a mean survival time of approximately 172 days.
- The rPrP-res(14kDa) conformer showed no disease-inducing capability in mice.
Conclusions:
- sPMCA can initiate the formation of various self-perpetuating PK-resistant rPrP conformers.
- Not all generated rPrP conformers possess in vivo infectivity.
- This study establishes that infectious prions can be formed de novo from bacterially expressed rPrP in a prion-free environment.
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