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International Journal of Cell Biology
Volume 2013, Article ID 704546, 14 pages
Review Article

Prions Ex Vivo: What Cell Culture Models Tell Us about Infectious Proteins

1Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Street 25, 53127 Bonn, Germany
2Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
3Department of Neurology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany

Received 3 June 2013; Accepted 3 September 2013

Academic Editor: Roberto Chiesa

Copyright © 2013 Sybille Krauss and Ina Vorberg. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Prions are unconventional infectious agents that are composed of misfolded aggregated prion protein. Prions replicate their conformation by template-assisted conversion of the endogenous prion protein PrP. Templated conversion of soluble proteins into protein aggregates is also a hallmark of other neurodegenerative diseases. Alzheimer’s disease or Parkinson’s disease are not considered infectious diseases, although aggregate pathology appears to progress in a stereotypical fashion reminiscent of the spreading behavior ofmammalian prions. While basic principles of prion formation have been studied extensively, it is still unclear what exactly drives PrP molecules into an infectious, self-templating conformation. In this review, we discuss crucial steps in the life cycle of prions that have been revealed in ex vivo models. Importantly, the persistent propagation of prions in mitotically active cells argues that cellular processes are in place that not only allow recruitment of cellular PrP into growing prion aggregates but also enable the multiplication of infectious seeds that are transmitted to daughter cells. Comparison of prions with other protein aggregates demonstrates that not all the characteristics of prions are equally shared by prion-like aggregates. Future experiments may reveal to which extent aggregation-prone proteins associated with other neurodegenerative diseases can copy the replication strategies of prions.