Vol.:(0123456789) 1 3 Acta Neuropathol (2018) 135:179–199 https://doi.org/10.1007/s00401-017-1782-y ORIGINAL PAPER Cofactors infuence the biological properties of infectious recombinant prions Natalia Fernández‑Borges 1  · Michele A. Di Bari 2  · Hasier Eraña 1  · Manuel Sánchez‑Martín 3,4  · Laura Pirisinu 2  · Beatriz Parra 5  · Saioa R. Elezgarai 1  · Ilaria Vanni 2  · Rafael López‑Moreno 1  · Gabriele Vaccari 2  · Vanessa Venegas 1  · Jorge M. Charco 1  · David Gil 1  · Chafk Harrathi 1  · Claudia D’Agostino 2  · Umberto Agrimi 2  · Tomás Mayoral 5  · Jesús R. Requena 6  · Romolo Nonno 2  · Joaquín Castilla 1,7   Received: 11 August 2017 / Revised: 20 October 2017 / Accepted: 21 October 2017 / Published online: 1 November 2017 © Springer-Verlag GmbH Germany 2017 of PrP C to PrP Sc . We thus obtained a mix of distinguish- able infectious prion strains. Subsequently, we replaced brain homogenate, by diferent polyanionic cofactors that were able to drive the evolution of mixed prion populations toward specifc strains. Thus, our results show that a variety of infectious recombinant prions can be generated in vitro and that their specifc type of conformation, i.e., the strain, is dependent on the cofactors available during the propagation process. These observations have signifcant implications for understanding the pathogenesis of prion diseases and their ability to replicate in diferent tissues and hosts. Importantly, these considerations might apply to other neurodegenerative diseases for which diferent conformations of misfolded pro- teins have been described. Keywords Cofactors · In vitro propagation · Infectious recombinant prions · Prion strains · PMCA · TSE Introduction A group of rare and fatal neurodegenerative disorders called transmissible spongiform encephalopathies (TSEs) or prion diseases, characterized by long incubation periods and neu- ronal loss, are well known due to their unusual causative agent. TSEs, as defned in the early eighties by the protein- only hypothesis, are caused by an aberrantly folded isoform (PrP Sc ) of the normal cellular prion protein (PrP C ). Once formed, PrP Sc induce neurodegeneration and have the ability to transform other PrP C into PrP Sc [2]. Distinct prion diseases have been described in humans which afect diferent brain areas and result in clearly distin- guishable clinical manifestations such as Creutzfeldt–Jakob disease (CJD), Gerstmann–Straussler–Scheinker syndrome (GSS) and fatal familial insomnia (FFI) [55]. Similarly, other Abstract Prion diseases are caused by a misfolding of the cellular prion protein (PrP) to a pathogenic isoform named PrP Sc . Prions exist as strains, which are characterized by specific pathological and biochemical properties likely encoded in the three-dimensional structure of PrP Sc . How- ever, whether cofactors determine these diferent PrP Sc con- formations and how this relates to their specifc biological properties is largely unknown. To understand how diferent cofactors modulate prion strain generation and selection, Protein Misfolding Cyclic Amplifcation was used to create a diversity of infectious recombinant prion strains by propaga- tion in the presence of brain homogenate. Brain homogenate is known to contain these mentioned cofactors, whose iden- tity is only partially known, and which facilitate conversion Electronic supplementary material The online version of this article (http://doi.org/10.1007/s00401-017-1782-y) contains supplementary material, which is available to authorized users. * Joaquín Castilla castilla@joaquincastilla.com 1 CIC bioGUNE, Parque tecnológico de Bizkaia, 48160 Derio, Bizkaia, Spain 2 Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy 3 Servicio de Transgénesis, Nucleus, Universidad de Salamanca, Salamanca, Spain 4 IBSAL, Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain 5 Laboratorio Central de Veterinaria (LCV), Madrid, Spain 6 CIMUS Biomedical Research Institute & Department of Medical Sciences, University of Santiago de Compostela-IDIS, Santiago de Compostela, Spain 7 IKERBASQUE, Basque Foundation for Science, Bilbao, Bizkaia, Spain