Abstract
Last decade witnessed an enormous progress in generating authentic infectious prions or PrPSc in vitro using recombinant prion protein (rPrP). Previous work established that rPrP that lacks posttranslational modification is able to support replication of highly infectious PrPSc with assistance of cofactors of polyanionic nature and/or lipids. Unexpectedly, previous studies also revealed that seeding of rPrP by brain-derived PrPSc gave rise to new prion strains with new disease phenotypes documenting loss of a strain identity upon replication in rPrP substrate. Up to now, it remains unclear whether prion strain identity can be preserved upon replication in rPrP. The current study reports that faithful replication of hamster strain SSLOW could be achieved in vitro using rPrP as a substrate. We found that a mixture of phosphatidylethanolamine (PE) and synthetic nucleic acid polyA was sufficient for stable replication of hamster brain-derived SSLOW PrPSc in serial Protein Misfolding Cyclic Amplification (sPMCA) that uses hamster rPrP as a substrate. The disease phenotype generated in hamsters upon transmission of recombinant PrPSc produced in vitro was strikingly similar to the original SSLOW diseases phenotype with respect to the incubation time to disease, as well as clinical, neuropathological and biochemical features. Infrared microspectroscopy (IR-MSP) indicated that PrPSc produced in animals upon transmission of recombinant PrPSc is structurally similar if not identical to the original SSLOW PrPSc. The current study is the first to demonstrate that rPrP can support replication of brain-derived PrPSc while preserving its strain identity. In addition, the current work is the first to document that successful propagation of a hamster strain could be achieved in vitro using hamster rPrP.
Highlights
Prion diseases or transmissible spongiform encephalopathies represent a class of lethal, transmissible neurodegenerative disorders of humans and animals [53]
What are the minimal molecular requirements for a faithful replication of a prion strain in vitro? Can faithful replication of a prion strain be achieved using recombinant PrP (rPrP) that lacks posttranslational modifications? What is the minimal set of cofactors sufficient for a faithful replication of a prion strain in vitro? Do prions from different species rely on different sets of cofactors? The current study reports that faithful replication of hamster strain SSLOW could be achieved in vitro using rPrP as a substrate
We found that a mixture of PE and polyA was sufficient for stable replication of hamster brain-derived SSLOW PrPSc in serial Protein Misfolding Cyclic Amplification (sPMCA) that use hamster rPrP as a substrate
Summary
Prion diseases or transmissible spongiform encephalopathies represent a class of lethal, transmissible neurodegenerative disorders of humans and animals [53]. The key event underlying prion diseases involves the conformational change of the α-helical, native, cellular form of the prion protein (PrPC) expressed by a host on a cell surface into a self-replicating, β-sheet rich, transmissible form (PrPSc) [52]. In the absence of cellular cofactors, rPrP readily adopts self-propagating β-sheet rich states including amyloid fibrils [7, 8]. While rPrP amyloid fibrils propagate well in vitro [9], they display miniscule specific infectivity in animals, as they do not recruit PrPC effectively [15, 29, 39, 43]. When inoculated into wild type hosts, rPrP amyloid fibrils initiate a process of synthetic strain evolution that
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