The Evolution of Experimental Rodent Models for Prion Diseases

Prion diseases are a group of fatal, neurodegenerative diseases that affect animals and humans. These diseases are characterized by the conformational conversion of normal, host-encoded PrP^C into a disease-causing prion isoform, PrP^Sc. Significant advancements in biological, genetic, and prion research have led to the capability of studying this pathogenetic process using recombinant proteins, ex vivo systems, in vitro models, and mammalian hosts, the latter being the gold standard for assaying prion infectivity, transmission, and strain evolution. While devoid of nucleic acid, prions encipher strain information by the conformation of their constituent infectious proteins, with diversity altering pathogenesis, host-range dynamics, and the efficacy of therapeutics. To properly study the strain properties of natural prions and develop appropriate therapeutic strategies, it is essential to utilize models that authentically recapitulate these infectious agents in experimental mammalian hosts. In this review, we examine the evolution of research on prion diseases using non-transgenic and transgenic animals, primarily focusing on rodent models. We discuss the successes and limitations of each experimental system and provide insights based on recent findings in novel gene-targeted mice.