Tau aggregation into ordered assemblies causes neurodegenerative tauopathies. We
previously reported that tau monomer exists in either inert (M i) or seed-competent (M s)
conformational ensembles and that M s encodes strains, that is, unique, self-replicating,
biologically active assemblies. It is unknown if disease begins with M s formation followed by
fibril assembly or if M s derives from fibrils and is therefore an epiphenomenon. Here, we
studied a tauopathy mouse model (PS19) that expresses full-length mutant human (1N4R) …