Genetic and infectious prion diseases

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Prion diseases, including Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker syndrome (GSS), are linked to the prion protein (PrP).
• Understanding the species barrier and prion replication mechanisms is crucial for studying these neurodegenerative disorders.

Purpose of the Study:

• To investigate the molecular basis of the species barrier in prion diseases.
• To elucidate the mechanism of prion replication using transgenic mouse models.
• To explore the genetic and infectious nature of prion diseases.

Main Methods:

• Utilized transgenic (Tg) mice expressing Syrian hamster (SHa) and mouse (Mo) PrP genes.
• Conducted bioassays of brain extracts from infected Tg mice.
• Studied artificial prions from chimeric Mo/SHaPrP transgenes.
• Analyzed PrP gene mutations in human GSS and familial CJD cases.
• Investigated structural differences between cellular PrP (PrPC) and scrapie PrP (PrPSc).

Main Results:

• Prion synthesis is dictated by the inoculum, not solely by host PrP gene expression.
• Mutations in human PrP genes confirm the genetic basis of GSS and familial CJD.
• Tg mice expressing a GSS-linked mutation (MoPrP-P101L) spontaneously developed prion disease.
• Prion infectivity inactivation correlates with diminished beta-sheet content in PrPSc.
• Prion propagation appears to involve the unfolding and refolding of PrPC into PrPSc.

Conclusions:

• Prion diseases are both genetic and infectious, with prions likely devoid of foreign nucleic acids.
• The prion strain, potentially a distinct PrPSc conformer, dictates the pattern of replication.
• Prion replication involves a conformational change of PrPC to PrPSc, differentiating them from other pathogens.