Destabilizing polymorphism in cervid prion protein hydrophobic core determines prion conformation and conversion...

Area of Science:

• Neurodegenerative Disorders
• Prion Biology
• Molecular Virology

Background:

• Prion diseases, like Chronic Wasting Disease (CWD), are fatal neurodegenerative conditions caused by misfolded prion proteins (PrPSc) that convert normal cellular PrP (PrPC).
• CWD is highly contagious among cervids, with disease presentation influenced by genetic variations in the prion protein gene.
• The impact of these genetic variations on PrP structure, PrPSc formation, and prion propagation remains largely unknown.

Purpose of the Study:

• To investigate the structural and functional consequences of the cervid 116A>G PrP gene substitution.
• To determine how this substitution affects PrPC stability, conversion efficiency, and the conformation and infectivity of resulting prions.
• To assess the adaptability and transmissibility of prions influenced by this genetic variation.

Main Methods:

• Utilized molecular dynamics simulations to analyze the structural impact of the 116A>G substitution on PrP.
• Employed real-time quaking-induced conversion (RT-QuIC) assays to assess in vitro conversion efficiency and prion seeding activity.
• Conducted in vitro and in vivo experiments to evaluate the infectivity of prions carrying the 116A>G substitution.

Main Results:

• The 116G-PrP variant exhibited structural destabilization, leading to enhanced in vitro conversion efficiency.
• Prions associated with the 116A>G substitution (116AG-prions) were conformationally less stable and showed reduced seeding activity in RT-QuIC.
• 116AG-prions displayed reduced infectivity in vitro and in vivo, although infectivity increased upon secondary passage in mice while retaining conformational features.

Conclusions:

• Structurally destabilized PrPC is readily converted by cervid prions, forming adaptable prion conformations.
• Prion conformation is critical for assessing transmission barriers, and variants can alter host range.
• Further analysis of CWD isolates and species-barrier reassessment is crucial to exclude zoonotic potential.