Cell invasive amyloid assemblies from SARS-CoV-2 peptides can form multiple polymorphs with varying neurotoxicity

Area of Science:

• Neuroscience
• Biochemistry
• Virology

Background:

• Neurological symptoms of COVID-19 (neuro-COVID) can persist, leading to Post-Acute Sequalae of COVID-19 (PASC).
• SARS-CoV-2 protein fragments self-assembling into amyloid nanofibrils are implicated in neuro-COVID and PASC.
• Previous work identified ORF6 and ORF10 fragments forming neurotoxic amyloid assemblies.

Purpose of the Study:

• To investigate the self-assembly mechanisms and nano-architectures of SARS-CoV-2 ORF6 and ORF10 fragments.
• To determine the biological responses, including neurotoxicity, of these viral amyloid assemblies.
• To explore the role of amyloid polymorphism in neuro-COVID pathogenesis.

Main Methods:

• Utilized a fluorinated solvent to solubilize SARS-CoV-2 ORF6 and ORF10 peptides, preventing pre-existing aggregates.
• Characterized the self-assembly mechanisms and nano-architectures, including ribbons and amorphous aggregates.
• Assessed the neurotoxicity and mitochondrial respiration effects on cultured neurons.
• Provided direct evidence of cellular uptake of viral amyloids.

Main Results:

• Solubilization in fluorinated solvent shifted assembly towards higher free energy structures (ribbons, amorphous aggregates).
• These higher free energy assemblies exhibited reduced toxicity to cultured neurons but impacted mitochondrial respiration.
• Demonstrated the first direct evidence of viral amyloid cellular uptake.
• Highlighted the correlation between amyloid polymorphism and neurotoxicity.

Conclusions:

• Understanding viral amyloid polymorphism is crucial for comprehending neuro-COVID and PASC.
• The nano-architecture and polymorphic landscape of viral amyloids influence their neurotoxic potential.
• Viral amyloids can be internalized by cells, contributing to neurological dysfunction.