priones

Prions, or priones in Spanish, are infectious protein particles composed solely of misfolded prion protein (PrP^Sc) that propagate by converting the regular cellular prion protein PrP^C into the diseased form. They lack nucleic acids, making them distinct from conventional pathogens. The PrP gene PRNP encodes PrP^C; the pathogenic PrP^Sc forms aggregates resistant to proteases, enabling brain accumulation and neurodegeneration.

Pathology and symptoms: PrP^Sc-induced aggregation causes spongiform changes in the brain, gliosis, and neuron loss. Clinically, prion diseases are rapidly progressive neurodegenerative illnesses marked by dementia, myoclonus, ataxia, and behavioral changes. On neuropathology, they show vacuolation (“spongiform” changes) and PrP deposition.

Diseases and transmission: In humans, prion diseases include sporadic CJD, familial prion diseases (e.g., GSS, FFI), iatrogenic CJD, and variant CJD linked to BSE exposure. In animals, scrapie (sheep/goats), BSE in cattle, and chronic wasting disease in cervids are recognized. Transmission routes include spontaneous misfolding, inherited PRNP mutations, and ingestion or exposure to infectious PrP-containing tissue; iatrogenic transmission can occur through contaminated surgical instruments or human-derived therapeutic products. Prions are highly resistant to conventional decontamination.

Diagnosis and treatment: Diagnosis relies on clinical evaluation combined with MRI, EEG, and CSF biomarkers such as 14-3-3 protein or RT-QuIC; definitive confirmation requires neuropathology or RT-QuIC on CSF or tissue. No cure exists; treatment is supportive and focused on symptom management.

Prevention and research: Public health measures limit exposure (especially BSE controls in cattle and surveillance). Decontamination requires stringent methods (strong alkali or extended autoclaving). Research aims to develop diagnostics and disease-modifying therapies.