Let me share with you a comparison between prions and viroids.
| Aspect | Prions | Viroids |
| Composition | Composed of protein (usually a misfolded form of a cellular protein) | Composed of single-stranded, circular RNA |
| Replication | Prions replicate by inducing misfolding in normal, host proteins, leading to the formation of more prions | Viroids replicate autonomously through an RNA-dependent RNA polymerase (replicase) encoded by the viroid itself |
| Disease Association | · Creutzfeldt-Jakob disease in humans · Scrapie in sheep | · Associated with plant diseases e.g., Potato spindle tuber viroid in potatoes |
| Host Range | Primarily affects animals, including humans | Primarily affects plants |
| Examples | PrPSc (Scrapie isoform of the prion protein) | Potato spindle tuber viroid (PSTVd) |
| Association with Cells | Prions are associated with the cellular membrane and can affect neural tissues | Viroids are found in the nucleus, chloroplasts, and cytoplasm of infected plant cells |
| Protein Synthesis | Prions do not affect host cell protein synthesis | Viroids can affect host cell protein synthesis by interfering with RNA processing |
| Treatment | Currently, there are no effective treatments for prion diseases | No specific antiviral drugs are available for viroid infections |