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Prions, The Unkillable Infectious Agents That Turn Your Brain into Swiss Cheese

Decades after their discovery, these parasitic mysteries remain to persist in the environment we live in. To date, it is unclear how they metastasise. They don’t contain the fundamental capacity of being alive nor do they possess a nucleic acid genome (DNA sequence).

Rendering them unkillable, prions don’t have any pathogenic bodies to engulf and exterminate by our body’s immune system whilst spreading, deforming, and replicating like viral bacteria. Prions, otherwise recognised as proteinaceous infectious particles are essentially misfolded versions of the normal protein PrPC, found on cell membranes(C, for Cellular). Prions only affect the brain and other neural tissues.

It is bewildering how our body can do such a thing to ourselves. With an abnormal protein tertiary structure (the three-dimensional structure) of a protein molecule, prions are known to demonstrate their infectious properties in collapsing proteins they come near to into the same distorted shape. These collapsed proteins accumulate into irregular aggregates of proteins called amyloids which are observed in neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s. What is especially significant about this transformation is to do with the stability of the new structure. The amyloid is resistant to denaturation by any chemical or physical agents such as ultraviolet radiation, disinfectants, boiling and intense sterilisation. Prions seem to remain infectious even after treatments that destroy nucleic acids are used. They replicate using methods of humanistic and widely known qualities such as epimutation and natural selection. Epimutation, derived from epigenetics, suggests that there are no alterations to the DNA sequence of the protein but only addition, which implies that a newly formed structure of the protein can come to rise with complete eradication of the old one. Normal PrPCs are transformed into PrPscs which are the “scrapie form”. The scrapie form is resistant to protease enzymes that can break down proteins and can change the conformation of PrPCs interconnect. PrPres is a protease-resistant protein but these may not necessarily be infectious.