What are Prions?

Can they be attached to the SARS-COV-2 virus spike and not be noticed by virologists?

First, What are prions? Prions are short proteins found on the surface of many types of animal cells, including neurons, glial cells, and lymphocytes. They have the ability to fold in more than one way. In contrast to bacteria, viruses, and parasites, prions do not contain nucleic acid but consist of a short sequence of amino acids. (My source for information on prions can be found here and here.)

Abnormal conformations of prions exist in nature but their emergence is apparently very rare. Abnormal prions can be infectious by recruiting normal prions to change shape to the disease-forming isoform. Disease-forming isoforms, such as that which causes “mad-cow” disease, result in neurogenerative conditions in both humans and animals and are always fatal.

All isoforms, normal and pathological, share the exact same amino acid sequence but fold into different configurations. Normal prion configurations are protease sensitive while the pathological isoform is partially protease resistant. The protease-resistant core of the pathological isoform provides a specific and reliable molecular marker for the presence of the infectious agent and thus is easily identified in lab settings.

Because of their location at the outer surface of cells, prions are candidates for cell signaling, cell adhesion, and perhaps even for some transport functions. All prion proteins currently known contain four to five ‘octa repeats,’ repetitive sequences of eight amino acids. Amplification of the number of octa repeats has been found in hereditary prion diseases such as familial Creutzfeldt–Jakob disease (fCJD) and GSS syndrome.

The pathological isoform eventually kills its host by clumping in tissue, especially brain tissue, with no ability of the body to clear the debris. Prions are extremely difficult to destroy and are thus resistant to treatment. For an excellent, short (3.5-minute) animation on prion disease, go here.

Because the biomarker for the abnormal prion is easily identified, it is highly unlikely that a prion exists as part of the SAVS-COV-2 spike protein, as some lay persons have suggested. Likely, every major virology lab in world has looked at SARS-COV-2 and would have noticed such a startling finding.

Also, because prion diseases progress slowly, taking years for symptoms to develop, it is unreasonable to attribute the relatively immediate onset of COVID-19 pathology to prions. Even long-COVID has not been around long enough to suspect prion causation.

Please leave a comment if you think otherwise.

(Note: I am not a virologist and thus this essay reflects only my best assumptions based on a cursory investigation. I apologize if I over-simplified any part of the prion story or expressed my understanding in a clumsy way. If any virologist is reading this post, please weigh in.)



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Marilyn Goldhaber

Marilyn Goldhaber

Medical research scientist/biostatistician in epidemiology formerly with Kaiser-Permanente, now retired and volunteers in wildfire science and ecology.