SCIENCEThe Real Reason Prion Diseases Spread Without DNA8 min read

Six Lines of Evidence in One Paper

On April 9, 1982, Prusiner published his findings in Science. The paper presented six separate and distinct lines of experimental evidence, all pointing to the same conclusion: the infectious agent in scrapie was a protein, and only a protein. Every approach that degraded or destroyed protein structures eliminated the ability of the tissue to transmit the disease. Every approach that targeted DNA or RNA had no effect on transmissibility. Prusiner was careful and precise in his language, stating that the evidence showed a protein was “required for infectivity” rather than claiming he had proven it was the sole cause. This was not a rushed or incomplete study — it was the product of years of painstaking work designed specifically to rule out alternative explanations before presenting the protein hypothesis to the scientific community.

What the Word “Prion” Actually Means

In the same 1982 paper, Prusiner proposed a name for the infectious protein he had identified: prion, derived from the words “proteinaceous infectious particle.” The name was deliberate — it distinguished the agent from all known categories of pathogen. But the implications of prion biology went further than just naming something new. Prusiner suggested that prions could “code for their own biosynthesis,” meaning they could somehow direct the production of more copies of themselves without the use of nucleic acids. He acknowledged directly that this hypothesis contradicted what biologists called the central dogma of molecular biology — the principle that genetic information flows from DNA to RNA to protein, never the other way around. Proposing an infectious agent that existed entirely outside this framework was not a minor claim.