SCIENCEThe Real Reason Prion Diseases Spread Without DNA8 min read

The Scientific Community Was Not Convinced

Prusiner’s proposal met with substantial skepticism. Established researchers pushed back, arguing that the evidence was circumstantial or that contaminating nucleic acids too small to detect might still explain the results. Some critics questioned whether the experiments were rigorous enough to rule out all alternative explanations. Others simply found the idea biologically implausible — proteins were not supposed to be capable of self-replication or infectious transmission on their own. The resistance was not irrational. Science depends on established frameworks, and prion theory required abandoning one of the most fundamental principles in molecular biology. Prusiner spent the following years continuing to build the case, while other research groups worked to characterize the structure of the prion protein and understand exactly how it behaved.

How Prions Convert Healthy Proteins

Over the 15 years following the 1982 paper, researchers gradually worked out the molecular mechanism behind prion transmission. The key insight was conformational: the same protein could exist in two distinct three-dimensional shapes, one normal and one pathological. When the misfolded, pathological version encountered a normal protein, it could induce the healthy protein to refold into the same abnormal shape — essentially converting it. This chain reaction, once started, was self-sustaining. The pathological form also resisted the enzymes that would normally break down misfolded proteins, allowing it to accumulate in neural tissue. This explained not only how prions could spread without nucleic acids, but also why the diseases were progressive and why brain tissue deteriorated over time. It also explained the hereditary component: certain genetic mutations produced proteins that were more prone to misfolding in the first place.