Scrapie, ribosomal proteins and biological information.

Consideration of the autocatalytic synthesis of ribosomal proteins leads to a criterion for the infectivity of a foreign proteinaceous species in terms of the biochemical rate constants governing the propagation of errors during the translation of genetic information in a model system. Evidence pertaining to the suggestion that scrapie and its analogues are caused by proteinaceous infectious agents (prions) which replicate by invading the translation process and altering ribosomal specificity is examined. It is found that anomalous aetiological features of scrapie infection are explained by the model. An analysis suggesting that the possibility of prion replication undermines the basis of current molecular biological theory is provided and it is concluded that the exclusive identification of biological information with nucleic acid sequences is unjustified.