| Abstract: | A concept that considers the causative nature of the so-called "slow virus infections", causing syndromes of spongiform encephalopathies in man and animals as a chain autocatalytic process is put forward. According to this concept, PrP(27-30) protein, isolated recently from the brains of scrapie-infected animals, is a C-terminal domain of the normal protein component of brain tissue which is a latent zimogen. Certain clinical and experimental data are discussed within the framework of this concept. Exogenous proteinases are presumed to be capable of triggering such a chain autocatalytic process in the brains of susceptible animals. Indeed, in one of our experiments, a subtoxic dose of pronase injected into mouse brain induced the development of a syndrome indistinguishable from spongiform encephalopathy in its clinical and pathomorphological manifestations. The probable role of neuron-specific proteins of intermediate filaments in such pathological processes is discussed. It seems possible that spongiform encephalopathies are particular cases of pathological processes that have catalytic nature. Presumably, the Alzheimer disease has such a catalytic causative nature. |
