THE NONCONVENTIONAL TRANSMISSIBLE AGENTS AT THE ORIGIN OF TRANSMISSIBLE SUBACUTE SPONGIFORM ENCEPHALOPATHIES

The transmissible subacute spongiform human encephalopathies are neuro logical diseases, always fatal and with a prolonged incubation time. I n infected patients, an accumulation of a host protein from the genes, the prion protein, is observed in proportionality to the infectious l oad. The prion protein gene is the major determinant of the genetic su sceptibility in relation to subacute spongiform encephalopathies. On n europathological examination, patients have a characteristic triad: ne uronal vacuolisation, neuronal death and glial reaction. The nature of agents involved in these subacute spongiform encephalopathies is not known. Most authors think that the causal agent is a pathological form of the PrP protein partially resistant to proteinase K (the prion). F or others, it is a more classical structure including an independent g enome for which the prion protein will be either the receptor or the v irulent factor. The apparition of bovine spongiform encephalopathy in the United Kingdom and of the new variant of Creutzfelt-Jakob disease brings into question the discovery of new subacute spongiform diseases and involves the proposition of efficacious protective measures for p ublic and animal health.