[Prions and protein inhibitors of proteinases: structural analogies and their consequences. IV. The nature of the interspecies barrier of prion disease].

Declining of unproved supposition about the transformation of the cellular isoform of prion protein into pathogenic one allows the pathogenesis of prion diseases to be reduced to the series of interdependent processes caused by prion-mediated selective damage of the components of the cell chaperoning system with following membrane folding of the de novo synthesized prion protein. Dependence of the level of the cell chaperoning system damage on the similarity of the sequences of cellular and infectious prion proteins explains exhaustively the existence of interspecies barrier in prion pathogenesis as well as makes it natural and inevitable property of the latter. The structural ensurance of separate prion diseases strains, their transformation at repeated infectious passages commonly with known and supposed ways for prion-less initiation of spongiform encephalopathies are discussed.