Discrimination of classical and atypical BSE by a distinct immunohistochemical PrPSc profile

Résumé

Bovine spongiform encephalopathy (BSE) belongs to the group of transmissible spongiform encephalopathies and is associated with the accumulation of a pathological isoform of the host-encoded glycoprotein, designated prion protein (PrPSc). Classical BSE (C-type) and two atypical BSE forms (L- and H-type) are known, and can be discriminated by biochemical characteristics. The goal of our study was to identify type-specific PrPSc profiles by using Immunohistochemistry. In our study, brain samples from 21 cattle, intracerebrally inoculated with C-, H-, and L-type BSE, were used. In addition, the corresponding samples from three orally C-type BSE infected animals were also included. From all animals, a lesion and PrPSc-profiles of six brain regions were determined. The lesion profile and the neuroanatomical distribution of PrPSc was highly consistent between the groups, but the immunohistochemical analysis revealed a distinct PrPSc profile for the different BSE-types, which included both the topographic and cellular pattern of PrPSc. This qualitative and quantitative analysis of PrPSc affected structures sheds new light into the pathogenesis of the different BSE types. Furthermore, immunohistochemical characterization is supported as an additional diagnostic tool in BSE surveillance programs, especially when only formalin-fixed tissue samples are available.