Discrimination of Classical and Atypical BSE by a Distinct Immunohistochemical PrP Sc Profile.

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 (PrP Sc ). 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 PrP Sc 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 PrP Sc -profiles of six brain regions were determined. The lesion profile and the neuroanatomical distribution of PrP Sc was highly consistent between the groups, but the immunohistochemical analysis revealed a distinct PrP Sc profile for the different BSE-types, which included both the topographic and cellular pattern of PrP Sc . This qualitative and quantitative analysis of PrP Sc 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.