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BAVARIAN RESEARCH ASSOCIATION PRIONS

LMU 21 Investigation of Sporadically Occurring Spongiform Brain Lesions in Cattle

We performed autopsies of cattle in Bavaria with clinical suspect for BSE (bovine spongiform encephalopathy) and performed detailed histopathological analyses of the brain. We concentrated on the pathogenesis and significance of brain stem neuronal vacuolations in BSE-positive and –negative cattle (Western blot diagnosis). In BSE animals a premature aging of most neurons with excessive storage of lipoproteins was found, accompanied by loss of synaptophysin immunoreactivity and an increase of a marker protein (GFAP) specific for astrocytic reactivity. Occurrence of neuronal vacuoles was neither topographically nor by extent strictly correlated to the latter immunhistochemical results. However in BSE-negative animals, neuronal vacuolations were constantly an isolated finding without any simultaneous effects at the synaptophysin or GFAP level. Thus we conclude, that pathogenesis of these “false-positive” vacuoles is not linked to any long-term alteration of functional parameters as observed in BSE within weeks or months of disease evolvement. Consequently we have to regard brain stem vacuolation in BSE-negative animals as a rather peracute inducible phenomenon, most probably by euthanasia of the animals.