Prion protein: detection in ‘spiked’ anaerobic sludge and degradation experiments under anaerobic conditions

The behavior of the transmissible spongiform encephalopathies (TSE) causing agent denominated “prion protein” in anaerobic sludge (biogas reactor) was assessed with incubation tests. A widely applied screening method for BSE in cattle on the basis of the Western blotting protocol was adapted to detect the Proteinase K resistant, scrapie-form prion protein (PrP^SC). As PrP^SC source homogenized TSE infected brain tissue of animals late in the clinical phase of disease was taken (301V/VM mouse-BSE; bovine BSE and 22A/SV mouse-scrapie). The incubation under mesophilic conditions did not show any significant reduction of the PrP^SC titer. Under thermophilic conditions contradictory results were obtained. The reduction time of PrP^SC in water was equal to or longer than the PrP^SC reduction time in anaerobic sludge. In comparison, with sterilized (121 °C, steam pressure) or poisoned (sodium azide, 1% w/v) sludge used as incubation matrix a much shorter time resulted until no prion protein could be detected.