A Comparison of Rapid Bovine Spongiform Encephalopathy Testing Methods on Autolyzed Bovine Brain Tissue

Abstract

Abstract. In 1999, the European Union (EU) approved 3 rapid methods for the testing of bovine brain samples for the presence of bovine spongiform encephalopathy (BSE). The evaluation that led to the approval did not include an analysis of autolyzed material. Member states of the EU have active surveillance programs for BSE, which target fallen stock as well as other categories of cattle. Autolysis is a common feature of fallen stock samples because there can be a considerable delay between death and collection of samples. Therefore, it is important to know whether these tests perform optimally on autolyzed samples. The Veterinary Laboratories Agency (VLA) selected 250 positive fallen stock samples. These had been detected during routine testing using the Prionics-Check Western blot and confirmed as BSE cases by immunohistochemistry or electron microscopy. Samples were graded according to the degree of autolysis and then tested by the 3 methods: PrionicsCheck Western blot, Platelia test, and Enfer test. All 3 methods correctly classified the samples as positive BSE cases, therefore alleviating doubt about their ability to do so. Subsequent EU validation exercises, such as those conducted in [2002][2003], have included the testing of autolyzed material. It is important that all new methods be evaluated on autolyzed tissue before approval for official use.

Diagnosis of Transmissible Spongiform Encephalopathies in Animals: A Review

“…The PrP Sc is very resistant to degradation, and its detection is not significantly compromised by autolysis. 18,22,99 Trials to evaluate the performance of rapid tests before approval by the EU now include a category of poor-quality samples, mostly autolytic. 24 However, the early accumulation of PrP Sc in the brain is very neuroanatomically restricted, and the biggest threat to sensitivity in the autolyzed tissues is the uncertainty as to whether the target areas were actually tested.…”

Identification and Characterization of two Bovine Spongiform Encephalopathy cases Diagnosed in the United States

“…35,49 There is currently no validated ante mortem test for BSE. The original diagnostic test method was histopathology in which brain sections exhibiting the classical vacuoles and spongiform changes in specific areas are used for diagnosis.…”

Effect of Time and Temperature on PrPCWD Immunoreactivity as Evidenced by Western Blot

“…However, it has largely been concluded that autolysis does not compromise the accuracy of assays that detect the proteinase-resistant, pathogenic isoform of the prion protein (PrP res ). 2,5,7,8,12,16 It was hypothesized that over a relatively long period of time, exposure to heat may have a more substantial effect on PrP res immunodection than previously considered. The objective of the present study was to characterize PrP CWD detectability with time in brain samples subjected to heat in vitro as determined by Western blot.…”