Effect of autolysis on the specificity of bovine spongiform encephalopathy rapid tests

The specificity of the four systems was 100% for all three grades of autolysis, while the percentage of initially reactive results was 0.00 (95%CI 0.00-0.82), 0.22 (95%CI 0.006-1.23), 0.44 (95%CI 0.05-1.60), and 0.89 (95%CI 0.24-2.26) for the Biorad TeSeE, the Prionics？ Check LIA, the IDEXX Herd Check BSE and the Enfer TSE tests, respectively. No association with the degree of autolysis could be drawn.The present study demonstrates that the four rapid tests can be considered well-running diagnostic tools regardless of tissue quality; nevertheless, the number of initial reactive samples reported for some systems must not be underestimated in routine testing.Furthermore the compliance with the reported performance can be guaranteed only when an ongoing high careful batch quality control system is in place.Bovine spongiform encephalopathy (BSE), a fatal infectious neurodegenerative disease of cattle, is characterized by the concentration of an anomalous isoform of the natural prion protein (PrPc), denominated PrPres, in the central nervous system (CNS) [1,2]. PrPres differs from PrPc in its high insolubility and partial protease resistance: these characteristics are exploited by the majority of the methods currently used for BSE diagnosis. Evidence for the origin of variant Creutzfeldt-Jakob Disease (vCJD) from BSE [3,4] led the European Commission (EC) to strengthen control programs, introducing active surveillance by means of rapid tests to monitor the ruminant infection [5]. Since 1999 the EC has assessed 19 rapid tests, 9 of which were approved for survey including a new version of the Enfer TSE test for BSE diagnosis [6].In 1999 the EC carried out the first scientific evaluation of four new rapid post mortem BSE tests in which diagnostic accuracy and analytic sensitivity on brain tissue from clinically affected bovines was assessed [7]. Subsequent EU validation exercises extended assessment parameters to include test robustness on autolyzed material as a fundament