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From: TSS ()
Date: March 24, 2007 at 8:23 am PST

Opinion of the Scientific Panel BIOHAZ on the CRL report on batch testing of TSE rapid tests: sample selection and test sensitivity issues

Adopted on 7 March 2007. (Question Nº EFSA-Q-2006-204)
Last updated: 23 March 2007 Publication Date: 23 March 2007


The European Food Safety Authority (EFSA) and its Scientific Panel on Biological Hazards and the Expert Working Group on Transmissible Spongiform Encephalopathy (TSE) Testing were asked by the European Commission (EC) to evaluate a report of the Community Reference Laboratory (CRL) on batch testing of TSE rapid test kits which highlighted some matters of concern including sample selection and test sensitivity issues. At present, 12 rapid BSE test kits are approved by the EC for the post mortem testing of slaughtered cattle in accordance with the TSE Regulation (EC) No 999/2001.
The aim of a “Batch testing” programme is to compare different batches of a particular test kit for consistency of performance. A panel of samples is tested using each new batch of kits produced. The results obtained must fall within pre-determined limits. Batch release testing and /or approval are carried out to varying degrees by Member States. In order to establish a European wide batch testing procedure the CRL has assembled a panel of brain homogenates prepared from BSE positive bovine brain to be used for batch testing purposes. This sample panel was tested by the test manufacturers in their own laboratories using EU approved rapid tests. Most of the tests identified all of the positive samples in the set as positive, with medium to high readings. However, several of the tests failed to detect some of the positive samples, including some strongly positive samples. The CRL prepared a report on the testing and this was communicated to the companies concerned. These companies were given time to respond to the report and their replies were forwarded together with the CRL report to the EFSA for evaluation.
The experts of the Scientific Panel on Biological Hazards (BIOHAZ Panel) reviewed the CRL report on batch testing data and concluded that not all of the nine tests evaluated performed equally. The implications of this are twofold; firstly, the sample panel cannot be used in its current state to provide a batch testing system for all currently approved EU BSE rapid tests, although it is suitable for most of them. Secondly, they also suggest that there are profound differences in performance in terms of robustness, with respect to sample format, displayed by currently approved rapid tests. Consequentially, any observed differences in performance, if real, would be of concern. The observation that aliquots of the same positive sample were found to be highly positive according to some of the approved rapid tests but negative according to others, could be attributable to aspects of the test performance and/or to properties of the sample material tested. These concerns are addressed in a number of recommendations, as formulated in the Opinion.
The BIOHAZ Panel further concluded that these batch testing data do not compromise the previous Institute for Reference Materials and Measurements (IRMM)-EFSA evaluation of rapid BSE tests.


1 For citation purposes: Opinion of the Scientific Panel on Biological Hazards on a request from the European Commission on the CRL report on batch testing of TSE rapid tests: sample selection and test sensitivity issues, The EFSA Journal (2007), 443, 1-18.




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