NR AORU
AU Deslys,J.P.; Comoy,E.E.; Marce,D.; Auvre,F.; Grassi,J.; Jackman,R.
TI Screening and confirmatory rapid prion diagnostic tests: from sensitivity to strain discriminiation
QU International Conference - Prion diseases: from basic research to intervention concepts - TSE-Forum, 08.10.-10.10.2003, Gasteig, München - Oral sessions OS-29
PT Konferenz-Vortrag
AB
The development of rapid biochemial methods for the detection of PrPres (the abnormal form of the prion protein) has significantly increased the potential for the detection of scrapie and BSE. The large scale screening that is now possible, mainly by Elisa, also demands an evolution in the confirmatory methods due to the greater number of samples to be handled, and their potential lack of sensitivity relative to some rapid tests. By definition the methods for ascertainment have to rely on a different technique than that used for the screening. Histology turned out to be insufficient when it was limited to the detection of spongiosis but the evolution of PrP immunohistochemistry and the development of the techniques allowing discrimintaion between cellular PrP and pathological PrP deposition has tremendously increased diagnostic potential. This technique constitutes the refernce method in many laboratories. Western blotting is an alternative method, often more sensitive and easy to set up, hence increasingly used in refernce laboratories. In additrion, it has important potential for differential diagnosis between scrapie and BSE in sheep.
We have observed that the octapeptide region of the PrPres can be preserved from protease digestion and that this repeated epitope can not only increase the sensitivity of diagnostic tests but also allow differential diagnosis between BSE and scrapie. Moreover, some scrapie strains in sheep cannot be detected without protection of PrPres from proteolysis. This repeated epitope is used in the most sensitive diagnostic test commercialised today. An alternative approach to preserve abnormal PrP is to eliminate completely the use of protease treatment but the risk of false positives due to the detection of normal PrP is a hurdle to the development of very sensitive tests.
Highly sensitive techniques provide the best guarantee for consumer protection. The next challenge is to reliably detect abnormal PrP in blood. To achieve this, the standardisation of the methods of screening and confirmation turns out to be a key point for the future.
AD J.P. Deslys, Emmanuel E. Comoy (comoy@dsvidf.cea.fr), D. Marcé, F. Auvré, CEA, DSV/DRM/GIDTIP, France; J. Grassi, CEA, DSV/DRM/SPI, CEA/Saclay, France; R. Jackman, Veterinary Laboratory Agency, UK
SP englisch
PO Deutschland