NR AXJR
AU Bozzetta,E.; Nappi,R.; Crudeli,S.; Meloni,D.; Melis,P.G.; Ibba,M.B.; Vargiu,M.P.; Mazza,M.; Nonno,R.; Ru,G.; Ligios,C.
TI Evaluation of the diagnostic sensitivity of approved rapid tests for the active surveillance in clinically-healthy sheep from scrapie affected flocks
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Protein Misfolding P01.12
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB TSE active surveillance in EU in sheep and goats is based since 2006 on a screening procedure using TSE rapid tests specific for ovine and caprine animals, approved according to the Commission Regulation (EC) 253/2006. The amendment to EC 999/2001 follows the Institute of Reference and Material Measurements evaluation performed on 9 rapid tests for small ruminants, in which diagnostic sensitivity and specificity were assessed; furthermore the analytical sensitivity, defined as the lowest concentration of pathological prion protein (PrPsc), obtained in a dilution series of clinical, confirmed cases of classical scrapie and that can be distinguished from background noise, was calculated. Aim of the current study was to evaluate the diagnostic sensitivity of 3 of the 8 approved TSE rapid tests in order to verify, in field conditions, their suitability for the detection of affected animals in the early preclinical stage of scrapie. The study was carried out starting from 716 asymptomatic Sarda breed sheep of various genotype, aged over 18 months and belonging to 16 flocks in which, previously, classical scrapie cases were confirmed. Those flocks were known to have a quite high mean prevalence of preclinical-scrapie infection (over 10%) thus providing an adequate number of scrapie cases. The medulla oblongata was collected from each sheep in the framework of "stamping out" actions, which were carried out in accordance to the European regulations. The samples were submitted to an appropriate pre-homogenization protocol and then divided into 5 aliquots to be available for examination by confirmatory Western Blotting (WB) and by three rapid tests (Test Bio-Rad TeSeE Sheep/Goat, IDEXX HerdChek BSE-Scrapie Antigen Test Kit EIA, Test Prionics Check Western Small Ruminant) and for molecular characterization. To date, a first group of 49 positive samples, confirmed through confirmatory WB, were available for sensitivity evaluation. A total of 47 samples resulted positive at Biorad test (sensitivity 95.92 % with 95% confidence interval 86.02-99.50), 48 at IDEXX (97.96, 95% CI 89.15-99.95) and 47 at Prionics (95.92 %, 95% CI 86.02-99.50), with 46 samples being positive for all the three tests. Our preliminary findings show that all three tests are valid tools for scrapie diagnosis in clinically-healthy sheep displaying a low amount of PrPsc, with minor differences in sensitivity among them. Using such accurate tests, an estimate of scrapie prevalence can be obtained.
AD E. Bozzetta, R. Nappi, D. Meloni, M. Mazza, G. Ru, Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d'Aosta, CEA - Area Neuroscienze e Genetica, Italy; S. Crudeli, P.G. Melis, M.B. Ibba, M.P. Vargiu, C. Ligios, Istituto Zooprofilattico Sperimentale della Sardegna, Italy; R. Nonno, Istituto Superiore di Sanità, Dep. of Food Safety and Veterinary Public Health, Italy
SP englisch
PO Schottland