NR AWFU
AU Gonzalez,L.; Dagleish,M.P.; Martin,S.; Siso,S.; Terry,L.; Horton,R.; Dexter,G.; Steele,P.; Reid,H.W.; Jeffrey,M.J.
TI Diagnosis of preclinical scrapie in rectal biopsy specimens
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions DIA-19
PT Konferenz-Poster
AB The current approach for sheep scrapie surveillance is based on laboratory examinations for disease-associated prion protein (PrPd ) on samples of central nervous system (CNS) collected at post-mortem. Diagnosis of scrapie in live asymptomatic sheep has so far been confined to palatine tonsil or third eyelid biopsies, but these are not practical field procedures. Blood tests are being developed, but their diagnostic efficiency is still to be shown. We conducted a large survey of immunohistochemical (IHC) detection of PrPd in rectal mucosa samples collected at post-mortem. Positive results were obtained in 97% of clinical and 86% of preclinical scrapie cases; these rates of PrPd detection were not affected by factors such as breed, PrP genotype or age of the animals. Furthermore, we assessed the efficacy of rapid tests on the same samples; once optimized, their sensitivity reached 94% of that of IHC. We have also performed IHC examinations in around 400 rectal mucosa biopsy samples collected from asymptomatic sheep of susceptible PrP genotypes exposed to natural or experimental infection. In natural disease, PrPd was initially detected approximately half way through the incubation period, and the rate of detection increased in subsequent samplings, as did on tonsil biopsies taken simultaneously. Rectal biopsies also provided positive results animals infected experimentally with either scrapie or BSE agents, with similar efficiency regardless of the route of challenge. Rectal biopsy samples selected from sheep with previous IHC positive results were examined by rapid methods, which provided sensitivity values near 100%. With training, rectal mucosa biopsies can be performed simply and quickly. Anaesthesia or sedation is not required, and the procedure has no adverse effects on the sheep even when carried out repeatedly. Detection of PrPd in rectal biopsy samples is a promising approach for diagnosis of clinical and preclinical scrapie in live animals, which can be applied for the screening of sheep flocks; it is also providing good results for the detection of chronic wasting disease in cervids. Samples of rectal mucosa can also be easily taken from animals that are culled as a result of scrapie control measures or that are slaughtered in abattoirs, and can complement scrapie surveillance and monitoring.
AD Lorenzo González (l.gonzalez@vla.defra.gsi.gov.uk), Stuart Martin, Sílvia Sisó (s.siso@vla.defra.gsi.gov.uk), Martin J. Jeffrey (m.jeffrey@vla.maff.gov.uk), VLA Lasswade Veterinary Laboratory, Pentlands Science Park, Bush Loan, Penicuik, Edinburgh EH26 OPZ, Scotland, UK; M.P. Dagleish, P. Steele, H.W. Reid: Moredun Institute, Pentlands Science Park, Bush Loan, Midlothian EH26 0PZ, UK; L. Terry, R. Horton, G. Dexter: VLA-Weybridge, Addlestone, Surrey KT15 3NB, UK
SP englisch
PO Italien