NR ATJQ
AU Gonzalez,L.; Bellworthy,S.J.; Dagleish,M.P.; Martin,S.; Siso,S.; Stack,M.J.; Chaplin,M.J.; Davis,L.; Reid,H.W.; Jeffrey,M.J.
TI Diagnosis of pre-clinical scrapie in biopsy samples of rectal mucosa
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Poster Session: Diagnosis DIA-02
PT Konferenz-Poster
AB
An ability to diagnose pre-clinical disease in live sheep would advance the design of scrapie control strategies. Detection of abnormal PrP -the most reliable marker of infection- in live asymptomatic sheep has so far been confined to tonsil and third eyelid biopsy specimens, but these tissues are not practical for screening of large populations.
We have studied by immunohistochemistry (IHC) the accumulation of abnormal PrP in the recto-anal mucosa-associated lymphoid tissue (RAMALT) of more than 500 sheep of different breeds, PrP genotypes, ages and clinico-epidemiological scrapie status. Our results indicate that over 95% of clinical and 70% of subclinical scrapie cases show detectable abnormal PrP in the RAMALT, regardless of any other factor considered. A selection of 100 samples was examined by NaPTA Western blotting, and the high correlation of results confirmed the suitability of this tissue sample for immunochemical analysis.
As the RAMALT is easily accessible, we have performed IHC examination of around 300 biopsy samples taken sequentially from individual sheep of different PrP genotypes and clinico-epidemiological scrapie status. Detection of abnormal PrP in naturally exposed Suffolk sheep of ARQ/ARQ genotype was achieved from approximately half-way through the incubation period, and was also possible at different times post-inoculation of orally or subcutaneously dosed sheep of different PrP genotypes.
Where available, both in necropsy and biopsy cases, parallel examination of palatine tonsil provided almost total correlation of results. In contrast with tonsil, RAMALT biopsies were larger with numerous follicles and thus suitable for rapid test analysis. They were quickly obtained using simple instrumentation and did not adversly affect sheep. The procedure may therefore be of use for the screening of sheep flocks and can be applied to the detection of TSEs in other species.
IN Die Autoren halten die Entnahme von Mandel- und Augenliedgewebe bei Schafen für wenig praktikabel und empfehlen stattdessen die ihrer Ansicht nach für Schaf und Tierarzt unproblematische Entnahme von lymphoidem Gewebe hinter der rectoanalen Schleimhaut. In diesem Gewebe fanden sie PrPsc per Western blot nach einer Phosphorwolframsäure-Fällung ebenso früh und zuverlässig wie in Mandelbiopsien. Deshalb ließen sich mit dieser Methode ganze Schafherden screenen und man müsste nicht warten, bis ein Schaf erkrankt.
AD L.González, S.Martin, S.Sisó, M.Jeffrey, Veterinary Laboratories Agency (VLA) - Lasswade; S.J.Bellworthy, M.Stack, M.Chaplin, L.Davis, VLA-Weybridge; M.P.Dagleish, H.Reid, Moredun Research Institute
SP englisch
PO Deutschland