NR AWGW
AU Heres,L.; Langeveld,J.P.M.; van Keulen,L.J.M.; Bossers,A.
TI Natural scrapie infection in experimental sheep flock in Lelystad
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 EPI-06
PT Konferenz-Poster
AB CIDC-Lelystad maintains two sheep flocks of Texel mixed breed. At the start in 1992, in one of these flocks a scrapie infection was introduced by purchase of scrapie affected sheep. This infection is sustained by natural infection within the flock. The other flock is kept scrapie free and can serve as a control flock with minimal infection pressure. The 2 flocks are kept outdoors and count about 65 and 35 heads respectively. Five allele types (ARR, ARH, AHQ, ARQ, VRQ) and most possible genotype combinations are maintained in the scrapie flock. All sheep are yearly tested by tonsil biopsies and immunohistochemistry (IHC) to monitor the scrapie status of the flocks. At the end of their life sheep are necropsied and different organs are collected in duplo and stored at -20 and in formaline. Obex and tonsil are tested by IHC for diagnosis of scrapie. The main characteristics of the two sheep flock will be described. The attack rate of scrapie in the different genotypes of the sheep born and raised in the scrapie flock are presented. Epidemiological data suggest that at least two scrapie strains are residing in the scrapie flock. This is supported by preliminary strain typing results in a bioassay. All VRQ/VRQ and ARQ/VRQ sheep and about half of ARQ/ARQ sheep are positive in brain and lymph nodes at the end of life with longer incubation times for the ARQ/VRQ and ARQ/ARQ sheep. Most ARR/VRQ sheep stay negative or have a long incubation time without evident lymphoid involvement. None of the ARR/ARR and ARR/ARQ animals were scrapie positive. The scrapie flock provides a well characterised living source of materials for development or first validation of (pre)clinical tests and reference materials.
AD Dept. Bacteriology & TSEs, CIDC-Lelystad, Wageningen UR, Lelystad, The Netherlands. E-mail: lourens.heres@wur.nl
SP englisch
PO Italien