NR ATPL
AU Dexter,G.E.; Bellworthy,S.J.; Jeffrey,M.J.; Davis,A.; Hawkins,S.A.C.; Simmons,M.M.
TI BSE in sheep - investigations of natural transmission within a breeding flock
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Poster Session: Pathogenesis PATH-22
PT Konferenz-Poster
AB
Following the recognition of the link between bovine BSE and the variant form of the human TSE Creutzfeldt Jakob Disease, there has been an urgent need to evaluate the risks of transmission of BSE both between animal species and to man. Accurate quantification of the risk requires data on the ease with which BSE can naturally transmit and persist within a group of sheep. In this study we investigated whether BSE can transmit naturally under near-normal farm conditions and sustain itself within a breeding flock of sheep. A group of 30 TSE free six-month-old ewe lambs of the susceptible ARQ/ARQ genotype were dosed with 5g each of BSE inoculum prepared from the brains of cattle clinically affected with BSE. A further 20 undosed matched ewe lambs were introduced and the sheep were kept together in a large yard within barrier accommodation. Following the introduction of TSE free breed/genotype matched tups, controlled breeding was permitted with 24 lambs born in the first season, 38 born in 2004 and 85 born this year. To June 2005 there were 24 clinical cases in the dosed sheep and one casualty. With incubation periods ranging from 569 to 1057 days pi. This range is consistent with our previous BSE in sheep studies. There have been no clinical cases in the original undosed sheep and no evidence of infection on tonsil biopsy to date (36 months post mixing). Two lambs born in 2003 to dosed ewes, have succumbed to disease with incubation periods of 653 & 725 days. The lambs were negative on tonsil biopsy at 12 months but positive at 18 months of age. This is the first confirmation that BSE can transmit either in utero or perinatally in sheep.
Funding: Defra grant SE1946
IN Von 50 Lämmern der Rassen Suffolk und Romney mit dem empfänglichen Genotyp ARQ/ARQ fütterten Dexter et al. 30 im Alter von 6 Monaten mit jeweils 5 g Hirnhomogenat von BSE-Rindern und hielten dann alle 50 Schafe gemeinsam. Später wurden die Schafe mit genotypisch passenden gesunden Widdern verpaart und bekamen im ersten Jahr 24, im nächsten 38 und im letzten Jahr 85 Lämmer. Bis Juni 2005 waren von den 30 oral inokulierten Schafen 24 erkrankt und eines verunglückt. Die Inkubationszeiten bewegten sich zwischen 569 und 1057 Tagen. Es gab aber keine Erkrankungen und keine positiven präklinischen Testergebnisse unter den nicht inokulierten Schafen, mit Ausnahme zweier 2003 geborener Lämmer von inokulierten Müttern. Bei diesen beiden Schafen waren die Mandelbiopsien noch nicht nach 12, aber nach 18 Monaten PrPsc-positiv und im Alter von 653 bzw. 725 Tagen erkrankten sie.
AD Glenda E. Dexter, Susan J. Bellworthy, Andrew Davis, Stephen A.C. Hawkins, Marion M. Simmons, Veterinary Laboratory Agency Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB. UK.; Martin Jeffrey, Veterinary Laboratory Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ. UK.
SP englisch
PO Deutschland