title: Experimental oral transmission of atypical scrapie to sheep.
abstract: To investigate the possibility of oral transmission of atypical scrapie in sheep and determine the distribution of infectivity in the animals' peripheral tissues, we challenged neonatal lambs orally with atypical scrapie; they were then killed at 12 or 24 months. Screening test results were negative for disease-specific prion protein in all but 2 recipients; they had positive results for examination of brain, but negative for peripheral tissues. Infectivity of brain, distal ileum, and spleen from all animals was assessed in mouse bioassays; positive results were obtained from tissues that had negative results on screening. These findings demonstrate that atypical scrapie can be transmitted orally and indicate that it has the potential for natural transmission and iatrogenic spread through animal feed. Detection of infectivity in tissues negative by current surveillance methods indicates that diagnostic sensitivity is suboptimal for atypical scrapie, and potentially infectious material may be able to pass into the human food chain.
authors.affiliation: Department of Pathology and Host Susceptibility, Veterinary Laboratories Agency-Weybridge, Addlestone, UK. m.m.simmons@vla.defra.gsi.gov.uk
authors.forename: Marion M
authors.initials: MM
authors.lastname: Simmons
authors.forename: S Jo
authors.initials: SJ
authors.lastname: Moore
authors.forename: Timm
authors.initials: T
authors.lastname: Konold
authors.forename: Lisa
authors.initials: L
authors.lastname: Thurston
authors.forename: Linda A
authors.initials: LA
authors.lastname: Terry
authors.forename: Leigh
authors.initials: L
authors.lastname: Thorne
authors.forename: Richard
authors.initials: R
authors.lastname: Lockey
authors.forename: Chris
authors.initials: C
authors.lastname: Vickery
authors.forename: Stephen A C
authors.initials: SA
authors.lastname: Hawkins
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Chaplin
authors.forename: John
authors.initials: J
authors.lastname: Spiropoulos
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000469:parasitology / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D012608:Scrapie / Q000175:diagnosis / Q000635:transmission*; D012756:Sheep