Experimental transmission of atypical scrapie to sheep
1 Department of Pathology, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
2 Department of Molecular Pathogenesis and Genetics, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
3 Animal Services Unit, Veterinary Laboratories Agency – Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
BMC Veterinary Research 2007, 3:20 doi:10.1186/1746-6148-3-20Published: 28 August 2007
Active surveillance for transmissible spongiform encephalopathies in small ruminants has been an EU regulatory requirement since 2002. A number of European countries have subsequently reported cases of atypical scrapie, similar to previously published cases from Norway, which have pathological and molecular features distinct from classical scrapie. Most cases have occurred singly in flocks, associated with genotypes considered to be more resistant to classical disease. Experimental transmissibility of such isolates has been reported in certain ovinised transgenic mice, but has not previously been reported in the natural host. Information on the transmissibility of this agent is vital to ensuring that disease control measures are effective and proportionate.
This report presents the successful experimental transmission, in 378 days, of atypical scrapie to a recipient sheep of homologous genotype with preservation of the pathological and molecular characteristics of the donor. This isolate also transmitted to ovinised transgenic mice (Tg338) with a murine phenotype indistinguishable from that of Nor 98.
This result strengthens the opinion that these cases result from a distinct strain of scrapie agent, which is potentially transmissible in the natural host under field conditions.