Characterization of Strains of Ovine Transmissible Spongiform Encephalopathy with a Short PrP d Profiling Method S. Siso ´ * , M. Jeffrey * , S. Martin * , F. Chianini † , M. P. Dagleish † and L. Gonza ´ lez * * Veterinary Laboratories Agency-Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ and † Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK Summary Scrapie is the transmissible spongiform encephalopathy (TSE) that naturally affects sheep and goats; these spe- cies are also susceptible to experimental infection with the bovine spongiform encephalopathy (BSE) agent. Discrimination between different strains of sheep scrapie and ovine BSE has been achieved by descriptive and quantitative profiling of deposits of the disease-associated prion protein (PrP d ) in different areas of the brain, but this process is time-consuming and difficult to standardize between laboratories. The present paper describes an alternative PrP d profiling method that is less demanding and addresses these difficulties. It is based on the scoring of similar 14 PrP d types in 11 precisely defined areas of the telencephalon. When applied to 48 archived cases of experimental sheep BSE, SSBP/1, CH1641 and natural scrapie, it gave comparable results to the original profiling method, previously conducted on the same brains, and allowed differentiation between the different infectious sources. This new ‘short PrP d profiling’ method has the advantages of being less time-consuming and easier to standardize, so that it can be readily adopted by different laboratories to provide comparable results. Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. Keywords: PrP d ; scrapie; sheep; transmissible spongiform encephalopathy Introduction Scrapie, a neurodegenerative disease of sheep and goats, is the archetypal transmissible spongiform en- cephalopathy (TSE). TSEs or prion diseases include several neurological disorders of animals and man, notably, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) of cervids and human CreutzfeldteJakob disease and its variant (CJD and vCJD, respectively). Common to all TSEs are spongiform changes and the accumulation of the disease-associated prion protein (PrP d ) in the brain. The classical typing of strains of TSEs involves transmission and serial passage of infectious material (‘isolate’) in a panel of inbred mouse lines. Following cloning by limiting dilution, murine scrapie strains are characterized by (1) their relative incubation periods in inbred mouse lines, (2) the pattern of vacuolation in the brain known as the ‘lesion profile’ (Dickinson, 1976; Bruce et al., 1991) and (3) the pat- tern of PrP d deposition in the brain (Bruce et al., 1976, 1989). This method has allowed discrimination be- tween BSE and several sheep scrapie strains, leading to the conclusion that the BSE agent is a unique, sin- gle strain that is stable after passage. However, the significance of mouse-adapted scrapie strains remains obscure, as they might not reflect strain diversity in the donor sheep, but could arise from selection or mu- tation on inter-species passage. In sheep scrapie there are reports describing corre- lation between the scrapie source or strain and the le- sion profile (Wood et al., 1997; Ligios et al., 2002), while others show high individual variability in vacu- olation profiles between sheep inoculated with the Correspondence to: S. Siso´ (e-mail: s.siso@vla.defra.gsi.gov.uk). 0021-9975/$ - see front matter Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jcpa.2009.12.003 J. Comp. Path. 2010, Vol. 142, 300e310 Available online at www.sciencedirect.com www.elsevier.com/locate/jcpa