Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2002
Publication Date: 3/1/2003
Citation: Valdez, R.A., Rock, M.J., Anderson, A.K., O'Rourke, K.I. 2003. Immunohistochemical detection and distribution of prion protein in a goat with natural scrapie. Journal of Veterinary Diagnostic Investigation. 15(2):157-162. Interpretive Summary: Scrapie is a fatal prion disease occurring primarily in sheep. Although goats are susceptible to the disease, very few cases have been reported and essential information on the characteristics and tissue location of the marker protein (PrP-Sc) is not known. In this study, tissues from the central nervous system, the gastrointestinal tract, and the lymphoid system were examined for PrP-Sc, using a standardized immunohistochemistry assay. The results of this study indicate that the current testing system used for scrapie diagnosis in the US is suitable for use in goats, although precise determination of the diagnostic sensitivity and specificity of the assay as a diagnostic test for scrapie in goats will require examination of a sufficiently large sample size.
Technical Abstract: Formalin-fixed, paraffin-embedded tissue sections from a 3-year-old female Angora goat suffering from clinical scrapie were immunostained using a monoclonal antibody (mAb, F99/97.6.1; IgG1) specific for a conserved epitope on the prion protein. Widespread and prominent deposition of the scrapie isoform of the prion protein (PrPSc) was observed in the brain, brainstem, spinal cord, retina, post-ganglionic neurons associated with parasympathetic ganglia of myenteric and submucosal plexuses, Peyer's patches, peripheral lymph nodes and pharyngeal and palatine tonsils. The goat was homozygous for PrP alleles encoding five octapeptide repeat sequences in the N-terminal region of the prion protein and isoleucine at codon 142, a genotype associated with high susceptibility and short incubation times in goats. The results of this study indicate that mAb F99/97.6.1 is useful for detection of PrPSc deposition as a specific and reliable immunohistochemical adjunct to histopathology for diagnosis of natural caprine scrapie. Similar to ovine scrapie, prion protein in natural caprine scrapie is widely distributed in the central and peripheral nervous systems, gastrointestinal tract and lymphoid tissues.