Submitted to: Emerging Infectious Diseases
Publication Type: Proceedings
Publication Acceptance Date: 3/31/2000
Publication Date: N/A
Technical Abstract: Scrapie is a naturally occurring, prion-associated disease of sheep and goats. A major impediment to research and control of scrapie has been the lack of a method to predict infection prior to the onset of clinical disease. The scrapie-associated prion isoform PrP-Sc is detectable in lymphoid tissues, including those of the third eyelid (nictitating membrane) of infected sheep months or years before development of clinical disease. In this study, we show a 97% concordance between the third eyelid preclinical test for ovine scrapie and the current diagnostic standards of spongiform lesions and/or immunohistochemistry of the medulla at the level of the obex. The results of third eyelid immunohistochemistry assay agreed with the scrapie status of sheep in 182 out of 187 tested. These samples included 16 sheep that progressed to clinical disease with confirmed scrapie 3 to 20 months following biopsy. All sheep with PrP-Sc accumulation in lymphoid tissue or brain were homozygous for glutamine at codon 171. The assay used MAb F89/160.1.5, which binds residues 142-145 of ovine PrP. This antibody can be used in combination with MAb F99/97.6.1, which binds residues 220-225. One or both monoclonal antibodies in this cocktail recognize PrP sequences conserved in most mammalian species in which natural TSEs have been reported. The third eyelid test for PrP-Sc will be useful in diagnostic, surveillance and research programs.