|Knowles Jr, Donald|
Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2000
Publication Date: N/A
Interpretive Summary: This manuscript provides performance data for the third eyelid test of sheep. This test is for the transmissible spongiform encephalopathy of sheep known as scrapie. A total of 241 sheep were tested. The concordance (percentage agreement) between the third eyelid test and the gold standard of pathology and or immunohistochemistry (prion detection with monoclonal antibodies) was 97.5 %. These data show that the third eyelid test is suitable and accurate in individual animal testing and that such testing has value in scrapie control and eradication programs.
Technical Abstract: Scrapie is a member of the transmissible spongiform encephalopathies (TSEs), a heterogeneous family of fatal neurologic disorders characterized by deposition of an abnormal isoform (PrP-Sc) of a cellular sialoglycoprotein (PrP-C) in neural tissue. PrP-Sc is also detectable in the lymphoid tissues of infected sheep months or years before development of clinical disease. In this study, we characterize the performance of a preclinical diagnostic test for ovine scrapie based on monoclonal antibody (MAb) immunohistochemistry assay of nictitating membrane (¿third eyelid¿) associated lymphoid tissue. The results of third eyelid immunohistochemistry agreed with the scrapie status of the sheep in 36/37 clinical suspects with confirmed scrapie, 174/175 sheep without scrapie, and 25/29 infected sheep without clinical signs, including 16 sheep that progressed to clinical disease with confirmed scrapie 3 to 20 months following biopsy. The assay used MAb F89/160.1.5 that 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.