title: Detection of misfolded prion protein in retina samples of sheep and cattle by use of a commercially available enzyme immunoassay.
abstract: OBJECTIVE
  To determine the usefulness of retina samples for detection of disease-associated prion protein by use of a commercially available enzyme immunoassay (EIA) intended for rapid identification of sheep and cattle with transmissible spongiform encephalopathies (TSEs).
  
  
  METHODS
  Retina, brainstem at the level of the obex, and retropharyngeal lymph node samples obtained from 15 TSE-inoculated sheep (scrapie [n = 13] or transmissible mink encephalopathy passaged through a bovid [2]); retina and brainstem samples obtained from 11 TSE-inoculated cattle (transmissible mink encephalopathy passaged through a bovid [7] or classical BSE [4]); and negative control tissue samples obtained from 2 sheep and 2 cattle that were not inoculated with TSEs.
  
  
  METHODS
  Tissue samples were homogenized and analyzed for detection of abnormally folded disease-associated prion protein with a commercially available EIA and 2 confirmatory assays (western blot analysis or immunohistochemical analysis).
  
  
  RESULTS
  Retina sample EIA results were in agreement with results of brainstem sample EIA or confirmatory assay results for negative control animals and TSE-inoculated animals with clinical signs of disease. However, TSE-inoculated animals with positive confirmatory assay results that did not have clinical signs of disease had negative retina sample EIA results. Retina sample EIA results were in agreement with brainstem sample immunohistochemical results for 4 TSE-inoculated sheep with negative retropharyngeal lymph node EIA results.
  
  
  CONCLUSIONS
  Results of this study suggested that retina samples may be useful for rapid EIA screening of animals with neurologic signs to detect TSEs.
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA 50010.
authors.forename: Jodi D
authors.initials: JD
authors.lastname: Smith
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Greenlee
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis*; D007124:Immunoenzyme Techniques / Q000379:methods / Q000662:veterinary*; D007150:Immunohistochemistry; D017096:Prion Diseases / Q000175:diagnosis / Q000662:veterinary*; D011328:Prions / Q000302:isolation & purification*; D012160:Retina; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis*
chemical_list: D011328:Prions