Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/3/2005
Publication Date: 3/3/2006
Citation: Baszler, T.V., Kiupel, M., Williams, E.S., Thomsen, B.V., Gidlewski, T., Montgomery, D.L., O'Rourke, K.I., Hall, S.M. 2006. Comparison of two automated immunohistochemical procedures for the diagnosis of scrapie in domestic sheep and chronic wasting disease in north American white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus). Journal of Veterinary Diagnostic Investigation. 18(2):147-155. Interpretive Summary: Scrapie and chronic wasting disease are prion disorders in which a marker protein accumulates in the lymph nodes and brain of affected sheep, deer, and elk. Diagnosis can be performed by immunohistochemistry assay, in which preserved tissue sections are treated with antibodies to the marker protein and detected with compounds that produce a color change. The assay can be performed on a number of automated systems. In this paper, the authors describe the comparison between two commercially available systems for detection of the marker protein. Concordance between the systems was 98.6% for lymph nodes and 99.9% for brain. The results indicate that the systems are equivalent. These findings indicate that laboratories will be able to test samples using either piece of equipment, following final approval of the test format by USDA APHIS.
Technical Abstract: Scrapie and chronic wasting disease are transmissible spongiform encephalopathies of sheep and cervid ruminants respectively. These diseases are often diagnosed by immunohistochemistry using one or a cocktail of two monoclonal antibodies on an automated immunostainer that delivers commercially available detection reagents in sequence with intervening washing steps. Automated immunohistochemistry allows federal contract laboratories in different parts of the US to test large numbers of samples using a standard uniform protocol. Testing by the USDA Animal Plant Health Inspection Service (APHIS) has been conducted with equipment and reagents marketed by Ventana Medical Systems. A recent survey revealed that the autostainer and reagents marketed by the DAKO Corporation were commonly used in veterinary diagnostic laboratories and adaptation of the testing to that equipment would allow these laboratories to participate in the national testing program without purchasing additional equipment. A trial to determine concordance between the two autostainers was conducted with tissues from sheep and two species of deer exposed to transmissible spongiform encephalopathies. Discordance between the methods was minimal and there were no significant qualitative differences. Equal performance of the two platforms in a semi-quantitative grading classification of tissues considered positive supported the conclusion that the systems perform similarly.