Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/1998
Publication Date: N/A
Interpretive Summary: In the cattle industry, quick, reliable, and reproducible tests to assess the overall health status of animals destined for human consumption are desirable. We have developed such a test that measures the levels of a specific protein, referred to as haptoglobin, in the blood of cattle. We have validated this test, and have used it to measure the blood levels of haptoglobin in both healthy and unhealthy cattle. Our results indicate that measurement of haptoglobin is a good indicator of the general health status of cattle. Measurement of the blood levels of haptoglobin in cattle could play a role in improving food safety by providing a tool for inspectors to evaluate animal health prior to slaughter. Additionally, this test could be of economic benefit to veterinarians and producers by providing an additional managment tool.
Technical Abstract: Modification of a monoclonal antibody-based enzyme immunoassay to detect haptoglobin in cattle serum samples is reported. In this modified two-site (MTS) haptoglobin-binding procedure, the enzyme label is directly conjugated to the mouse anti-haptoglobin monoclonal antibody versus using an enzyme conjugated second antibody. The haptoglobin in a sample is initially bound to hemoglobin previously coated onto the bottom of microtiter plates. The enzyme conjugated monoclonal antibody then forms a complex with the bound haptoglobin. Binding occurs at a second site on the haptoglobin molecule. This represents a simplification of the original enzyme immunoassay by eliminating the incubation step which required enzyme conjugated anti-mouse before final color development. Correlation coefficients of r=0.8157 and r=0.8439 were observed when aliquots from 57 samples were analyzed independently at two other laboratories, each using different assays. The substitution of conjugated polyclonal antibody in lieu of conjugated monoclonal antibody was equally effective, with resultant correlation coefficients of r=0.8303 and r=0.8812. The MTS assay, utilizing enzyme conjugated monoclonal antibody, was used to detect haptoglobin in serum samples collected at a slaughterhouse representing healthy and diseased cattle. The healthy group was represented by antemortem normal steers and culled dairy cows. The potentially diseased carcasses were those retained during postmortem inspection pending closer examination for a final disposition. Results from these tests are summarized in this communication.