Lipid-based ELISA test for detection of dairy cattle with Johne`s disease

Johne's disease (JD) is a significant problem in animal health, and this is underscored by its identification by the USDA as the most important infectious disease in ruminants and one of the priority diseases for 2009/2010. Infection with MAP usually occurs after birth and infected calves go through a short period with mild or no symptoms during which they shed the bacteria in feces. This short period, which usually goes unrecognized, is followed by a long incubation period of two to five years in which the animals are presumably healthy, non-shedding, and without any symptoms hinting toward the development of JD. Following the incubation period, MAP-infected cattle develop disease with the characteristic symptoms of chronic diarrhea (with shedding) and weight-loss, loss of milk production, and finally death. There are no specific tools for the prevention or treatment of JD. The only effective control measures are culling the infected animals and/or instituting good herd management practices. Either approach depends on quickly and accurately identifying MAP-infected animals, and separating them from the rest of the herd before they spread the disease through fecal shedding. There is a strong demand from diagnostic laboratories for a test for Johne's disease with no batch-to-batch variation, no extra pre-absorption step, and a higher sensitivity. In this Phase II proposal we present an integrated plan for the final evaluation of the Lipid-ELISA. The proposed experiments will provide essential data on the specificity, sensitivity, stability, and robustness of the Lipid-ELISA assay. The strengths of the Lipid-ELISA as a diagnostic test for Johne's disease are that it is a simpler test without the need for pre-absorption of sera, high reproducibility due to the use of a synthesized lipid antigen, and that it has excellent specificity and better sensitivity than the existing serodiagnostic tests. Eckstein Diagnostics will determine the final sensitivity and specificity of this newly designed diagnostic test for Johne's disease using defined and field study sera from several regions within the US. The test will also be used in a 2-year field study of dairy farms in Northern Colorado. Furthermore, Eckstein Diagnostics will define stability, repeatability, suitability and ruggedness of the diagnostic test kit. Eckstein Diagnostics will file for a sales license with USDA for the US. The licensed diagnostic test will be made available for purchase. It is anticipated that licenses will be obtained in the USA and Canada, several countries within the European Union (Germany, France, Great Britain, Ireland, Spain, Greece, Italy, and The Netherlands), as well as in Australia and New Zealand. The test will be used within the latter countries for sheep instead of cattle.