Applied Microbiology, Inc. (AMBI), will develop enzyme-tagged antigens for use as probes in a unique, competitive immunodiagnostic assay system. The competitive immunoassay will be formatted in such a way that the antigen in the test sample will compete with the enzyme-tagged probe for binding to an immobilized "universal" capture system. The displaced antigen-enzyme probe remaining in solution will be quantitated by enzymatic activity and will be directly proportional to the amount of antigen in the test sample. Enzyme-tagged antigens will be constructed via (1) recombinant DNA methodology to create fusion proteins and (2) chemical coupling. The thermostable indicator enzyme chosen for these studies, staphylococcal nuclease, can be formatted for assay with fluorescent, colored, and radioactive substrates. The radioactive assay is extremely sensitive: 100 fg nuclease can be detected in 30 minutes. The initial focus will be on the construction of specific tagged-antigen probes for the detection of the bacterial extracellular toxin, TSST-1, responsible for toxic shock syndrome. In the longer term, other extracellular bacterial toxins will be targeted along with various peptide hormones. The system will be established in a homogeneous format that will not require separation or washing steps and will therefore be easily adaptable to automation.
Anticipated Results:The immunodiagnostics field is dominated by Hybritech's 11 "sandwich" immunoassay. AMBI's alternative immunoassay has potential in all areas relating to the diagnosis of infectious and metabolic disease in humans and animals, and for the detection of microbial toxins in the food-processing industry.National Institute of Allergy And Infectious Diseases
