An ELISA sandwich capture assay for recombinant fusion proteins containing glutathione-S-transferase

A sandwich capture ELISA technique is presented for detection of recombinant proteins sharing a common affinity domain or reagents such as antibodies that bind to these proteins. An activated carrier protein (BSA) is modified with reduced glutathione (GT), forming an affinity capture reagent for glutathione-S-transferase (GST) and recombinant fusion proteins bearing the GST moiety. GT-BSA is immobilized on microtiter plates, and a sandwich is formed consisting of the recombinant fusion protein, reactive antibodies, and detection antibodies. An example is given that demonstrates that this format yields equivalent results to a conventional ELISA test with a panel of newly diagnosed diabetic sera reacting with an islet cell autoantigen.