Genetically fused single-chain anti-Salmonella antibody with aequorin: a bioluminescence immunoassay for a Salmonella antigen

We report the development of a competitive heterogeneous immunoassay for BS A-conjugated Salmonella antigen using a fusion protein between an anti-Salm onella single-chain antibody (scFv) and the photo-protein aequorin (AEQ). I t has been demonstrated that the fusion protein (scFvLAEQ) maintains both t he antibody binding affinity toward the Salmonella antigen as well as the l uminescence properties of the photoprotein. Using scFvLAEQ, the competitive immunoassay gave a detection limit of 10 mug ml(-1) of Salmonella antigen. The assay eliminates the need for a labeled secondary antibody usually req uired in enzyme-linked immuosorbent assays (ELISAs), and therefore, it may find potential applications in detecting Salmonella contamination. (C) 2001 Elsevier Science B.V. All rights reserved.