Rapid and sensitive immunomagnetic-electrochemiluminescent detection of staphyloccocal enterotoxin B

Sensitive, rapid and reproducible detection of staphyloccocal enterotoxin B (SEB) in a range of different biological matrices was achieved using the O RIGEN(R) Immunoassay System (Igen, Inc). The homologous immunoassay format consisted of a double antibody sandwich in which a biotinylated capture ant ibody pre-bound to streptavidin-coated paramagnetic beads, was used to bind antigen from test samples. A detector antibody, labeled with ruthenium (II ) tris-bipyridal chelate, was added and, when bound to the bead immunocompl ex, generated light in the presence of an excess of tripropylamine. The lig ht was detected and measured by the ORIGEN analyzer. The sensitivity of thi s assay was 1 pg of enterotoxin per ml of serum, urine, tissue, or buffer a nd was highly reproducible. Concentration curves generated from SEB standar ds produced consistently wide linear ranges (0.1-100 ng/ml), making quantit ation possible with only two dilutions of sample (undiluted and 1:1000). Th e assay used 50 mu l of sample per test and required a 30 min incubation pe riod in addition to a 1 min per tube reading time (50 tubes maximum). This assay was significantly better in terms of sensitivity, linear range, and a ssay time than the standard microplate enzyme-linked immunosorbent assay an d should permit early SEB detection in clinical samples. food, and environm ental samples. (C) 2000 Elsevier Science B.V. All rights reserved.