title: Characterization of toxins A and B of Clostridium difficile with monoclonal antibodies.
abstract: Two monoclonal antibodies (MAbs) were used to learn more about the structures of Clostridium difficile toxins A and B. One of the antibodies, the PCG-4 MAb, reacted specifically with toxin A. This MAb precipitated toxin A and neutralized the enterotoxic but not the cytotoxic activity of the toxin. The site to which the antibody bound was resistant to denaturation with sodium dodecyl sulfate; however, it was destroyed by N-bromosuccinimide. Immunoblot analysis with the PCG-4 MAb revealed the presence of a large number of bands in preparations of denatured toxin A, suggesting that toxin A exists as an aggregate of smaller components. The antibody was covalently coupled to Affi-Gel 10, and the gel was used to purify toxin A from the culture filtrate of a highly toxigenic strain of C. difficile by immunoaffinity chromatography. The second antibody, the G-2 MAb, cross-reacted with toxins A and B. The cross-reaction was confirmed by immunoblot analysis. These results show that toxins A and B share an epitope and suggest that they have a common subunit. The G-2 MAb did not neutralize or precipitate either toxin. The site to which the G-2 MAb bound was partially destroyed by sodium dodecyl sulfate and was resistant to oxidation with N-bromosuccinimide.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000276:immunology*; D002846:Chromatography, Affinity; D003013:Clostridium / Q000276:immunology*; D004768:Enterotoxins / Q000276:immunology* / Q000302:isolation & purification; D000939:Epitopes; D007163:Immunosorbent Techniques; D008970:Molecular Weight; D009500:Neutralization Tests; D011487:Protein Conformation; D013388:Succinimides
chemical_list: D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D000939:Epitopes; D013388:Succinimides; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile