Receptor binding-like specificity of two anti-cholera toxin monoclonal antibodies detected by latex agglutination immunoassay.

Six mouse monoclonal IgG antibodies (mAbs) reacting with the cholera toxin B-subunit (CT-B) were obtained from the spleen cells of mice immunized with CT. They were divided into two groups according to their different reactivities with CT in latex (Lx) agglutination. One group of two mAbs was called "non-repetitive" (NR) because they apparently recognized a single epitope on CT, which was unable to agglutinate Lx coated with these NRmAbs, in contrast with the other group of four mAbs that we called "repetitive" (RmAbs). The two NRmAbs, but not the four RmAbs, failed to react with CT when CT was bound first to its GM1-receptor. Thus, the NRmAbs seemed directed at an epitope close to the GM1-binding site of CT-B. These NRmAbs could represent valuable immunogenic candidates for anti-idiotypic immunization against CT and related enterotoxins.