Checkerboard immunoblotting recognizes twenty epitopes among the B subunit proteins of the cholera enterotoxin family.

Checkerboard immunoblotting (CBIB) was used to analyze the reactions of a series of monoclonal antibodies with proteins of the cholera enterotoxin (CT) family, including heat labile enterotoxins (LTs) produced by diarrheagenic strains of Escherichia coli and genetically engineered chimeric proteins in which single amino acids of the CT-B subunit protein or human (H) LT-B subunit protein were substituted for corresponding residues in porcine (P) LT-B. The result indicated that there were at least twenty different patterns of reactivity suggesting that there are at least twenty recognizable epitopes among the proteins studied. An epitope which includes Ala46 appears to be particularly important. This epitope is common to CT and H-LT but not P-LT, and the epitope is not blocked by the Gm1 ganglioside. Human convalescent sera react with this epitope. CBIB is a versatile technique for epitope analysis.