Identification of consensus epitope structures expressed in recombinant DNA libraries

In the course of screening cDNA expression libraries with a monospecific polyclonal antibody to topoisomerase I, we isolated three different immunopositive cDNA clones. By comparing their derived amino acid sequences, a consensus region of similarity in otherwise completely dissimilar sequences was identified as an epitope. The approach described here should identify both continuous and discontinuous topological epitopes. The probability of occurrence of "spurious" immunopositive clones is shown to depend on the number of codons of each critical amino acid within the antigenic determinant.