EFFICIENT GENERATION OF A RESHAPED HUMAN MAB SPECIFIC FOR THE ALPHA-TOXIN OF CLOSTRIDIUM-PERFRINGENS

We have used the technique of antibody reshaping to produce a humanize d antibody specific for the a toxin of Clostridium perfringens. The st arting antibody was from a mouse hybridoma from which variable (V) reg ion nucleotide sequences were determined, The complementarity-determin ing regions (CDRs) from these V regions were then inserted into human heavy and light chain V region genes with human constant region gene f ragments subsequently added. The insertion of CDRs alone into human fr ameworks did not produce a functional reshaped antibody and modificati ons to the V region framework were required. With minor framework modi fications, the affinity of the original murine mAb was restored and ev en exceeded. Where affinity was increased, an altered binding profile to overlapping peptides was observed. Computer modelling of the reshap ed heavy chain V regions suggested that amino acids adjacent to CDRs c an either contribute to, or distort, CDR loop conformation and must be adjusted to achieve high binding affinity.