Generation of rabbit single-chain variable fragments with different physicochemical and biological properties by complementary determining region-grafting technology.

In this study, we have demonstrated a complementary-determining region (CDR) grafting technology for the generation of rabbit scFvs with different antigen recognition and physicochemical properties. The antigen-binding affinity of the CDR-grafted anti-CRP scFv, C1R/B1R (V1), which was generated by the CDR/framework region (CDR/FR) definition based on the traditional numbering rule, was insufficient when compared to that of the original clone, C1R, suggesting that the amino acid residues outside the original CDRs might significantly contribute to antigen recognition in rabbit scFvs. We redefined new CDRs and FRs to maintain antigen-binding affinities through the extension of multiple amino acid residues for CDRH1 and CDRH2, based on the amino acid sequence alignments of rabbit scFvs isolated from phage libraries.