Recombining germline-derived CDR sequences for creating diverse single-framework antibody libraries

We constructed a single-chain Fv antibody library that permits human comple mentarity-determining region (CDR) gene fragments of any germline to be inc orporated combinatorially into the appropriate positions of the variable-re gion frameworks VH-DP47 and VL-DPL3. A library of 2 x 10(9) independent tra nsformants was screened against haptens, peptides, carbohydrates, and prote ins, and the selected antibody fragments exhibited dissociation constants i n the subnanomolar range. The antibody genes in this library were built on a single master framework into which diverse CDRs were allowed to recombine , These CDRs were sampled from in vivo-processed gene sequences, thus poten tially optimizing the levels of correctly folded and functional molecules, and resulting in a molecule exhibiting a lower computed immunogenicity comp ared to naive immunoglobulins. Using the modularized assembly process to in corporate foreign sequences into an immunoglobulin scaffold, it is possible to vary as many as six CDRs at the same time, creating genetic and functio nal variation in antibody molecules.