Rational library design by functional CDR resampling.

Successful antibody discovery relies on diversified libraries, where two aspects are implied, namely the absolute number of unique clones and the percentage of functional clones. Instead of pursuing the absolute quantity thresholded by current display technology, we have sought to maximize the effective diversity by improving functional clone percentage. With the combined effort of bioinformatics, structural biology, molecular immunology and phage display technology, we devised a bioinformatic pipeline to construct and validate libraries via combinatorial assembly of sequences from a database of experimentally validated antibodies. Furthermore, we showed that the libraries constructed as such yielded a significantly increased success rate against different antigen types and generated over 20-fold more unique hits per targets compared with libraries based on traditional degenerate nucleotide methods. Our study indicated that predefined CDR sequences with optimized CDR-framework compatibility could be a productive direction of functional library construction for in vitro antibody development.