An antibody VH domain with a lox-Cre site integrated into its coding region: Bacterial recombination within a single polypeptide chain

Bacterial lox-Cre recombination within a single antibody VH domain was achieved through integration of a loxP site into its coding sequence, The 5' half of the VH gene, in which the H2 loop was replaced by a mutant loxP site, was fused to geneIII in an 'acceptor' fd-phage vector containing also a wild type loxP site, With a 'donor' plasmid vector harbouring the 3' half of the VH gene flanked by tbe same, differing loxP sites it recombined into a full-length VH with the loxP site-H2 loop, This VH was purified from bacterial periplasm, where it folded into a typical immunoglobulin domain, The system allows the generation of large VH repertoires using lox-Cre recombination.