Expression of human lambda expands the repertoire of OmniChickens.

Most of the approved monoclonal antibodies used in the clinic were initially discovered in mice. However, many targets of therapeutic interest are highly conserved proteins that do not elicit a robust immune response in mice. There is a need for non-mammalian antibody discovery platforms which would allow researchers to access epitopes that are not recognized in mammalian hosts. Recently, we introduced the OmniChicken®, a transgenic animal carrying human VH3-23 and VK3-15 at its immunoglobulin loci. Here, we describe a new version of the OmniChicken which carries VH3-23 and either VL1-44 or VL3-19 at its heavy and light chain loci, respectively. The Vλ-expressing birds showed normal B and T populations in the periphery. A panel of monoclonal antibodies demonstrated comparable epitope coverage of a model antigen compared to both wild-type and Vκ-expressing OmniChickens. Kinetic analysis identified binders in the picomolar range. The Vλ-expressing bird increases the antibody diversity available in the OmniChicken platform, further enabling discovery of therapeutic leads.