Generation of Antibody Libraries for Phage Display: Chimeric Rabbit/Human Fab Format

Rabbit monoclonal antibodies are attractive reagents for research, and have also found use in diagnostic and therapeutic applications. This is owed to their high affinity and specificity, along with their ability to recognize epitopes conserved between mouse and human antigens. Phage display is a powerful method for the de novo generation, affinity maturation, and humanization of rabbit monoclonal antibodies from naive, immune, and synthetic antibody repertoires. Using phagemid family pComb3, a preferred phage display format is chimeric rabbit/human Fab, which consists of rabbit variable domains (V_H, V_κ, and V_λ) fused to human constant domains. The human constant domains, C_H1 of IgG1 and C_L (C_κ or C_λ), not only provide established purification and detection handles but also facilitate higher expression in Escherichia coli compared to the corresponding rabbit constant domains. Here, we describe the use of a pComb3 derivative, phagemid pC3C, for the generation of chimeric rabbit/human Fab libraries with randomly combined rabbit variable domains of high sequence diversity, starting from the preparation of total RNA from rabbit spleen and bone marrow. Depending on the complexity of the parental antibody repertoire, the protocol can be scaled for yielding a library size of 10⁸-10¹¹ independent chimeric rabbit/human Fab clones. As such, it can be used, for instance, for the generation of either specialized immune or large naive rabbit antibody libraries.