Baculovirus Surface Display

The aim of this work was to establish an efficient method for the generation of a surface display library by using the baculoviral gene expression system. The selected target proteins were so-called Fcab molecules, which are antibody Fc-fragments with an antigen binding site engineered in their CH3 domains loops. Our strategy was to combine optimized surface display vectors1 with an in vitro recombination system providing sufficient library size and diversity. Viral vectors were designed to express and display Fcab on the surface of insect and mammalian cells2 from the same construct. Therefore the Fcab was fused to the membrane anchorage domain of Influenza A neuraminidase, controlled by a dual promoter system. Surface expression was confirmed by FACS analysis. Correct folding and dimer formation were tested with Staphylococcus aureus Protein A and human FcRI (CD64), respectively, which bind with high affinity to human immunoglobulin Fc regions. The functionality of the antigen binding site was investigated by binding to specific targets like “Human Epidermal growth factor Receptor 2” (Her2). For the generation of suitable libraries, an in vitro recombination system was established based on adaptation of the Gateway Technology by Invitrogen. Our approach demonstrated that the baculovirus surface display system is efficient for library construction and screening of antigen binding in insect and mammalian cells.

Figure 1: Schematic representation on an Fcab - molecule