STRUCTURAL AND BIOPHYSICAL CHARACTERIZATION OF THE INTERACTION BETWEEN INFLUENZA A NON-STRUCTURAL PROTEIN 1 AND MONOCLONAL ANTIBODIES

Abstract

Influenza A virus (IAV) continues to pose great threat to human life, while there is an unmet medical need of available antiviral strategies. To discover alternative strategy, we found two antibodies -- 2H6 and 19H9 specifically targeting IAV Non-structural 1 protein (NS1) which is involved in viral replication and pathogenicity. By X-ray crystallography and HADDOCK simulation, the complementary determining region 2 of heavy chain variable region of 2H6-fragment antigen binding (Fab) was responsible for the binding to NS1 RNA-binding domain (RBD) positions 48 and 49. Intracellular delivery of 2H6-Fab was able to inhibit viral replication by disrupting NS1(RBD)-dsRNA interaction. Furthermore, monoclonal antibody (mAb)-19H9 was determined to bind to the positions 85 and 89 at NS1 effector domain. Y89 is required for activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway. MAb-19H9 was able to reduce viral replication and NS1-PI3K interaction. Thus, both antibodies are good candidates for further development as antiviral agents.