Structural Basis for the Broad, Antibody-Mediated Neutralization of H5N1 Influenza Virus

Abstract

Infection by highly pathogenic avian influenza A virus remains a threat to public health. Our broadly neutralizing antibody, 13D4, is capable of neutralizing all representative H5N1 viruses and protecting mice against lethal challenge. Structural analysis revealed that 13D4 uses heavy-chain complementarity-determining region 3 (HCDR3) to fit the receptor binding site (RBS) via conformational rearrangement. Four conserved residues within the RBS are critical for the broad potency of 13D4. Importantly, polymorphism of Lys193 on the RBS may be associated with the antigenicity shift from H5N1 to other newly emerging viruses, such as H5N6 and H5N8. Our findings may pave the way for highly pathogenic avian influenza virus vaccine development and therapeutic RBS inhibitor design.