the epitope and neutralization mechanism of avfluigg01, a broad-reactive human monoclonal antibody against h5n1 influenza virusavfluigg01的表位和中和机制broad-reactive人类单克隆抗体对h5n1型流感病毒.pdf

The Epitope and Neutralization Mechanism of AVFluIgG01, a Broad-Reactive Human Monoclonal Antibody against H5N1 Influenza Virus 1 1 1 2 3 1 Zhiliang Cao , Jiazi Meng , Xingxing Li , Ruiping Wu , Yanxin Huang , Yuxian He * 1 MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2 Wenzhou Medical College, Wenzhou, China, 3 National Engineering Laboratory for Druggable Gene and Protein Screening, Northern Normal University, Changchun, China Abstract The continued spread of highly pathogenic avian influenza (HPAI) H5N1 virus underscores the importance of effective antiviral approaches. AVFluIgG01 is a potent and broad-reactive H5N1-neutralizing human monoclonal antibody (mAb) showing great potential for use either for therapeutic purposes or as a basis of vaccine development, but its antigenic epitope and neutralization mechanism have not been finely characterized. In this study, we first demonstrated that AVFluIgG01 targets a novel conformation-dependent epitope in the globular head region of H5N1 hemagglutinin (HA). By selecting mimotopes from a random peptide library in combination with computational algorithms and site-directed mutagenesis, the epitope was mapped to three conserved discontinuous sites (I-III) that are located closely at the three- dimensional structure of HA. Further, we found that this HA1-specific human mAb can efficiently block both virus-receptor binding and post-attachment steps, while its Fab fragment exerts the post-attachment inhibition only. Consistently, AVFluIgG01 could inhibit HA-mediated