Abstract: Objective To generate and characterize neutralizing monoclonal antibodies against highly pathogenic avian influenza (HPAI) H5N1 strains in China and corresponding epitopes. Methods 9 candidate peptides of HAs were designed tandem epitopes to generate monoclonal antibodies using a patent technology of SEAL (Surface Epitope Antibody Library). Ascites were purified by affinity chromatography. Neutralizing monoclonal antibodies were characterized by ELISA, western blot and micro neutralization assays. Results 23 hybridomas clones anti-HA epitope monoclonal antibodies were obtained，in which 3 IgG3 subtype clones showed efficient neutralizing activity to H5N1 pseudotype virus and recognized corresponding epitopes " LIKKNNAYPT " and " R/KSSFFRNVVW " in a dose dependent manner. These 3 mAbs recognized rHA from 4 different branches of H5N1 demonstrated by immunoblot. Conclusions 3 high levels of neutralizing monoclonal antibodies were characterized. Two important neutralizing epitopes of HA were identified which might serve as a strong potential candidate for an effective vaccine to protect from highly pathogenic avian influenza H5N1 virus in China.

Key words: Key words: H5N1 avian influenza, hemagglutinin, pseudotype virus, neutralizing monoclonal antibodies