An antibody against a novel and conserved epitope in the hemagglutinin 1 subunit neutralizes numerous H5N1 influenza viruses.
The spread of the recently emerged, highly pathogenic H5N1 avian influenza virus has raised concern. Preclinical studies suggest that passive immunotherapy could be a new form of treatment for H5N1 virus infection. Here, a neutralizing monoclonal antibody (MAb) against the hemagglutinin (HA) of the influenza A/chicken/Hatay/2004 H5N1 virus, MAb 9F4, was generated and characterized. MAb 9F4 binds both the denatured and native forms of HA. It was shown to recognize the HA proteins of three heterologous strains of H5N1 viruses belonging to clades 1, 2.1, and 2.2, respectively. By use of lentiviral pseudotyped particles carrying HA on the surface, MAb 9F4 was shown to effectively neutralize the homologous strain, Hatay04, and another clade 1 strain, VN04, at a neutralization titer of 8 ng/ml. Furthermore, MAb 9F4 also neutralized two clade 2 viruses at a neutralizing titer of 40 ng/ml. The broad cross-neutralizing activity of MAb 9F4 was confirmed by its ability to neutralize live H5N1 viruses of clade 2.2.2. Epitope-mapping analysis revealed that MAb 9F4 binds a previously uncharacterized epitope below the globular head of the HA1 subunit. Consistently, this epitope is well conserved among the different clades of H5N1 viruses. MAb 9F4 does not block the interaction between HA and its receptor but prevents the pH-mediated conformational change of HA. MAb 9F4 was also found to be protective, both prophylactically and therapeutically, against a lethal viral challenge of mice. Taken together, our results showed that MAb 9F4 is a neutralizing MAb that binds a novel and well-conserved epitope in the HA1 subunit of H5N1 viruses.
Cancer and Developmental Cell Biology Division, Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, 61 Biopolis Drive, Proteos Building, Singapore.
Hsueh-Ling Janice
HL
Oh
Sara
S
Akerström
Shuo
S
Shen
Sándor
S
Bereczky
Helen
H
Karlberg
Jonas
J
Klingström
Sunil K
SK
Lal
Ali
A
Mirazimi
Yee-Joo
YJ
Tan
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000302:isolation & purification / Q000627:therapeutic use; D057134:Antibodies, Neutralizing / Q000276:immunology* / Q000302:isolation & purification / Q000627:therapeutic use; D000914:Antibodies, Viral / Q000276:immunology* / Q000302:isolation & purification / Q000627:therapeutic use; D001835:Body Weight; D017124:Conserved Sequence; D056738:Cross Protection; D003429:Cross Reactions; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D009976:Orthomyxoviridae Infections / Q000188:drug therapy / Q000473:pathology / Q000517:prevention & control; D016019:Survival Analysis; D053586:Virus Internalization / Q000187:drug effects
D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000939:Epitopes; D019267:Hemagglutinin Glycoproteins, Influenza Virus; C109963:hemagglutinin, avian influenza A virus