Cross-protective potential of a novel monoclonal antibody directed against antigenic site B of the hemagglutinin of influenza A viruses

PLoS Pathog. 2009 Mar;5(3):e1000350. doi: 10.1371/journal.ppat.1000350. Epub 2009 Mar 20.

Abstract

The hemagglutinin (HA) of influenza A viruses has been classified into sixteen distinct subtypes (H1-H16) to date. The HA subtypes of influenza A viruses are principally defined as serotypes determined by neutralization or hemagglutination inhibition tests using polyclonal antisera to the respective HA subtypes, which have little cross-reactivity to the other HA subtypes. Thus, it is generally believed that the neutralizing antibodies are not broadly cross-reactive among HA subtypes. In this study, we generated a novel monoclonal antibody (MAb) specific to HA, designated MAb S139/1, which showed heterosubtypic cross-reactive neutralization and hemagglutination inhibition of influenza A viruses. This MAb was found to have broad reactivity to many other viruses (H1, H2, H3, H5, H9, and H13 subtypes) in enzyme-linked immunosorbent assays. We further found that MAb S139/1 showed neutralization and hemagglutination-inhibition activities against particular strains of H1, H2, H3, and H13 subtypes of influenza A viruses. Mutant viruses that escaped neutralization by MAb S139/1 were selected from the A/Aichi/2/68 (H3N2), A/Adachi/2/57 (H2N2), and A/WSN/33 (H1N1) strains, and sequence analysis of the HA genes of these escape mutants revealed amino acid substitutions at positions 156, 158, and 193 (H3 numbering). A molecular modeling study showed that these amino acids were located on the globular head of the HA and formed a novel conformational epitope adjacent to the receptor-binding domain of HA. Furthermore, passive immunization of mice with MAb S139/1 provided heterosubtypic protection. These results demonstrate that MAb S139/1 binds to a common antigenic site shared among a variety of HA subtypes and neutralizes viral infectivity in vitro and in vivo by affecting viral attachment to cells. The present study supports the notion that cross-reactive antibodies play some roles in heterosubtypic immunity against influenza A virus infection, and underscores the potential therapeutic utility of cross-reactive antibodies against influenza.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / immunology*
  • Antibodies, Viral / immunology*
  • Antibody Specificity / immunology*
  • Cross Reactions
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / chemistry
  • Epitopes / genetics
  • Epitopes / immunology*
  • Female
  • Hemagglutinin Glycoproteins, Influenza Virus / genetics
  • Hemagglutinin Glycoproteins, Influenza Virus / immunology*
  • Immunization, Passive
  • Influenza A virus / genetics
  • Influenza A virus / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / prevention & control
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Epitopes
  • Hemagglutinin Glycoproteins, Influenza Virus