IgA tetramerization improves target breadth but not peak potency of functionality of anti-influenza virus broadly neutralizing antibody

PLoS Pathog. 2019 Jan 3;15(1):e1007427. doi: 10.1371/journal.ppat.1007427. eCollection 2019 Jan.


Mucosal immunoglobulins comprise mainly secretory IgA antibodies (SIgAs), which are the major contributor to pathogen-specific immune responses in mucosal tissues. These SIgAs are highly heterogeneous in terms of their quaternary structure. A recent report shows that the polymerization status of SIgA defines their functionality in the human upper respiratory mucosa. Higher order polymerization of SIgA (i.e., tetramers) leads to a marked increase in neutralizing activity against influenza viruses. However, the precise molecular mechanisms underlying the effects of SIgA polymerization remain elusive. Here, we developed a method for generating recombinant tetrameric monoclonal SIgAs. We then compared the anti-viral activities of these tetrameric SIgAs, which possessed variable regions identical to that of a broadly neutralizing anti-influenza antibody F045-092 against influenza A viruses, with that of monomeric IgG or IgA. The tetrameric SIgA showed anti-viral inhibitory activity superior to that of other forms only when the antibody exhibits low-affinity binding to the target. By contrast, SIgA tetramerization did not substantially modify anti-viral activity against targets with high-affinity binding. Taken together, the data suggest that tetramerization of SIgA improved target breadth, but not peak potency of antiviral functions of the broadly neutralizing anti-influenza antibody. This phenomenon presumably represents one of the mechanisms by which SIgAs present in human respiratory mucosa prevent infection by antigen-drifted influenza viruses. Understanding the mechanisms involved in cross neutralization of viruses by SIgAs might facilitate the development of vaccine strategies against viral infection of mucosal tissues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Neutralizing / immunology*
  • Antibodies, Neutralizing / physiology
  • Antibodies, Viral / immunology
  • Antiviral Agents
  • Cell Line
  • Chick Embryo
  • Dogs
  • Hemagglutinin Glycoproteins, Influenza Virus / immunology
  • Humans
  • Immunoglobulin A / immunology
  • Immunoglobulin A / metabolism
  • Immunoglobulin A, Secretory / immunology*
  • Immunoglobulin A, Secretory / metabolism*
  • Immunoglobulin A, Secretory / physiology
  • Influenza A virus / immunology
  • Influenza Vaccines
  • Influenza, Human / immunology
  • Madin Darby Canine Kidney Cells
  • Neutralization Tests
  • Orthomyxoviridae / immunology
  • Polymerization
  • Protein Binding
  • Recombinant Proteins / metabolism


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Antiviral Agents
  • Hemagglutinin Glycoproteins, Influenza Virus
  • Immunoglobulin A
  • Immunoglobulin A, Secretory
  • Influenza Vaccines
  • Recombinant Proteins

Grant support

The work was supported in part by the Emerging/Re-emerging Infectious Diseases Project of Japan, from the Japan Agency for Medical Research and Development, AMED under Grant Number JP18fk0108012 and JP18fk0108051; J-PRIDE from AMED under Grant Number JP18fm0208002; grants for Scientific Research from the Ministry of Education, Culture, Science, Sports and Technology (MEXT) of Japan (17K08386). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.