Relationship of the quaternary structure of human secretory IgA to neutralization of influenza virus.

Secretory IgA (S-IgA) antibodies, the major contributors to humoral mucosal immunity to influenza virus infection, are polymeric Igs present in many external secretions. In the present study, the quaternary structures of human S-IgA induced in nasal mucosa after administration of intranasal inactivated influenza vaccines were characterized in relation to neutralization potency against influenza A viruses. Human nasal IgA antibodies have been shown to contain at least five quaternary structures. Direct and real-time visualization of S-IgA using high-speed atomic force microscopy (AFM) demonstrated that trimeric and tetrameric S-IgA had six and eight antigen-binding sites, respectively, and that these structures exhibited large-scale asynchronous conformational changes while capturing influenza HA antigens in solution. Furthermore, trimeric, tetrameric, and larger polymeric structures, which are minor fractions in human nasal IgA, displayed increased neutralizing potency against influenza A viruses compared with dimeric S-IgA, suggesting that the larger polymeric than dimeric forms of S-IgA play some important roles in protection against influenza A virus infection in the human upper respiratory tract.
AuthorsTadaki Suzuki, Akira Kawaguchi, Akira Ainai, Shin-ichi Tamura, Ryo Ito, Pretty Multihartina, Vivi Setiawaty, Krisna Nur Andriana Pangesti, Takato Odagiri, Masato Tashiro, Hideki Hasegawa
JournalProceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 112 Issue 25 Pg. 7809-14 (Jun 23 2015) ISSN: 1091-6490 [Electronic] United States
PMID26056267 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Immunoglobulin A, Secretory
  • Humans
  • Immunoglobulin A, Secretory (chemistry, immunology)
  • Neutralization Tests
  • Orthomyxoviridae (immunology)
  • Protein Structure, Quaternary

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