Impact of preexisting memory to seasonal A/H1N1 influenza virus on the immune response following vaccination against avian A/H5N1 virus
- Resource Type
- Authors
- Francesca, Buricchi; Monia, Bardelli; Carmine, Malzone; Barbara, Capecchi; Uwe, Nicolay; Elena, Fragapane; Flora, Castellino; Giuseppe, Del Giudice; Grazia, Galli; Oretta, Finco
- Source
- European journal of immunology. 43(3)
- Subject
- Adult
B-Lymphocytes
Influenza A Virus, H1N1 Subtype
Influenza A Virus, H5N1 Subtype
Influenza Vaccines
Immunoglobulin G
Influenza, Human
Animals
Humans
Cross Reactions
Antibodies, Viral
Immunologic Memory
- Language
- ISSN
- 1521-4141
Cross-protection against divergent strains of influenza virus is an objective of various vaccination approaches. B cells cross-neutralizing several influenza A heterosubtypes have been isolated from cultured human memory B cells (MBCs) and plasmablasts early after influenza vaccination or infection. However, a systematic assessment of the frequency of MBCs and plasmablasts in the blood of healthy individuals is lacking. Here, we show that under resting conditions about 45% of human adults never vaccinated nor exposed to avian A/H5N1 influenza have detectable circulating MBCs cross-reacting with H5N1. This proportion rises to 63.3% among subjects with a large pool of MBCs specific for seasonal H1N1 (i.e. frequency ≥1% of total IgG MBCs). Moreover, subjects with high baseline frequencies of H1N1-specific MBCs had an expansion of H5N1-specific MBCs producing H5-neutralizing antibodies already after the first dose of an MF59-adjuvanted H5N1 vaccine. These results suggest that H1N1-specific MBCs contain a subset of cells cross-reacting to H5. We propose that a proportion of human adults have a pool of H5/H1 cross-reactive MBCs that contribute to the rapid rise of the antibody response to divergent influenza strains. This may have implications on vaccination strategies aimed at counteracting future influenza pandemics.