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Potent neutralization by monoclonal human IgM against SARS‐CoV‐2 is impaired by class switch
Author(s) -
Callegari Ilaria,
Schneider Mika,
Berloffa Giuliano,
Mühlethaler Tobias,
Holdermann Sebastian,
Galli Edoardo,
Roloff Tim,
Boss Renate,
Infanti Laura,
Khanina,
Egli Adrian,
Buser Andreas,
Zimmer Gert,
Derfuss Tobias,
Sanderson Nicholas S R
Publication year - 2022
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.202153956
Subject(s) - avidity , antibody , virology , neutralization , monoclonal antibody , biology , antigen , potency , recombinant dna , immunoglobulin m , immunoglobulin g , virus , immunology , gene , in vitro , biochemistry
To investigate the class‐dependent properties of anti‐viral IgM antibodies, we use membrane antigen capture activated cell sorting to isolate spike‐protein‐specific B cells from donors recently infected with SARS‐CoV‐2, allowing production of recombinant antibodies. We isolate 20, spike‐protein‐specific antibodies of classes IgM, IgG, and IgA, none of which shows any antigen‐independent binding to human cells. Two antibodies of class IgM mediate virus neutralization at picomolar concentrations, but this potency is lost following artificial switch to IgG. Although, as expected, the IgG versions of the antibodies appear to have lower avidity than their IgM parents, this is not sufficient to explain the loss of potency.