Identification of SARS-COV-2 specific antibodies from patient serum during the First Wave of the COVID-19 pandemic

Proteomic Ig-SEQ identification of SARS-COV-2 specific antibodies from serum of two convalescent patients during the first wave of the COVID-19 pandemic. Total IgG was isolated from serum, digested with IdeS protease to generate F(ab)2 fragments, and subjected to antigen affinity chromatography using agarose beads coupled with SARS-COV-2 spike protein. Purified F(ab)2 fragments were reduced, alkylated, and digested with trypsin prior to LC-MSMS analysis on an Orbitrap Fusion Lumos mass spectrometer. Resulting peptide IDs were used to identify IgG clonotypes in antigen-specific and flow-through fractions.