Assessment of the Humoral Immune Response to the SARS-CoV-2 Spike Protein Receptor Binding Motif

<p><strong>Figure S1.</strong> Purification of human antibodies against the RBM region of the SARS-CoV-2 spike protein using a recombinant RBM Sepharose 4B affinity column (3 x 1 cm, inner diameter) (A) and SDS-PAGE (10%) analysis of the eluate (1) alongside a standard low molecular weight marker (Sigma Chemical Co, Saint Louis, Mo, U.S.A.) stained with Coomassie Blue.&nbsp;<strong>Table S1</strong>: Microscale thermophoresis (MST) traces of anti-RBM antibodies binding to different concentrations of S1WT (red) and S2WT (green) peptides by MST. Relative fluorescence (RF) between the bound and unbound state was determined over a time of 21s with 20s MST-on time for evaluation. The blue bar indicates the ΔRF before the temperature gradient was applied, whereas the red bar shows the ΔRF during the thermophoresis. For interaction experi ments, the amount of NT.647-labeled antibodies was kept constant, while the concentration of unlabeled peptides varied from 0.5 µg/mL–0.12 ng/mL. The assay was performed in PBS containing 0.05% Tween 20 and after a short incubation period, the samples were analyzed in standard glass MST NT.115 capillaries. <strong>Table S2:</strong> One-dose regime AstraZeneca-Oxford vaccinated serum information. <strong>Table S3</strong>: Heterologous booster dose vaccinated serum information.</p>