Extended Data Fig. 2: Antibody-depletion assay.
From: Imprinting of serum neutralizing antibodies by Wuhan-1 mRNA vaccines
a, Schematic of the anti-spike antibody-depletion assay. Dp, depletion. b-c, Wuhan-1 spike-binding and antibody titres obtained after interpolating with CV3-25 standard curves of mAbs SARS2-38 and 2B04 mixed at the indicated ratios and pre-cleared with empty depletion beads (no Dp), B.1.351 spike-loaded beads (B.1.351 Dp), or Wuhan-1 spike-loaded beads (Wuhan-1 Dp) (numbers at the top in b indicate the derived fraction of Wuhan-1 spike-specific antibody; three experiments; mean values ± SDs are shown, and dotted lines show the LOD). d, Antibody binding of 3-week post-boost sera harvested from mice primed with 0.25 μg and boosted one month later with 1 μg of mRNA-1273 (1273/1273) or mRNA-1273.351 (351/351) (n = 10, two experiments) to Wuhan-1 and B.1.351 spike proteins. Sera were pre-cleared with empty beads, B.1.351 spike-loaded beads, or Wuhan-1 spike-loaded beads (connecting lines represent sera from the same mouse; dotted lines show the LOD; values at the LOD are plotted slightly below the LOD for visualization). e, Percentages of Wuhan-1 (left) and B.1.351 (right) spike-specific antibodies, derived from d. The fraction of Wuhan-1 spike-specific IgG is calculated by dividing the Wuhan-1 spike-binding titre of B.1.351 spike depleted sera (blue circles in d left panel) by that without depletion (dark grey circles in d left panel) from the same individual (B.1.351 Dp/no Dp) (type-specific titres at the LOD in d are designated 0% type-specific response in e; horizontal lines and numbers at the top indicate median values). e, Two-sided Mann-Whitney test with Bonferroni correction (P = 0.000011).