Figure 2.

Angiotensin-converting enzyme 2 (ACE2) binding inhibition and correlations of binding capacity between BA.1, BA.2, and wild-type (WT) for different antigens. ACE2 binding inhibition (A) and immunoglobulin G (IgG) binding capacity (B–F) were compared for the Omicron BA.1 and BA.2 receptor-binding domain (RBD), and spike (S) to the WT RBD and S. A, Boxplot showing that ACE2 binding inhibition is significantly reduced toward BA.1 for both RBD and S for both vaccinated (n = 226) and convalescent (n = 86) samples. Boxes represent the median with 25th and 75th percentiles; whiskers show the largest and smallest nonoutlier values. Outliers were determined by 1.5 interquartile range. Statistical significance was calculated by Wilcoxon signed-rank test; ***P < .001. B, Correlation analysis of IgG binding capacity for the BA.1 spike compared to the BA.1 RBD. Spearman rank was calculated to assess ordinal association between the variables. C–F, Linear regressions of IgG binding capacity for the BA.1 S compared to WT S (C), BA.1 RBD compared to wild-type RBD (D), BA.2 RBD compared to WT RBD (E), and BA.2 nucleocapsid compared to WT nucleocapsid (F). R² is included to indicate the correlation. Abbreviations: ACE2, angiotensin-converting enzyme 2; IgG, immunoglobulin G; Inf, infected; MFI, median fluorescence intensity; NC, nucleocapsid; RBD, receptor-binding domain; S, spike; Vac, vaccinated; WT, wild-type.