+CD27
+ B cells at each sampling time point (top). Mean frequencies of SARS-CoV-2 S-specific B cells expressing the indicated isotype in mild and severe donors (bottom). Error bars denote standard deviation and black bars indicate means. (F) Proportion of SARS-CoV-2 S-specific swIg
+ B cells that express CD71 at each sampling time point (top). Mean frequencies of SARS-CoV-2 S-specific swIg
+CD71
+ B cells in mild and severe donors (bottom). Error bars denote standard deviation and black bars indicate means. The dotted line indicates the level of CD71 expression on swIg
+ B cells in pre-pandemic donor samples. (G) Representative gating for SARS-CoV-2 S-specific B cells. The gated populations were single cell sorted for mAb cloning. Statistical comparisons between naive and convalescent donors were made by two-sided one-way Welsh ANOVA for unpaired samples with Dunnett’s T3 multiple comparisons test. Statistical comparisons between timepoints among convalescent donors were perfo
n 111) and contacts (
K and
L) The normalized AUC of anti-RBD IgA (K) or IgG (L) ELISA for patients with gastrointestinal (GI) symptoms (
n 32) and without GI symptoms (
n 117) was plotted. The
r and
P values for the correlations in (C) to (G) were determined by two-tailed Spearman’s correlations. For (H) to (L), horizontal bars indicate median values. Statistical significance was determined using a two-tailed Mann-Whitney
U test.
P 0.005) and severity of symptoms (
P 0.0001) but not timing of sample collection relative to onset (
P 0.69) or age (
P 0.22) (Fig. 1, C to F). Concentrations of anti-RBD IgA antibodies correlated strongly with anti-RBD IgG concentrations (