Fig. 4: Mucosal antibody responses after bivalent immunization and XBB.1.5 infection.

A, B Neutralizing antibody titers against SARS-CoV-2 WA-1 (A) and Omicron BA.4/5 (B) in the BAL fluid after immunization (n = 2–9 biological replicates per group). C Fold increase in neutralizing titers in the BAL fluid two weeks after bivalent immunization compared to pre-immunization timepoint (n = 2–4 biological replicates per group). D, E Neutralizing antibody titers against SARS-CoV-2 WA-1 (D) and Omicron BA.4/5 (E) in the BAL fluid after XBB.1.5 infection (n = 3–10 biological replicates per group). F Fold increase in neutralizing titers in the BAL fluid two weeks after XBB.1.5 infection compared to pre-infection timepoint (n = 3–10 biological replicates per group). G Comparison of fold increase in WA-1 and BA.4/5 neutralization in the blood and BAL fluid after XBB.1.5 infection (n = 3–12 biological replicates per group). Related to Fig. 3B, 4F. All endpoint and neutralizing titers in the BAL are normalized to the retrieved volume of the BAL fluid. Samples with total IgG endpoint titer <1000 (Supplementary Fig. 3D) were excluded from the analysis. Data is presented as geometric mean ± geometric SD (A–G). Horizontal dotted line represents a fold change of 1 (C, F, G). Statistical analysis was performed using a non-parametric two-tailed Wilcoxon test (C) or a non-parametric Kruskal-Wallis test with Dunn’s correction for multiple analysis (F). Source data are provided as a Source Data file.