IgA and IgG responses in serum and BALF after immunization and bacterial challenge.

<p>(A) OMV-specific IgGs in BALF were detected in mice that were passively immunized with antiserum; (B) OMV-specific IgGs in BALF were detected in mice receiving active immunization; (C) and (D) OMV-specific IgAs were detected in BALF and serum, respectively. The samples were collected 5 days after the bacterial challenge. (E), (F), and (G). Immunization with OMVs elicited Th1-like antibody responses. OMV-specific IgG₁ and IgG_2a levels were measured using ELISA, and the ratio of IgG₁/IgG_2a was calculated for each mouse. The bacterial challenge occurred 11 days after the last immunization. The <i>p</i> value was determined by one-way ANOVA with Tukey's multiple comparison test. *, <i>p</i><0.05, **, <i>p</i><0.01, ***, <i>p</i><0.001; n = 12 mice per group.