FIG. 3.

Induction of OVA-specific antibody responses by coadministered Stx1 derivatives. Mice were subcutaneously immunized with OVA plus mStx1, nStx1, or StxB1. Specifically, C57BL/6 mice were subcutaneously immunized with 100 μg of OVA plus 10 μg of the Stx1 mutant (E167R/R170L; mStx1) (hatched bars), 50 ng of nStx1 (dotted bars), or 10 μg of StxB1 (black bars) as an adjuvant or with OVA alone (white bars) on days 0 and 14. OVA-specific serum IgG, IgM, and IgA Ab (A) and splenic OVA-specific antibody-forming cell (AFC) (B) responses were determined by ELISAs and ELISPOT assays, respectively. Furthermore, OVA-specific IgG subclass Ab responses (C) were also analyzed by ELISAs. Serum samples were collected on day 21 and examined for OVA-specific Abs and OVA-specific IgG subclass Ab responses by ELISAs. Mononuclear cells were isolated from the spleens of subcutaneously immunized mice on day 21 and examined by Ag-specific ELISPOT assays. *, P < 0.05 compared with mice immunized with OVA alone. The results are expressed as means ± SEM from a total of three separate experiments, each of which used five or six mice per group.