FIG. 3.

LPS-specific serum IgG (A) and mucosal IgA (B) antibody responses of orally immunized BALB/c mice. Sera and gut homogenates were collected from nonimmunized mice (NI) or mice immunized with three doses of noninduced HG3 cells (HG3), CFA/I-expressing HG3 cells (HG3/IPTG), or CFA/I-expressing HG3 cells plus LT_(R192G) (HG3/IPTG/LT). Samples were collected 1 week following the last immunization. Results are reported as mean ± the standard error. Statistical significance (P < 0.05), indicated by an asterisk, was determined using the Student's t test.