FIG. 3.

Gerbils orally immunized with CtxB fusion proteins have serum IgG to CtxB (A) and 170CR2-PEP5 (C) as well as stool IgA to CtxB (B) but not to 170CR2-PEP5 (D). Shown are the IgG and IgA anti-CtxB and anti-170CR2-PEP5 responses in serum and stool samples, respectively, from CtxB- and CtxB fusion protein-immunized gerbils before (pre) and 7 days after the final boost (post) as measured by ELISA. Serum samples were measured at dilutions of 1:50, and stool samples were measured at dilutions of 1:4. Bars show the mean values ± the standard deviations (error bars) from the respective groups of gerbils as shown in Table 3. Asterisks indicate that the mean OD of vaccinated animals is significantly different from the value of the respective preimmune sera (P < 0.05).