FIG. 3.

(A) Antigen-specific serum IgG1 Ab responses increased 1 week after oral immunization with the Salmonella-CFA/I vaccine. (B) While serum IgG2a CFA/I-specific Ab responses are delayed, they become equivalent to serum IgG1 titers by 4 weeks. Serum IgG, IgG1, and IgG2a titers (log₂) were determined by using the ELISA procedure. No serum IgG titers against CFA/I fimbriae were elicited in mice orally immunized with the isogenic, H647 construct (which lacks the cfaABCE insert). Values represent the average of duplicate samples from each of 10 mice/group. ∗, P < 0.001.