Fig 3. IgA titers of mice immunized with PrgI or SipD (A) or PrgI/SipD (B).

Serum IgA antibodies specific for PrgI (left) and SipD (right) were measured by sandwich ELISA 2 weeks after the last immunization as described in Materials and Methods. Data represent mean titers and the standard errors (SEM) from 14–16 individual mice per group. Asterisks indicate P values: *** p < 0.001, ** 0.001<p <0.01 and * p< 0.05 when comparing mice immunized by the IN or OG route versus mice immunized by the SC route and control mice. No cross-reactions were observed between PrgI and SipD (data not shown). [°: indicates injected immunogen; *: indicates biotinylated recombinant protein].