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. 2004 Sep 3;101(37):13584–13589. doi: 10.1073/pnas.0405297101

Fig. 4.

Fig. 4.

E. coli produced CTB-P1 elicits transcytosis-neutralizing Abs in mice. (A) Immunization regimen. Mice were immunized i.n. (black arrows) with CTB (group 1), CTB-P1 (group 2), or CTB-P1 plus CT (group 3) and then by an i.p. injection of P1 (red arrow) and CTB-P1 (blue arrow). (B) Serum and mucosal anti-P1 Abs detected in mice of groups 2 and 3, but not in group 1. Shown are average net values (mean ± SEM). Symbols indicate statistical significance estimated by Kruskal-Wallis and SNK analog tests: *, P < 0.010; **, P < 0.025; and ***, P < 0.05. (C) Abs raised against CTB-P1 inhibit HIV-1 transcytosis. Transcytosis neutralizing activities of enriched Ig fractions from serum, feces and unfractionated vaginal secretions of the two best responding mice from groups 2 and 3 were compared to fractions obtained from a group 1 mouse (expressed as percentage of control). (D–F) Neutralization is due to P1-specific IgA. Fecal Ig fractions were preincubated with P1 to block P1-specific Ab activity, resulting in abrogation of neutralizing activity (D, hatched bars). In separate experiments, fecal IgG-depleted fractions, containing mostly IgA, retained their neutralizing activity (E, hatched bars), whereas IgA depleted fractions, containing mostly IgG, lost their neutralizing potential (F, hatched bars).