Fig. 3.
ELISPOT analysis of Ab-secreting cells in splenocytes (A) and determination of serum IgG titers (B) after the third boost immunization with F1-V-MPR649-684. One week prior to analysis, Groups 1 and 2 mice were boosted i.p. with 10 μg of F1-V-MPR649-684 (at week 41). As a control, splenocytes and serum samples prepared from unimmunized mice (N=5) were used, which did not show any detectable spots or antibody responses (not shown). (A) Splenocytes were pooled from the same group of animals and analyzed for Ab-secreting cells specific to F1-V, CTB, and F1-V-MPR649-684. See Materials and Methods for detail. (B) Endpoint titers of anti-MPR649-684, anti-F1-V, and anti-CTB IgGs. Bars represent arithmetic means of triplicate samples (±S.E.M.) of pooled splenocyte cultures and sera. Symbols indicate statistical significance between groups, as analyzed by unpaired two-tailed Student's t-test (* p < 0.05; ** p < 0.01; *** p < 0.01; ns: not significant).