Figure 6.

Intraperitoneal and intranasal immunisations with DacB, MetQ, or PnrA predominantly induce IgG1 responses. Antigen-specific total IgG, IgG1, and IgG2 titres were monitored using an ELISA in either post-immune sera following an intraperitoneal immunisation with Alum as the adjuvant (A,B) or in post-challenge sera obtained after intranasal immunisation with CTB as the adjuvant followed by an intranasal challenge with S. pneumoniae D39 (C,D). Antibody titres of each serum specimen are denoted as the log₁₀ of the reciprocal dilution of the serum giving twice the average absorbance of the sera derived from the PBS-treated group. The data were statistically analysed using a Mann-Whitney U-test. Symbols represent individual mice (n = 6 for Alum group, n = 12 for CTB group) and bars represent the group median. *p < 0.05; **p < 0.01; ***p < 0.001.