Figure 1: Induction of PspA-specific IgG (closed bars)(A), PspA-specific IgG1 (open bars) and IgG2a (gray bars) (B) in serum by intranasal immunization with either PspA plus each TLR agonist or PspA alone. Mice were nasally immunized three times at weekly intervals with 10 µg of TLR agonist and 0.1 µg of PspA. One week after the final immunization, the mice were euthanized to obtain serum, and PspA-specific antibody titers were determined using ELISA. The results are expressed as the mean S.D. for six mice per group. *p < 0.05, **p < 0.01, when compared with mice that were nasally immunized PspA plus LPS. ND, not detected.