FIG. 4.
Anti-G5 systemic and mucosal immune responses in mice primed with K. pneumoniae (Kp) and immunized three times i.n. with P40-G5 3 weeks after priming. BALB/c mice (n = 5) were primed twice i.n. with K. pneumoniae (109 bacteria) and then immunized three times at 10-day intervals with P40-G5, with or without CTB as a mucosal adjuvant. (A and B) Mice were bled 9 days after each immunization, and serum anti-G5 IgG (A) or IgA (B) was determined by ELISA. White bars, vertically hatched bars, horizontally hatched bars, and black bars represent anti-G5 titers at day 0 and after one, two, or three immunizations, respectively. (C) At 10 days after the last immunization, mice were sacrificed and nasal fluids were collected for IgA titer determination. For each group of mice, results are expressed as geometric means and standard deviations. The asterisk indicates a P value of <0.05 for a statistical analysis of primed and nonprimed mice.