FIG 5.

5CP induced long-lived plasma and Th17 cells and provided efficient long term-protection. (a to e) Six months after the last immunization, 5CP-specific antibody-secreting cells in the bone marrow (a and b), spleen (c and d), and NALT (e) were measured by ELISPOT assays. (f and g) GAS-specific serum IgG (f) and saliva IgA in mouth wash (g) were measured by ELISA. (h and i) Spleen (h) and NALT (i) cells were isolated from immunized mice 6 months after the last immunization and stimulated with HK GAS, and IL-17A-secreting cells were measured by ELISPOT assay. Data are presented as means plus SEM (n = 8). (j) Mice were intranasally challenged with 2 × 10⁸ GAS M1 (strain 90-226) 6 months after the last immunization. CFU in NALT were determined 24 h after challenge. Data from two independent experiments are presented as means ± SEM (n = 4 to 8). Statistical significance was determined by one-way ANOVA with Tukey’s posttest and indicated as follows: ****, P < 0.0001; ***, P < 0.001; **, P < 0.01.