BALB/c mice (7/group) were immunized i.v. with 50μg cOVA in alum with or without: (A) 50μg PB-BSA or NP-BSA (as control) or 2 × 108 CFU R36A, (B) 2 × 108 CFU WT R36A or periodate-treated R36A, (D) 4×108 CFU E. rhusiopathiae or 2×108 CFU N. meningitidis, or (E) 2×108 CFU R36A or 5×108 CFU H. influenzae.. All mice were boosted i.v. with 50 μg cOVA + alum without bacteria, on d14. Serum titers of cOVA-specific IgG were measured by ELISA. (C) PC expression by R36A or R36A (periodate) by flow cytometry (“control”, R36A stained with FITC-anti IgG2a only [no primary anti-PC Ab]). Significance * p≤0.05.