(A) PC expression by R36A or R36Apc- by flow cytometry (“control”, R36Apc- stained with FITC-anti IgG2a only [no primary anti-PC Ab]). BALB/c mice (7 per group) were immunized i.v. with 50 μg cOVA in alum: (B) with or without 2×108 CFU R36A or R36Apc-, (C) R36A (grown in standard THB medium) or CDM-grown R36A, or (D) R36A, sonicated R36A or sonicated R36Apc-. All mice were boosted i.v. with 50 μg cOVA + alum without bacteria, on d14. Serum titers of cOVA-specific and PC-specific IgG were measured by ELISA. Significance * p≤0.05