We previously demonstrated that Bordetella (B.) bronchiseptica antigen (Ag) showed high immunostimulatory effects on mouse bone marrow cells (BMs) while Mycoplasma (M.) hyopneumoniae Ag showed low effects. The focus of this study was to determine if B. bronchiseptica Ag can enhance the M. hyopneumoniae Ag-specific immune response and whether the host's immune system can recognize both Ags. MTT assay results revealed that each or both Ags did not significantly change BM metabolic activity. Flow cytometry analysis using carboxyfluorescein succinimidyl ester showed that B. bronchiseptica Ag can promote the division of BMs. In cytokine and nitric oxide (NO) assays, B. bronchiseptica Ag boosted production of tumor necrosis factor-alpha in M. hyopneumoniae Ag-treated BMs, and combined treatment with both Ags elevated the level of NO in BMs compared to that from treatment of M. hyopneumoniae Ag alone. Immunoglobulin (Ig)G enzyme-linked immunosorbent assay using the sera of Ag-injected mice clearly indicated that B. bronchiseptica Ag can increase the production of M. hyopneumoniae Ag-specific IgG. This study provided information valuable in the development of M. hyopneumoniae vaccines and showed that B. bronchiseptica Ag can be used both as a vaccine adjuvant and as a vaccine Ag.
Keywords: Bordetella bronchiseptica; Mycoplasma hyopneumoniae; antigen-specific immune response; bone marrow cells; vaccine adjuvant.