Evaluation of Helicobacter pylori OipA protein as a vaccine candidate and propolis as an adjuvant in C57BL/6 mice

OBJECTIVE(S): Outer inflammatory protein A (OipA) is an essential adhesin of Helicobacter pylori. We aimed to evaluate the effects of a recombinant OipA in the induction of crucial cytokines as a vaccine candidate and propolis as an adjuvant in C57BL/6 mice. MATERIALS AND METHODS: C57BL/6 mice were divided into nine groups according to the disposition of antigen and adjuvant and route of administration: subcutaneous (sc) or gavage. The administrated recombinant purified OipA and propolis concentrations were 10 μg/ml and 40 μg/ml, respectively. After vaccination, we measured expression levels of IFN-γ and IL-4 cytokine genes in the spleen cells of mice by real-time PCR. RESULTS: All results were contrasted with the negative sample. By sc injection, the expression of INF-γ was increased 3.5 and 2.9-fold for OipA and OipA plus propolis, respectively. By gavage 4.4 and 11-fold increase was found for OipA and OipA plus propolis, respectively. The administration of propolis by gavage showed more increase than Sc injection concerning the production of INF-γ. The 11-fold increase for injection of OipA plus propolis by gavage was comparable OipA plus Freund’s adjuvant injected subcutaneously. This result suggested an excellent immunological response toward OipA concerning the production of INF-γ in mice. In all cases there were no notable IL-4 production increases. CONCLUSION: The results confirm the efficiency of OipA in induction of IFN-γ production, and thereby the cellular immune response. Propolis could be a suitable adjuvant.