Protection against Helicobacter pylori Infection in BALB/c Mice by Oral or Intramuscular Administration of Multicomponent Vaccine of rCagA +LPS +CpG

Aims: In this research, the protective effects of this multicomponent vaccine were investigated using the BALB/c mice model.

Place and Duration of Study: This study was performed in Laboratory of Bacteriology, University of Tarbiat Modares, Tehran, IRAN, 2011 and 2012.

Methodology: BALB/c mice were immunized with different formulations three times orally followed by two times intramuscularly (i.m.) at 10-day intervals. The protective effects of two component vaccines plus CpG Adjutants were assessed after H. pylori ss1 challenge in different studies. The specific IgG antibodies titers in sera were studied by using ELISA, and Antigen specific IL-4, IL-10, IL-12, TGFβ and IFN-γ responses were measured in spleen of immunized mice after challenge using ELISA test. Clearance of H. pylori carried out according to standard protocol.

Results: In this study the IgG1/IgG2a ratio in the mice immunized with rCagA and rCagA plus CpG was <1. Analysis of lymphocyte proliferation of mice showed that one microgram rCagA increases lymphocytes proliferation excellent compared to control group. CpG oligodeoxy nucleotides are known for their ability to induce entirely Th1-biased immune responses. Immunization of mice with H. pylori rcagA+LPS+CpG induced a strong local and systemic Th1 immune response. Only mice immunized with rCagA+LPS+CpG and LPS+CpG secreted significantly more IFNγ than others (P<0.05). Protection were correlated with an increase in H. pylori-specific interleukin-12 and IFN-γ and both immunoglobulin G1 (IgG1) and IgG2a serum titers following challenge.

Conclusion: Because of strong Th1 response, mice were protected from infection with H. pylori 6-fold reduction in the number of H. pylori in the gastric mucosa compared to no immunized mice. This study illustrates the crucial role of the immunization route and immunogenic candidate.