Immunological response of recombinant H. pylori multi-epitope vaccine with different vaccination strategies

To investigate different protective effects of recombinant H. pylori multi-epitope antigen (rIB) with cholera toxin subunit B (rCTB) as the intramolecular/extramolecular adjuvant though different immunization routes in a Helicobacter pylori infected mouse model.

By using rCTB as the intramolecular/extramolecular adjuvant of rIB, BALB/c mice were immunized through oral administration or intramuscular injection, on day 0, 14, 28. Every 14 days, ELISA was used to detect serum specific IgG and IgA titers after immunization. After the last immunization, H. pylori SS1 challenge was performed, and urease test, Gram staining after smearing of mouse gastric tissue, PCR, pathology and immunohistochemistry were used to evaluate preventive effect of the recombinant protein vaccine.

After immunization three times, intramolecular injection could induce high titers of serum specific IgG antibody, and the antibody titer in rIB group, rCTB+rIB and rBIB group was 2000, 5000 and 7500, respectively (P < 0.05). Specific IgA antibody was only detected in rBIB oral administration group. The immune protection rate in rBIB oral administration group was significantly higher than that in rBIB intramolecular injection group (33.3% vs. 83%), indicating significant difference.

rCTB has good intramolecular/extramolecular immune adjuvant effects, and its intramolecular immune adjuvant effect is better. Both intramolecular injection and oral administration of rBIB have immune protective effect against H. pylori challenge, and oral administration of rBIB exerts better immune protective effect.