Immunization with recombinant FliD confers protection against Helicobacter pylori infection in mice

Area of Science:

• Microbiology
• Immunology
• Vaccinology

Background:

• Helicobacter pylori infection affects nearly half the global population, leading to various gastrointestinal diseases.
• Antibiotic resistance and poor patient compliance necessitate alternative strategies like vaccines.
• The bacterial flagellar protein FliD is crucial for flagellar structure and stability.

Purpose of the Study:

• To evaluate the immunogenicity and protective efficacy of recombinant FliD (rFliD) from H. pylori as a subunit vaccine candidate.
• To assess the immune responses induced by subcutaneous and oral administration of rFliD with different adjuvants in mice.

Main Methods:

• Recombinant FliD (rFliD) was purified and formulated with adjuvants.
• C57BL/6 mice were immunized subcutaneously or orally with rFliD.
• Humoral and cellular immune responses (IgG titers, cytokine secretion) were analyzed.
• Bacterial load of H. pylori was measured post-challenge to assess protective efficacy.

Main Results:

• Subcutaneous immunization with rFliD induced strong Th1 and Th17 immune responses, characterized by high IgG1, IgG2a titers, and elevated IFN-γ and IL-17 secretion.
• Splenocytes from immunized mice showed robust antigen-specific memory responses.
• Immunization with rFliD led to a significant reduction in H. pylori bacterial load compared to controls (p < 0.001).

Conclusions:

• Subcutaneous vaccination with rFliD, particularly when formulated with CpG or Addavax, demonstrates significant protective efficacy against H. pylori infection in a mouse model.
• rFliD is a promising candidate for developing a novel subunit vaccine against H. pylori.
• The study highlights the potential of targeting bacterial structural proteins for vaccine development.