[Pathogenicity in mice infected with three different strains H. pylori]

Area of Science:

• Microbiology
• Immunology
• Pathogenesis

Background:

• Helicobacter pylori infection is a major cause of gastric diseases.
• The cytotoxin-associated gene A (CagA) is a key virulence factor in H. pylori.
• Understanding the role of CagA in pathogenesis is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the differential effects of CagA-positive (CagA+) and CagA-negative (CagA-) H. pylori strains on gastric colonization and histopathology in a mouse model.
• To assess the correlation between bacterial load, host immune response (serum IgG), and gastric inflammation.

Main Methods:

• C57BL/C mice were orally inoculated with three different H. pylori strains: wild-type CagA+, isogenic CagA- knockout mutant, and Sydney strain (CagA+).
• Bacterial colonization and gastric tissues were examined histopathologically 8 weeks post-inoculation.
• Serum IgG antibody levels were quantified using ELISA.

Main Results:

• CagA+ strains (Sydney and wild-type) exhibited significant gastric colonization and induced moderate neutrophil and monocyte infiltration.
• CagA- strains showed minimal colonization and no significant difference in IgG levels compared to controls.
• Serum IgG antibody levels were significantly elevated in mice infected with CagA+ strains.

Conclusions:

• A strong correlation exists between the presence of CagA+, bacterial colonization, gastric mucosa inflammation, and elevated serum IgG antibodies.
• This mouse model provides insights into the pathogenicity of CagA+ H. pylori strains in humans.
• The findings contribute to understanding H. pylori infection and associated gastric diseases.