Construction and Characterization of CdtB Mutant Helicobacter hepaticus

CdtB mutant strain (ΔCdtB H. hepaticus) was constructed by Zhu et al. (2020) , and conserved in our lab. In brief, the CdtB gene was replaced to Chloramphenicol resistant gene (Cm) by homologous recombination through electro-transforming the CdtA-Cm-CdtC fragment to H. hepaticus competent cell; then, the positive transformants were continuously subcultured on Brucella agar plates with chloramphenicol for five times. H. hepaticus 3B1 (ATCC 51449) and ΔCdtB H. hepaticus were cultured on Brucella agar plates (BD, USA) supplemented with 5% defibrinated sheep blood and antibiotics for 4–5 days under microaerobic conditions (85% N₂, 10% CO₂, 5% O₂) at 37°C. Bacteria were harvested in PBS and used for oral infection when OD₆₀₀ reading was 1 (Xu et al., 2018 (link)).