VacA

VacA is a secreted protein toxin produced by Helicobacter pylori, known as vacuolating cytotoxin A, rather than a conventional pharmaceutical product. It forms anion-selective membrane channels and pores, disrupts endosomal and lysosomal trafficking, perturbs mitochondrial function, and induces cytoplasmic vacuolization and apoptosis in gastric and immune cells, contributing to gastric injury and carcinogenesis in H. pylori infection.[7] VacA also has potent immunomodulatory effects, including inhibition of T‑cell proliferation, reduced B‑cell activation, and promotion of regulatory T cells, which facilitates chronic colonization; because of its central role in H. pylori pathogenesis and strong antigenicity, it has been investigated as a component antigen in experimental H. pylori vaccines.[7]