Figure 1.

VacA prevents phagosome maturation in professional antigen-presenting cells. Most strains of H. pylori express the secreted virulence factors VacA to affect phagosome maturation and lysosome fusion. The receptor for VacA on myeloid cells is not known. It has been proposed that H. pylori-containing phagosomes fail to mature and instead resemble early endosomes that have resisted lysosome fusion; this process appears to be specific to type I strains and is dependent on VacA expression [12]. Treatment with recombinant IFN-γ allows phagocytes to overcome their block in phagosome maturation and to kill intracellular type I strains of H. pylori.