Helicobacter pylori is a Gram negative bacterium that infects the gastric tissue of more than 3 billion people worldwide. Infection with H. pylori almost always persists within the host for life, and results in a spectrum of diseases ranging from gastritis in all individuals, which can progress to the formation of gastric ulcers or gastric cancer. H. pylori uses a range of virulence determinants and mechanisms to manipulate the hosts immune system into mounting an ineffective and chronic immune response. This ineffective immune response creates an environment in which the bacterium can survive almost indefinitely, and ultimately results in the destruction of host cells, gastric pathology and cancer in some individuals. Our research examines the cellular and molecular mechanisms whereby H. pylori and their products, such as outer membrane vesicles, mediate pathogenesis and chronic immune suppression in the host. Our findings ultimately aim to broaden our understanding of how H. pylori mediates disease in an attempt to develop novel therapies with the potential to facilitate clearance of chronic H. pylori infections.