It has been estimated that half the world's population carries H. pylori.Most infected people remain asymptomatic during their lifetime, and only about 15% develop gastroduodenal disorders. This implies near perfect adaptation to the niche and an ability to evade the human immune response. Of those infected, about 10% develop peptic ulceration, roughly 1% develop gastric adenocarcinoma and less than 0.1% MALT (mucosa-associated lymphoid tissue lymphoma. Infection with H pylori elicits a systemic, strong and polymorphic humoral immune response. CagA is the important pathologic marker with a...