Theories of vaccination for Helicobacter pylori

Abstract

Successful eradication of Helicobacter pylori infection leading to cure of peptic ulceration has led to intensive antimicrobical therapy involving combinations of antibiotics on a very large scale. However, the failures of chemotherapy due to compliance, cost, development of resistant organisms, the very high global prevalence of H. pylori infection, and its association with gastric malignancy provide a compelling case for considering other preventive strategies. Recent insights into the nature of antigen uptake by mucosal surfaces and recognition by T cells have suggested new strategies for antigen delivery by oral vaccines, for overcoming oral tolerance and for enhancing mucosal immune responses. The concept of developing an oral vaccine to prevent H. pylori infection in humans however, poses several questions. Why doesn’t the readily detected antibody response found in infected patients kill the organism? Why doesn’t previous infection protect against reinfection? Given the finding that H. pylori infection occurs in infancy or early childhood in developing countries, will immunization of already-infected populations provide any therapeutic benefit? Are there concerns about the ability of H. pylori vaccines to eliminate all the Helicobacter strains?