Eradication of chronic Helicobacter pylori infection by therapeutic vaccination

Abstract

The development of a vaccine against H pylori which confers long term protective immunity is the best strategy to circumvent the problem of antibiotic resistance and to eradicate H pylori on a global scale. The feasibility of inducing protective immune responses to helicobacter by oral vaccination with bacterial antigens and a mucosal adjuvant was initially demonstrated in the H felis murine model.4-6 Vaccination with both H pylori urease5 and heat shock proteins (HspA and HspB)6 protected against subsequent challenge withH felis. However, H felis lacks many of the virulence factors present inH pylori, such as thecag pathogenicity island7 and the cytotoxin VacA,8 precluding analysis of these antigens as candidate vaccines in the H felis model. The development of mouse adapted H pyloristrains which cause chronic infection in mice was a major advance.9 The H pylori mouse model has permitted the testing of vaccines containing purifiedH pylori antigens against homologous challenge infection.9 To date, a number of protectiveH pylori antigens have been identified which confer immunity against H pylori infection in the mouse, including purified VacA,9urease,9 CagA,10 and catalase.11