Abstract: Methods and compositions are provided for prophylactic and antibacterial therapy for Helicobacter, particularly for Helicobacter pylori, infection of humans. The immunogenic composition of the invention is composed of a plurality of multimeric complexes, each complex being composed of recombinant, enzymatically inactive Helicobacter pylori urease. Each multimeric complex is composed of six Urease A subunits and six Urease B subunits. Alternatively, the composition is composed of a mixture of multimeric complexes, wherein each multimeric complex in the mixture is composed of six Urease A subunits and six Urease B subunits or four Urease A subunits and four Urease B subunits.