Abstract: The invention provides methods for stabilizing recombinant Helicobacter urease by genetically modifying a urease amino acid. The stabilized urease is prevented from the molecular aggregation or activation (e.g., in vitro activation) characteristic of untreated urease.

Abstract: A method for preventing the activation of inactive, recombinant Helicobacter pylori apourease is presented. The method comprises contacting the apourease with a compound that modifies a sulfhydryl or lysyl residue of the urease. The covalently modified apourease is prevented from molecular aggregation.

Abstract: Method of eliciting in a mammalian host a protective immune response to Helicobacter infection by administering to the host an immunogenically effective amount of a Helicobacter urease or urease subunits as antigen. Vaccine compositions are also provided.

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.