title: Helicobacter pylori cytotoxin: importance of native conformation for induction of neutralizing antibodies.
abstract: We have attempted to express the Helicobacter pylori vacuolating cytotoxin in Escherichia coli. Although the 95-kDa VacA polypeptide was expressed abundantly, it completely lacked any biological activity. In addition, this material failed to induce neutralizing antibodies after immunization of rabbits. In contrast, highly purified high-molecular-mass cytotoxin from the supernatant of H. pylori cultures was active in a HeLa cell assay and effectively induced a neutralizing response in rabbits. Neutralizing sera were shown to contain a high proportion of antibodies which recognized conformational epitopes found only on the native toxin. The data indicate that toxin-neutralizing epitopes are conformational and that potential vaccines based on the cytotoxin may benefit from the use of the intact molecule.
authors.affiliation: IRIS, Chiron-Biocine Immunobiological Research Institute Siena, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Manetti
authors.forename: P
authors.initials: P
authors.lastname: Massari
authors.forename: D
authors.initials: D
authors.lastname: Burroni
authors.forename: M
authors.initials: M
authors.lastname: de Bernard
authors.forename: A
authors.initials: A
authors.lastname: Marchini
authors.forename: R
authors.initials: R
authors.lastname: Olivieri
authors.forename: E
authors.initials: E
authors.lastname: Papini
authors.forename: C
authors.initials: C
authors.lastname: Montecucco
authors.forename: R
authors.initials: R
authors.lastname: Rappuoli
authors.forename: J L
authors.initials: JL
authors.lastname: Telford
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D000942:Antigens, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000276:immunology / Q000633:toxicity; D001427:Bacterial Toxins / Q000737:chemistry* / Q000276:immunology / Q000633:toxicity; D003603:Cytotoxins / Q000737:chemistry* / Q000276:immunology / Q000633:toxicity; D004926:Escherichia coli; D006367:HeLa Cells; D016480:Helicobacter pylori / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D011487:Protein Conformation; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D011994:Recombinant Proteins; C074689:VacA protein, Helicobacter pylori