Helicobacter pylori cytotoxin: importance of native conformation for induction of neutralizing antibodies.
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.
Manetti
R
R
IRIS, Chiron-Biocine Immunobiological Research Institute Siena, Italy.
Massari
P
P
Burroni
D
D
de Bernard
M
M
Marchini
A
A
Olivieri
R
R
Papini
E
E
Montecucco
C
C
Rappuoli
R
R
Telford
J L
JL
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
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D011994:Recombinant Proteins; C074689:VacA protein, Helicobacter pylori