Serum antibody response to the superficial and released components of Helicobacter pylori

Abstract

Superficial and released components were extracted from six selected Helicobacter pylori strains. The protein and antigenic profiles of these extracts were representative of the profiles found most frequently among the clinical strains and included major peptidic fractions at 19, 23.5, 57, 68, 76, 118, and 132 kDa and major antigens at 68, 57, and 23.5 kDa. Immuno-cross-reactions were seen with a hyperimmune rabbit serum to Campylobacter fetus but not with sera to Campylobacter jejuni or Salmonella spp. An antigenic preparation was obtained by pooling equivalent quantities of each extract, and the antigenic preparation was used to study the antibody responses of sera from 65 French patients and 127 Tunisian patients. By enzyme-linked immunosorbent assay, we observed that the sera from French and Tunisian patients clustered into two populations, defined as antibody positive (72 patients) and antibody negative (120 patients). The antibody-positive patients were more frequently infected with H. pylori (P < 0.01) and were more frequently affected with gastritis (P = 0.05). However, no correlation between antibody levels and clinical signs of dyspepsia was noticed. The proportions of antibody-positive patients were similar in France and Tunisia. Antibody-positive and antibody-negative sera were studied by western blot (immunoblot) analysis. The antibody-positive sera revealed an average of 7.7 antigenic bands, whereas the antibody-negative sera revealed an average of 2.4 antigenic bands (P < 0.01). The antigens between 15 and 40 kDa and greater than 66 kDa were specifically recognized by the antibody-positive sera, although in this molecular size range the antibody profiles of these sera exhibited a fairly high degree of diversity. We conclude that the superficial and released components from H. pylori contain a variety of bacterial immunogens and may be useful in antigenic preparations for the serodiagnosis of H. pylori infections. Moreover, a group of antigens in combination appears to be useful for discriminating antibody-positive and antibody-negative patients.