Specific identification of three low molecular weight membrane‐associated antigens of Helicobacter pylori

Background: A large number of Helicobacter pylori proteins are antigenic, but antibodies to these proteins persist in spite of the eradication of the infection. Methods and results: The analysis of sera from H. pylori‐infected and non‐infected patients, before and 3 and 5 months after eradication, showed that the antibody response against unknown H. pylori antigens at 32, 30, 22 and 14 kDa in sodium dodecylsulphate polyacrylamide gel electrophoresis decreased by ≥ 60% at 3 months and ≥ 70% at 5 months after treatment. Two‐dimensional gel electrophoresis and mass spectrometry allowed the identification of eight proteins at these positions: neuraminyl‐lactose‐binding haemagglutinin precursor, 3‐oxoadipate CoA‐transferase subunit A, elongation factor P, peptidoglycan‐associated lipoprotein precursor, hypothetical protein HP0596, adhesin‐thiol peroxidase, 50S ribosomal protein L7/L12 and subunit b′ of the F0 ATP synthase. Three of these eight, expressed as recombinant proteins (32 kDa neuraminyl‐lactose‐binding haemagglutinin precursor, 30 kDa peptidoglycan‐associated lipoprotein precursor and 22 kDa hypothetical protein HP0596), reacted specifically with sera from infected patients, while the 14 kDa 50S ribosomal protein L7/L12 cross‐reacted with one out of five sera from H. pylori‐negative patients. The other recombinant proteins did not show significant immunoreactivity. Conclusions: Four low molecular weight antigens were identified by these methods, three of which were specific. Immunoreaction with these three proteins (neuraminyl‐lactose‐binding haemagglutinin precursor, peptidoglycan‐associated lipoprotein precursor and hypothetical protein HP0596) could provide a serological assessment not only of H. pylori infection, but also of eradication.