Helicobacter pylori Antigens Inducing Early Immune Response in Infants.

To identify the Helicobacter pylori antigens operating during early infection in sera from infected infants using proteomics and immunoblot analysis. Two-dimensional (2D) large and small gel electrophoresis was performed using H. pylori strain 51. We performed 2D immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) antibody immunoblotting using small gels on sera collected at the Gyeongsang National University Hospital from 4-11-month-old infants confirmed with H. pylori infection by pre-embedding immunoelectron microscopy. Immunoblot spots appearing to represent early infection markers in infant sera were compared to those of the large 2D gel for H. pylori strain 51. Corresponding spots were analyzed by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS). The peptide fingerprints obtained were searched in the National Center for Biotechnology Information (NCBI) database. Eight infant patients were confirmed with H. pylori infection based on urease tests, histopathologic examinations, and pre-embedding immunoelectron microscopy. One infant showed a 2D IgM immunoblot pattern that seemed to represent early infection. Immunoblot spots were compared with those from whole-cell extracts of H. pylori strain 51 and 18 spots were excised, digested in gel, and analyzed by MALDI-TOF-MS. Of the 10 peptide fingerprints obtained, the H. pylori proteins flagellin A (FlaA), urease β subunit (UreB), pyruvate ferredoxin oxidoreductase (POR), and translation elongation factor Ts (EF-Ts) were identified and appeared to be active during the early infection periods. These results might aid identification of serological markers for the serodiagnosis of early H. pylori infection in infants.