3Institut für Mikrobiologie,

Immunoproteomics of Helicobacter pylori infection and relation to gastric disease The Gram negative bacterium Helicobacter pylori is a human pathogen which infects the gastric mucosa and causes an inflammatory process leading to gastritis, ulceration and cancer. A systematic, proteome based approach was chosen to detect candidate antigens ofH. pylori for diagnosis, therapy and vaccine development and to investigate potential associations between specific immune responses and manifestations of dis-ease. Sera from patients with active H. pylori infection (n = 24), a control group with unrelated gastric disorders (n = 12) and from patients with gastric cancer (n = 6) were collected and analyzed for the reactivity against proteins of the strain HP 26695 separ-ated by two-dimensional electrophoresis. Overall, 310 antigenic protein species were recognized by H. pylori positive sera representing about 17 % of all spots separated. Out of the 32 antigens most frequently recognized by H. pylori positive sera, nine were newly identified and 23 were confirmed from other studies. Three newly identified anti-gens which belong to the 150 most abundant protein species of H. pylori, were spec-ifically recognized by H. pylori positive sera: the predicted coding region HP0231, ser-ine protease HtrA (HP1019) and Cag3 (HP0522). Other antigens were recognized differently by sera from gastritis and ulcer patients, which may identify them as can-didate indicators for clinical manifestations. The data from these immunoproteomic analyses are added to our public databas