Human serum antibody response against iron-repressible outer membrane proteins of Helicobacter pylori

In Helicobacter pylori, in vitro iron limitation induces the expression of several iron repressible outer membrane proteins (IROMPs), which are not expressed under normal growth conditions. To substantiate their proposed role in virulence of H. pylori, we determined whether these IROMPs are also expressed in vivo. Therefore, we tested whether sera of patients with H. pylori infection contained antibodies against IROMPs. All sera from 20 H. pylori positive patients showed a clear immune response against a 77 kDa heme-binding IROMP in an immunoblot assay. Antibody responses against the other IROMPs were also found, but with lower frequencies. Serum samples from 18 patients negative for H. pylori infection did not show any immunoreactivity with IROMPs. These results indicate that the IROMPs of H. pylori are immunogenic and are expressed in vivo.