In an early branching metazoan, bacterial colonization of the embryo is controlled by maternal antimicrobial peptides.

Early embryos of many organisms develop outside the mother and are immediately confronted with myriads of potential colonizers. How these naive developmental stages control and shape the bacterial colonization is largely unknown. Here we show that early embryonic stages of the basal metazoan Hydra are able to control bacterial colonization by using maternal antimicrobial peptides. Antimicrobial peptides of the periculin family selecting for a specific bacterial colonization during embryogenesis are produced in the oocyte and in early embryos. If overexpressed in hydra ectodermal epithelial cells, periculin1a drastically reduces the bacterial load, indicating potent antimicrobial activity. Unexpectedly, transgenic polyps also revealed that periculin, in addition to bactericidal activity, changes the structure of the bacterial community. These findings delineate a role for antimicrobial peptides both in selecting particular bacterial partners during development and as important components of a "be prepared" strategy providing transgenerational protection.

Development of immunoreagents for diagnostics of CagA-positive Helicobacter pylori infections.

BACKGROUND: Helicobacter pylori strains expressing cytotoxic CagA protein are more likely to provoke severe gastric mucosal pathology and cause adenocarcinoma development than that lacking CagA. Determination of the CagA-status of a pathogen, therefore, is regarded as informative approach in H. pylori infection diagnostics and disease risk prediction. MATERIALS AND METHODS: Molecular cloning, recombinant protein expression in Escherichia coli, affinity chromatography, electrophoresis and commonly used techniques of hybridoma production and screening were used as well as different immunosorbent assays and Western blot procedures. RESULTS: Four overlapping N-terminally His(6)-tagged recombinant fragments of CagA that covered the entire CagA sequence were produced and purified. An ELISA for specific anti-CagA serum antibodies detection was developed and evaluated. Utilizing recombinant fragments, the first set of monoclonal antibodies against CagA-antigen was produced and characterized. Three antibodies recognized distinct linear epitopes inside conserved regions of the cytotoxin whereas the epitope of the forth antibody was mapped in the variable area of CagA. The monoclonal antibodies allowed discriminating CagA-positive and CagA-negative H. pylori strains by means of Western blot and immunosorbent assays. CONCLUSIONS: The use of recombinant protein technology allowed obtaining pure CagA antigen, thus providing new perspectives for development of immunodiagnostic reagents. The set of monoclonal antibodies is a valuable tool for determination of CagA-status of H. pylori infection and for the investigation of cytotoxin molecule as well.