Background: Staphylococcus aureus is an opportunistic pathogen that produces many virulence factors, and the most important regulator system of virulence factors expression in these bacteria is the agr system. Expression of virulence factors is not the same under in vitro conditions in standard laboratory medium and in vivo in the host.

e20813th International Congress on Infectious Diseases Abstracts, Poster Presentations organic hydroperoxides into the corresponding non-toxic alcohols. This conserved antigen has been earlier described as specific and unique for H. pylori and therefore, both H. pylori AhpC and Anti-AhpC could be useful in the development of serologic and stool antigen tests, for detecting and monitoring H. pylori infection. AhpC may also serve as a potential target for an antimicrobial agent or for vaccine development. The aim of this study was to simplify isolation and purification of the AhpC.Materials and Methods: For whole cell protein extraction, the bacterial cells were ruptured by octly-␤-Dglucopyranoside. The isolation and purification of AhpC protein were attempted by various techniques including ammonium sulfate precipitation, dialysis, preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution.Results: Assuming that the total protein content of the cells is 30% on a dry weight basis, then the expected maximum protein content in 0.92 g (dry weight) of bacterial cell lysate in a volume of 25 ml PBS, pH 7.4 would be 11 mg/ml, assuming 100% protein release. In practice, the total intracellular protein, 3.5 mg/ml, was determined by completely extracting the protein from the cells with 4.0 M sodium hydroxide. After protein extraction, preparative SDS-PAGE was performed with 4.0 mg protein extract. Then, AhpC was eluted from its corresponding band by electroelution technique. The AhpC concentration was determined be 80.0 g/ml by Bradford assay and in an analytical SDS-PAGE the electroeluted protein migrated as a single band confirming its purity to homogeneity.Conclusion: The presented method is simple, rapid and cost-effective and will make it possible to preparation AhpC from Helicobacter pylori.

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