Functional Characterization of the IlpA Protein of Vibrio vulnificus as an Adhesin and Its Role in Bacterial Pathogenesis

다국어 초록 (Multilingual Abstract)

<B>ABSTRACT</B><P><I>Vibrio vulnificus</I> is a Gram-negative bacterium that causes a fatal septicemia. One of its virulence factors is a membrane-bound lipoprotein, IlpA, which can induce cytokine production in human immune cells. In the present study, the role of IlpA as an adhesion molecule was investigated. An <I>ilpA</I>-deleted <I>V. vulnificus</I> mutant showed significantly decreased adherence to INT-407 human intestinal epithelial cells, which in turn resulted in reduced cytotoxicity. The <I>ΔilpA</I> mutant recovered the adherence ability of the wild type by complementation in <I>trans</I> with the intact <I>ilpA</I> gene. In addition, pretreatment of <I>V. vulnificus</I> with anti-IlpA polyclonal antibodies resulted in a significant reduction of bacterial adherence. To localize the domain of IlpA required for cytoadherence, three truncated recombinant IlpA polypeptides were constructed and tested for the ability to adhere to human cells by a ligand-binding immunoblot assay and fluorescence microscopy. The polypeptide containing the carboxy (C)-terminal hydrophilic domain exhibited direct binding to INT-407 cells. Therefore, the C-terminal domain of IlpA allows this protein to be an adhesion molecule of <I>V. vulnificus</I>.</P>