Objective: Acinetobacter baumannii (A. baumannii) has a good potential to colonize on various surfaces. As a virulence factor, adhesion to surfaces is the first step in colonization. The Two-Partner Secretion System (TPS) proteins are key factors for bacterial attachment. The purpose of this study is to identify and study the role of this family of proteins in adhesion of A. baumannii to human epithelial cells. Methods: Gene homologues that encoded the TPS were analyzed by bioinformatics tools and the primers were designed accordingly. The constructs synthesized in the pET22b vector were transferred to BL21(DE3). The transformed cells were named FhaB1 and FhaB2. The protein expression on the cell membrane was studied in addition to bacterial adhesion and biofilm formation by recombinant strains, A. baumannii and E.coli BL21(DE3). Results: Bioinformatic studies showed the bacterial potential of producing two exoproteins (FhaB1 and FhaB2). Expression of the recombinant proteins on the outer membrane was confirmed by Western Blot Analysis and whole cell ELISA. The results revealed an association between the recombinant cells and bacterial adhesion and biofilm formation. FhaB1, FhaB2  and A. baumannii exhibited enhanced adherence to human lung epithelial cells compared to E.coli BL21(DE3) Conclusion: TPS in A.baumannii is of adherence and colonization factors and is one of the bacterial virulence factors.

Keywords: Acinetobacter baumannii, Adhesion, Two-Partner Secretion System

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