CHARACTERIZATION OF THE ADHESIN RESPONSIBLE FOR THE AGGREGATIVE ADHERENCE OF Esche...
Molecular characterization of the virulence of classic atypical Enteropathogenic E...
Atypical enteropathogenetic Escherichia coli (atypical EPEC)
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Author(s): |
Sarita Schneider Rossato
Total Authors: 1
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Document type: | Master's Dissertation |
Press: | São Paulo. |
Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
Defense date: | 2009-09-15 |
Examining board members: |
Roxane Maria Fontes Piazza;
Tania Aparecida Tardelli Gomes do Amaral;
Glaucia Maria Machado Santelli
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Advisor: | Roxane Maria Fontes Piazza |
Abstract | |
Atypical Enteropathogenic Escherichia coli (EPEC) has been a leading cause of childhood diarrhea in developing countries. The main mechanism of atypical EPEC pathogenesis is a lesion called attaching and effacing (A/E), which is characterized by intimate adherence of the bacteria to the intestinal epithelium and destruction of microvillus. Nevertheless, it represents a heterogeneous group and other virulence factors may be involved in atypical EPEC pathogenesis. Previously, we have identified one isolate of atypical EPEC, serotype O26:H11, which secretes proteins that interact with ECM macromolecules. The interactions between pathogenic bacteria and ECM molecules such as fibronectin, laminin and collagen may play an important role in the bacterium adherence to and invasion of host cells. Adhesion is critical for successful E. coli colonization of gastrointestinal tract and is mediated by adhesins. The aim of this study is to identify and characterize putative adhesins that may contribute to the binding of the isolate of atypical EPEC to extracellular matrix components. The supernatant of the atypical EPEC isolate was submitted to a solid phase binding assay with matrigel (a mouse basement membrane composed mainly of laminin, collagen IV and fibronectin), the adhered proteins were stripped from the wells, separated by SDS-PAGE, transferred to nitrocellulose membranes and submitted to immunoblotting assay. Three major proteins of apparent molecular weights of 107, 44 e 35 kDa were recognized by the anti-proteins polyclonal serum (produced in rabbit immunized with the isolate\'s supernatant) through immunoblotting assay. Besides, we observed that in the presence of ECM components the isolate clearly changes its adherence pattern of the isolate to HEp-2 cells, and the number of adhered bacteria to epithelial cells. The atypical EPEC do not share a unique pattern of virulence, suggesting that many virulence factors may contribute to the pathogenesis. The identification of proteins involved in the adhesion with extracellular matrix components in one isolate of this category of diarrheagenic E. coli confirms the heterogeneity among the atypical EPEC. (AU) |