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Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Escherichia coli O157:H7 adherence to HEp-2 cells is implicated with curli expression and outer membrane integrity | J. Vet. Sci. 2004 5 2 119-124 JOURNAL OF Veterinary Science Escherichia coli O157 H7 adherence to HEp-2 cells is implicated with curli expression and outer membrane integrity Sang-Hyun Kim Yong-Hwan Kim1 Department of Pathobiology Ontario Veterinary College University of Guelph Guelph Ontario N1G 2W1 Canada College of Veterinary Medicine Research Institute of Life Science Gyeongsang National University Jinju 660-701 Korea Escherichia coli E. coli has ability to express thin aggregative fimbriae known as curli on the cell surface. Previously a few example of curli expression in serogroup O157 H7 of enterohemorrhagic E. coli EHEC were reported compared to other E. coli groups. However significance of curliation in the EHEC pathobiology has not been described well in the literature. A highly curliated O157 H7 strain was used in this study in order to elucidate role of curliation in EHEC adherence to cultured HEp-2 cells. The expression of curli in the EHEC isolate was consistent with strong positive indication of Congo-red CR binding and formation of clumps in the bottom of the tube containing Luria-Bertani LB broth when cultured overnight at 37oC. A few CR-binding negative CR- colonies occurred spontaneously within the population of CR isolate. The CR EHEC showed massive aggregative adhesion pattern whereas the spontaneous CR- strain showed typical localized adherence on HEp-2 cells. Electron microscopy confirmed highly curliated bacteria in the CR EHEC sample. Interestingly the curliation disappeared in a msbBl and msbB2 double mutant derived from the CR EHEC. These results suggest that the compromised outer membrane integrity caused by msbB mutations may abrogate curli production in the CR EHEC harbouring penta-acylated lipid A structure in their outer membrane. Key words E. coli O157 H7 Curli Adhesion HEp-2 cells Introduction Shiga toxin Stx -producing Escherichia coli STEC have been emerged as important food- and water-borne pathogens worldwide 1 . STEC causes a
