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Abstract:
Trimeric autotransporter adhesins (TAAs) are important virulence factors of Gram-negative bacteria responsible for adherence to extracellular matrix (ECM) and host cells. Here, we analyzed three different TAAs [Bartonella adhesin A (BadA) of Bartonella henselae, variably expressed outer membrane proteins (Vomps) of Bartonella quintana, Yersinia adhesin A (YadA) of Yersinia enterocolitica] for mediating bacterial adherence to ECM and endothelial cells. Using static (cell culture vials) and dynamic (capillary flow chambers) experimental settings, adherence of wildtype bacteria and the respective TAA-negative strains were compared. Under static conditions, ECM adherence of B. henselae, B. quintana and Y. enterocolitica was strongly dependent on the expression of their particular TAAs. YadA of Y. enterocolitica did neither mediate bacterial binding to plasma nor cellular fibronectin both under static and dynamic conditions. TAA-dependent host cell adherence appeared more significant under dynamic conditions although the total number of bound bacteria was diminished compared to static conditions. The herein described results allow to dissect the biological role of particular TAAs in ECM and host cell adherence and to identify differences in bacterial binding under static and dynamic conditions. Dynamic models expand the methodology to perform bacterial adherence experiments under more realistic blood-stream like conditions.
