[WS7] 選抜ワークショップ：病原因子と生態防御（毒素・エフェクター・生理活性物質等）

[WS7-7/ODP-127] 百日咳菌におけるIII型分泌タンパク質の産生条件の検討

○後藤 雅貴¹，桑江 朝臣¹，花輪 智子²，阿部 章夫¹ (¹北里大・院・感染制御科学府・分子細菌，²杏林大・医・感染症)

Bordetella pertussis uses a type III secretion system (T3SS) to inject virulence proteins into host cells. Although the B. pertussis T3SS was presumed to be involved in host colonization, efficient secretion of type III secreted proteins from B. pertussis has not been observed. To investigate the roles of type III secreted proteins during infection, we attempted to optimize culture conditions for the production and secretion of a type III secreted protein, BteA, in B. pertussis. We observed that B. pertussis efficiently secretes BteA in ascorbic acid-depleted (AsA⁻) medium. When L2 cells, a rat lung epithelial cell line, were infected with B. pertussis cultured in the (AsA⁻) medium, BteA-dependent cytotoxicity was observed. We also performed an immunofluorescence assay of L2 cells infected with B. pertussis. Clear fluorescence signals of Bsp22, a needle structure of T3SS, were detected on the bacterial surface of B. pertussis cultured in the (AsA⁻) medium. Since ascorbic acid is known as a reducing agent, we cultured B. pertussis in liquid medium containing other reducing agents such as 2-mercaptoethanol and dithioerythritol. Under these reducing conditions, the production of type III secreted proteins was repressed. These results suggest that in B. pertussis, the production and secretion of type III secreted proteins are downregulated under reducing conditions.