Temperature Depended Role ofShigella flexneriInvasion Plasmid on the Interaction withAcanthamoeba castellanii

[摘要] Shigella flexneriis a Gram-negative bacterium causing the diarrhoeal disease shigellosis in humans. The virulence genes required for invasion are clustered on a large 220 kb plasmid encoding type three secretion system (TTSS) apparatus and virulence factors such as adhesions and invasion plasmid antigens (Ipa). The bacterium is transmitted by contaminated food, water, or from person to person.Acanthamoebaeare free-living amoebae (FLA) which are found in diverse environments and isolated from various water sources. Different bacteria interact differently with FLA sinceFrancisella tularensis, Vibrio cholerae, Shigella sonnei, andS. dysenteriaeare able to grow insideA. castellanii. In contrast,Pseudomonas aeruginosainduces both necrosis and apoptosis to killA. castellanii. The aim of this study is to examine the role of invasion plasmid ofS. flexnerion the interaction withA. castellaniiat two different temperatures.A. castellaniiin the absence or presence of wild type, IpaB mutant, or plasmid-cured strainS. flexneriwas cultured at30∘C and37∘C and the interaction was analysed by viable count of both bacteria and amoebae, electron microscopy, flow cytometry, and statistical analysis. The outcome of the interaction was depended on the temperature since the growth ofA. castellaniiwas inhibited at30∘C, andA. castellaniiwas killed by invasion plasmid mediated necrosis at37∘C.

[学科分类] 微生物学和免疫学