Effect of Calcium on the Cell Infectivity of Virulent Shigella flexneri 2a

Abstract

Effect of calcium ions (Ca⁺⁺) on the virulence of Shigella flexneri 2a was examined with reference to its infeetivity to cultured cells, the guinea pig eye, and the ligatcd small intestine of rabbits. The organism grown in a calcium-containing medium showed a significantly higher ability to penetrate HeLa cells than that of organism grown in a calcium-deficient medium. This ability was constantly maintained in the presence of Ca⁺⁺, while readily lost in the absence of Ca⁺⁺. Similarly, its pathogenicity for the guinea pig eye and the ligated small intestine of rabbits was more or less greater in cases with Ca⁺⁺ than in cases tt ithout Ca⁺⁺, Ca⁺⁺ seemed to play an important role in bacterial adhesion to the cell membrane, by which the cellular engulfment was induced. The presence of Ca⁺⁺ in the environment of bacterial growth was emphasized on development and maintenance of virulence of S. flexneri 2a.