Cinemicrographic study of tissue cell cultures infected with Shigella flexneri.

HeLa S3 and Henle's intestinal epithelial cells infected with virulent and avirulent strains of Shigella flexneri bacilli were studied by phase contrast, time-lapse cinemicrography. Virulent Shigella bacilli were found to attach to the surface of the cells evoking vigorous ruffling movement of the cell membrane. This was followed by the formation of pinocytotic vesicles and incorporation of bacilli into cells. In contrast, avirulent bacilli never became attached to cultured cells. Intracellular Shigella bacilli moved conspicuously independent of the movement of cellular organella and were seen within microfibrillar protrusions from the surface of the host cell. The bacilli exhibited polarity while moving and this movement was inhibited or halted by tetracycline. The nature of the movement of intracellular Shigella bacilli is discussed.