Morphological variety of intracellular microcolonies of Legionella speciesin vero cells

Intracellular microcolonies of six Legionella species growing in Vero cells showed distinctly varied morphologies. The varieties were observed by ligh t microscopy of Gimenez-stained, Legionella-infected Vero cells and by elec tron microscopy (EM). Legionella pneumophila Philadelphia-1 formed needle-s haped crystal-like microcolonies. Legionella bozemanii WIGA formed microcol onies like wool balls containing filamentous cells, In EM, these organisms proliferated in endosomes, which were adjacent to swollen rough endoplasmic reticula, Legionella oakridgensis OR-10 showed serpentine chains. Many mit ochondria were observed around the microcolonies, Legionella jordanis BL-54 0 formed spherical moss-like microcolonies which were or were not surrounde d by endoplasmic membranes. Legionella feeleii WO-44C spread throughout the cytoplasm without making clusters. Legionella dumoffii Tex-KL made big clu sters that spread in the cytoplasm, a portion of which was outside the endo some membranes, These different morphologies imply diversity in modes of in tracellular multiplication of Legionella spp.