FIG. 3.

L. pneumophila morphology in the early replicative phase. Loose enlarged vacuoles associated with rough endoplasmic reticulum (arrowheads) and containing morphologically unchanged 2064 (A) or SVir (B) bacteria from a plate-grown inoculum, at about 6 h postinfection. (C) At 12 h postinfection, morphologically unchanged SVir bacterial cells from a plate-grown inoculum were often seen individually contained in tight vacuoles. (D) Morphologically unchanged and replicating SVir bacteria from a plate-grown inoculum in tight vacuoles that followed the contour of the enclosed bacteria. (E) Many vacuoles prominently surrounded by ribosomes and/or rough endoplasmic reticulum contained numerous bacteria (SVir shown at 12 h postinfection). Note the vacuolar membrane closely following the contour of the contained bacteria. (F) Bacteria from a HeLa cell-grown inoculum singly contained in tight vacuoles and showing the replicative morphology (strain 2064 at about 20 h postinfection). Bars, 0.5 μm.