title: Characteristic morphology of intracellular microcolonies of  Legionella oakridgensis  OR-10.
abstract: Legionella oakridgensis  occasionally causes pneumonia in humans. We report here the characteristic morphology of intracellular microcolonies of L. oakridgensis OR-10 in infected epithelial cells. By light microscopy after Gimenez staining, the bacteria showed serpentine-like chain, disk-like conglomerate, and granular forms when they grew intracellularly in Vero cells, HeLa cells, and A549 cells. In a time-lapse study, we observed the progressive change from a serpentine-like chain form to a conglomerate form in Vero cells. Transmission electron microscopy showed that L. oakridgensis OR-10 proliferated both inside membrane structures and in the cytoplasm. Such highly serpentine chain growth has not been reported in any intracellular bacteria. Furthermore, these results imply that L. oakridgensis OR-10 may be proliferating inside the endoplasmic reticulum.
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Takekawa
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Saito
authors.forename: Changle
authors.initials: C
authors.lastname: Wang
authors.forename: Tian
authors.initials: T
authors.lastname: Qin
authors.forename: Midori
authors.initials: M
authors.lastname: Ogawa
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kanemaru
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000382:microbiology*; D004721:Endoplasmic Reticulum / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology; D006367:HeLa Cells; D006801:Humans; D007875:Legionella / Q000254:growth & development* / Q000502:physiology; D014709:Vero Cells