title: Lack of lysosomal fusion with phagosomes containing Ehrlichia risticii in P388D1 cells: abrogation of inhibition with oxytetracycline.
abstract: Fusion of lysosomes with phagosomes containing Ehrlichia risticii, an obligate intracellular parasite, was evaluated in P388D1 murine macrophagelike cells. Lysosomes in cells ranging in infectivity from 30 to 70% were labeled cytochemically with acid phosphatase or via endocytosis of thorium dioxide or cationized ferritin to document phagosome-lysosome (P-L) fusion in untreated cells and cells treated with oxytetracycline. Regardless of the marker used, P-L fusion was generally not observed in E. risticii-containing vacuoles in untreated cells, while significantly greater P-L fusion with ehrlichia-containing vacuoles was observed after oxytetracycline treatment. When latex beads were introduced into uninfected cell cultures, P-L fusion was observed with vacuoles containing latex. Fusion of lysosomes with latex-containing vacuoles in cells was significantly greater than fusion of lysosomes with ehrlichia-containing vacuoles in the same infected cells. These findings indicate that E. risticii is able to inhibit P-L fusion, whereas oxytetracycline deprives organisms of this ability.
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092.
authors.forename: M Y
authors.initials: MY
authors.lastname: Wells
authors.forename: Y
authors.initials: Y
authors.lastname: Rikihisa
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D004536:Ehrlichia / Q000502:physiology*; D005293:Ferritins / Q000378:metabolism; D007425:Intracellular Membranes / Q000502:physiology; D008247:Lysosomes / Q000502:physiology*; D008264:Macrophages / Q000382:microbiology* / Q000502:physiology / Q000648:ultrastructure; D008561:Membrane Fusion / Q000187:drug effects*; D008854:Microscopy, Electron; D010118:Oxytetracycline / Q000494:pharmacology*; D010588:Phagosomes / Q000502:physiology*; D012287:Rickettsiaceae / Q000502:physiology*; D013911:Thorium Dioxide / Q000378:metabolism
chemical_list: C010297:polycationic ferritin; D005293:Ferritins; D013911:Thorium Dioxide; D000135:Acid Phosphatase; D010118:Oxytetracycline