Toxoplasma gondii: fusion competence of parasitophorous vacuoles in Fc receptor-transfected fibroblasts

• Published in: Science (American Association for the Advancement of Science) Vol. 249; no. 4969; pp. 641 - 646
• Main Authors: Joiner, K. A., Fuhrman, S. A., Miettinen, H. M., Kasper, L. H., Mellman, I.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 10-08-1990; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Acidification; Animals; Antibodies; Biological and medical sciences; Cell Line; Cell lines; Cell membranes; cells; Cellular biology; cellule; celulas; CHO cells; fagocitos; Fc receptors; fibroblaste; fibroblastos; Fibroblasts; Fibroblasts - parasitology; Fibroblasts - physiology; Fibroblasts - ultrastructure; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Hamsters; infecciones; infection; Invertebrates; Life cycle. Host-agent relationship. Pathogenesis; Lysosomes; Lysosomes - physiology; Lysosomes - ultrastructure; Macrophages - immunology; Medical research; Membrane Fusion; Mice; Mice, Inbred BALB C; Parasites; Parasitism; phagocyte; phagocytes; Phagocytosis; Physiological aspects; Protozoa; Protozoans; Receptors, Fc - genetics; Receptors, Fc - physiology; Research Article; Tachyzoites; Toxoplasma; Toxoplasma - growth & development; Toxoplasma - physiology; Toxoplasma gondii; Transfection; vacuola; vacuole; Vacuoles; Vacuoles - parasitology; Vacuoles - physiology; Vacuoles - ultrastructure; Protozoa; Host parasite relation; Melting; Lysosome; Rodentia; Parasite; Vacuole; Vertebrata; Mammalia; Toxoplasma gondii; Immunofluorescence; Sporozoa; Cell; Phagocytosis
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.2200126

After actively entering its host cells, the protozoan parasite Toxoplasma gondii resides in an intracellular vacuole that is completely unable to fuse with other endocytic or biosynthetic organelles. The fusion blocking requires entry of viable organisms but is irreversible: fusion competence of the vacuole is not restored if the parasite is killed after entry. The fusion block can be overcome, however, by altering the parasite's route of entry. Thus, phagocytosis of viable antibody-coated T. gondii by Chinese hamster ovary cells transfected with macrophage-lymphocyte Fc receptors results in the formation of vacuoles that are capable of both fusion and acidification. Phagocytosis and fusion appear to involve a domain of the Fc receptor cytoplasmic tail distinct from that required for localization at clathrin-coated pits. These results suggest that the mechanism of fusion inhibition is likely to reflect a modification of the vacuole membrane at the time of its formation, as opposed to the secretion of a soluble inhibitor by the parasite.