Inhibitory effect of interferon-gamma activated ovine umbilical vein endothelial cells on the intracellular replication of Toxoplasma gondii

• Published in: Veterinary research (Paris) Vol. 27; no. 4-5; pp. 527 - 534
• Main Authors: Dimier, I.H. (Institut National de la Sante et de la Recherche Medicale, Tours (France). Immunologie des Maladies Infectieuses), Bout, D.T
• Format: Journal Article
• Language: English; French
• Published: England BioMed Central 1996
• Subjects: Amino Acids - pharmacology; Animal biology; Animal genetics; Animals; Arginine - pharmacology; Biochemistry, Molecular Biology; BLOOD VEINS; Cattle; Cell Behavior; CELLS; Cells, Cultured; Cellular Biology; CELLULE; CELULAS; Endothelium, Vascular - drug effects; Endothelium, Vascular - immunology; Endothelium, Vascular - parasitology; Fibroblasts - immunology; Fibroblasts - parasitology; Genetics; Humans; Immunity, Innate; Immunology; INHIBICION; INHIBITION; INTERFERON; Interferon-gamma - pharmacology; INTERFERONAS; INTERFERONS; Life Sciences; Macrophages - immunology; Macrophages - parasitology; Mice; Microbiology and Parasitology; Molecular biology; Neurons and Cognition; omega-N-Methylarginine - pharmacology; OVIN; OVINOS; Recombinant Proteins; RNA, Protozoan - biosynthesis; Santé publique et épidémiologie; SHEEP; Sheep Diseases; Toxoplasma - growth & development; Toxoplasma - physiology; TOXOPLASMA GONDII; Toxoplasmosis, Animal - immunology; Tryptophan - pharmacology; Umbilical Veins; Uracil - metabolism; VEINE; VENAS
• ISSN: 0928-4249; 1297-9716

Toxoplasma gondii is an obligate intracellular parasite that is a major cause of abortion and neonatal mortality in sheep. In congenital toxoplasmosis, T gondii first invades the umbilical vein endothelial cells and are then disseminated throughout the fetus. Treatment of ovine umbilical vein endothelial cells with bovine recombinant gamma-interferon (IFN-gamma) blocked the growth of T gondii. Growth of the parasite was measured by 3H-uracil incorporation 18 h after the onset of the infection and by microscopic enumeration of parallel cultures. This assay revealed that when the cells were pretreated with IFN-gamma in concentrations ranging from 0.15-1,250 U/mL, a high degree of inhibition of T gondii replication was observed with the effect being dose-dependent. Maximum activation was achieved by incubating with 625 U/mL IFN-gamma and no activity was present at 0.15 U/mL. This technique could be of relevance as a first line of defense against congenital ovine Toxoplasma infection. Inhibition of T gondii replication is due to a different mechanism from that existing in mouse macrophages and human fibroblasts. L-Arginine-dependent production of reactive nitrogen and oxygen intermediates was not responsible for the inhibition of T gondii replication. Supplements of five amino acids were able to overcome the inhibition partially but significantly. The mechanism of the inhibition remains to be elucidated.