title: Parasiticidal activity of bovine lactoperoxidase against Toxoplasma gondii.
abstract: Toxoplasma gondii is an obligatory intracellular parasitic protozoan transmitted via the ingestion of raw, infected meat that causes congenital infections. In a cell-free environment, virulent Toxoplasma was strikingly resistant to H2O2. The activity of H2O2 or H2O2 generated by glucose-glucose oxidase against the resistant tachyzoite stage of pathogenic T. gondii was enhanced by adding KI and bovine lactoperoxidase (bLPO), referred to here as the bLPO system. Replacing bLPO (heme content, 90%) with recombinant bLPO (heme content, 6%) did not enhance the parasiticidal activity with KI and H2O2. These results indicated that heme contributed to the enzyme activity and resulted in the killing of tachyzoites of T. gondii. Tachyzoites treated with the bLPO system also lost the ability to penetrate the mouse fibroblast cell line (NIH/3T3), and could be killed intracellularly after exposure by bLPO to a mouse macrophage cell line (J774A.1). These findings suggested that toxicity was mediated through small amounts of H2O2 generated by phagocytic events in naive macrophages, and by the peroxidative activity of bLPO. Our observations suggest that the bLPO system could help prevent the development of Toxoplasmosis in humans after ingesting raw, infected meat.
authors.affiliation: Laboratory of Dairy Food Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan. tetsuya@anim.agr.hokudai.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tanaka
authors.forename: Shin
authors.initials: S
authors.lastname: Murakami
authors.forename: Haruto
authors.initials: H
authors.lastname: Kumura
authors.forename: Ikuo
authors.initials: I
authors.lastname: Igarashi
authors.forename: Kei-Ichi
authors.initials: K
authors.lastname: Shimazaki
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006418:Heme / Q000502:physiology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007784:Lactoperoxidase / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology; D051379:Mice; D041681:NIH 3T3 Cells; D011193:Potassium Iodide / Q000494:pharmacology; D013997:Time Factors; D014122:Toxoplasma / Q000187:drug effects*; D014123:Toxoplasmosis / Q000469:parasitology; D014709:Vero Cells
chemical_list: D000977:Antiparasitic Agents; D004338:Drug Combinations; D011193:Potassium Iodide; D006418:Heme; D006861:Hydrogen Peroxide; D007784:Lactoperoxidase; D002374:Catalase