title: Toxoplasma gondii: acquired ocular toxoplasmosis in the murine model, protective role of TNF-alpha and IFN-gamma.
abstract: DNA and mRNA amplification by the polymerase chain reaction (PCR), immunohistochemical, and histopathology were performed in the eyes and brains from C57BL/6 mice infected with an avirulent strain of Toxoplasma gondii (ME49). Focal ocular inflammation and retinal pigment epithelial involvement were commonly observed after 15 days of infection. Four weeks after infection a stable number of cysts was observed in the brain but rarely in the eye, and they did not elicit an inflammatory response. In most of the ocular lesions the presence of the parasite could not be demonstrated even with the PCR technique. B1 DNA fragments of T. gondii were detected in only 4 of 11 eyes tested by PCR and Southern blot hybridization. Treatment of mice with mAbs against T cells (CD4 plus CD8) or cytokines (IFN-gamma or TNF-alpha) resulted in a marked increase of ocular lesions, more often associated with the presence of the parasite and the severity of inflammatory response. This model and the techniques utilized here can improve our understanding of the respective roles of parasite proliferation and immune mechanisms involved in the pathogenesis of acquired ocular toxoplasmosis.
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: R T
authors.initials: RT
authors.lastname: Gazzinelli
authors.forename: A
authors.initials: A
authors.lastname: Brézin
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: R B
authors.initials: RB
authors.lastname: Nussenblatt
authors.forename: C C
authors.initials: CC
authors.lastname: Chan
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015139:Blotting, Southern; D001921:Brain / Q000469:parasitology / Q000473:pathology; D015704:CD4 Antigens / Q000276:immunology; D016827:CD8 Antigens / Q000276:immunology; D016054:DNA, Protozoan / Q000032:analysis; D004195:Disease Models, Animal; D005123:Eye / Q000469:parasitology / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D016867:Immunocompromised Host; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology; D014122:Toxoplasma / Q000235:genetics / Q000302:isolation & purification*; D014126:Toxoplasmosis, Ocular / Q000209:etiology* / Q000276:immunology / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D016827:CD8 Antigens; D016054:DNA, Protozoan; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma