title: Immune responses of mice intraduodenally infected with Toxoplasma gondii KI-1 tachyzoites.
abstract: Toxoplasma gondii Korean isolate (KI-1) tachyzoites were inoculated intraduodenally to BALB/c mice using a silicon tube, and the course of infection and immune responses of mice were studied. Whereas control mice, that were infected intraperitoneally, died within day 7 post-infection (PI), the intraduodenally infected mice survived until day 9 PI (infection with 1 × 10(5) tachyzoites) or day 11 PI (with 1 × 10(6) tachyzoites). Based on histopathologic (Giemsa stain) and PCR (B1 gene) studies, it was suggested that tachyzoites, after entering the small intestine, invaded into endothelial cells, divided there, and propagated to other organs. PCR appeared to be more sensitive than histopathology to detect infected organs and tissues. The organisms spread over multiple organs by day 6 PI. However, proliferative responses of splenocytes and mesenteric lymph node (MLN) cells in response to con A or Toxoplasma lysate antigen decreased significantly, suggesting immunosuppression. Splenic CD4(+) and CD8(+) T-lymphocytes showed decreases in number until day 9 PI, whereas IFN-γ and IL-10 decreased slightly at day 6 PI and returned to normal levels by day 9 PI. No TNF-α was detected throughout the experimental period. The results showed that intraduodenal infection with KI-1 tachyzoites was successful but did not elicit significant mucosal immunity in mice and allowed dissemination of T. gondii organisms to systemic organs. The immunosuppression of mice included reduced lymphoproliferative responses to splenocytes and MLN cells to mitogen and low production of cytokines, such as IFN-γ, TNF-α, and IL-10, in response to T. gondii infection.
authors: Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul National University Medical Research Center, Seoul 110-799, Korea.
authors: Eun-Hee
authors: EH
authors: Shin
authors: Yeoun Sook
authors: YS
authors: Chun
authors: Won-Hee
authors: WH
authors: Kim
authors: Jae-Lip
authors: JL
authors: Kim
authors: Kyoung-Ho
authors: KH
authors: Pyo
authors: Jong-Yil
authors: JY
authors: Chai
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004386:Duodenum / Q000276:immunology / Q000469:parasitology / Q000473:pathology; D042783:Endothelial Cells / Q000469:parasitology; D006651:Histocytochemistry; D007108:Immune Tolerance; D008198:Lymph Nodes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D016133:Polymerase Chain Reaction; D012376:Rodent Diseases / Q000276:immunology / Q000469:parasitology / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology* / Q000472:pathogenicity; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000469:parasitology / Q000473:pathology
chemical_list: D016207:Cytokines