Korean J Parasitol.  2011 Jun;49(2):115-123. 10.3347/kjp.2011.49.2.115.

Immune Responses of Mice Intraduodenally Infected with Toxoplasma gondii KI-1 Tachyzoites

• Shin EH
• Chun YS
• Kim WH
• Kim JL
• Pyo KH
• Chai JY

• KMID: 1090610
• DOI: http://doi.org/10.3347/kjp.2011.49.2.115

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 1x10(5) tachyzoites) or day 11 PI (with 1x10(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-gamma and IL-10 decreased slightly at day 6 PI and returned to normal levels by day 9 PI. No TNF-alpha 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-gamma, TNF-alpha, and IL-10, in response to T. gondii infection.

Keyword

Toxoplasma gondii; Korean Isolate-1 (KI-1); intraduodenal infection; immunosuppression

MeSH Terms

Animals
Cell Proliferation
Cytokines/secretion
Disease Models, Animal
Duodenum/immunology/parasitology/pathology
Endothelial Cells/parasitology
Histocytochemistry
Immune Tolerance
Lymph Nodes/immunology
Mice
Mice, Inbred BALB C
Polymerase Chain Reaction
Rodent Diseases/immunology/parasitology/pathology
T-Lymphocyte Subsets/immunology
Toxoplasma/*immunology/pathogenicity
Toxoplasmosis, Animal/*immunology/parasitology/pathology