AN ANIMAL MODEL FOR ESTABLISHING CHEMOTHERAPY AGAINST INTRACTABLE TOXOPLASMOSIS IN IMMUNOCOMPROMISED HOSTS BY THE USE OF IFN-γ KNOCKOUT MICE

The Toxoplasma gondii number was evaluated by quantitative competitive polymerase chain reaction (QC-PCR) assay with or without sulfamethoxazole treatment in the heart, blood, brain, and small intestine of IFN-γ knockout (GKO) BALB/c (B/c) mice after peroral infection with the cyst-forming Fukaya strain. T. gondii infection was observed in the heart, blood, and brain, but not in the small intestine, of mice treated with sulfamethoxazole for 4 weeks. No correlation between T. gondii loads and sulfamethoxazole concentrations in tissues and blood was observed. T gondii was not detected in the heart and blood after continuous sulfamethoxazole treatment for two months, but a small number of parasites was demonstrated in the brain. Thus, we successfully established an animal model for evaluating chemotherapy regimens in immunocompromised hosts by using GKO B/c mice infected with T. gondii.