COMPARISON OF TISSUE CYSTS FORMATION, ORGAN WEIGHT GAIN AND KINETICS OF ANTIBODIES IN SWISS MICE INFECTED WITH Toxoplasma gondii

Abstract

Groups of six Swiss albino mice, 30 days of age, females, were inoculated with 20 tissue cysts of strains ME49 (genotype II): G1 and G2 and M7741 (genotype III): G3 and G4), by oral (G1 and G3) or subcutaneous (G2 and G4) routes, and not inoculated (G5). Animals were observed daily for clinical changes and were killed 60 days after inoculation. The liver, spleen, kidneys, lungs, heart and brain were weighted, and the brain was macerated for cyst counting. Blood samples were collected every 15 days and serum samples were submitted to modified agglutination test (MAT) for the detection of anti-Toxoplasma gondii antibodies. There was a significant difference in the weight of the organs of infected animals when compared with the control group, mainly for the oral inoculation, no matter the strain used. Strain M7741 did not produce cysts visible in light microscopy, whereas strain ME49 showed a greater number of cysts in oral infection compared with the subcutaneous infection. No serum sample of the control group and all serum samples of the experimental groups showed antibodies anti-Toxoplasma, demonstrating the sensitivity and specificity of MAT for this species. Although antibody profiles of the four groups inoculated were different, antibody detection generally occurred starting 14 days post-inoculation (DPI), peaked at 28 or 42 DPI and antibody titers dropped or were maintained at 56 DPI.