José de Angelis Côrtes

Comportamento imunológico e antigênico de cinco amostras de Toxoplasma gondii inoculadas em gatos

The biology of Toxoplasma gondii demonstrate that cats are the complete host responsable for the dissemination of this parasites. Two domestic cats were immunised with Toxoplasma gondii strains VPS (human), LIV-IV and LIV-V (porcine), CPL (caprine) and CN (feline). Live tachyzoites were utilized in intravenous inoculation of 2x107 (first inoculum) and 4x107 (second inoculum - 35 days later), except for strain VPS, where one cat died 10 days after the first inoculation and another showed symptoms of acute toxoplasmosis. In all other strains, no clinical signs were detected during 6 months of observation. The antibody response after immunization was monitored by indirect immunofluorescence (IF) test by the use of anti-cat IgG conjugate. The antibody titers obtained at the 20th day varied from 1:1,024 to 1:4,096 and from 1:1,024 to 1:8,000 at the 40th day. Only the VPS strain attained titers of 1:16,000 at the 30th day of immunization. Homologous and heterologos titers were equivalem without any difference among the strain. When the immune sera were adsorbed with live tachyzoites, a reduction in the antibody titers was demonstrated both in homologous and heterologous levels. These results suggest that although dijferences in virulence for cats are evident among the strains. The surface antigens are commom among the T. gondii strains on the basis of IF antibody level. The results also demonstrated that apparently there is no correlation between virulence and serological characteristics of the studied strains of Toxoplasma gondii. However the importance of the IF test in the laboratorial diagnosis of Toxoplasmosis is reinforced.