RESUMO
Distinct Toxoplasma gondii antigens were entrapped within liposomes and evaluated for their ability to protect Balb/c mice against congenital transmission: soluble tachyzoite antigen (L/STAg), soluble tissue cyst antigen (L/SCAg), soluble tachyzoite plus tissue cyst (L/STCAg) or purified 32kDa antigen of tachyzoite (L/pTAg). Soluble tachyzoite antigen alone in PBS (STAg) or emulsified in Freund's Complete Adjuvant (FCA/STAg) was also evaluated. Dams were inoculated subcutaneously with these antigens 6, 4 and 2 weeks prior to a challenge with four tissue cysts of the P strain of T. gondii orally between 10 and 14 days of pregnancy. Significant diminution differences were observed between the frequency of infected pups born of the dams immunized with the antigens incorporated into liposomes and that of pups born of the dams immunized with antigen emulsified in FCA or non immunized group (p<0.05). There was a significant decrease in the number of pups born dead in the groups L/STAg, L/SCAg and L/pTAg when compared with pups from all other groups (p <0.05). All dams immunized with or without adjuvant showed an antibody response and a proliferation of T-cells. However, no correlation was found between immune response and protection against the challenge.
Assuntos
Antígenos de Protozoários/administração & dosagem , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Toxoplasma/imunologia , Toxoplasmose Congênita/transmissão , Animais , Animais Recém-Nascidos , Anticorpos Antiprotozoários/imunologia , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Feminino , Lipossomos , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Toxoplasmose Congênita/imunologia , Toxoplasmose Congênita/prevenção & controleRESUMO
Different toxoplasma antigens were entrapped within liposomes and evaluated, in this form, for their ability to protect Swiss mice against toxoplasma infection: soluble tachyzoite antigen (L/TAg), tissue cyst (L/CAg), tachyzoite plus tissue cyst (L/TCAg) or purified antigen of tachyzoite (L/pTAg). The protein used in L/pTAg was purified from tachyzoites using a stage-specific monoclonal antibody which reacted at a molecular weight of 32 kD in SDS PAGE and silver stain using reduced condition. To compare the immuno-adjuvant action of liposomes and of Freund's Complete Adjuvant (FCA), another group of mice was immunized with soluble tachyzoite antigen (STAg) emulsified in FCA (FCA/TAg). Control groups were inoculated with (STAg) alone, phosphate-buffered saline (PBS), FCA with PBS (FCA/PBS) and empty liposomes (L/PBS). Mice were inoculated subcutaneously with these antigens six, four and two weeks before a challenge with 80 tissue cysts of the P strain of Toxoplasma gondii orally. All mice immunized with or without adjuvant showed a humoral response, as measured by Elisa. However, no correlation was found between antibody titer and protection against the challenge. All mice immunized with L/pTAg or L/TCAg survived (100), whereas 80% and 90% of mice from groups which received respectively PBS or FCA/PBS and L/PBS died. All mice immunized with antigens entrapped within liposomes (L/TAg, L/CAg, L/TCAg and L/pTAg) showed low numbers of intracerebral cysts.
Assuntos
Antígenos de Protozoários/administração & dosagem , Proteínas de Protozoários/imunologia , Vacinas Protozoárias/imunologia , Toxoplasma/imunologia , Toxoplasmose/prevenção & controle , Animais , Anticorpos Monoclonais , Antígenos de Protozoários/isolamento & purificação , Relação Dose-Resposta Imunológica , Portadores de Fármacos , Feminino , Lipossomos , Camundongos , Toxoplasma/isolamento & purificação , Toxoplasmose/imunologiaRESUMO
Tissue cysts of Besnoitia sp. were found in muscles and several organs from a naturally infected Akodon montensis captured in the rural area of the municipality of Timbó, Santa Catarina State, in southern Brazil. Indirect fluorescence and enzyme-linked immunosorbent assays carried out with sera from mice chronically infected with Toxoplasma gondii and Besnoitia sp. showed, as expected, a stronger reaction against homologous than heterologous antigens. No cross-protection was observed in mice immunized with T. gondii when challenged with Besnoitia sp. This is the first description of a natural infection of A. montensis by parasites of the genus Besnoitia sp. in Brazil.
Assuntos
Arvicolinae/parasitologia , Coccidiose/veterinária , Eimeriida/imunologia , Enteropatias Parasitárias/veterinária , Doenças dos Roedores/parasitologia , Animais , Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Brasil , Coccidiose/parasitologia , Eimeriida/isolamento & purificação , Eimeriida/patogenicidade , Ensaio de Imunoadsorção Enzimática/veterinária , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Enteropatias Parasitárias/parasitologia , Masculino , Camundongos , VirulênciaRESUMO
A Dot enzyme-linked immunosorbent assay (Dot-ELISA) was standardized and evaluated for the serodiagnosis of human toxoplasmosis. Out of 538 serum samples tested by the immunofluorescence test for toxoplasmosis (IFAT-IgG) as reference test, 183 (34%) were positive at cut off 1:16 and 192 (36%) were positive for Dot-ELISA-IgG at cut-off 1:256. For Dot-ELISA, co-positivity was 0.94, co-negativity 0.94 and concordance 0.88 in relation to IFAT-IgG. These results suggest the usefulness of Dot-ELISA (cut-off titer of 1:256) for the serodiagnosis of human toxoplasmosis. The main advantage of this technique is simplicity, positive test can be visually identified (colored precipitate). It does not require a special equipment and it can be used as a qualitative test to screen large numbers of samples or as a quantitative assay to determine end-point titration of individual sera.