Soroprevalência e fatores associados à infecção por Toxoplasma gondii em caprinos de propriedades rurais do município de Mossoró, RN / Seroprevalence and factors associated with Toxoplasma gondii infection in goats on farms in the municipality of Mossoró, Rio Grande do Norte, Brazil

O município de Mossoró/RN, no Nordeste do Brasil, tem como destaque a criação de caprinos. A toxoplasmose é uma zoonose que é mais patogênico para os caprinos do que para os demais animais de abate. Em caprinos, o protozoário frequentemente é responsável por problemas reprodutivos e perdas econômicas. Com o objetivo de identificar a soroprevalência e os fatores de risco da toxoplasmose em caprinos de propriedades rurais do Município de Mossoró, amostras de soro de 338 animais (320 fêmeas e 18 machos) de 15 unidades produtoras foram testados pelo Ensaio Imunoenzimático (ELISA). Das 15 propriedades, 14 apresentaram animais soropositivos para toxoplasmose, e nestas o total de animais positivos foram de 125 (123 fêmeas e 2 machos), obtendo uma prevalência de 37,0%. Houve uma relação significativa (p<0,05) entre a prevalência e o sexo, e entre a prevalência e raça dos animais. As chances de ocorrer (OR) mais importantes associados à infecção por Toxoplasma gondii foram: fonte de água (OR=2,635), vasilhames para a água dos animais localizado fora das instalações da propriedade (OR=3,121) e a exploração do tipo leiteira (OR=2,546). Pela análise do ELISA de avidez, foram encontradas fêmeas em idade reprodutiva na fase aguda da infecção.

The municipality of Mossoró, RN, Northeastern Brazil, is featured on goat rearing. Toxoplasmosis is a zoonosis which is more pathogenic for goats when compared with other animals for slaughter. In this species, the protozoan is often responsible for reproductive problems and economic losses. In order to identify the seroprevalence and risk factors of toxoplasmosis in goats of farms in this municipality, serum samples from 338 animals (320 females and 18 males) of 15 production units were tested by enzyme immunoassay (ELISA). Of the 15 farms, 14 had animals positive for Toxoplasma gondii, and in these the total number of seropositive animals were 125 (123 females and 2 males), yielding a prevalence of 37.0%. There was a significant relationship (p<0.05) between prevalence and sex, and between the prevalence and breed of animals. The most important risk factors associated with T. gondii infection were: water supply with odds ratio (OR=2.635), containers for water animals located outside the premises of property (OR=3.121) and the exploitation of dairy type (OR=2.546). For the analysis of the avidity ELISA, was found females of reproductive age in the acute phase of infection.

Toxoplasmose congênita em filho de mãe cronicamente infectada com reativação de retinocoroidite na gestação / Congenital toxoplasmosis from a chronically infected woman with reactivation of retinochoroiditis during pregnancy an underestimated event?

Objetivo: Apresentar um caso raro de toxoplasmose congênita de uma mãe imunocompetente com infecção crônica que teve reativação da doença ocular durante a gestação. Descrição: O recém-nascido estava assintomático no nascimento e foi identificado através de triagem neonatal (IgM anti-Toxoplasma gondii em sangue seco) entre outros 190 bebês com toxoplasmose congênita durante um período de 7 meses. Sua mãe tinha tido um episódio não tratado de reativação de retinocoroidite toxoplásmica durante a gestação, com títulos de IgG estáveis e resultados negativos para IgM. Os resultados de IgM e IgG no soro do recém-nascido e o teste de immunoblotting para IgG foram positivos, e detectou-se lesões retinocoroideanas ativas na periferia da retina. O recém-nascido foi tratado com sulfadiazina, pirimetamina e ácido folínico. Aos 14 meses de vida, a criança permanecia assintomática, com regressão das lesões retinocoroideanas e persistência de IgG. Comentários: É possível que a triagem neonatal sistemática em áreas com alta prevalência de infecção possa identificar esses casos.

Objectives: To report a rare case of congenital toxoplasmosis from an immunocompetent mother with chronic infection who had reactivation of ocular disease during pregnancy. Descriptions:The newborn was asymptomatic at birth and identified by neonatal screening (IgM anti-Toxoplasma gondii in dried blood) among other 190 infants with congenital toxoplasmosis during a 7-month period. His mother had had a non-treated episode of reactivation of toxoplasmic retinochoroiditis during pregnancy, with stable IgG titers and negative IgM results. Results of IgM and IgG in the newborn’s serum, as well as IgG immunoblotting were positive and active retinochoroidal lesions were detected in his peripheral retina. The neonate was treated with sulfadiazine, pyrimethamine and folinic acid. At 14 months of life, the child remained asymptomatic, with regression of retinochoroidal lesions and persistence of IgG. Comments: It is possible that systematic neonatal screening in areas with high prevalence of infection may identify these cases.

The role of MHC haplotypes H2d/H2b in mouse resistance/susceptibility to cyst formation is influenced by the lineage of infective Toxoplasma gondii strain

Toxoplasma gondii strains displaying the Type I/III genotype are associated with acquired ocular toxoplasmosis in humans. Here, we used a mice model to characterize some immunological mechanisms involved in host resistance to infection with such strains. We have chosen the Type I/III strains D8, G2 and P-Br, which cause a chronic infection in mice that resembles human toxoplamosis. Mice deficient of molecules MyD88, IFN-gamma, and IL-12 were susceptible to all three parasite strains. This finding indicates the importance of innate mechanisms in controlling infection. On the other hand, MHC haplotype did not influenced resistance/susceptibility; since mice lineages displaying a same genetic background but different MHC haplotypes (H2b or H2d) developed similar mortality and cyst numbers after infection with those strains. In contrast, the C57BL/6 genetic background, and not MHC haplotype, was critical for development of intestinal inflammation caused by any of the studied strains. Finally, regarding effector mechanisms, weobserved that B and CD8+ T lymphocytes controlled survival,whereas the inducible nitric oxide synthase influenced cyst numbers in brains of mice infected with Type I/III strains. These findings are relevant to further understanding of the immunologic mechanisms involved in host protection and pathogenesis during infection with T. gondii.

Cepas de Toxoplasma gondii que apresentam o genótipo I/III são associadas a toxoplasmose ocular adquirida em humanos. No presente trabalho, nós utilizamos um modelo da doença em camundongos para caracterizar mecanismos imunológicos envolvidos na resistência do hospedeiro à infecção por aquelas cepas. Escolhemos as cepas D8, G2 e P-Br, que causam infecção crônica em camundongos, semelhante à toxoplasmose humana. Camundongos deficientes em MyD88, IFN-G e IL-12 foram susceptíveis a infecções com todas as três linhagens do parasita. Esses dados indicam a importância de mecanismos inatos no controle da infecção. Por outro lado, o haplótipo do MHC não influenciou na resistência/susceptibilidade, na medida em que linhagens de camundongos com um mesmo "background'' genético, mas diferentes haplótipos de MHC (H2b e H2d) apresentam o índice de mortalidade e número de cistos semelhantes após a infecção com aquelas cepas do parasita. Em contraste, o "background'' genético de C57BL/6, mas não o haplótipo de MHC, foi crítico para o desenvolvimento de inflamação intestinal causada pelas cepas estudadas. Finalmente, com relação aos mecanismos efetores, observamos que linfócitos B e T CD8+ controlam a sobrevivência após infecção. Por outro lado, a ativação da enzima óxido nítrico sintase induzida foi um fator importante para controle do número de cistos cerebrais em camundongos infectados com cepas do Tipo I/III. Esses achados são relevantes para o melhor entendimento dos mecanismos imunológicos envolvidos na proteção e patogênese durante infecção com T. gondii.

Vertical toxoplasmosis in a murine model. Protection after immunization with antigens of Toxoplasma gondii incorporated into liposomes

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

Protection against Toxoplasmosis in Mice Immunized with Different Antigens of Toxoplasma gondii Incorporated into Liposomes

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 percent and 90 percent 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

Avaliacao parasitologica e sorologica de caprinos inoculados experimentalmente pelo Trypanosoma cruzi / Serological and parasitological evaluation of goats experimentally inoculated with Trypanosoma cruzi

A infeccao experimental pelo Trypanosoma cruzi foi estudada em nove caprinos jovens. Os animais foram inoculados via intraperitoneal com 1000 tripomastigotas sanguineos/Kg de peso com as cepas 147 (Grupo 1) e 229 (Grupo 2), isoladas de pacientes chagasicos cronicos de Babui, MG. Realizaram-se exames de sangue a fresco, xenodiagnostico, hemocultura e sorologia (RIFI e ELISA)...