Regulatory T Cells as an Escape Mechanism to the Immune Response in Taenia crassiceps Infection.

Murine cysticercosis by Taenia crassiceps is a model for human neurocysticercosis. Genetic and/or immune differences may underlie the higher susceptibility to infection in BALB/cAnN with respect to C57BL/6 mice. T regulatory cells (Tregs) could mediate the escape of T. crassiceps from the host immunity. This study is aimed to investigate the role of Tregs in T. crassiceps establishment in susceptible and non-susceptible mouse strains. Treg and effector cells were quantified in lymphoid organs before infection and 5, 30, 90, and 130 days post-infection. The proliferative response post-infection was characterized in vitro. The expression of regulatory and inflammatory molecules was assessed on days 5 and 30 post-infection. Depletion assays were performed to assess Treg functionality. Significantly higher Treg percentages were observed in BALB/cAnN mice, while increased percentages of activated CD127+ cells were found in C57BL/6 mice. The proliferative response was suppressed in susceptible mice, and Treg proliferation occurred only in susceptible mice. Treg-mediated suppression mechanisms may include IL-10 and TGFß secretion, granzyme- and perforin-mediated cytolysis, metabolic disruption, and cell-to-cell contact. Tregs are functional in BALB/cAnN mice. Therefore Tregs could be allowing parasite establishment and survival in susceptible mice but could play a homeostatic role in non-susceptible strains.

Usefulness of serological ELISA assay for Taenia saginata to detect naturally infected bovines.

Bovine cysticercosis, a cosmopolitan disease caused by Taenia saginata, leads to economic losses due to carcass devaluation at slaughter. Sanitary inspection at slaughterhouses, the routine diagnostic method in Brazil, lacks the necessary sensitivity to detect the mildly infected cattle that are typically encoutered in Brazil. In this study we have tested cattle sera from animals diagnosed as positive and negative by veterianry inspection for (1) anti-parasite antibodies using metacestodes antigens (T. solium vesicular fluid and T. saginata secretions) and (2) the HP10 secreted antigen of viable metacestodes. The cut-off values were calculated by ROC curve for intense and mild infections conditions, and by the classical method ( for negative samples). The sensitivity and specificity of these diagnostic tests were different depending on the assumed cut-off value and, importantly, whether the infection was mild or intense. In spite of these observations, however, such ELISA assays for serum antibodies and parasite antigens constitute an important tool for epidemiological porposes, and in establishing priorities for the control of bovine cysticercosis.

Usefulness of serological ELISA assay for Taenia saginata to detect naturally infected bovines / Utilização de teste sorológico ELISA para a detecção de bovinos naturalmente infectados por Taenia saginata

Bovine cysticercosis, a cosmopolitan disease caused by Taenia saginata, leads to economic losses due to carcass devaluation at slaughter. Sanitary inspection at slaughterhouses, the routine diagnostic method in Brazil, lacks the necessary sensitivity to detect the mildly infected cattle that are typically encoutered in Brazil. In this study we have tested cattle sera from animals diagnosed as positive and negative by veterianry inspection for (1) anti-parasite antibodies using metacestodes antigens (T. solium vesicular fluid and T. saginata secretions) and (2) the HP10 secreted antigen of viable metacestodes. The cut-off values were calculated by ROC curve for intense and mild infections conditions, and by the classical method ( X + 2DP for negative samples). The sensitivity and specificity of these diagnostic tests were different depending on the assumed cut-off value and, importantly, whether the infection was mild or intense. In spite of these observations, however, such ELISA assays for serum antibodies and parasite antigens constitute an important tool for epidemiological porposes, and in establishing priorities for the control of bovine cysticercosis.

A cisticercose bovina, uma doença cosmopolita causada pela Taenia saginata, resulta em perdas econômicas devido á desvalorização de carcaças durante o abate. A inspeção sanitária nos frigoríficos, método de diagnóstico de rotina no Brasil, não possui sensibilidade necessária para detectar animais levemente infectados, os quais são tipicamente encontrados no Brasil. Neste estudo testou-se soro de animais diagnosticados positivos e negativos pela inspeção veterinária por (1) anticorpos anti-parasita usando antígenos de metacestóides (fluido vesicular de T. solium e secreções de T. saginata) e (2) antígeno secretado de metacestóides viáveis. Os pontos de corte foram calculados pela curva ROC, considerando condições de intensa e leve infeção, e pelo método clássicoo ( X + 2DP das amostras negativas).. A sensibilidade e a especificidade dos testes diagnósticos foram diferentes dependendo do valor de ponto de corte assumido e, sobretudo, se a infecção era intensa ou leve. Apesar destas observações, no entanto, tanto o ensaio ELISA para anticorpos séricos quanto para antígeno de parasita constituem importante ferramenta para propósitos epidemiológicos e no estabelecimento de prioridades no controle da cisticercose bovina.