Fasciola hepatica: characterization of somatic and excretory-secretory antigens of adult flukes recognized by infected sheep.

The immune response of sheep to somatic components and excretory/secretory products of adult Fasciola hepatica, was studied during an experimental infection. Antibodies against adult fluke somatic and excretory/secretory antigens were detected by thin layer immunoassay from the second week post infection. Similarly, the results of Western blot analysis showed specific recognition of several components as early as two weeks after infection. However, an increase in the number and intensity of bands with time of infection was observed in the patterns of antigenic recognition. Most notorious was the strong reactivity of all infected sheep sera towards components of 20-23 kDa in the somatic preparation and components of 23-27 kDa in the excretory/secretory products of adult F. hepatica, specially noticeable after the sixth week post-infection. Since these polypeptides were recognized by all infected animals, they could play an important role in the diagnosis of sheep fascioliasis.

Comparison of dot enzyme-linked immunosorbent assay (Dot-ELISA), passive haemagglutination test (PHT) and thin layer immunoassay (TIA) in the diagnosis of natural or experimental Fasciola hepatica infections in sheep.

The dot enzyme-linked immunosorbent assay (Dot-ELISA) was compared with the passive haemagglutination test (PHT) and thin layer immunoassay (TIA) for the detection of antibodies against Fasciola hepatica in naturally and experimentally infected sheep. The infected animals gave titres from 1:25,000 to 1:204,000, while control animals gave titres of from 1:100 to 1:800. The titres of the infected sheep obtained by Dot-ELISA were 1000-2000 times higher than the ones obtained using TIA or PHT. Due to its high sensitivity, this technique could be very useful for the diagnosis of ovine fascioliasis.

Complejos inmunes circulantes en ovinos infestados con Fasciola hepatica / Circulating immune complex in sheep infected with Fasciola hepatica

Se determinó la presencia de complejos inmunes circulantes (CIC) en 38 sueros de ovinos infestados con Fasciola hepatica y 15 sueros de ovinos libres del parásito, por precipitación con polietilenglicol 6000 (PEG) al 4, 6, 8 y 10%. La cantidad de proteína precipitada fue mucho mayor en los ovinos parasitados que en los testigos en todas las concentraciones de PEG utilizadas, observándose la mayor diferencia con PEG al 10%. Para corroborar la presencia de CIC se precipitaron los sueros con PEG al 2.5% y se determinó el consumo de complemento (CC) de estos precipitados obteniéndose valores promedio de 57% en los ovinos con fasciolasis y de 29% en los ovinos testigos. Se determinaron los títulos de anticuerpos contra F. hepatica por hemoaglutinación pasiva (HP), difusión doble en agar (DD) e inmunoensayo en capa delgada (ICD). No hubo relación entre la presencia de CIC y los títulos determinados en las pruebas serológicas, excepto en ICD dondo los sueros en títulos más altos fueron los sueros que dieron mayor preciptación con PEG y mayor CC

The action of macrophages and immune serum on growth of Babesia microti in short-term cultures.

The effect on growth of B. microti of macrophages from normal or B. microti recovered animals was tested in short-term cultures. Normal macrophages did not or only slightly inhibited parasite growth. When immune serum was added to the normal macrophage containing cultures, inhibition greater than that produced by immune serum alone was observed. Macrophages from immune animals had an inhibitory effect on parasite growth even in the absence of immune serum. Inhibition of B. microti growth was greater in cultures containing immune serum and immune macrophages than in cultures containing either immune serum or immune macrophages alone. Supernatants from B. microti cultures which contained immune macrophages or macrophages which had been stimulated by addition of immune serum inhibited parasite growth while cell free supernatant from cultures which contained no macrophages or normal macrophages did not. At 72 and 96 hr of culture erythrophagocytosis by macrophages was more prominent in immune serum containing B. microti cultures than in B. microti cultures not containing immune serum. More macrophages were retained in the immune serum containing cultures than in cultures not containing immune serum. Alternate culture-hamster passage yielded a B. microti strain which grew better in hamster erythrocyte short-term cultures than did the original strain.

Effect of immune serum on the growth of Babesia microti in hamster erythrocytes in short-term culture.

Short-term in vitro culture of Babesia microti was obtained. Immune hamster serum had an inhibitory effect on the growth of B. microti in vitro. It is suggested that these antibodies act by preventing penetration of erythrocytes by the parasite.