RESUMO
Localization of antigens homologous to excretory-secretory proteins in developing embryos of Setaria digitata has been carried out by indirect fluorescent antibody test, [14C] labelling studies and Western blotting. Indirect fluorescent antibody test showed binding of excretory-secretory antibodies at perivitelline space. The fluorescent antibody binding was almost absent at small morulae stage and increasing in intensity in the successive developmental stages with maximum at coiled microfilaria stage. Hatched microfilaria did not show the presence of antigens by immunofluorescence. Immunocomplex of excretory-secretory antiserum against "amniotic fluid" collected from developing embryos of Setaria digitata labelled with [14C] amino acids showed highest radioactivity at coiled and tadpole stages and differed significantly from small morulae, big morulae and hatched microfilaria. Immunoblot analysis of amniotic fluid showed two proteins, 16·5 and 11 kDa, to be highly antigenic. The antigenic protein (11 kDa) content as seen by immuno blotting increased during embryogenesis and decreased at the stage of hatching.
RESUMO
Setaria digitata, a filarial parasite of cattle possesses certain unique characteristics like cyanide insensitivity, and lack of cytochromes. In the present study, we have shown that the parasite has an incomplete tricarboxylic acid cycle with the absence of activities of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase and succinyl-CoA synthase. However the parasite showed the existence of glyoxylate cycle and phosphoenolpyruvate-succinate pathway. The widely used antifilarial drug diethylcarbamazine caused general inhibition of all enzymes of phosphoenolpyruvate-succinate pathway and glyoxylate cycle except that of fumarase and isocitrate lyase. The results may pave the way for new targets for chemotherapy in the control of filarial parasites.