Phosphoenolpyruvate-succinate-glyoxylate pathway in the filarial parasiteSetaria digitata

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.