Purification of an antigen from the Taenia crassiceps metacestode vesicular fluid highly sensitive in detecting IgG-antibodies (ELISA) in calves with experimental cysticercosis.

This study reports on the purification of an antigen predominant within the vesicular fluid (VF) of T. crassiceps metacestodes and shown to share identity with the major vesicular fluid protein of the T. saginata larval stage. Purification was achieved by gel filtration of the VF on Sephacryl S-300 superfine, followed by ion exchange HPLC. The antigen represents a single polypeptide chain (Mr appr. 37,000) with carbohydrate moieties without affinity to ConA. Isoelectric focusing of the electrophoretical and immunological homogeneous antigen resulted in five bands focusing at pH 4.0, 4.2, 4.4, 4.6 and 4.8, respectively. In ELISA, the purified antigen detected serum IgG-antibodies in all 21-35 weeks old calves (n = 10) with experimental cysticercosis (70 to 6,000 viable larvae recovered). When compared to T. saginata metacestode VF the antigen was the better reagent for discriminating between infected and non-infected animals. As shown by immunodiffusion and ELISA the antigen is also common to the T. saginata adult stage and obviously to other taeniid metacestodes where it is accumulated in the VF or hydatid fluid.