Isolation and characterization of a diagnostic polysaccharide antigen from larval Echinococcus multilocularis

A diagnostic antigen, C-antigen, was evaluated in serodiagnosis of alveolar hydatid disease by Western blotting. The C-antigen migrated diffusely to the region of 30-35 kDa in 8% polyacrylamide-SDS gel electrophoresis. We isolated this antigen from a crude metacestode extract by a simple method of phenol/chloroform extraction. The isolated antigen was resistant to boiling, proteolysis and acid hydrolysis, but destroyed with sodium periodate. Such lectins as peanut agglutinin (PNA), Ricinus communis lectin (RCA120) and wheatgerm agglutinin (WGA) were capable of binding with the isolated antigen; no binding to concanavalin A (Con A), Lens culinaris agglutinin (LCA) or Phaseolus vulgaris (PHA-E4) was demonstrated. C-antigen is associated with a polysaccharide containing galactose and N-acetyl glucosamine residues.