Isolation and structural characterization of Toxocara vitulorum specific antigen and its potency in diagnosis of toxocariasis among buffalo calves.

A method of affinity chromatography purification of species-specific antigen from Toxocara vitulorum adult worm is described. The purification process resulted in a fraction with 9315 fold increase in specific activity compared to crude extract. Structural characterization of the isolated fraction by SDS polyacrylamide gel electrophoresis, isoelectric focusing and amino acid analysis showed that the fraction consists of only two polypeptides of 92 kD and 87 kD with isoelectric points of 8.8 and 8.9. Moreover, 17 amino acids were identified in the fraction with high proportions of only three of them (tyrosine, glycine and glutamic). The isolated antigen proved potency in the diagnosis of toxocariasis among buffalo claves using ELISA which recorded 100% sensitivity.