Ascaris sensitivity in the dog. I. isolation and characterization of an antigen

After an infection dogs will develop a high titer of reaginic antibody to Toxocara canis, which cross reacts with an antigen from pig Ascaris suum. This report describes the purification of the Ascaris antigen by molecular sieve and ion-exchange chromatography. The end product is immuno-electrophoretically pure, with a molecular weight of 18,400; 3.46 moles of tryptophan; 4.35 of tyrosine and 5.4 of hexose per mole. The pI appears to be 5.1. The purified protein will cause an immediate hypersensitivity reaction in the skin or pulmonary system of a sensitive dog and appears to be the only such material present in the crude preparation. Unlike other preparations of Ascaris reported in the literature (Uvnas and Wold, 1967), this material has no direct mast cell degranulation properties.