Studies on the immunoglobulin E responses to Teladorsagia circumcincta in sheep: purification of a major high molecular weight allergen

Studies on the immunoglobulin (Ig)E immune responses to the gastric nematod e, Teladorsagia circumcincta, have demonstrated a major high molecular weig ht allergen (HMWTc). Cross reactive allergens of similar MW were demonstrat ed for Trichostrongylus colubriformis and Cooperia curticei, but not for Ha emonchus contortus. Purification of HMWTc was achieved by gel-filtration ch romatography, and nonreducing SDS-PAGE and Western blot analysis revealed t wo closely associated bands with a molecular weighs of approximately 140-15 0 kDa. Reduction showed four IgE reactive bands of 120, 50, 45 and 30 kDa, and deglycosylation abrogated the immunoreactivity of the 120 and 30 kDa ba nds. Ultrastructural immunolocalization by electron microscopy revealed tha t the IgE reactivity was confined to the cuticular surface of the infective (L3) larvae. ELISA studies to determine the IgE anti-HMWTc responses in la mbs during Their first grazing season, demonstrated significantly higher Ig E antibody in lambs with low accumulative faecal egg count (FEC) compared t o animals with high accumulative FEC. These studies provide evidence for a protective function of IgE antibody in Teladorsagia infections in lambs.