ISOLATION, CHARACTERIZATION AND IMMUNOLOCALIZATION OF A GLOBIN-LIKE ANTIGEN FROM OSTERTAGIA-OSTERTAGI ADULTS

Western blot analysis using an anti-globin rabbit serum Rb94 revealed a major band of 17 kDa in extracts of Ostertagia ostertagi adults and 4th-stage larvae. The adult stage globin-like antigen (OoAdGlb) was pu rified from total worm extracts by liquid chromatography. The protein has an estimated molecular mass of 36 kDa under non-reducing condition s, suggesting a dimeric structure containing 2 non-covalently linked 1 7 kDa monomers. Tryptic peptides were sequenced and showed strong simi larities with the globins of free-living and parasitic nematodes. Immu nolocalization revealed the presence of this globin-like antigen in th e body wall musculature and/or the cuticle of O. ostertagi adults. An enzyme-linked immunosorbent assay based on the purified OoAdGlb showed no differences in response between calves infected by O. ostertagi an d/or Cooperia oncophora and the negative controls.