Background and Aim : The aim of the current study was to assess the usefulness of sheep crude hydatid CHCF of Echinococcus granulosus, obtained from sheep naturally infected for evaluation of antibody responses of human, mice, sheep and cattle IgG responses.Methods : Hydatid cysts obtained from lungs and livers of sheep slathered from local abattoirs in Ilam, Iran was used as the source of antigen either for the SDS, Western blotting or ELISA analysis or for experimentally infecting the mice .HCF recovered from cysts was centrifuged at 10000 rpm for 25 minutes. The supernatant was dialysed against PBS, freezed- thawed and used as crude CHCF.Results : There was an increasing in IgG4 subclass level compared to total IgG, IgG2 and IgG3 subclass responses against sheep CHCF. In this analysis all antibody class and subclass responses showed a higher mean OD than that of the cut off indicating that all human sera from patients with hydatidosis recognized reacted with sheep crude hydatid cyst fluid antigen at an acceptable level. The sensitivity and specificity of ELISA using IgG class and IgE, was 100% and 70.8% and also 93.3% and 100% respectively while for the IgG2, IgG3 and IgG4 it was 100%, 93.8%; 95, 100% and 100, 100% respectively.Conclusion : HCFs obtained from sheep were significantly useful in serodiagnosis of hydatidosis similar to that of human and mice and therefore can be used in hydatid cyst diagnosis kit using ELISA and immunoblotting. Keywords Background and Aim : The aim of the current study was to assess the usefulness of sheep crude hydatid CHCF of Echinococcus granulosus, obtained from sheep naturally infected for evaluation of antibody responses of human, mice, sheep and cattle IgG responses.Methods : Hydatid cysts obtained from lungs and livers of sheep slathered from local abattoirs in Ilam, Iran was used as the source of antigen either for the SDS, Western blotting or ELISA analysis or for experimentally infecting the mice .HCF recovered from cysts was centrifuged at 10000 rpm for 25 minutes. The supernatant was dialysed against PBS, freezed- thawed and used as crude CHCF.Results : There was an increasing in IgG4 subclass level compared to total IgG, IgG2 and IgG3 subclass responses against sheep CHCF. In this analysis all antibody class and subclass responses showed a higher mean OD than that of the cut off indicating that all human sera from patients with hydatidosis recognized reacted with sheep crude hydatid cyst fluid antigen at an acceptable level. The sensitivity and specificity of ELISA using IgG class and IgE, was 100% and 70.8% and also 93.3% and 100% respectively while for the IgG2, IgG3 and IgG4 it was 100%, 93.8%; 95, 100% and 100, 100% respectively.Conclusion : HCFs obtained from sheep were significantly useful in serodiagnosis of hydatidosis similar to that of human and mice and therefore can be used in hydatid cyst diagnosis kit using ELISA and immunoblotting. Keywords : Hydatid Cyst, Cross-reaction, CHCF, Sheep antigens
