PURIFICATION AND EVALUATION OF MAJOR HYDATID CYST FLUID ANTIGENS IN IMMUNODIAGNOSIS OF HYDATIDOSIS

Regarding remarkable prevalence of human hydatidosis and despite introduction of novel sensitive techniques such as ELISA for immunodiagnosis of disease in the word, there has not been much progress in that field in Iran. Preparation and purification of suitable antigens is the basic and first step in serodiagnosis of this disease. The present study, thus, is designed and carried out for preparation, purification and evaluation of major hydatid fluid antigens in immunodiagnosis of hydatidosis. Among the various methods for pirification of antigens, we used gel filtration chromatography, anion exchange chromatography and partial purification of antigen B procedure. Elution of crude hydatid fluid antigen (CHFAg) sample through gel filtration and anion exchange columns resulted in four separately peaks from each of columns. To evaluate the diagnostic value of CHFAg and purified antigens by ELISA, we tested 64 sera from patients who had hydatid cyst disease, 55 sera from patients with fascioliasis and toxocariasis, 50 sera from various malignancies and 73 sera from healthy controls. Despite low specificity of the CHFAg-ELISA(83%) owing to non specific reactions with some cases of non-hydatid sera, its sensitivity was relatively high (94%). Although, CHFAg-ELISA may be useful for primary screening in seroepidemiological studies, but we suggest ELISA using the first antigenic peak of gel filtration(PlG-ELISA), which exhibits nearly equal sensitivity wich CHFAg, and relatively high specificity of 87% Among the purified antigens, Antigen B of Oriol procedure and second antigenic peak of gel filtration (P2G) showed the highest specificity of 98% and 96% respectively. In conclusion, we suggest that the P1G-ELISA, which exhibits a relatively high sensitivity, be convenient for primary screening test and AgB-ELISA or P2G-ELISA can be considered as confirmatory tests for specific immunodiagnosis of hydatidosis.