[Preliminary evaluation on the diagnostic performance of five native antigens from Echinococcus granulosus].

Objective: To evaluate the diagnostic potential of 5 native antigens obtained from Echinococcus granulosus.
Methods: The cyst fluid and protoscoleces were collected from infected livers of slaughtered sheep near Urumqi. The protoscolex somatic soluble antigen (EgPS), crude hydatid cyst fluid antigen (EgHF), partially purified hydatid fluid antigen (Burstein's antigen, EgBu) and the native antigen B (EgAgB) were prepared. Echinococcus granulosus adult worms were collected from experimentally infected dogs, and then used to prepare adult somatic soluble antigen (EgAS). Serum samples from patients with cystic echinococcosis (369 cases), alveolar echinococcosis (14 cases), cysticercosis (20 cases), schistosomiasis (50 cases), paragonimiasis westermani (10 cases), visceral leishmaniasis (5 cases), and healthy individuals (366 cases) were examined for the antibodies against 5 native antigens with indirect ELISA. A ROC analysis was performed to determine a cut-off value for each native antigen.
Results: EgPS presented the highest AUC(BOC) (0.958 +/- 0.067), sensitivity (88.7%), positive predictive value (0.96), positive likelihood ratio (16.61), diagnostic efficiency (91.7%), and odds ratio (138.475). The specificity of EgBu (96.1%) was the highest, followed by EgAgB (95.7%), EgPS (94.7%), EgAS (89.0%), and EgHF (80.4%). The Youden index was ranked in order of EgPS>EgBu>EgHF>EgAS>EgAgB. The antibody reactive intensity of EgBu-ELISA was highest (4.055 +/- 1.365) and the EgAS-ELISA was lowest (2.947 +/- 1.276), and there was no significant difference between them (P > 0.05). The five native antigens presented high cross-reactivity with sera from alveolar echinococcosis (9/14-12/14) and from cysticercosis (8/20-16/20).
Conclusion: There are significant differences among the five native antigen-ELISA. The EgPS antigen has the best diagnostic performance , which is followed by EgBu and EgAgB.