High performance latex reagent for hydatid serology using an Echinococcus granulosus lipoprotein antigen fraction purified from cyst fluid in one step.

A lipoprotein fraction from fertile bovine hydatid cyst fluid (FBHCF) was isolated by affinity chromatography on acrylic-heparin. The heparin-binding lipoprotein fraction (HBLF) was proved to be free from host immunoglobulins and albumin. Immunoblotting with confirmed human hydatid sera showed that the major relevant diagnostic bands in FBHCF were also present in HBLF. HBLF or FBHCF were used to sensitize polystyrene latex particles. HBLF-latex showed both higher reactivity with positive hydatid human sera and higher batch-to-batch reproducibility than FBHCF-latex. Titration of sera from 119 surgically confirmed hydatid patients, 48 with other parasitic diseases, 6 with unrelated diseases and 37 healthy subjects was performed using HBLF-latex and conventional ELISA (using FBHCF). Sensitivity and specificity were 83 and 87% for ELISA and 87 and 88% for HBLF-latex. These results indicate that, while being simpler and faster to perform, the HBLF-latex has a similar diagnostic value to that of the conventional ELISA test.