Identification and diagnostic evaluation of cross-reactive antigen between hydatid cyst fluid of Echinococcus granulosus and Trichinella spiralis larval extract.

A cross reactive fraction was isolated from hydatid cyst fluid antigen of E. granulosus using CNBr Sepharose 4B affinity chromatography in which anti-T. spiralis antibodies were coupled with the column. Biochemical characterization of the isolated fraction included the use of SDS-PAGE, isoelectric focusing and amino acid analysis. The fraction showed 5 polypeptides of 165, 95.5, 63.5, 30.6 and 24 KDa. The isoelectric points of these polypeptides were 7.8, 7.2, 6.7, 6.2 and 5.7. The fraction exhibited 17 amino acids and was rich in tyrosine (20.81) and glutamic (15.28) ug/100 mg. The fraction proved higher potency in the diagnosis of experimental trichinellosis in rats than echinococcosis in dogs by ELISA. All experimentally infected animals reacted positively, recording 100% diagnostic sensitivity. Collectively, the present study proved that the hydatid cyst fluid cross-reactive fraction could be used in the diagnosis of trichinellosis at different intervals of infection and as early as 1 week post infection.