Purification of Specific Proteins From Hydatid Cyst Fluids of Sheep Liver and Application to ELISAs

Abstract

The aims of this study were to determine the sensitivity and specificity of ELISA tests using cyst fluid antigens or purified 8, 68, 116 kDa immunoreactive proteins for diagnosis of hydatid cyst in mice and humans and to compare them with the performances of 2 commercial kits available in humans. For that, serum samples were obtained, on one hand, from mice (n = 25) intraperitoneally infected with 3 000 protoscoleces from ovine liver cyst 10 months ago or from healthy mice (n = 25) and on the other hand, from 10 patients with hydatidosis (radiologically confirmed), from 6 patient with other parasite diseases than hydatidosis (serologically confirmed) and from 10 healthy patients. The sensitivity of the ELISA tests using purified proteins or the cyst fluid antigens varied in mice from 96% to 100% for the 116 kDa antigen and in humans from 90% to 100% for the 68 kDa antigen and was higher than with commercial tests (60% and 80%). The specificity determined from healthy mice was maximal (80%) with the 8 kDa and 116 kDa proteins as antigens and the specificity determined from humans not infected with hydatidosis ranged from 93.8% with one of the 2 commercial kits and 87.5% with the 8 kDa antigen to 75% with the 68 kDa antigen and the total antigen preparation and 62.5% with the other commercial kit. Some cross-reactions in human sera were observed between Echinococcus purified antigens and Toxocara or Trichinella at a lesser extend. These results clearly show that some purified hydatid cyst proteins, especially 8 kDa and 116 kDa proteins, can be used as antigens for ELIS As and improve the sensitivity and the specificity of the tests.