The immunodiagnostic potential of protoscolex antigens in human cystic echinococcosis and the possible influence of parasite strain.

The results of ELISA, SDS-PAGE and western blotting indicated that the protoscolex antigens of Echinococcus granulosus (of 10-125 kDa) included antigens recognized by sera from human cases of cystic echinococcosis (CE). Some of the latter antigens (of approximately 79, 59, 45, 38, 31 and 29 kDa) exhibited cross-reactivity with sera from humans with other parasitic infections, including alveolar echinococcosis, cysticercosis and African trypanosomiasis. The 31-kDa antigen recognized by IgG antibodies in human CE sera only appeared to be present in the extracts of protoscoleces from sheep, and not in the corresponding extracts from horse or camel cysts. In contrast, the human CE sera recognized a 45-kDa protoscolex antigen only present in the horse cysts and a 125-kDa antigen present in the camel and horse (but not sheep) cysts. Extracts of protoscoleces from different species of hosts might therefore provide a source of strain-specific diagnostic antigens for human CE.