Characterization of excretory–secretory products from protoscoleces of Echinococcus granulosus and evaluation of their potential for immunodiagnosis of human cystic echinococcosis

Abstract

This study describes, for the first time, the characterization of excretory-secretory antigens (ES-Ag) from Echinococcus granulosus protoscoleces, evaluating their usefulness in the immunodiagnosis of human cystic echinococcosis. ES-Ag were obtained from the first 50 h maintenance of protoscoleces in vitro. This preparation contained over 20 major protein components which could be distinguished by 1-dimensional SDS-PAGE with apparent masses between 9 and 300 kDa. The culture of of protoscoleces from liver produced a greater variety of excretory-secretory protein components than those from lung. Determination of enzymatic activities of secreted proteins revealed the presence of phosphatases, lipases and glucosidases, but no proteases. These findings were compared to those obtained from somatic extracts of protoscoleces and hydatid cyst fluid products. Immunochemical characterization was performed by immunoblotting with sera from individuals infected by cystic echinococcosis (n = 15), non-hydatidic parasitoses (n = 19), various liver diseases (n = 24), lung neoplasia (n = 16), and healthy donors (n = 18). Antigens with apparent masses of 89, 74, 47/50, 32, and 20 kDa showed specificity for immunodiagnosis of human hydatidosis. The 89 and 74 kDa components corresponded to antigens not yet described in E. granulosus, whereas proteins of 41-43 kDa and 91-95 kDa were recognized by the majority of the non-hydatid sera studied.

Shared and non-shared antigens from three different extracts of the metacestode of Echinococcus granulosus

“…On the other hand, ES-Ag showed non-shared antigenic components of 89,66,42,40,37, and 35 kDa. The protein of 89 kDa has already demonstrated specificity for immunodiagnosis of human cystic echinococcosis and dog echinococcosis in previous reports (Carmena et al 2004. This component In summary we can conclude that HCF, S-Ag, and ESAg share an important proportion of antigens, which explains the high level of cross-reactivity found in ELISAinhibition and immunoblot-inhibition assays when these extracts were used.…”

“…So far, little information is available in regard to the description of ES-Ag. We have recently carried out the biochemical characterization of this antigenic extract, evaluating its potential for immunodiagnosis of human cystic echinococcosis and dog echinococcosis (Carmena et al 2004. However, until now no studies have been performed to determine the homology degree among HCF: hydatid cyst fluid; S-Ag: somatic antigens; ES-Ag: excretory-secretory antigens; NA: not available the antigenic components of HCF, S-Ag, and ES-Ag, and to find out their non-shared and shared proteins.…”

Preliminary study of the presence of antibodies against excretory-secretory antigens from protoscoleces of Echinococcus granulosus in dogs with intestinal echinococcosis

“…In our work, we have corroborated this result, identifying this antigenic protein both in ES-Ag and S-Ag. Recently, we have also found the 41-43 kDa component in the ES-Ag by immunoblotting with non-hydatidic human sera, including sera from individuals with other parasitoses, from individuals with non-parasitological pathologies and from healthy donors (Carmena et al 2004).…”

“…Although characterization of somatic antigens of E. granulosus protoscoleces for diagnostic purposes has been described in several reports (Gasser et al 1989, Rafiei & Craig 2002, very little information is available about excretory-secretory products of protoscoleces (Gasser et al 1992, Carmena et al 2004. In this preliminary work we show the presence of antibodies that recognize excretory-secretory antigens of E. granulosus protoscoleces in sera from dogs infected with E. granulosus and other helminths.…”

“…However, information about the characterization of ES-Ag from this parasite is very rare, which can be partially due to difficulties in obtaining enough amounts of ES-Ag. Recently, our laboratory has identified over 20 major protein components in the ES-Ag which could be distinguished by 1-dimensional SDS-PAGE and revealed apparent masses between 9 and 300 kDa (Carmena et al 2004). In this study, we present preliminary data about the immunochemical characterization of ES-Ag from protoscoleces of E. granulosus, which may help to identify new candidate antigens with potential for immunodiagnosis of dog echinococcosis.…”