Immunodiagnosis of Echinococcus Infections: Confirmatory Testing and Species Differentiation by a New Commercial Western Blot

Abstract

The Echinococcus Western Blot IgG (LDBIO Diagnostics, Lyon, France), using a whole larval antigen from Echinococcus multilocularis, was evaluated for serodiagnosis and differentiation between two human parasitic infections of worldwide importance: cystic echinococcosis, due to Echinococcus granulosus, and alveolar echinococcosis, due to E. multilocularis. Fifty and 61 serum samples from patients with cystic and alveolar echinococcosis, respectively, were used for assessing diagnostic sensitivity. The sensitivity of the assay was compared with those of screening tests used for these applications. Sera used for assessing cross-reactivities were from 154 patients with other diseases, either parasitic or not. The assay allowed the detection of serum immunoglobulin G antibodies in 97% ofEchinococcus-infected patients. It had a higher sensitivity than screening assays for the detection for each echinococcosis. The assay allowed us to correctly distinguish between E. granulosus- and E. multilocularis-infected patients in 76% of cases. It did not allow us to distinguish active from inactive forms of both echinococcoses. The occurrence of cross-reactivities with neurocysticercosis indicates the necessity for retesting sera with species-specific antigens, for rare patients with neurologic disorders. This study shows the usefulness of the commercially available Echinococcus Western Blot IgG for the serological confirmation of human echinococcosis.

A set of recombinant antigens from Echinococcus granulosus with potential for use in the immunodiagnosis of human cystic hydatid disease

“…The recombinant AgB8/2 presented the best discriminatory value in total IgG ELISA in comparison to the other recombinants and the native antigens tested. As expected, HCFA an AgB showed relatively poor specificities, due to their content of epitopes shared with other helminth parasites, evidenced in previous studies [13,15,16,19]. The lower diagnostic sensitivity of AgB in relation to both AgB recombinant subunits (AgB8/1 and AgB8/2) is due probably to the presence of other subunits, already identified by González et al .…”

“…from patients with or without surgical confirmation of infection) and the quality of the parasite antigens utilized in the assay. Crude or partially purified antigen preparations are useful, but often present problems associated with low concentration of specific antigens and the presence of cross‐reactive ones [13,15]. As an alternative, E. granulosus antigen‐encoding genes can be cloned and expressed in heterologous systems, in order to obtain recombinant antigens that can be produced and purified easily, and may be less prone to cross‐reactivity [10,16,17].…”

The intermediate host immune response in cystic echinococcosis

“…Cross‐reactivity occurs with other helminthiases or more rarely with nonparasitic diseases. Most frequently, this happens with other cestodes, in particular E. multilocularis (50–100% cross‐reactivity) . Better Sp has been reported with the detection of IgG 4 isotypes; however, Se is much decreased .…”

Species specificity preliminary evaluation of an IL‐4‐based test for the differential diagnosis of human echinococcosis

“…[7][8][9] Several approaches, such as the use of different sources of antigens and different readout systems, have been attempted to overcome the serology shortfalls. [9][10][11][12][13][14] The most commonly used serological tests for human CE are based on the detection of IgG antibodies against E granulosus hydatid cyst fluid (HCF). These tests show an 80%-99% sensitivity with variable specificity (60%-97%), while tests detecting IgG against purified or recombinant antigens show a better specificity (80%-100%) but lower sensitivity (38%-93%).…”