Immunodetection of Fasciola gigantica Circulating Antigen in Sera of Infected Individuals for Laboratory Diagnosis of Human Fascioliasis

Abstract

c Currently, the laboratory diagnosis of human fascioliasis is based on the parasitological examination of parasite eggs in stool specimens and serological detection of specific antibodies in serum samples, which are often unreliable diagnostic approaches. Ideally, a sensitive and specific diagnostic test for Fasciola infection should be based on the detection of circulating Fasciola antigen, which implies active infection. Here, a 27-kDa-molecular-mass antigen was identified in a Fasciola gigantica adult worm antigen preparation, excretory-secretory products, and sera from F. gigantica-infected individuals, and it was not detected in antigenic extracts of other parasites and sera from noninfected individuals. The target antigen was isolated and partially characterized as a protein. Immunoperoxidase staining located the target epitope within teguments and guts of F. gigantica adult worms. The performance characteristics of a newly developed enzyme-linked immunosorbent assay (ELISA) based on F. gigantica circulating antigen detection in serum (FgCA-27 ELISA) were investigated using sera of 120 parasitologically diagnosed F. gigantica-infected individuals and 80 noninfected individuals. The area under the receiving operating characteristic (ROC) curve (AUC) for ELISA was significantly high (AUC ‫؍‬ 0.961, P < 0.0001) for discriminating Fasciola-infected and noninfected individuals. The developed assay showed high degrees of sensitivity, specificity, and efficiency (>93%), and a significant correlation (r ‫؍‬ 0.715, P < 0.0001) between antigen level and parasite egg count was shown. In conclusion, a 27-kDa Fasciola antigen was identified in sera of F. gigantica-infected individuals. A highly sensitive and specific Fasciola antigen detection assay, FgCA-27 ELISA, was developed for laboratory diagnosis of human fascioliasis.

Diagnosis of human fascioliasis by stool and blood techniques: update for the present global scenario

“…In contrast there was correlation in Huacullani regarding low burden cases (<400 epg) (Valero et al 2012 a ). Observed lack of correlation in two of these studies is in contrast to the positive correlation between epg counts and OD readings obtained by other authors (Espino and Finlay, 1994; Mezo et al 2004; Demerdash et al 2011; Attallah et al 2013), but agrees with results found in hospital patients (Ubeira et al 2009). Results suggest that the OD/epg correlation found by other authors may be due to the analysis of stool from low to very low fluke burdens.…”

“…Besides the most used ES78 monoclonal antibody used for the FasciDIG test (Espino et al 1993, 1998; Espino and Finlay, 1994; Marcet Sanchez et al . 2012) and MM3 monoclonal antibody used for the MM3-COPRO test (Ubeira et al 2009; Valero et al 2009 b , 2012 a ; Muiño et al 2011), other monoclonal antibodies have also been described (Arafa et al 1999; El-Bassiouny et al 2008; Demerdash et al 2011; Allam et al 2012; Attallah et al 2013). Several are commercially available: (i) ‘ Fasciola hepatica Antigen ELISA Kit Bio K 201’; (ii) ‘Bovine Fasciola hepatica Antigenic ELISA Kit’; (iii) ‘ Fasciola hepatica Ag’; (iv) ‘FasciDIG IPK La Havana’.…”

“…When applied to sera from 120 infected individuals and 80 non-infected ones, another ELISA assay for the detection of a F. gigantica circulating antigen of 27 kDa (FgCA-27 ELISA) showed high degrees of sensitivity, specificity and efficiency (>93%) and a significant correlation between antigen level and parasite egg count. The target epitope was located within the tegument and gut of F. gigantica adult worms and was not detected in antigenic extracts of other parasites (Attallah et al 2013).…”

A prospective view of animal and human Fasciolosis

“…. Similar ELISA tests are available for F. gigantica using a variety of different antigens: (a) Fas1 and Fas2 cysteine proteases, resulting in 91·9% and 89·1%, sensitivity and specificity, respectively ; (b) sandwich ELISA using fatty acid binding protein, resulting in 94·7% sensitivity and 84·62% specificities ; (c) 27 kDa circulating antigen from sera of infected individuals gave >93% sensitivity and specificity . A lateral flow test (SeroFluke) was developed by Martinez‐Sernandez and colleagues using samples obtained from F. hepatica‐ infected patients in Spain and Portugal, for use with serum or whole blood samples, which requires minimal training .…”

Evaluation of a set of refolded recombinant antigens for serodiagnosis of human fascioliasis

“…Fascioliasis is a food-borne zoonotic disease caused by liver trematodes of the genus Fasciola . The disease has been considered as a global disease of domestic ruminants and cause economic losses in livestock [ 1 ]. Nowadays, human fascioliasis has been recognized as an important reemerging parasitic disease by World Health Organization, with an estimated 17 million people affected worldwide [ 2 ].…”