Evaluation of a 14.5 kDa-Fasciola gigantica fatty acid binding protein as a diagnostic antigen for human fascioliasis

The aim of the present study was to evaluate the efficiency of 14.5 kDa-Fasciola gigantica fatty acid binding protein (FABP) as a diagnostic antigen for human fascioliasis. 14.5 kDa FABP was isolated from the crude extract of adult F. gigantica worms by ion exchange chromatography followed by gel filtration chromatography and then analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing condition. Anti-FABP IgG polyclonal antibody (pAb) was generated in rabbits and purified by using sequential use of ammonium sulfate, caprylic acid, and then ion exchange chromatography. Conjugation of purified rabbit anti-FABP IgG with horse reddish peroxidase (HRP) was conducted and used in detecting the coproantigen in the stool and the circulating Fasciola antigen (CA) in the sera of Fasciola-infected patients using sandwich enzyme-linked immunosorbent assay (ELISA). The sensitivities of sandwich ELISA test were 96.43% and 94.74%, while the test specificities were 94.87% and 84.62% for the detection of coproantigen and CA, respectively. The parasitological diagnosis using the Kato-Katz technique revealed 64.29% sensitivity with 100% specificity. The diagnostic efficacy of sandwich ELISA was 95.52% for coproantigen and 87.93% for CA detection. In contrast, the diagnostic efficacy of Kato-Katz technique was 85.07%. It was concluded that 14.5 kDa FABP represented a valuable antigen for the immunodiagnosis of human fascioliasis using sandwich ELISA.