Evaluation of immunoglobulin G subclass antibodies against recombinant Fasciola gigantica cathepsin L1 in an enzyme-linked immunosorbent assay for serodiagnosis of human fasciolosis.

A cystatin capture enzyme-linked immunosorbent assay (ELISA) using recombinant Fasciola gigantica cathepsin L1 antigen was developed to detect specific immunoglobulin G (IgG) subclass antibodies (IgG1, IgG2, IgG3, and IgG4) and was evaluated for its diagnostic potential for human fasciolosis. In an analysis of the sera of 13 patients infected with F. gigantica, 209 patients with other parasitic infections, 32 cholangiocarcinoma patients, and 42 healthy controls, the IgG4-ELISA gave the highest diagnostic values. The sensitivity, specificity, accuracy, and positive and negative predictive values of this method based on the detection of IgG4 antibody were 100%, 99.3%, 99.3%, 86.7%, and 100%, respectively. The results revealed that restricting the ELISA to the detection of specific IgG4 antibody enhanced the specificity and accuracy for the serodiagnosis of human fasciolosis.