Designing and Developing Serological Test for the Diagnosis of Human Fascioliasis Using a New Recombinant Multi-epitope

Fascioliasis is a common parasitic disease in humans and herbivores which is caused by Fasciola hepatica and Fasciola gigantica and has a worldwide distribution. Serological tests such as the enzyme-linked immunosorbent assay (ELISA) technique play a prominent role in the fast diagnosis of the disease. However, there are diagnostic limitations, including cross-reactivity with other worms, which decline the specificity of the results. This study aimed to evaluate the structure of a recombinant multi-epitope antigen produced from linear and conformational B-cell epitopes of three parasitic proteins with sera of individuals with fasciolosis, healthy controls, and those with other diseases to gain accurate sensitivity and specificity.

After designing the multi-epitope structure of cathepsin L1, FhTP16.5, and SAP-2 antigens and then synthesizing, cloning, and expressing, the extracted purified protein was evaluated by indirect ELISA to detect IgG antibodies against Fasciola hepatica parasite among the sera of 39 serum samples of Fasciola hepatica, 35 healthy individual samples, and 20 samples of other types of parasitic diseases. The synthesized multi-epitope produced from cathepsin L1, FhTP16.5, and SAP-2 antigens was evaluated using the indirect ELISA.

The analysis of the samples mentioned for IgG antibody diagnosis against Fasciola hepatica showed 97.43% (95% confidence interval, 94.23–100%) sensitivity and 100% (95% confidence interval, 97–100%) specificity.

The recombinant B-cell multi-epitope with high antigenic potency may increase the specificity of epitopic peptides and ultimately help improve and develop indirect ELISA commercial kits for the diagnosis of fascioliasis in humans.