Developing a serological test for the diagnosis of toxocarasis using a novel recombinant multi-epitope

Human toxocariasis, a zoonotic infection caused by the ingestion of embryonated eggs of Toxocara canis (T. canis) or Toxocara cati (T. cati), or by consuming paratenic hosts, is characterized by diverse clinical manifestations. Diagnosis of this disease predominantly relies on serological testing, for which the selection of appropriate antigens is crucial to ensure accurate detection. Prior research has highlighted the potential of multi-epitope antigens to improve diagnostic precision. This study focused on evaluating the immunogenicity of synthetic proteins containing multiple immunodominant epitopes derived from T. canis antigens, specifically Toxocara excretory-secretory (TES) proteins TES-120, TES-30, and TES-26. A multi-epitope structure was designed, synthesized, and cloned into the pET28-b expression plasmid. The plasmid was then introduced into Escherichia coli (E. coli) BL21 competent cells, and the recombinant protein was expressed and purified after 16 h of bacterial cultivation. The diagnostic utility of the recombinant antigen for detecting anti-toxocariasis IgG antibodies was evaluated using an indirect Enzyme-Linked Immunosorbent Assay (ELISA). The results showed a sensitivity of 94.2 % and a specificity of 100 %, indicating high diagnostic accuracy. These findings underscore the potential of the synthetic multi-epitope recombinant antigen as a valuable diagnostic tool for improving the accuracy of human toxocariasis diagnostic kits. The designed multi-epitope proteins exhibit strong potential as diagnostic markers, offering high sensitivity and specificity for the development of indirect ELISA-based diagnostic assays. This study contributes to the development of more reliable and precise diagnostic tools for toxocariasis.