The development and evaluation of a multi-epitope antigen as a serodiagnostic marker of Toxoplasma gondii infection.

Background: Toxoplasma gondii (T. gondii) is a ubiquitous protozoan parasite which causes a serious disease called toxoplasmosis. The high prevalence of T. gondii infection has attracted a great deal of interest in its diagnosis and treatment. The use of pure antigens shows high sensitivity and specificity, but challenges such as cross-reactivity remain diagnostic difficulties.

Objectives: The aim of this study was to use 3 surface antigens (SAGs) of T. gondii to design gene-encoding a multi-epitope and immunogenic protein as a serodiagnostic marker.

Material And Methods: The multi-epitope antigen was expressed using Escherichia coli BL21 (DE3) cells and purified using affinity chromatography. To evaluate acute toxoplasmosis, 95 human sera with anti-T. gondii IgG, 25 human sera without anti-T. gondii IgG and 6 serum samples with nosocomial infections were collected and submitted to an enzyme-linked immunosorbent assay (ELISA) analysis. The potential of purified protein as a diagnostic marker of T. gondii infection was also investigated using ELISA analysis.

Results: The western blot analysis for both protein expression and purification confirmed that the protein was expressed and purified successfully. The results of validation showed a sensitivity of 72.6% and a specificity of 90.3% for recombinant ELISA.

Conclusions: Although this protein showed potential for detecting T. gondii, the sensitivity and specificity were lower than in tests that use the whole body of the parasite.