The Trivalent Recombinant Chimeric Proteins Containing Immunodominant Fragments of Toxoplasma gondii SAG1 and SAG2 Antigens in Their Core-A Good Diagnostic Tool for Detecting IgG Antibodies in Human Serum Samples.

Toxoplasmosis is one of the most common and neglected parasitic diseases caused by the intracellular parasite Toxoplasma gondii. The parasitic invasion in humans is associated with certain problems, such as the lack of effective immunoprophylaxis or a complex diagnostic algorithm, which require continuous improvement. Both problems can be overcome by the recent development of T. gondii proteomics, which has allowed the design of different recombinant antigens. In this study we evaluated the potential usefulness of nineteen recombinant chimeric T. gondii proteins for serodiagnosis. A chimeric antigen composed of the surface antigens SAG1-SAG2 was developed and used as the basis for the generation of 18 subsequent trivalent chimeric antigens containing different immunodominant fragments of the parasite proteins. The recombinant antigens were used in an indirect enzyme-linked immunosorbent assay (ELISA) test to evaluate their ability to detect specific IgG antibodies in human sera. A total of 338 human sera were analyzed to assess the sensitivity and specificity of the tests. Sixteen of the antigens tested demonstrated 100% sensitivity and specificity in the ELISA for the detection of specific IgG antibodies. These results provide an optimistic outlook for the potential replacement of the currently used native antigen mix with recombinant antigens in human T. gondii serodiagnostics.