Construction, production and evaluation of the diagnostic utility of a recombinant Toxoplasma gondii chimeric antigen MIC1-MAG1-AMA1

The intracellular parasite Toxoplasma gondii has the ability to infect a wide range of warm-blooded animals, including humans. Currently, diagnosis of toxoplasmosis is based mainly on the use of the native antigens in enzyme immunoassay which allow for detection of IgG, IgM and IgA antibody classes. However, in some cases the performed studies give the ambiguous results. Moreover, the commercially available diagnostic tests due to its price are not generally applicable in the serodiagnosis of toxoplasmosis in animals, which requires the analysis of a large number of samples. For this reason, many research groups are currently working on new diagnostic tools, which are mainly recombinant antigens. Compared to the native antigens their production is much easier, cheaper, faster and safer. An additional advantage of the recombinant antigens is easier way to standardize assays.This study presents the construction of an efficient Escherichia coli expression system for the production of recombinant chimeric protein composed of the immunodominant regions of three Toxoplasma gondii antigens MIC1, MAG1 and AMA1. The produced and purified proteins are composed of amino acid residues from:  A) 25-182 of the MIC1 antigen, 30-452 of the MAG1 antigen, 67-483 of the AMA1 antigen; B) 25-456 of the MIC1 antigen, 30-452 of the MAG1 antigen, 67-483 of the AMA1 antigen; C) 25-456 of the MIC1 antigen, 30-222 of the MAG1 antigen, 67-483 of the AMA1 antigen; D) 25-182 of the MIC1 antigen, 30-222 of the MAG1 antigen, 67-483 of the AMA1 antigen. In the next part of the work the diagnostic usefulness of obtaining proteins for detection of anti-T. gondii antibodies were evaluated in the IgG ELISA assay and agglutination test using animal sera (e.g. horses, ovine, and pigs) and human serum samples.