High-level expression and evaluation of the antigenicity of a recombinant Toxoplasma gondii GRA2 protein

Toxoplasmosis is a worldwide infection which is commonly asymptomatic but can cause serious health problems in immunocompromised individuals and fetus. GRA2 is a dense granule protein of Toxoplasma gondii, which induces strong antibody and T-cell response in human and mice. The purpose of this study was to prepare recombinant GRA2 and evaluate its antigenic properties using infected mice sera. To reach this point, GRA2 gene was highly expressed as a fusion protein with Thioredoxin (TRX) in Escherichia coli BL21pLysS strain. The protein was purified in a single step on Ni-NTA affinity column. TRX-GRA2 was confirmed by Western blot technique using a monoclonal antibody specific for GRA2. Sera from mice infected with Toxoplasma gondii showed high reactivity toward GRA2 and the level of IgG2a isotype was predominant and significantly higher than IgG1.Taken together, TRX-GRA2 might be considered as an ideal antigen to be used as a vaccine target as well as diagnostic tool for detection of toxoplasmosis.