Molecular cloning and prokaryotic expression of truncated surface antigen protein (SAG1) of Toxoplasma gondii

The WTO guidelines on control strategies, especially of food-borne diseases, insist on mandatory systematic serological investigations of the causative agent(s) at the farm level and in slaughtered animals for serodetection purposes. Amongst the several target molecules for sensitive detection of Toxoplasma gondii, surface antigens are considered important as these are always exposed to host's cellular immune response. The communication deals with the molecular cloning, prokaryotic expression and purification of SAG 1, a surface antigen protein, from standard RH strain of T. gondii. Accordingly, the SAG! protein (mature) was subsequently expressed in prokaryotic expression system. It had molecular size of similar to 47 kDa and the level of expression was measured as 42% of the total protein. The concentration of the mature recombinant SAG1 protein was 0.678 mg/ml. Western blot with Ni-NTA anti-histidine HRPase conjugate confirmed the presence and purity of protein by immunoreactivity at the unique similar to 47 kDa region.