Clone of the gene of the dense granule antigen (GRA6) of the Toxoplasma gondii pig strain.

The gene of GRA6 of Toxoplasma gondii pig strain was cloned; and the value of recombinant GRA6 as a diagnostic antigen of toxoplasmosis in China was investigated. A pair of primers was synthesized according to the DNA sequence of GRA6 of T. gondii RH strain, and the DNA of pig strain tachyzoites was prepared. A single, specific DNA fragment was successfully amplified from the genomic DNA of tachyzoites of T. gondii. This gene fragment was cloned into the plasmid pUC19 to form the recombinant. The recombinant plasmid was purified and the foreign DNA fragment was sequenced. The result of DNA sequencing showed that the open reading frame of GRA6 is composed of 693 base pairs and encodes 230 amino acids and is 100% homologous with the sequence of GRA6 of T. gondii RH strain.