[Cloning and expression of actin gene of Toxoplasma gondii].

OBJECTIVE: To clone and express the actin gene of Toxoplasma gondii, and analyze the immunoreactivity of the recombinant protein. METHODS: Total RNA was extracted from tachyzoites of RH strain of T. gondii. The open reading frame of TgACT gene was amplified with a pair of specific primers which were designed according to the coding sequence of TgACT gene (Accession No. XM_002369622.1). The RT-PCR product was cloned into the prokaryotic expression pET-30a (+) vector. The recombinant pET30a-TgACT plasmid was transformed into E. coli DH5alpha. The positive clones were selected through the colony-PCR and confirmed by the double restrict enzyme digestion and sequencing. The correct pET30a-TgACT plasmid was transformed into E. coli BL21(DE3) and induced by IPTG. The expressed proteins were analyzed by SDS-PAGE. Western blotting assay was performed with anti-poly-histidine tag (anti-His) antibody or rabbit anti-T. gondii serum. RESULTS: The product of RT-PCR was with 1 100 bp. The recombinant plasmid pET30a-TgACT was confirmed by colony-PCR, double restriction enzyme digestion and sequencing. SDS-PAGE results showed that the target protein was expressed in E. coli BL21(DE3) in the form of inclusion bodies with a rough molecular weight of 49 000. The purified soluble protein was obtained by using denaturation, renaturation and purification. Western blotting revealed that rTgACT can be recognized by anti-His antibody and rabbit anti-T. gondii serum. CONCLUSION: The recombinant plasmid pET30a-TgACT has been successfully constructed, and the recombinant protein TgACT is produced in E. coli and maintains specific immunoreactivity.