[Expression, purification and antigenicity of P35 gene of Toxoplasma gondii].

OBJECTIVE: P35 is an important surface protein for Toxoplasma gondii. To obtain the highly pure and specific antigenicity protein, the gene P35 was cloned and its product was expressed in E. coli Rosetta. The expressed protein was purified and its immunogenecity was studied. METHODS: A pair of primers was designed according to cDNA sequence of P35, and then the P35 gene amplified by PCR was cloned into the vector pGEM-T and proved by DNA sequencing. The P35 gene was subcloned into prokaryotic expression vector pET-KDO, its expression was induced by IPTG, and the target protein was obtained by affinity chromatography. RESULTS: The P35 gene was successfully amplified from genome DNA of Toxoplasma gondii RH strain and a fusion protein was expressed in E. coli. The molecular weight of the expressed protein was about Mr 42 000. Western blotting indicated that the antigenicity of the protein was specific. CONCLUSIONS: The plasmid pET-KDO-p35 is constructed and the high efficient expression of P35 fusion protein has been achieved in E. coli. The fusion protein shows a specific antigenicity, the P35 fusion protein has a potential value in the diagnosis of toxoplasmosis.