Cloning and sequencing of Toxoplasma gondii major surface antigen (SAG۱) gene

Genetic typing methods of T. gondii strains have been extensively perfected in recent years. From a technical point of view, many tools usable for genetic studied on single-copy loci have been used: RFLP, PCR-RFLP, sequencing, RAPD-PCR and isoenzyme analysis. We described the cloning and sequence analysis of the gene which encodes the major surface antigen (SAG۱ or P۳۰) of T. gondii. SAG۱ is the immunodominant antigen of Toxoplasma gondii tachyzoites being considered as the most promising molecule for a recombinant vaccine or such as DNA vaccine against toxoplasmosis. In the present work, first, genomic DNA of Toxoplasma gondii was extracted and used for amplifying of SAG۱ gene as a template. Then PCR product was cloned into pTZ۵۷R/T vector and plasmid containing SAG۱ gene (pT-SAG۱) was extracted from transformed bacteria and SAG۱ gene cloned into pTZ۵۷R/T was sequenced. Results showed that the P۳۰ gene contains no introns and can extract it from genomic DNA of tachyzoite stage. Results showed also that SAG۱ gene is cloned in pTZ۵۷R/T plasmid, forming pT-SAG۱ recombinant plasmid and E. coli TG۱ strain is the best host for pT-SAG۱ transformation. Sequence analysis of SAG۱ gene cloned into pTZ۵۷R/T vector showed that SAG۱ gene sequence from a high virulent strain of T. gondii (Known as RH strain) has ۱۰۰% sequence identity with P-Br strain, P strain and C strain and high homology of ۹۸% with RH strain and ZS۱ strain.

کلیدواژه ها:

Cloning ، Sequencing ، Toxoplasma gondii ، SAG۱ ، P۳۰