目的　比较弓形虫不同地理株 (RH株、ZS2株、GT株 )GRA7基因的异同。　方法　从弓形虫不同地理株的基因组DNA中扩增出GRA7基因 ,对目的基因用限制性内切酶 (Esp3I、CfrI、MboI)酶切并比较。将目的基因克隆至pGEX 4T 1质粒 ,转化大肠埃希菌JM 10 9,进行测序并比较。　 结果　PCR扩增出 3株弓形虫的目的基因片段 ,大小均在 5 0 0～ 75 0bp之间 ;经 3种限制性内切酶酶切 ,其大小均与理论值相符 ;3株弓形虫GRA7基因序列相同。　 结论　弓形虫不同地理株GRA7基因具有高度保守性 Objective To compare the similarities and differences of GRA7 gene between different geographical strains (RH strain, ZS2 strain and GT strain) of Toxoplasma gondii. Methods The GRA7 gene was amplified from the genomic DNA of different geographical strains of Toxoplasma gondii and the target gene was digested with restriction endonucleases (Esp3I, CfrI and MboI). The target gene was cloned into pGEX 4T1 plasmid and transformed into Escherichia coli JM109 for sequencing and comparison. Results The target gene fragments of 3 Toxoplasma gondii were amplified by PCR. The size ranged from 5 0 0 to 75 0 bp. The results of three restriction enzyme digestion showed that the size of the target gene was consistent with the theoretical value. Three strains of Toxoplasma gondii GRA7 Gene sequences are the same. Conclusion The GRA7 gene of different geographical strains of Toxoplasma gondii is highly conserved