弓形虫棒状蛋白17基因的克隆与序列分析

摘要

为研究弓形虫棒状体蛋白17(ROP17)基因的遗传变异,本研究以弓形虫RH株、PRU株和TgC7株为研究对象,首次PCR扩增了其ROP17基因部分序列,将PCR产物纯化后克隆到pMD18-T并测序.将测定的序列与网上下载的弓形虫VEG株、GT1株和ME49株相应序列进行比对,然后用Mega 5.0程序的NJ法和Puzzle 5.2程序的ML法构建系统发育树.结果表明,3株弓形虫分离株的ROP17基因部分序列长度均为1375 bp,A+T含量在49.53％～50.04％之间,3个虫株相应序列的变异碱基数皆小于20个,其变异率为2.3％,氨基酸序列变异率在0～6.11％之间.系统发育结果显示,ROP17基因部分序列能区分弓形虫基因Ⅰ型和Ⅱ型的虫株.本研究结果为进一步研究弓形虫ROP17基因的变异及研制弓形虫ROP17基因的亚单位疫苗提供了理论依据.%Toxoplasma gondii ROP17 gene was amplified from individual T. gondii strains from different geographical locations and hosts by PCR. These PCR products were subjected to be cloned and sequenced and ROP17 sequences were aligned using the ClustalX 1. 81. The phylogenetic relationships among T. gondii strains were constructed using the software Mega 5. 0 and Puzzle 5. The lengths of all ROP17 sequences were 1375 bp, and the A+T contents were 49. 53% to 50. 04%. The in-tra-specific variation among the T. gondii strains was up to 23%. The variation rate in amino acid sequences was 0 to 6. 11%. Phylogenetic analysis revealed that ROP17 gene sequences could be used as a marker for studying genetic relationships of T. gondii isolates. The low variation in ROP17 gene sequences among T. gondii strains might indicate that ROP17 gene could be used as a potential anti-toxoplasmosis vaccine candidate molecule in further studies.