论文部分内容阅读
目的研究我国结核分枝杆菌复合群(Mycobacterium tuberculosis complex,MTBC)菌株中pstS1基因及其中的人T细胞和B细胞表位区的序列多态性。方法选取180株临床分离MTBC菌株及11株世界不同来源的BCG疫苗株,PCR扩增其pstS1基因并测序后,结合已经公布的1株牛分枝杆菌(Mycobacterium bovis)及3株BCG菌株的pstS1基因序列,与从免疫表位数据库(Immune Epitope Database,IEDB)中查询到的表位序列进行比对和分析,总结该基因序列中的变异特征。结果在所有菌株中,共发现2个单碱基插入造成的移码突变(Frame-shift mutation)和4个单核苷酸多态性(Single nucleotide polymorphism,SNP)位点,共造成79.17%(19/24)的B细胞表位和65.22%(15/23)T细胞表位区的序列变异。pstS1基因的dN值为0.000 14,其中T细胞表位区与非T细胞表位区的dN值分别为0.000 17和0.000 05,B细胞表位区与非B细胞表位区的dN值分别为0.000 23和0,由于未发现同义突变位点,所有序列区的dS值均为零。结论 MTBC菌株的pstS1基因具有较高的序列多态性,且其中的T、B细胞表位区具有更高的多态性水平。
Objective To study the sequence polymorphism of pstS1 gene and its human T cell and B cell epitopes in Mycobacterium tuberculosis complex (MTBC) strains in China. Methods 180 isolates of clinical isolates of BCBC and 11 BCG vaccine strains from different sources were selected. After pstS1 gene was amplified by PCR and sequenced, a total of 1 strains of Mycobacterium bovis and 3 strains of BCG The sequence of the gene is compared with the epitope sequence queried from the Immune Epitope Database (IEDB) to summarize the variation features in the gene sequence. Results In all the strains, two frame-shift mutations and four single nucleotide polymorphism (SNP) sites were found, which resulted in 79.17% 19/24) B-cell epitopes and 65.22% (15/23) T-cell epitope regions. The dN value of pstS1 gene was 0.00014. The dN values of T cell epitope region and non-T cell epitope region were 0.000 17 and 0.000 05, respectively. The dN values of B cell epitope region and non-B cell epitope region were 0.000 23 and 0, since no synonymous mutation sites were found, the dS values of all sequence regions were all zero. Conclusion The pstS1 gene of MTBC strain has high sequence polymorphism, and the T and B cell epitopes have higher polymorphism.