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目的对抗原编码基因esxA、fbpB、Rv2660c进行测序,了解esxA、fbpB、Rv2660c的基因多态性。方法选取135株结核分枝杆菌(Mycobacterium tuberculosis,MTB)临床分离株,运用PCR方法扩增目的基因esx A、fbp B、Rv2660c并进行测序,与结核标准株H37Rv基因序列以及从免疫表位数据库(immune epitope database,IEDB)中查询到的表位序列进行对比,分析esx A、fbp B、Rv2660c基因序列中的变异特征。结果在135株菌株中,esx A、Rv2660c序列暂未发现基因变异。fbpB共66株(48.89%)发现了基因变异,5个单核苷酸多态性(single nucleotide polymorphism,SNP)位点共造成8个(14.81%)T细胞抗原表位以及9个(24.32%)B细胞抗原表位序列的多态性。fbpB基因的d N值为0.000 120,d S为0.002 126,其中T细胞表位区与非T细胞表位区的d N值分别为0.000 067和0.000 408,d S分别为0.002 382和0.000 470,B细胞表位区dN和dS值分别为0.000 063和0.002 380,非B细胞表位区dN和dS均为0。结论 esxA、Rv2660c基因序列较保守,fbp B存在基因多态性,预测会对蛋白Ag85B的免疫功能造成影响,从而影响H56的免疫有效性。
Objective To sequence the genes encoding esxA, fbpB and Rv2660c and to understand the genetic polymorphisms of esxA, fbpB and Rv2660c. Methods A total of 135 clinical isolates of Mycobacterium tuberculosis (MTB) were selected and amplified by PCR. The target genes esx A, fbp B and Rv2660c were amplified by PCR, sequenced and compared with the H37Rv gene sequence of the tuberculosis standard and from the immunophenotype database immune epitope database (IEDB), and analyzed the variation characteristics of the esx A, fbp B and Rv2660c gene sequences. Results Of 135 strains, esx A, Rv2660c sequence found no genetic mutation. A total of 66 isolates (48.89%) of fbpB were found to have genetic variation. A total of 5 single nucleotide polymorphism (SNP) sites caused 8 (14.81%) T cell epitopes and 9 (24.32% ) B-cell epitope sequence polymorphism. The dN value of the fbpB gene was 0.000120 and the dS was 0.002126, where the dN values of the T cell epitope region and the non-T cell epitope region were 0.000 067 and 0.000 408, respectively, and the ds values were 0.002382 and 0.000470, respectively , The dN and dS values of B cell epitopes were 0.000 063 and 0.002 380, respectively, and the non-B cell epitopes dN and dS were 0. Conclusion The esxA and Rv2660c genes are conserved and fbp B is polymorphic. It is predicted that the immunosuppressive effect of Ag85B may be affected, which may affect the immunogenicity of H56.