PCR-RFLP技术在布氏菌鉴定与分型中的应用

Application of PCR-RFLP technique on identification and genotyping of Brucella spp

目的利用PCR-RFLP技术扩增7株布氏菌临床分离株16S RNA基因片段,为该菌的分子诊断学、遗传学和流行病学研究提供实验依据。方法参考GenBank公布的布氏菌ATCC 25840标准株序列,设计针对该菌16S RNA保守区的特异性引物,从临床分离培养7株布氏菌,提取DNA并行16S RNA片段的PCR扩增。将PCR产物克隆至PGEM-T载体进行测序并选用合适的限制性内切酶进行RFLP分析,将分析结果用于临床株的同源性及变异位点的研究,并对感染患者的临床资料进行回顾性分析,研究不同布氏菌基因型与感染患者临床特征的相关性。结果利用PCR扩增出的目的片段与预期一致,大小约为1500bp。测序及同源性分析表明,7株临床分离株之间存在98.88%的同源性和11个变异位点。RFLP结果将7株菌分为4个基因型,临床资料回顾性分析患者不同基因型与临床表现之间无明显联系。结论利用PCR技术扩增布氏菌16SRNA基因片段可以实现对该菌的早期诊断,为布氏菌的分子遗传学和流行病学提供依据。

Objective To amplify the 16S RNA fragments of 7 clinically isolated strains of Brucella spp. by PCR-RFLP technique, so as to provide experimental basis for the studies on diagnostics, genetics and epidemiology of Brucella spp. Methods According to the gene sequence of ATCC 25840 standard strain in GenBank, special primers for the 16S RNA conservative area in the Brucella spp. were designed. DNA extraction and PCR amplification of the 16S RNA fragments were performed with the 7 isolated strains. PCR products were then sequenced and RFLP analysis was conducted with appropriate restricted enzymes to study the homology and the mutation sites in those strains. Meanwhile, the clinical data of infected patients were retrospectively analyzed to evaluate the relationship between the clinical features and genotypes of Brucella infection. Results The amplified target fragments were about 1500bp in length and consistent with what was expected. The sequencing and homology analysis showed a 98.88% homology and 11 mutation sites among the 7 isolated strains. Four genotypes were identified by RFLP. Retrospective analysis of the clinical data indicated that no obvious relationship existed between the genotypes and the clinical features. Conclusions Amplifying 16S RNA fragments by PCR technique is a feasible method to make an early diagnosis of Brucella infection. The 7 clinically isolated strains are different in genotypes and 16S RNA fragment is a highly conservative fragment in bacterial genome with some mutations. The research provides evidence for the genetics and epidemiology of brucellosis.