变形链球菌表面蛋白可变区(extended-V)的遗传多态性分析

目的:从分子水平探讨变形链球菌(血清c、f型)表面蛋白可变区(extended-V,V )的遗传状况,分析其基因中存在的变异,为进一步研究其结构和功能提供遗传信息。方法:选择临床最常见的血清型c、f型菌株117株(包括7株参考株),提取DNA,行PCR扩增,获得SrV 区片段基因;利用限制性内切酶DdeI进行限制性片段长度多态性分析(RFLP),并与部分国际参考株进行比较归类。从所占比例较多的基因型中,各选一代表株的PCR产物分别测序,将测序结果用Clone3.1version软件比较各型酶切位点。结果:117株菌株共分出5种基因型(A、B、C、D、E型);血清f型OMZ175为其中的一种;A型48株,B型45株,C型20株,D、E型则分别只有1株和3株,显示出明显差异;以参考株基因型为准,分别将A、B、C型定为p1样、spaP样或sr样、pac样;D型只有1株临床株,不排除实验过程中突发变异的可能;E型的3株也为临床株,尚无参考株与其相对应。结论:变形链球菌(血清c、f型)表面蛋白可变区呈多态性分布,有5种基因型,分布较为集中者分别为p1样、spaP或sr样、pac样,且血清f型属于血清c型的spaP样。

Study on the genetic diversity within the extended-V region of the surface protein of Streptococcus mutans

PURPOSE: The purpose of this study was to investigate the genicity of the extended- variable region (V )of surface proteins of Streptococcus mutans (S. mutans, serotype c,f)and provide some genetic informations on the molecular structure of S. mutans surface protein. METHODS: 7 standard strains and 110 clinical isolates of S.mutans were selected.The bacterial DNA was extracted and the extended-V region(srV 1384-2514bp)was amplified using polymerase chain reaction (PCR).The genetic diversity of srV was assessed by using restriction fragment length polymorphism(RFLP)with restriction endonuclease DdeI. RESULTS: The results showed that five different patterns(A,B,C,D,E)of the PCR-RFLP among the 117 strains were reveled by DdeI. The ration of the genotype A and B were the most among the strains,C followed by genotype,the D and E were 1 and 3 strains per genotype,respectively.OMZ175(serotype f)belonged to B genotype. CONCLUSIONS: The study supported that the extended-variable region (srV ) of the surface proteins of Streptococcus mutans have diversity. There are five patterns of genotypings.The most genotypings were p1-like,spaP /sr-like and pac-like. Supported by National Natural Science Foundation of China (Grant No.30171013); Research Fund of Bureau of Science and Technology of Guizhou Province(Grant No. 20013093) and Research Fund of Medicine and Public Health of Zhejiang Province (Grant No. 2005B125).