封闭型维族儿童变形链球菌乳酸脱氢酶基因多态性研究

摘要

Objective Lactate dehydrogenase (LDH) is shown to be an important virulence factor resulting in acid production of Streptococcus mutans(S.mutans), on which the cariogenic potential of S.mutans depends.Differences in cariogenic abilities of S.mutans isolates may be determined by genetic heterogeneity from virulent factors.The relationship between enclosed Uyghur children LDH activity or genetic diversity and cariogenicity of S.mutans(serotype c)isolates was studied in this research.MethodsChoose 6 original inhabitants of the countryside from the age of 3 to 5 years old closed Uighur children in kashika.These isolates came from 35 caries-active individuals and 37 caries-free enclosed Uyghur ones, in which 27 strains showed the high LDH activity and 24 strains showed the low LDH activity.Then genetic diversity of PCR products were analyzed or assessed by restriction fragment-length polymorphism(RFLP).Some of amplified LDH genes from different group were sequenced and assayed.ResultsIt is testified that two genotypes A and B of ldh-RFLP were revealed when LDH genes were digested with MseI,but MnlI,DdeI,NlaⅡI and AluI digesting fragments of ldh gene did not show different pattern.Furthermore,Fisher Exact one-Tail Test showed that the proportion of Genotype B strains from caries-active individuals was higher than that from caries-free ones(P<0.05),while the distribution genotypes A,B with different LDH activity was different between two groups(P<0.05),high proportion of the LDH active group genotype B strains than the low activity group.ConclusionThis study indicated that LDH gene of S.mutans strains from Enclosed Uyghur children different individuals is conservative, while there still is the gene mutation in.The ldh genetic diversity may be related to the high caries sensitivity, and closely correlated with the differences in LDH enzyme activity of S.mutansstrains.%目的 初步探究封闭型维吾尔族不同龋敏感儿童变形链球菌乳酸脱氢酶基因多态性与龋敏感性的关系.方法 选取喀什地区6个原始居住民乡村3~5岁封闭型维吾尔族高龋[龋失补牙数(dmft) ≥5],无龋[龋失补牙数(dmft)=0]儿童口腔中分离的变形链球菌35和37株,采用还原性辅酶Ⅰ氧化法测定乳酸脱氢酶的活性,经测定后其中被分离的临床菌株27株高活性,24株低活性.使用特异引物从细菌组DNA扩增出结构基因ldh,利用限制性内切酶多态性检测技术将酶切图谱进行基因分型和测序对比.结果 不同限制性片段长度多态性对比后产生不同种的基因型,MseⅠ酶切ldh-RFLP表现为A与B两种基因类型;MnlⅠ、DdeⅠ、NlaⅢ和AluⅠ消化扩增产物后没有发现其他的多态性表现.MseⅠ产生的B基因型菌株在高龋组中检测出要明显高于无龋组(P<0.05),在不同酶活性组中,A、B两种基因的分布也不同(P<0.05),高酶活性组中的B基因型菌株比例明显高于低酶活性组.结论 封闭型维吾尔族不同龋敏感儿童变形链球菌乳酸脱氢酶基因具有基因遗传多态性,不同基因分型ldh与LDH酶活性及龋敏感性具有正相关性.