A study of genetic diversity in lactate dehydrogenase of streptococcus mutans from caries-active and caries-free individuaIs in enclosed uyghur children / 中国生化药物杂志

ABSTRACT

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.