[Relationship of the genetic diversity within the V-region, P-region and C-terminus of surface protein of Streptococcus mutans to dental caries].

ABSTRACT

OBJECTIVE: To gain an understanding of the relationship between the genetic diversity within the V-region, P-region, C-terminus of surface protein of Streptococcus mutans (serotype c) and their adherent abilities. METHODS: The clinical isolates of S. mutans (serotype c) in two groups with different adherent abilities (cpm>2000, cpm<1000) had been prepared in our experimental laboratory. The genome DNA was extracted, and the spaP-pv (2060-3157 bp) and spaP-c (4003-4851 bp) were amplified by PCR, respectively. Genetic diversity was assessed by restriction fragment-length polymorphism (RFLP) with restriction endonucleases Alu I. RESULTS: (1) Two different patterns of spaP-pv RFLP among strains were revealed after the amplified product being digested with Alu I. The distributions of two genotypes (a and b) in the clinical strains with different adherent abilities differed significantly (P<0.05). The proportion of genotype b in the strains with higher adherent abilities was higher than that in the strains with lower adherent abilities. (2) Two different patterns (c and d) of spaP-c RFLP among strains were also revealed after the spaP-c being digested with Alu I. No statistically significant difference was observed in the distribution of the two genotypes in the clinical strains. CONCLUSION: The genetic diversity within spaP-pv of clinical isolates of S. mutans might be related to the differences of their adherent abilities.