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+ 1384-2514 bp) 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.