Detection Of Mutation In The Acid-resistant Gene GluA Of The Fluoride-resistant Strain Of Streptococcus Mutans

Streptococcus mutans is a recognized pathogen of caries,In addition to the ability of adhesion and the production of acid, cariogenicity is also closely related with its acid-resistant。acid-resistant is the ability to continue producing acid, and exercise functions in low pH environment, which is considered as an important determinant for cariogenic bacteria to survival in dental biofilm. acid-resistant includes two aspects: the basic acid-resistant and acid-resistant reaction. Streptococcus mutans acid tolerance by a combination of genetic factors, has isolated and cloned a number of genes related with acid resistance of Streptococcus mutans, including acid-resistant gene gluA close attention by scholars.Fluoride is the most widely used for preventing dental carie,whose role on the cariogenic bacteria is one of the important mechanisms fluoride against dental caries. Many studies have shown that fluoride ion-sensitive S. mutans can produce its fluoride-resistant strains after long-term fluoride exposure. Present in normal human oral cavity has been isolated from Streptococcus mutans fluoride-resistant strains, as present study, the cariogenic capacity of Streptococcus mutans fluoride-resistant strains has enhanced, including its ability to produce acid and acid resistance, and its gene type has changed, but the exact location of the gene mutation is unclear.In this experiment, we studied Streptococcus mutans fluoride-resistant strains, the first artificially induced fluoride-resistant strains of Streptococcus mutans in vitro (UA159), with V-gene Bacterial genomic DNA preparation kit a small amount of extract bacterial genome, in accordance with the primer design principles, according to published GenBank sequence of Streptococcus mutans gluA design a pair of PCR primers for PCR, fishing taking the sequence of acid-resistant gene gluA in fluoride-resistant strains of Streptococcus mutans, in the polymerase chain reaction that Streptococcus mutans fluoride-resistant strains genome as a template, specific fragments obtained were the same with the expected results. We cloned the PCR products into pMD18-T vector, and colonies were picked for restriction analysis , containing about 1053bp and 2692bp fragments , the clones were DNA sequenced to connect the results obtained deformation gluA gene sequence in fluoride- resistant strains of Streptococcus.Application BLAST network services measured in the GenBank database for sequence homology comparison, by BLASTN comparison, found that acid fluoride-resistant strains of Streptococcus mutans ffh gene sequence were not same with genes gluA sequence of Streptococcus mutans in GenBank. Note that the gene has not been any mutation, the acid resistant, acid production, adhesion capacity and demineralization may be caused by changes in acid-resistant mutations from the other.For a long time, fluoride is the first choose in the prevention of caries at home and abroad, but the long-term application of fluoride will produce resistant strains, which was not only anti-fluoride, but also cariogenic stronger. Therefore, in recent years, scholars from various countries are committed to finding new and better anti-caries agents, has been trying to use immunological methods to prevent dental caries, hope to prevent oral cariogenic bacteria to host the adhesion and colonization through active immunization or passive immunization, thereby reducing the incidence of dental caries. Immunization against dental caries is an effective means, however, the emergence of DNA vaccine for the caries vaccine develop a new way.DNA vaccine refers to containing the exogenous genes sequence coding some sort of antigen protein (DNA or RNA) as a vaccine vector, directly into animal cells, and through the host cell expression system the compound antigen, induced the immune response of host to the antigen protein, in order to achieve the purpose of prevention and treatment of disease. DNA vaccines as a third generation of new vaccines, their application has broad social significance, in the prevention and treatment of human diseases have a broad application prospects. For the inactivated vaccine and attenuated vaccine, we can not know the exact immune protection epitopes. As recombinant subunit vaccine, the DNA vaccine are both use of a single protein antigen to induce immune responses. First necessary to define DNA encoding specific-antigen with immune activity. Therefore, access to appropriate gene coding antigen and insert it into the vector DNA, is an important part of the genetic vaccine development.In short, research about acid-resistant gene gluA has now become hot spots concerned by scholars home and abroad, the research presents new ideas for caries prevention ,as well as building a suitable anti-caries vaccine antigens for active immunization .