Flagellin-rPAc vaccine inhibits biofilm formation but not proliferation ofS. mutans

Abstract

As the main etiologic bacterium of dental caries, Streptococcus mutans (S. mutans) has been considered as the primary object of vaccine research. We previously constructed a recombinant flagellin-rPAc fusion protein (KF-rPAc) that consists of an alanine-rich region to proline-rich region fragment of PAc (rPAc) from S. mutans and flagellin KF from E.coli K12 strain. Intranasal (i.n) immunization of KF-rPAc could induce high level of rPAc-specific antibody responses and offer robust protection against dental caries. In caries development, biofilm formation was considered as the necessary process involved. As PAc possesses other activities besides affecting adherence of S. mutans to salivary glycoproteins, we wondered whether rPAc-specific antibody responses induced by KF-rPAc could inhibit biofilm formation. Hence, in the present study, a simple and convenient in vitro biofilm model of S. mutans was constructed without saliva pre-coated. Both serum and saliva from KF-rPAc immunized rats significantly inhibited biofilm formation. Moreover, with the presence of serum or saliva, the biofilm formation is negatively correlated with the level of rPAc-specific antibody, and positively correlated with caries scores in rat. Moreover, in immunized mice, the level of rPAc-specific antibody also negatively correlated with the biofilm formation. Unlike ampicillin, serum of KF-rPAc immunized mice only inhibited biofilm formation but not proliferation. All together, we discovered that besides the well known blocking adherence of S. mutans to salivary glycoproteins by rPAc-specific antibody, flagellin-rPAc vaccine could also protects tooth from caries by inhibiting biofilm structure formation in between bacteria.

Antibodies against dextransucrase from Streptococcus mutans display anti-biofilm and growth suppressing activities

“…The present ndings showed that dextransucrase antibody reduced the adherence of S. mutans by 58% as compared to control when grown in presence of 28µg of antibody for 20 hours. These results are similar to the ndings of Huang et al 31 who have reported that S-IgA antibodies reduced signi cantly the adherence of S. mutans in experimental rats. The adherence of S. mutans was also reduced by anti-caries pGJA-P/VAX antibodies as reported by Xu et al 44 .…”

“…Further the uorescence microscopy data also corroborated these ndings of reduction in the bio lm formation in presence of dextransucrase antibody. These observations are in line with the results of antibio lm formation of secretary immunoglobulin A as reported by Huang et al 30 and rPAc-speci c IgG reduced signi cantly bio lm formation in S. mutans challenged rats described by Sun et al 31 Li et al 32 have shown that adherence to tooth surface, bio im formation and growth of S. mutans involves a range of genetic networks which have a signi cant role to interact and coordinate to various environmental signals like surface oxygen, cell density carbon source pH and nutrient availability 33 .…”

Second-generation Flagellin-rPAc Fusion Protein, KFD2-rPAc, Shows High Protective Efficacy against Dental Caries with Low Potential Side Effects

“…3b ). Then, the quality of the specific antibody responses in the serum and the saliva were tested by an in vitro biofilm formation model, which could indicate the inhibitory efficacy of rPAc-specific antibody responses in samples 34 . As shown in Fig.…”

“…Serum and saliva samples were collected on d 70 and analyzed for KF- and rPAc-specific antibody responses by ELISA as described previously 33 . The biofilm formation inhibition assay was carried out to check the quality of rPAc-specific antibody response in the serum and saliva of immunized mice by biofilm assay as previously described 34 .…”

A Nanoparticle-Based Anticaries Vaccine Enhances the Persistent Immune Response To Inhibit Streptococcus mutans and Prevent Caries

“…Recombinant PAc is constructed with the A-region and P-region originating from the PAc protein linked with several amino acids and is utilized more commonly as an immunogen to develop a caries vaccine. This caries vaccine induces specific humoral immunity to inhibit the adherence and colonization of S. mutans on teeth ( 7 ). However, PAc shows low immunogenicity and induces low immune responses that do not maintain adequate protection against dental caries without adjuvants ( 6 , 8 ).…”