Protective efficacy of two new anti-caries DNA vaccines.

As we know, the catalytic region of glucosyltransferases (GTFs) is a key region responsible for sucrose-dependent adherence of cariogenic bacteria to teeth. In this study, we evaluate the potential of the catalytic region to enhance the immunogenicity of the anti-caries DNA vaccine. We construct two new anti-caries DNA plasmids pGJGAC/VAX and pGJGA-5C/VAX by cloning different styles of the catalytic regions of GTFs into the previous plasmid pGJA-P/VAX. One is the 1.1 kb full length catalytic region of S. sobrinus GTF-I, the other is its catalytic core sequence which is conserved in the GTFs from mutans streptococci and plays a central role in the enzymatic activities of sucrose splitting and glucan synthesis. The results of caries protection experiment indicate that compared to pGJA-P/VAX, immunization with both new plasmids provides more effective protection against cariogenic bacteria, especially against S. sobrinus. The plasmid encoding full length catalytic region could provide more effective protection against cariogenic bacteria than that encoding catalytic core conserved sequence even though the differences are not very dramatic.