Improved immunogenicity of anti-caries DNA vaccine by prime-protein boost strategy

Objectives: To enhance the immunogenicity of anti-caries DNA vaccine, a prime-boost strategy using combinations of plasmid vector (pCIA-P) that express PAc protein and a pure secretec recombinant PAc protein (rPAc) was investigated.

Methods: BALB/c mice were immunized with DNA-DNA, DNA prime-protein boost, or protein-protein regimen by intranasal route. Then a gnotobiotic mouse model was constructed two weeks after the last immunization, and specific immune responses in vivo and their protection against dental caries were observed.

Results: The results show stronger antibody responses in the DNA prime-protein boost group than those elicited by either DNA-DNA vaccination or protein- protein vaccination. In particular, PAc-specific antibody titres were improved significantly after boosting the pCIA-P DNA-primed mice with rPAc. Moreover, protection against the Streptococcus mutans challenge was obtained in the mice treated with the DNA prime–protein boost vaccination, as shown by a significant reduction in Streptococcus mutans colonization when compared with control mice and the animals immunized with the DNA-DNA vaccination or protein-protein vaccination.

Conclusion: This study suggests that DNA prime-protein boost vaccination regimen is a novel strategy for the practical application of DNA vaccine against dental caries.

This study was supported by grant No. 30600707 from the National Science Foundation of China.