IL15 and periodontitis: In this study, we evaluated the specific immune responses and protective efficacy in SD rats given a periodontitis gene vaccine (pVAX1-HA2-fimA) plus CpG-ODN 1826 (30 μg) adjuvant to prevent oral infection by P. gingivalis and also compared the effect of CpG-ODN 1826 with that of the previously used IL-15 adjuvant.