Porphyromonas gingivalis is implicated in the etiology of chronic periodontitis. Fimbriae are one of several critical surface virulence factors of P. gingivalis. Interleukin 15 (IL-15) is a critical important cytokine for the differentiation of B-1 cells into IgA-inducing cells in mucosal tissues and the proliferation of B cells. The present study constructed a co-expression plasmid pIRES-fimA:IL-15 encoding fimbrinllin (FimA), a subunit of fimbriae and IL-15 as a sIgA-enhancing anti-P. gingivalis FimA vaccine. The plasmid pIRES-fimA:IL-15 was transfected to CHO cells. The expressions of FimA and IL-15 in CHO cells were verified by Western blot and ELISA. Mice were immunized with pIRES-fimA:IL-15 via nasal or intramucusal route. The results showed that nasal immunization was capable of promoting Ag-specific immune responses in the oral region as well as systemic immunity. When immunized via nasal route, IL-15 expressed by the plasmid enhanced FimA-specific sIgA antibody response. In conclusion, a co-expression plasmid pIRES-fimA:IL-15 has been constructed, and when immunized via nasal route, antigen-specific sIgA antibody response could be modulated positively in immunized mice.