Periodontitis are among the most frequent infectious diseases affecting children and adolescents. The primary etiology of periodontal diseases is the bacterial plaque. Studies have demonstrated the feasibility of inducing immune responses by DNA vaccines against Porphyromonas gingivalis, the major aetiological agent of chronic periodontitis, and the subsequent development of periodontitis in animal models. But until now, the poor immunogenicity, particularly in large animals, is still a major problem in DNA vaccination. Cytotoxic T lymphocyte-associated antigen 4 (CTLA4) is a membrane bound molecule mainly located on activated T cells. Its extracellular V-domain is considered to be involved in mediating the binding to the B7 molecule on antigen-presenting cells (APCs). By utilizing the interaction between CTLA4 and B7, specific antigens can be targeted to APCs by fusion to CTLA4 and DNA vaccines encoding CTLA4 and specific antigens greatly increased the systemic antibody responses following immunization in mice. We hypothesize that targeting antigens to APCs offers a potential strategy to enhance the immune responses generated by DNA vaccines against periodontitis.