Oral immunization with recombinant Streptococcus gordonii expressing Porphyromonas gingivalis FimA domains

Porphyromonas gingivalis, a gram negative anaerobe, is implicated in the et iology of adult periodontitis. P. gingivalis fimbriae are one of several cr itical surface virulence factors invoiced in both bacterial adherence and i nflammation. P. gingivalis fimbrillin (FimA), the major subunit protein of fimbriae, is considered an important antigen for vaccine development agains t P. gingivalis-associated periodontitis. We hale previously shown that bio logically acth e domains of P, gingivalis fimbrillin call be expressed on t he surface of the human commensal bacterium Streptococcus gordonii. In this study, we examined the effects of oral coimmunization of germfree rats wit h two S. gordonii recombinants expressing N (residues 55 to 145)- and C (re sidues 226 to 337)-terminal epitopes of P. gingivalis FimA to elicit FimA-s pecific immune responses. The effectiveness sf immunization in protecting a gainst alveolar bone loss following P, gingivalis infection was also evalua ted, The results of this study show that the oral delivery of P, gingivalis FimA epitopes ria S, gordonii vectors resulted in the induction of FimA-sp ecific serum (immunoglobulin G [IgG] and IgA) and salivary (IgA) antibody r esponses and that the immune responses were protective against subsequent P . gingivalis-induced alveolar bone loss. These results support the potentia l usefulness of the S, gordonii vectors expressing P. gingivalis fimbrillin as a mucosal vaccine against adult periodontitis.