Characteristics of systemic antibody responses of nonhuman primates following active immunization with Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis

Periodontal disease is an infectious disease manifested by the progressive change of a healthy resident commensal microbiota to a pathogenic one characterized by a specific microbiota. Thus, the prospect for the use of selected bacteria or their antigens as a vaccine to interfere with the microbial changes and resulting progression of periodontal tissue destruction has been proposed. As a first step in examining the use of bacterial antigens as immunogens in periodontitis. this study characterized the humoral immune response in Macaca fascicularis after systemic immunization with intact Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis. Parenteral immunization of the nonhuman primate with the intact bacteria resulted in the production of specific and significantly elevated levels of antibodies to P. gingivalis and P. intermedia, with the predominant isotype being immunoglobulin G (IgG). In contrast, the principal response to the nonoral, intestinal bacterium, B. fragilis. was of the IgM isotype. Immunization increased IgG, IgM and IgA antibody by 14-227 fold to P. gingivalis and 8-108 fold to P. intermedia. The level of serum IgA antibody increased (77-227 fold). The kinetics of the antibody response post-immunization and post-ligation differed with respect to each of the bacteria tested. IgG antibody to P. gingivalis increased through week 16 of the experiment and remained elevated above baseline through week 32. The IgG antibody level to P. intermedia peaked at 4 weeks following the third immunization and decreased post-ligation to near baseline levels by week 16. Characterization of the immune response after active immunization in the nonhuman primate has demonstrated a substantial and specific increase in antibody response which was sustained for several weeks. The insights obtained from these studies should help optimize the potential for immunologic interference with progressing periodontitis.