Influence of immunization on Porphyromonas gingivalis colonization and invasion in the mouse chamber model

The effects of immunization with invasive or noninvasive Porphyromonas (Bacteroides) gingivalis strains on the pathogenesis of infection in a mouse chamber model were examined. BALB/c mice were immunized by a single injection of heat-killed P. gingivalis invasive strain A7436 or W83 or noninvasive strain 33277, HG405, or 381 directly into subcutaneous chambers. P. gingivalis-specific antibody was detected in chamber fluid 21 days postimmunization, and mice were subsequently challenged by injection of exponential-phase P. gingivalis into chambers. Immunization with A7436 or W83 followed by challenge with A7436 protected mice against secondary abscess formation and death; however, P. gingivalis persisted in chambers for up to 14 days postchallenge. Immunization with noninvasive strain 33277, HG405, or 381 followed by challenge with invasive strain A7436 or W83 protected mice against secondary lesion formation and death. P. gingivalis was cultured from 33277- or HG405-immunized and nonimmunized animals to day 14. All P. gingivalis strains induced an immunoglobulin G response, as measured by an enzyme-linked immunosorbent assay and Western immunoblotting of P. gingivalis whole-cell and outer membrane protein preparations. Western blot analyses indicated that sera from mice immunized with different invasive and noninvasive strains recognized common P. gingivalis antigens. In summary, immunization with invasive P. gingivalis A7436 and W83 or noninvasive P. gingivalis 33277, HG405, and 381 protected mice from secondary lesion formation and death after challenge with invasive P. gingivalis A7436 or W83. P. gingivalis-specific antibody did not, however, inhibit the colonization of P. gingivalis within chambers.