Chamber fluid levels of P. gingivalis expressed in terms of CFU per milliliter. Chamber fluids were collected at 1 (solid bar), 3 (speckled bar), 7 (diagonal hatched bar), and 10 (horizontal hatched bar) days postchallenge from groups of mice that were challenged with P. gingivalis (A7436), P. gingivalis following passive antibody transfer of P. gingivalis-specific IgG (Pg-IgG) or IRR-IgG antibody, or P. gingivalis opsonized with P. gingivalis-specific IgG (OPZ Pg-IgG) or IRR-IgG (OPZ IRR-IgG). *, P < 0.05 compared with matched IRR-immunized groups by the Student t test; ND, P. gingivalis not detected in chamber fluid samples.