Infection of BALB/c/ByJ mice with P. gingivalis has previously been shown to induce key inflammatory mediators, e.g., interleukin-1 (IL-1), tumor necrosis factor (TNF), and IL-17 (22, –, 24), leading to the resorption of alveolar bone anchoring the teeth, the primary clinical presentation of periodontitis in humans. The gene discussed is IL17A; the disease is infection.