IL15 and periodontitis: A stereomicroscope observation showed that rats in groups B and C had severe alveolar bone destruction (Fig. 5b, c) compared with group A (Fig. 5a), and the administration of pVAX1-HA2-fimA with or without IL-15 or CpG-ODN 1826 inhibited the destruction of alveolar bone in the maxillary second molars of rats during the establishment of the rat periodontitis models (Fig. 5d–f).