Assessment of periodontitis vaccine using three different bacterial outer membrane vesicles in canine model

Bacterial outer-membrane vesicles (OMVs) are attractive for use as novel nanoparticle adjuvants, as well as delivery platforms. Periodontal diseases are the most prevalent oral diseases in humans and have serious health and economic burdens, greatly reducing quality of life. The aim of this study is to investigate the humoral immune responses to an OMV-based periodontal disease vaccine in beagles. The vaccine elicited strong mucosal immune responses when administered to beagles by a four-dose heterologous immunization (IN-IN-IN prime and subcutaneous [SC] boost). The OMV vaccine significantly altered the composition of the microbial community in the oral cavity. These findings suggest the utility of the intranasal (IN) prime followed by the SC boost regimen as a rational option to elicit robust humoral immune responses in canines, and most probably in humans as well. We here discuss the outcomes of beagle experiments, the mechanism behind immunological escape of Pg from host immunity, and a rational perspective toward sterilizing immunity in the oral cavity.