PROJECT SUMMARY Strengthening mucosal immune responses by oral vaccination has the potential to improve the efficacy of current vaccine strategies against HIV by eliciting protective immunity at sites of virus entry in mucosal tissues. The oral mucosa is a promising route for vaccination due to direct access to rich lymphoid tissue, and shared immunological features with the vaginal and rectal mucosae that would predict lymphocyte homing and common effector mechanisms at these mucosal surfaces. However, the development of oral vaccines has been partially hindered by our incomplete understanding of how to elicit vaccine-induced innate immunity in the oral cavity that will lead to robust and long-term mucosal and systemic adaptive immune responses against HIV. In particular, defining the immune correlates of protection related to the oral immunization site (buccal, sublingual, tonsillar ring) and the use of immune-enhancing adjuvants will enhance our understanding of oral immunity and inform development of oral vaccines. Here, we take advantage of an innovative technology for localized vaccine delivery combined with an innovative approach using fractional factorial experimental designs in nonhuman primates to delineate factors that will contribute to HIV-specific immunity from directly immunizing the oral mucosa. We have developed a solid oral dosage form integrating drug-eluting fibers into microneedles that has the capacity to increase vaccine retention time, modulate vaccine delivery kinetics, and localize the vaccine dose to the specific site of oral immunization. We propose to use our integrated fiber and microneedle device (iFMD) as a tool to investigate the effect that adjuvant-induced in situ expansion of antigen presenting cells (APCs) has on maximizing oral innate immunity to DNA vaccines. We hypothesize that expanding immunogenic oral dendritic cells will correlate with robust local and systemic adaptive immune responses. Our specific aims provide a framework that leverages innovative attributes of our iFMD technology with nonhuman primate oral mucosal models and cutting-edge next-generation sequencing tools to identify oral immune correlates of protection. This approach is enabled by a multidisciplinary team with expertise in mucosal vaccine delivery, microneedle device design and fabrication, and relevant nonhuman primate models and immunological tools to analyze oral immunization strategies. The success of this research proposal will expand our knowledge of oral immunity and inform development of strategies to elicit protective immunity against HIV transmission in the oral cavity and at other mucosal surfaces.