PROJECT SUMMARY/ABSTRACT Clostridium difficile is a highly threatening pathogen that has risen to prominence as a result of antibiotic overuse and misuse. The bacteria are particularly rampant in long-term care and hospital settings, where it is responsible for a significant number of infections. In response to this challenge, researchers are looking into different ways of managing C. difficile infections. One such strategy that holds significant potential is antivirulence vaccination, where the body is trained to recognize and neutralize the “weapons” employed by bacteria to colonize their hosts and proliferate. Despite their promise, these vaccines oftentimes suffer from a lack of efficacy, and their deployment can also be encumbered by the need for parenteral administration. In this exploratory project, our goal is to develop an entirely new biomimetic micromotor vaccine that can be orally administered to effectively protect against C. difficile infection. The platform consists of two key components: (1) a self-propelled magnesium (Mg)-based micromotor and (2) a macrophage membrane coating that detains bacterial virulence factors. When combined together, we hypothesize that these motor toxoids will be capable of delivering C. difficile toxins to the gut’s immune system, where it can elicit potent antibacterial immune responses that protect against subsequent challenge by the pathogen. By leveraging the natural affinity of toxins for cell membranes, this approach can be used to immobilize multiple antigens in a nonreversible manner. The Mg core enables the motor toxoids to propel upon entry into the intestines, and this will promote the active delivery of the antigenic payloads towards the mucosal barrier, enabling better antigen retention and therefore more efficient immune processing and activation. To achieve our goals, we will first develop a motor toxoid formulation loaded with C. difficile toxins and evaluate its characteristics both in vitro and in vivo (Aim 1). Then, in vivo prophylactic efficacy will be evaluated in a murine model of live C. difficile infection (Aim 2). If successful, this approach for the active delivery of oral vaccines can be readily applied to other high-priority pathogens by modulating the membrane coating and bacterial antigens used for synthesis.

PROJECT NARRATIVE The increasing use of antibiotics has led to a rise in the incidence of Clostridium difficile infections, and effective ways of managing this major public health threat are highly sought after. The goal of this proposal is to develop a biomimetic micromotor-based vaccine that is capable of actively delivering bacterial antigens in the gastrointestinal tract to elicit protective immunity. The success of this project will help to establish active propulsion as an important oral vaccine design parameter, which could represent a paradigm-changing concept that can be applied to the development of future vaccines against diseases such as bacteria, viruses, and cancer.