Grant: Proof of Principle Program - Phase I

Over 1 million people die from malaria each year, mostly young African children. There is an urgent need for a vaccine. We developed a vaccine called PlasProtect that shows great promise in laboratory experiments in mice, and is scheduled for Phase I clinical trials later this year. The approach to this vaccine is to attenuate the parasites encapsulated within red blood cells; the parasites are unable to grow but can stimulate the host immune response. This is a similar approach to attenuated viruses that are used to vaccinate children against other pathogens. However, we face an important challenge in preserving the vaccine for delivery in places like Africa. The efficacy of the vaccine depends on preserving the red blood cell membrane, which requires cryopreservation of the vaccine in liquid nitrogen. This is not feasible in most malaria-endemic regions where there is limited health system capacity and poor access to freezers and electricity. To address this, we developed a way to desiccate the vaccine such that the red cells are preserved upon rehydration. We showed that after rehydrating the desiccated vaccine, the parasites within the red cells are intact, express antigens on the red cell membrane, and stimulate a strong immune response in mice. In this proposal, we will optimize the desiccation process, characterize the properties of the red cells and the parasites, and test the efficacy of the desiccated vaccine under various storage conditions. The goal of this work is to define a methodology to preserve the vaccine for long-term storage that is compatible with vaccine delivery on a global scale.