Scientific Project 1: Immune Responses to Pre-erythrocytic Malaria Vaccination or Infection Abstract This project will identify and characterize key characteristics of human immune responses to the pre-erythrocytic (PE) falciparum malaria infection and vaccination that targets this stage with a focus on responses that correlate with protection or infection. We hypothesize that responses by protected vs. not protected, and infected subjects will identify the relevant immune constituents and processes. We will use complementary immunological analyses and systems immunology approaches and characterize responses in the innate and adaptive immune compartments to identify cellular and humoral responses that correlate with protection or infection. We will: 1. Define cellular and soluble mediators of early innate responses and test the hypothesis that innate response variations affect adaptive responses and are predictive of protective immunity development. We will also analyze the influence of prior malaria exposure on vaccine efficacy. 2. Define the stimulation and temporal programming of vaccine-elicited protective adaptive immune cells with a focus on the stimulation, signaling, and programming of T and B cells and which pathways lead to protective phenotypes. We hypothesize that key signaling and maturation pathways lead to protective adaptive immunity. Details of antigen receptor usage, cell lineages, transcriptional programming, and phenotypic changes will be integrated with innate signaling events to define events that shepherd cells through recall and maturation during immunization. 3. Connect protective phenotypes with adaptive immune functional activity to identify functional characteristics of cellular and humoral responses that correlate with protection. Antigen specific reactive T cell responses will be analyzed by cytometric, functional, single-cell sequencing, and multi-omics methods. B functions will be analyzed by deep multi-parametric analysis of sera and monoclonal antibodies. This will identify key functional characteristics of cell populations and antibodies that are associated with immune protection. Integration of cell phenotypes and functional activities of multiple immune compartments will give insights into immune signatures and processes that define protective responses to malaria vaccines and provide benchmarks to guide vaccine development. Overall, our integrated immunological and systems biology analyses of samples from malaria vaccine trials will identify immune signatures during critical stages following vaccination which correlate with protection against malaria or result from its infection and advance understanding of factors that impact development of elicited protective immune responses.