Mechanisms of Vaccine Immunity against Coccidioidomycosis

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ABSTRACT We will exploit a live attenuated ∆cps1 (null) strain of Coccidiodes posadasii to vaccinate against coccidiodomycosis, and elucidate the mechanics by which the lung epithelium coordinates the induction of durable T cell immunity against infection. Host resistance against inhaled pathogens is thought to reside with lung tissue-resident memory (TRM) cells and mucosal immunity, but little is known about whether or how a fungal vaccine creates resident T cell immunity at the lung mucosa. Our preliminary data reveal that mucosal vaccination elicits protective, Coccidioides endoglucanase 2 (C-Eng2) specific CD4+ T cells and that the lung epithelium is required to mobilize myeloid and lymphoid cells in response to the vaccine. This network of stromal and hematopoetic cell responses to vaccination has not been studied and is the subject of this project. To define cellular and molecular mechanisms required to elicit protective immunity at the lung mucosa, we have created innovative tools: i) a novel protective antigen C-Eng2 and peptide:MHCII tetramers to track and enumerate protective CD4+ T cells in C57BL6 in mice; ii) transgenic mice in which epithelial cells and their products are able to be conditionally deleted to dissect their role in generation of immunity; and (iii) a novel system of isolating and culturing human lung epithelium to translate results from mice to humans. We hypothesize that the mucosal delivery of ∆cps1 vaccine spores promotes devel- opment of protective TRM cells and that the lung epithelium coordinates durable protective immunity. We aim to: 1. Probe the intial stages of vaccine recognition and response by innate immune cells in lung. We will test the hypothesis that lung epithelium and their products regulate mobilization of innate immune cells that recognize and restrain growth of ∆cps1 vaccine spores, and also captures them to present their peptides to naïve T cells in the draining lymph nodes. 2. Elucidate intracellular signaling pathway during lung epithelial cell regulation of innate response to ∆cps1 vaccine. We will test the hypothesis that Ca++ and calcineurin dependent signaling events within the lung epithelium contribute to the dectin-1 dependency of host inflammatory responses to Coccidiodes spp. and vaccine in both mice and humans. 3. Define mechanisms of durable T cell immunity elicited by vaccination at the lung mucosa. We will test the hypothesis that lung epithelium shapes the phenotypic, functional and transcriptomic features of protective C-Eng2-specific CD4+ T cells following intransal administration ∆cps1 vaccine spores . Our work will exploit a highly effective vaccine against coccidioidomycosis to elucidate the mechanisms of lung immunity following mucosal administration. Little is known about the mechanisms of vaccine-induced protective immunity at the lung mucosa, and how the lung epithelium regulates the early recognition and restraint of vaccine spores and generation of protective T cells. Vaccination against coccidioidomycosis, an important public health problem, is a major unmet medical need. We anticipate that new insight into the mechanistic underpinnings of vaccine induced mucosal resistance, and the immune correlates of vaccine resistance will advance the development of preventive measures against coccidioidomycosis.