Associate Research Professor Northern Arizona University Flagstaff, Arizona, United States
Introduction/Rationale: Coccidioidomycosis (Valley fever (VF)) is frequently misdiagnosed and mistreated as bacterial or viral pneumonia due to similar clinical presentations. Severe VF manifests in < 5% of symptomatic cases and can be life-threatening. T cell responses play a vital role in vaccine-induced protection in mouse models and appear to be critical for resolution of infection in humans. We set out to identify T cell antigens and responses that are generated in pig-tailed macaques (PTM) and humans to aid antigen discovery and model development.
Methods: Peripheral blood mononuclear cells (PBMCs) were collected from both humans and PTM. The PBMCs were non-specifically expanded then stimulated with overlapping pools of Coccidioides-specific peptides from 27 antigens following an antigen multiplexing scheme. Activated T cells were sorted, T cell receptor (TCR) sequenced, and the TCR clonotypes were associated with the stimulating Coccidioides antigens. Specific T cell responses were determined by ELISPOT or single cell sequencing.
Results: Our results have confirmed reactivity of previously known Coccidioides antigens while also identifying new antigens not previously associated with T cell immunogenicity. T cell responses varied between animals and humans, but similar antigens were recognized. Th17 and Th1 immune responses and responding clones were identified by single cells sequencing.
Conclusion: Similar responses were seen in PTM and humans, supporting the PTM model for VF research. Some identified T cell clones recognized antigens that have been associated with a mouse protective DNA vaccination. These antigens and their related clones will be tracked in challenged or vaccinated PTM to aid in the identification of correlates of protection. Finally, the reactive antigens and their epitopes can be further investigated for potential diagnostic tools or vaccines.
