Intravenous Nanoparticle Vaccination Generates Stem-Like TCF1+ Neoantigen-Specific CD8 T Cells

Purpose: Single cell RNA sequencing technologies have dramatically increased the resolution at which cells can be characterized. The goal of this study was to characterize the expression differences between neoantigen (neoAg) specific CD8 T cells elicited by a TLR7/8 agonist nanoparticle vaccine delivered intravenously (IV) or subcutaneously (SC). Previous flow cytometry experiments had suggested that IV vaccination resulted in more TCF1+ cells as compared to the SC route. Methods: Mice (n=5) were vaccinated twice, with a 2 week interval between vaccinations. Two weeks after the boost, mice were sacrificed and spleens collected, dissociated and stained with hashtag antibodies/flow cytometry antibodies. NeoAg-specific cells were labelled with a tetramer and sorted on a FACS Aria. Cells were processed through the 10X pipeline. Results: We identified 12 clusters within our antigen specific CD8 T cells. The IV route elicited neoAg+ CD8 T cells with a predominantly stem-like gene signature whereas the SC route elicited more effector genes. Single cell RNA sequencing analysis of antigen specific CD8 T cells isolated from mouse spleens two weeks after prime boost vaccination with a synthetic peptide nanoparticle TLR-7/8 agonist vaccine.