Dr. Day’s research program is based on characterization of cellular immune responses in pediatric and adult cohorts across a spectrum of TB and HIV infection states. Specific research areas include 1) characterization of frequency, phenotype, and function of antigen-specific T cells and relationship to antigen load and disease status; 2) analysis of mechanisms of immune regulation of antigen-specific T cell responses; 3) analysis of NK cell correlates of protection in M.