Will include all or some of the following: assess A. phagocytophilum adhesin-receptor interactions and how this promote host cell signaling, effector delivery, cytoskeletal rearrangement, and bacterial entry; analyze exosome protein, nucleotide, and lipid profiles; assess A. phagocytophilum modulation of exosome content and effector function; assess A. phagocytophilum pathogenesis using the mouse model. tsutsugamushi modulates multiple host cell processes including immunity, membrane trafficking, cell cycle, apopotosis, lipid signaling, epigenetic gene regulation, and the ubiquitin-proteasome system; examining how A. phagocytophilum-host cell interactions drive bacterial binding, invasion, fitness, intracellular survival, immunity evasion, parasitism, and egress.