CD8A and congenital T-cell immunodeficiency: Taken together, we report a number of novel aspects of O. tsutsugamushi infection in our murine model that closely approximates natural infection: we report for the first time (1) the kinetics of CD8+ T cell activation in lung and spleen by flow cytometry during acute infection, (2) the impact of CD8+ T cell deficiency on bacterial growth control and survival, (3) a prolonged expansion of CD8+ T cells during the latency phase that prevents reactivation of bacterial replication and (4) CD8+ T-cell-dependent liver and lung injury.