387 In-vivo Analysis of Bacterial Antigen Delivery Dynamics and T Cell Immunity Against Staphylococcus Aureus Skin Infection

Staphylococcus aureus (S. aureus) is one of the most common causes in both community- and hospital-acquired bacterial infection. To clarify the underlying immune mechanism regulating the expansion of this bacterium is essential for better prevention and treatment of S.aureus infectious diseases. In this study, we generated several model antigen-expressing S.aureus strains to investigate the intravital distribution kinetics and the adaptive T cell responses against them. We demonstrated that S.aureus was delivered to the draining lymph nodes (LNs) by lymphatic flow immediately after the intradermal inoculation and initiated T cell proliferation via activating LN-resident dendritic cells. A significant number of neutrophils were recruited to the draining LNs to engulf bacteria; however, the treatment of neutrophil-depletion antibody did not impact on T cell response in the LNs. Activated T cells circulated into the blood and developed tissue-resident memory T cells in the bacterium-inoculated site. Yet, neither of blood circulating nor tissue-resident memory T cells failed to prevent secondary S.aureus infection. Our study demonstrates the dynamic delivery kinetics of bacterium and dispensable role of T cells during S.aureus skin infection. Further elucidation of regulatory mechanism underlying S.aureus infection is essential for the development of better strategy for the vaccination of this bacterium.