ESX-1 remodels the Mycobacterium tuberculosis antigen storage compartment in macrophages

Mycobacterium tuberculosis (Mtb) secretes antigenic proteins that drive protective T cell responses, yet how Mtb intracellular localization affects the trafficking and spatiotemporal distribution of mycobacterial antigens in macrophages remains elusive. Here, we developed a split fluorescent protein reporter to monitor the dynamics of the TB vaccine lead antigen Ag85B in infected human macrophages. We discovered that Mtb triggers the formation and remodeling of two distinct types of Mtb Antigen Storage Compartment (MASC) that retains Ag85 within macrophage membranes. Using subcellular spatial proteomics, we profiled the composition of the MASC, identifying both the Mtb and macrophage proteins that constitute these compartments. Unexpectedly, MASCs are defined by metabolic compartmentalization and rewiring to lipid metabolism in both the macrophage and Mtb. Thus, Mtb builds via the ESX-1 system a metabolically distinct antigen storage compartment in immune cells, with potential implications for antigen selection and delivery in TB vaccine development.