Mechanisms of efficient control of Mycobacterium tuberculosis in the lungs prior to granuloma

PROJECT SUMMARY/ABSTRACT. Novel vaccination strategies are necessary to contain the TB pandemic, as the currently licensed anti-tubercular vaccine, Bacille Calmette-Guerin (BCG), has limited and variable efficacy. Attenuated, live-replicating Mycobacterium tuberculosis (Mtb) express the full complement of protective antigens not present in BCG. As a result, these strains are most likely to induce long-lived immune responses and generate durable protection. Rhesus macaques vaccinated with an isogenic Mtb mutant in the allele encoding the stress-response master regular SigH (DsigH) were protected from TB after infection with a lethal dose of Mtb, and characterized by the presence of inducible bronchus associated lymphoid tissue (iBALT) and robust T cell responses in the lungs. Protection by DsigH could be reversed by the depletion of CD20+ B cells which ablates iBALT. Protection with DsigH was validated in cynomolgus macaques, a second NHP species used as a model for TB vaccination. Preliminary data presented in this proposal indicates that protection elicited by DsigH is based on the generation of very early, potent, innate immune responses in the lung that drive rigorous immune dynamics and interactions. We propose to use cutting-edge techniques that our group has optimized, such as single cell RNA sequencing in airways and lungs, PET/CT scans of whole animals and single cell imaging, to fully understand elite lung responses generated by DsigH compared to Mtb. Our proposed work will not only provide in-depth knowledge of immune responses generated by a potential human intervention for TB, but also identify mechanisms by which Mtb infection can be sterilized prior to the formation of the granuloma.