New anti-tubercular agents targeting intracellular bacteria

Summary Tuberculosis remains a major global health burden with ~1.6 million deaths in 2021 and a latently-infected population of billions. Mycobacterium tuberculosis, the causative agent, is a sophisticated pathogen which can persist for decades in the human host and which requires lengthy treatment for cure with multiple antibiotics. One of the features of M. tuberculosis is its ability to survive and replicate inside human cells, including macrophages, one of the normal host defense mechanisms against infection. Intracellular bacteria are a specific population which can be hard to kill, in part due to the requirement that molecules enter eukaryotic cells, and in part due to the different physiological state in which the bacteria persist. Increasing evidence points to a higher level of antibiotic tolerance in intracellular bacteria, as well as increased heterogeneity. In order to identify new drugs which can shorten therapy, we focused on the identification of novel anti-tubercular agents which are active against intracellular bacteria. We identified a number of scaffolds which inhibit mycobacterial intracellular replication using a high content screen to monitor bacterial and eukaryotic cell survival simultaneously. From these, we selected high priority series with attractive properties for further evaluation. The overall aims of this proposal are to (i) evaluate a high priority chemical series with intracellular activity, (ii) identify the target and mechanism of action of this novel series and (iii) determine the best companion agents for a new regimen. The major outcome will be a molecule series with a known mechanism of action with in vivo validation ready for lead optimization.