Discovery of D8–03 as an Inhibitor of Intracellular Growth of Francisella tularensis

Francisella tularensis is a Gram-negative facultative intracellular bacterial pathogen that is classified by the Centers for Disease Control and Prevention as a Tier 1 Select Agent. F. tularensis infection causes the disease tularemia, also known as rabbit fever. Treatment of tularemia is limited to few effective antibiotics which are associated with high relapse rates, toxicity, and potential emergence of antibiotic-resistant strains. Consequently, new therapeutic options for tularemia are needed. Through screening a focused chemical library and subsequent structure–activity relationship studies, we have discovered a new and potent inhibitor of intracellular growth of Francisella tularensis, D8–03. Importantly, D8–03 effectively reduces bacterial burden in mice infected with F. tularensis. Preliminary mechanistic investigations suggest that D8–03 works through a potentially novel host-dependent mechanism and serves as a promising lead compound for further development.