Title : Inhibitor activity and resistance mechanism of compound BTD7 against Mycobacterium tuberculosis
Abstract:
Background: Tuberculosis (TB) continues to pose a significant public health challenge as one of the leading causes of infectious diseases from a single infectious pathogen, M. tuberculosis. In light of the stagnant progress in novel tuberculosis drug development over the past five decades, there is an urgent need for innovative therapeutic strategies. This research aimed to characterize the efficacy of the novel compound BTD7 against M. tuberculosis and to elucidate its mechanism of action and associated resistance pathways.
Method: M. tuberculosis was subjected to the isolation of spontaneous mutants with different concentrations of BTD7. After three rounds of evolution, BTD7-resistant mutants were isolated and subjected to WGS. The results were confirmed through PCR and Sanger sequencing.
Results: To identify the target and resistance mechanism of BTD7, the novel compound BTD7 demonstrated excellent in vitro activity against Mycobacterium tuberculosis H37Rv, with a minimum inhibitory concentration (MIC) of 0.0078125µg/mL. This potency is significant, placing it among the most active anti-tubercular agents currently under investigation. Time-kill kinetics studies further revealed that BTD7 is bactericidal, achieving a 99.9% reduction in bacterial load within 7 days of exposure at 4x MIC. Crucially, BTD7 maintained its low MIC against a panel of drug-resistant. Specifically, an A266C point mutation was identified, resulting in a non- synonymous amino acid change from Arginine to Leucine at position 266 (R266L) in the PrrB sensor histidine kinase. BTD7 represents a promising new approach to target the PrrB histidine kinase. Resistance primarily arises from target modification (Arg266Leu mutation) in M. tuberculosis. Its potent activity, novel target, and effectiveness against drug-resistant strains warrant its further development as a potential component of new TB drug regimens.
Keywords: Mycobacterium tuberculosis, BTD7, WGS, spontaneous resistant mutants.
